// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Overview:
 *   This is the generic MTD driver for NAND flash devices. It should be
 *   capable of working with almost all NAND chips currently available.
 *
 *      Additional technical information is available on
 *      http://www.linux-mtd.infradead.org/doc/nand.html
 *
 *  Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
 *                2002-2006 Thomas Gleixner (tglx@linutronix.de)
 *
 *  Credits:
 *      David Woodhouse for adding multichip support
 *
 *      Aleph One Ltd. and Toby Churchill Ltd. for supporting the
 *      rework for 2K page size chips
 *
 *  TODO:
 *      Enable cached programming for 2k page size chips
 *      Check, if mtd->ecctype should be set to MTD_ECC_HW
 *      if we have HW ECC support.
 *      BBT table is not serialized, has to be fixed
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/mtd/nand_bch.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/mtd/partitions.h>
#include <linux/of.h>
#include <linux/gpio/consumer.h>

#include "internals.h"

/* Define default oob placement schemes for large and small page devices */
static int nand_ooblayout_ecc_sp(struct mtd_info *mtd, int section,
                                 struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct nand_ecc_ctrl *ecc = &chip->ecc;

        if (section > 1)
                return -ERANGE;

        if (!section) {
                oobregion->offset = 0;
                if (mtd->oobsize == 16)
                        oobregion->length = 4;
                else
                        oobregion->length = 3;
        } else {
                if (mtd->oobsize == 8)
                        return -ERANGE;

                oobregion->offset = 6;
                oobregion->length = ecc->total - 4;
        }

        return 0;
}

static int nand_ooblayout_free_sp(struct mtd_info *mtd, int section,
                                  struct mtd_oob_region *oobregion)
{
        if (section > 1)
                return -ERANGE;

        if (mtd->oobsize == 16) {
                if (section)
                        return -ERANGE;

                oobregion->length = 8;
                oobregion->offset = 8;
        } else {
                oobregion->length = 2;
                if (!section)
                        oobregion->offset = 3;
                else
                        oobregion->offset = 6;
        }

        return 0;
}

const struct mtd_ooblayout_ops nand_ooblayout_sp_ops = {
        .ecc = nand_ooblayout_ecc_sp,
        .free = nand_ooblayout_free_sp,
};
EXPORT_SYMBOL_GPL(nand_ooblayout_sp_ops);

static int nand_ooblayout_ecc_lp(struct mtd_info *mtd, int section,
                                 struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct nand_ecc_ctrl *ecc = &chip->ecc;

        if (section || !ecc->total)
                return -ERANGE;

        oobregion->length = ecc->total;
        oobregion->offset = mtd->oobsize - oobregion->length;

        return 0;
}

static int nand_ooblayout_free_lp(struct mtd_info *mtd, int section,
                                  struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct nand_ecc_ctrl *ecc = &chip->ecc;

        if (section)
                return -ERANGE;

        oobregion->length = mtd->oobsize - ecc->total - 2;
        oobregion->offset = 2;

        return 0;
}

const struct mtd_ooblayout_ops nand_ooblayout_lp_ops = {
        .ecc = nand_ooblayout_ecc_lp,
        .free = nand_ooblayout_free_lp,
};
EXPORT_SYMBOL_GPL(nand_ooblayout_lp_ops);

/*
 * Support the old "large page" layout used for 1-bit Hamming ECC where ECC
 * are placed at a fixed offset.
 */
static int nand_ooblayout_ecc_lp_hamming(struct mtd_info *mtd, int section,
                                         struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct nand_ecc_ctrl *ecc = &chip->ecc;

        if (section)
                return -ERANGE;

        switch (mtd->oobsize) {
        case 64:
                oobregion->offset = 40;
                break;
        case 128:
                oobregion->offset = 80;
                break;
        default:
                return -EINVAL;
        }

        oobregion->length = ecc->total;
        if (oobregion->offset + oobregion->length > mtd->oobsize)
                return -ERANGE;

        return 0;
}

static int nand_ooblayout_free_lp_hamming(struct mtd_info *mtd, int section,
                                          struct mtd_oob_region *oobregion)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct nand_ecc_ctrl *ecc = &chip->ecc;
        int ecc_offset = 0;

        if (section < 0 || section > 1)
                return -ERANGE;

        switch (mtd->oobsize) {
        case 64:
                ecc_offset = 40;
                break;
        case 128:
                ecc_offset = 80;
                break;
        default:
                return -EINVAL;
        }

        if (section == 0) {
                oobregion->offset = 2;
                oobregion->length = ecc_offset - 2;
        } else {
                oobregion->offset = ecc_offset + ecc->total;
                oobregion->length = mtd->oobsize - oobregion->offset;
        }

        return 0;
}

static const struct mtd_ooblayout_ops nand_ooblayout_lp_hamming_ops = {
        .ecc = nand_ooblayout_ecc_lp_hamming,
        .free = nand_ooblayout_free_lp_hamming,
};

static int nand_pairing_dist3_get_info(struct mtd_info *mtd, int page,
                                       struct mtd_pairing_info *info)
{
        int lastpage = (mtd->erasesize / mtd->writesize) - 1;
        int dist = 3;

        if (page == lastpage)
                dist = 2;

        if (!page || (page & 1)) {
                info->group = 0;
                info->pair = (page + 1) / 2;
        } else {
                info->group = 1;
                info->pair = (page + 1 - dist) / 2;
        }

        return 0;
}

static int nand_pairing_dist3_get_wunit(struct mtd_info *mtd,
                                        const struct mtd_pairing_info *info)
{
        int lastpair = ((mtd->erasesize / mtd->writesize) - 1) / 2;
        int page = info->pair * 2;
        int dist = 3;

        if (!info->group && !info->pair)
                return 0;

        if (info->pair == lastpair && info->group)
                dist = 2;

        if (!info->group)
                page--;
        else if (info->pair)
                page += dist - 1;

        if (page >= mtd->erasesize / mtd->writesize)
                return -EINVAL;

        return page;
}

const struct mtd_pairing_scheme dist3_pairing_scheme = {
        .ngroups = 2,
        .get_info = nand_pairing_dist3_get_info,
        .get_wunit = nand_pairing_dist3_get_wunit,
};

static int check_offs_len(struct nand_chip *chip, loff_t ofs, uint64_t len)
{
        int ret = 0;

        /* Start address must align on block boundary */
        if (ofs & ((1ULL << chip->phys_erase_shift) - 1)) {
                pr_debug("%s: unaligned address\n", __func__);
                ret = -EINVAL;
        }

        /* Length must align on block boundary */
        if (len & ((1ULL << chip->phys_erase_shift) - 1)) {
                pr_debug("%s: length not block aligned\n", __func__);
                ret = -EINVAL;
        }

        return ret;
}

/**
 * nand_extract_bits - Copy unaligned bits from one buffer to another one
 * @dst: destination buffer
 * @dst_off: bit offset at which the writing starts
 * @src: source buffer
 * @src_off: bit offset at which the reading starts
 * @nbits: number of bits to copy from @src to @dst
 *
 * Copy bits from one memory region to another (overlap authorized).
 */
void nand_extract_bits(u8 *dst, unsigned int dst_off, const u8 *src,
                       unsigned int src_off, unsigned int nbits)
{
        unsigned int tmp, n;

        dst += dst_off / 8;
        dst_off %= 8;
        src += src_off / 8;
        src_off %= 8;

        while (nbits) {
                n = min3(8 - dst_off, 8 - src_off, nbits);

                tmp = (*src >> src_off) & GENMASK(n - 1, 0);
                *dst &= ~GENMASK(n - 1 + dst_off, dst_off);
                *dst |= tmp << dst_off;

                dst_off += n;
                if (dst_off >= 8) {
                        dst++;
                        dst_off -= 8;
                }

                src_off += n;
                if (src_off >= 8) {
                        src++;
                        src_off -= 8;
                }

                nbits -= n;
        }
}
EXPORT_SYMBOL_GPL(nand_extract_bits);

/**
 * nand_select_target() - Select a NAND target (A.K.A. die)
 * @chip: NAND chip object
 * @cs: the CS line to select. Note that this CS id is always from the chip
 *      PoV, not the controller one
 *
 * Select a NAND target so that further operations executed on @chip go to the
 * selected NAND target.
 */
void nand_select_target(struct nand_chip *chip, unsigned int cs)
{
        /*
         * cs should always lie between 0 and nanddev_ntargets(), when that's
         * not the case it's a bug and the caller should be fixed.
         */
        if (WARN_ON(cs > nanddev_ntargets(&chip->base)))
                return;

        chip->cur_cs = cs;

        if (chip->legacy.select_chip)
                chip->legacy.select_chip(chip, cs);
}
EXPORT_SYMBOL_GPL(nand_select_target);

/**
 * nand_deselect_target() - Deselect the currently selected target
 * @chip: NAND chip object
 *
 * Deselect the currently selected NAND target. The result of operations
 * executed on @chip after the target has been deselected is undefined.
 */
void nand_deselect_target(struct nand_chip *chip)
{
        if (chip->legacy.select_chip)
                chip->legacy.select_chip(chip, -1);

        chip->cur_cs = -1;
}
EXPORT_SYMBOL_GPL(nand_deselect_target);

/**
 * nand_release_device - [GENERIC] release chip
 * @chip: NAND chip object
 *
 * Release chip lock and wake up anyone waiting on the device.
 */
static void nand_release_device(struct nand_chip *chip)
{
        /* Release the controller and the chip */
        mutex_unlock(&chip->controller->lock);
        mutex_unlock(&chip->lock);
}

/**
 * nand_bbm_get_next_page - Get the next page for bad block markers
 * @chip: NAND chip object
 * @page: First page to start checking for bad block marker usage
 *
 * Returns an integer that corresponds to the page offset within a block, for
 * a page that is used to store bad block markers. If no more pages are
 * available, -EINVAL is returned.
 */
int nand_bbm_get_next_page(struct nand_chip *chip, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int last_page = ((mtd->erasesize - mtd->writesize) >>
                         chip->page_shift) & chip->pagemask;
        unsigned int bbm_flags = NAND_BBM_FIRSTPAGE | NAND_BBM_SECONDPAGE
                | NAND_BBM_LASTPAGE;

        if (page == 0 && !(chip->options & bbm_flags))
                return 0;
        if (page == 0 && chip->options & NAND_BBM_FIRSTPAGE)
                return 0;
        if (page <= 1 && chip->options & NAND_BBM_SECONDPAGE)
                return 1;
        if (page <= last_page && chip->options & NAND_BBM_LASTPAGE)
                return last_page;

        return -EINVAL;
}

/**
 * nand_block_bad - [DEFAULT] Read bad block marker from the chip
 * @chip: NAND chip object
 * @ofs: offset from device start
 *
 * Check, if the block is bad.
 */
static int nand_block_bad(struct nand_chip *chip, loff_t ofs)
{
        int first_page, page_offset;
        int res;
        u8 bad;

        first_page = (int)(ofs >> chip->page_shift) & chip->pagemask;
        page_offset = nand_bbm_get_next_page(chip, 0);

        while (page_offset >= 0) {
                res = chip->ecc.read_oob(chip, first_page + page_offset);
                if (res < 0)
                        return res;

                bad = chip->oob_poi[chip->badblockpos];

                if (likely(chip->badblockbits == 8))
                        res = bad != 0xFF;
                else
                        res = hweight8(bad) < chip->badblockbits;
                if (res)
                        return res;

                page_offset = nand_bbm_get_next_page(chip, page_offset + 1);
        }

        return 0;
}

static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs)
{
        if (chip->options & NAND_NO_BBM_QUIRK)
                return 0;

        if (chip->legacy.block_bad)
                return chip->legacy.block_bad(chip, ofs);

        return nand_block_bad(chip, ofs);
}

/**
 * nand_get_device - [GENERIC] Get chip for selected access
 * @chip: NAND chip structure
 *
 * Lock the device and its controller for exclusive access
 *
 * Return: -EBUSY if the chip has been suspended, 0 otherwise
 */
static int nand_get_device(struct nand_chip *chip)
{
        mutex_lock(&chip->lock);
        if (chip->suspended) {
                mutex_unlock(&chip->lock);
                return -EBUSY;
        }
        mutex_lock(&chip->controller->lock);

        return 0;
}

/**
 * nand_check_wp - [GENERIC] check if the chip is write protected
 * @chip: NAND chip object
 *
 * Check, if the device is write protected. The function expects, that the
 * device is already selected.
 */
static int nand_check_wp(struct nand_chip *chip)
{
        u8 status;
        int ret;

        /* Broken xD cards report WP despite being writable */
        if (chip->options & NAND_BROKEN_XD)
                return 0;

        /* Check the WP bit */
        ret = nand_status_op(chip, &status);
        if (ret)
                return ret;

        return status & NAND_STATUS_WP ? 0 : 1;
}

/**
 * nand_fill_oob - [INTERN] Transfer client buffer to oob
 * @chip: NAND chip object
 * @oob: oob data buffer
 * @len: oob data write length
 * @ops: oob ops structure
 */
static uint8_t *nand_fill_oob(struct nand_chip *chip, uint8_t *oob, size_t len,
                              struct mtd_oob_ops *ops)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;

        /*
         * Initialise to all 0xFF, to avoid the possibility of left over OOB
         * data from a previous OOB read.
         */
        memset(chip->oob_poi, 0xff, mtd->oobsize);

        switch (ops->mode) {

        case MTD_OPS_PLACE_OOB:
        case MTD_OPS_RAW:
                memcpy(chip->oob_poi + ops->ooboffs, oob, len);
                return oob + len;

        case MTD_OPS_AUTO_OOB:
                ret = mtd_ooblayout_set_databytes(mtd, oob, chip->oob_poi,
                                                  ops->ooboffs, len);
                BUG_ON(ret);
                return oob + len;

        default:
                BUG();
        }
        return NULL;
}

/**
 * nand_do_write_oob - [MTD Interface] NAND write out-of-band
 * @chip: NAND chip object
 * @to: offset to write to
 * @ops: oob operation description structure
 *
 * NAND write out-of-band.
 */
static int nand_do_write_oob(struct nand_chip *chip, loff_t to,
                             struct mtd_oob_ops *ops)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int chipnr, page, status, len, ret;

        pr_debug("%s: to = 0x%08x, len = %i\n",
                         __func__, (unsigned int)to, (int)ops->ooblen);

        len = mtd_oobavail(mtd, ops);

        /* Do not allow write past end of page */
        if ((ops->ooboffs + ops->ooblen) > len) {
                pr_debug("%s: attempt to write past end of page\n",
                                __func__);
                return -EINVAL;
        }

        chipnr = (int)(to >> chip->chip_shift);

        /*
         * Reset the chip. Some chips (like the Toshiba TC5832DC found in one
         * of my DiskOnChip 2000 test units) will clear the whole data page too
         * if we don't do this. I have no clue why, but I seem to have 'fixed'
         * it in the doc2000 driver in August 1999.  dwmw2.
         */
        ret = nand_reset(chip, chipnr);
        if (ret)
                return ret;

        nand_select_target(chip, chipnr);

        /* Shift to get page */
        page = (int)(to >> chip->page_shift);

        /* Check, if it is write protected */
        if (nand_check_wp(chip)) {
                nand_deselect_target(chip);
                return -EROFS;
        }

        /* Invalidate the page cache, if we write to the cached page */
        if (page == chip->pagecache.page)
                chip->pagecache.page = -1;

        nand_fill_oob(chip, ops->oobbuf, ops->ooblen, ops);

        if (ops->mode == MTD_OPS_RAW)
                status = chip->ecc.write_oob_raw(chip, page & chip->pagemask);
        else
                status = chip->ecc.write_oob(chip, page & chip->pagemask);

        nand_deselect_target(chip);

        if (status)
                return status;

        ops->oobretlen = ops->ooblen;

        return 0;
}

/**
 * nand_default_block_markbad - [DEFAULT] mark a block bad via bad block marker
 * @chip: NAND chip object
 * @ofs: offset from device start
 *
 * This is the default implementation, which can be overridden by a hardware
 * specific driver. It provides the details for writing a bad block marker to a
 * block.
 */
static int nand_default_block_markbad(struct nand_chip *chip, loff_t ofs)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        struct mtd_oob_ops ops;
        uint8_t buf[2] = { 0, 0 };
        int ret = 0, res, page_offset;

        memset(&ops, 0, sizeof(ops));
        ops.oobbuf = buf;
        ops.ooboffs = chip->badblockpos;
        if (chip->options & NAND_BUSWIDTH_16) {
                ops.ooboffs &= ~0x01;
                ops.len = ops.ooblen = 2;
        } else {
                ops.len = ops.ooblen = 1;
        }
        ops.mode = MTD_OPS_PLACE_OOB;

        page_offset = nand_bbm_get_next_page(chip, 0);

        while (page_offset >= 0) {
                res = nand_do_write_oob(chip,
                                        ofs + (page_offset * mtd->writesize),
                                        &ops);

                if (!ret)
                        ret = res;

                page_offset = nand_bbm_get_next_page(chip, page_offset + 1);
        }

        return ret;
}

/**
 * nand_markbad_bbm - mark a block by updating the BBM
 * @chip: NAND chip object
 * @ofs: offset of the block to mark bad
 */
int nand_markbad_bbm(struct nand_chip *chip, loff_t ofs)
{
        if (chip->legacy.block_markbad)
                return chip->legacy.block_markbad(chip, ofs);

        return nand_default_block_markbad(chip, ofs);
}

/**
 * nand_block_markbad_lowlevel - mark a block bad
 * @chip: NAND chip object
 * @ofs: offset from device start
 *
 * This function performs the generic NAND bad block marking steps (i.e., bad
 * block table(s) and/or marker(s)). We only allow the hardware driver to
 * specify how to write bad block markers to OOB (chip->legacy.block_markbad).
 *
 * We try operations in the following order:
 *
 *  (1) erase the affected block, to allow OOB marker to be written cleanly
 *  (2) write bad block marker to OOB area of affected block (unless flag
 *      NAND_BBT_NO_OOB_BBM is present)
 *  (3) update the BBT
 *
 * Note that we retain the first error encountered in (2) or (3), finish the
 * procedures, and dump the error in the end.
*/
static int nand_block_markbad_lowlevel(struct nand_chip *chip, loff_t ofs)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int res, ret = 0;

        if (!(chip->bbt_options & NAND_BBT_NO_OOB_BBM)) {
                struct erase_info einfo;

                /* Attempt erase before marking OOB */
                memset(&einfo, 0, sizeof(einfo));
                einfo.addr = ofs;
                einfo.len = 1ULL << chip->phys_erase_shift;
                nand_erase_nand(chip, &einfo, 0);

                /* Write bad block marker to OOB */
                ret = nand_get_device(chip);
                if (ret)
                        return ret;

                ret = nand_markbad_bbm(chip, ofs);
                nand_release_device(chip);
        }

        /* Mark block bad in BBT */
        if (chip->bbt) {
                res = nand_markbad_bbt(chip, ofs);
                if (!ret)
                        ret = res;
        }

        if (!ret)
                mtd->ecc_stats.badblocks++;

        return ret;
}

/**
 * nand_block_isreserved - [GENERIC] Check if a block is marked reserved.
 * @mtd: MTD device structure
 * @ofs: offset from device start
 *
 * Check if the block is marked as reserved.
 */
static int nand_block_isreserved(struct mtd_info *mtd, loff_t ofs)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (!chip->bbt)
                return 0;
        /* Return info from the table */
        return nand_isreserved_bbt(chip, ofs);
}

/**
 * nand_block_checkbad - [GENERIC] Check if a block is marked bad
 * @chip: NAND chip object
 * @ofs: offset from device start
 * @allowbbt: 1, if its allowed to access the bbt area
 *
 * Check, if the block is bad. Either by reading the bad block table or
 * calling of the scan function.
 */
static int nand_block_checkbad(struct nand_chip *chip, loff_t ofs, int allowbbt)
{
        /* Return info from the table */
        if (chip->bbt)
                return nand_isbad_bbt(chip, ofs, allowbbt);

        return nand_isbad_bbm(chip, ofs);
}

/**
 * nand_soft_waitrdy - Poll STATUS reg until RDY bit is set to 1
 * @chip: NAND chip structure
 * @timeout_ms: Timeout in ms
 *
 * Poll the STATUS register using ->exec_op() until the RDY bit becomes 1.
 * If that does not happen whitin the specified timeout, -ETIMEDOUT is
 * returned.
 *
 * This helper is intended to be used when the controller does not have access
 * to the NAND R/B pin.
 *
 * Be aware that calling this helper from an ->exec_op() implementation means
 * ->exec_op() must be re-entrant.
 *
 * Return 0 if the NAND chip is ready, a negative error otherwise.
 */
int nand_soft_waitrdy(struct nand_chip *chip, unsigned long timeout_ms)
{
        const struct nand_sdr_timings *timings;
        u8 status = 0;
        int ret;

        if (!nand_has_exec_op(chip))
                return -ENOTSUPP;

        /* Wait tWB before polling the STATUS reg. */
        timings = nand_get_sdr_timings(nand_get_interface_config(chip));
        ndelay(PSEC_TO_NSEC(timings->tWB_max));

        ret = nand_status_op(chip, NULL);
        if (ret)
                return ret;

        /*
         * +1 below is necessary because if we are now in the last fraction
         * of jiffy and msecs_to_jiffies is 1 then we will wait only that
         * small jiffy fraction - possibly leading to false timeout
         */
        timeout_ms = jiffies + msecs_to_jiffies(timeout_ms) + 1;
        do {
                ret = nand_read_data_op(chip, &status, sizeof(status), true,
                                        false);
                if (ret)
                        break;

                if (status & NAND_STATUS_READY)
                        break;

                /*
                 * Typical lowest execution time for a tR on most NANDs is 10us,
                 * use this as polling delay before doing something smarter (ie.
                 * deriving a delay from the timeout value, timeout_ms/ratio).
                 */
                udelay(10);
        } while (time_before(jiffies, timeout_ms));

        /*
         * We have to exit READ_STATUS mode in order to read real data on the
         * bus in case the WAITRDY instruction is preceding a DATA_IN
         * instruction.
         */
        nand_exit_status_op(chip);

        if (ret)
                return ret;

        return status & NAND_STATUS_READY ? 0 : -ETIMEDOUT;
};
EXPORT_SYMBOL_GPL(nand_soft_waitrdy);

/**
 * nand_gpio_waitrdy - Poll R/B GPIO pin until ready
 * @chip: NAND chip structure
 * @gpiod: GPIO descriptor of R/B pin
 * @timeout_ms: Timeout in ms
 *
 * Poll the R/B GPIO pin until it becomes ready. If that does not happen
 * whitin the specified timeout, -ETIMEDOUT is returned.
 *
 * This helper is intended to be used when the controller has access to the
 * NAND R/B pin over GPIO.
 *
 * Return 0 if the R/B pin indicates chip is ready, a negative error otherwise.
 */
int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod,
                      unsigned long timeout_ms)
{

        /*
         * Wait until R/B pin indicates chip is ready or timeout occurs.
         * +1 below is necessary because if we are now in the last fraction
         * of jiffy and msecs_to_jiffies is 1 then we will wait only that
         * small jiffy fraction - possibly leading to false timeout.
         */
        timeout_ms = jiffies + msecs_to_jiffies(timeout_ms) + 1;
        do {
                if (gpiod_get_value_cansleep(gpiod))
                        return 0;

                cond_resched();
        } while (time_before(jiffies, timeout_ms));

        return gpiod_get_value_cansleep(gpiod) ? 0 : -ETIMEDOUT;
};
EXPORT_SYMBOL_GPL(nand_gpio_waitrdy);

/**
 * panic_nand_wait - [GENERIC] wait until the command is done
 * @chip: NAND chip structure
 * @timeo: timeout
 *
 * Wait for command done. This is a helper function for nand_wait used when
 * we are in interrupt context. May happen when in panic and trying to write
 * an oops through mtdoops.
 */
void panic_nand_wait(struct nand_chip *chip, unsigned long timeo)
{
        int i;
        for (i = 0; i < timeo; i++) {
                if (chip->legacy.dev_ready) {
                        if (chip->legacy.dev_ready(chip))
                                break;
                } else {
                        int ret;
                        u8 status;

                        ret = nand_read_data_op(chip, &status, sizeof(status),
                                                true, false);
                        if (ret)
                                return;

                        if (status & NAND_STATUS_READY)
                                break;
                }
                mdelay(1);
        }
}

static bool nand_supports_get_features(struct nand_chip *chip, int addr)
{
        return (chip->parameters.supports_set_get_features &&
                test_bit(addr, chip->parameters.get_feature_list));
}

static bool nand_supports_set_features(struct nand_chip *chip, int addr)
{
        return (chip->parameters.supports_set_get_features &&
                test_bit(addr, chip->parameters.set_feature_list));
}

/**
 * nand_reset_interface - Reset data interface and timings
 * @chip: The NAND chip
 * @chipnr: Internal die id
 *
 * Reset the Data interface and timings to ONFI mode 0.
 *
 * Returns 0 for success or negative error code otherwise.
 */
static int nand_reset_interface(struct nand_chip *chip, int chipnr)
{
        const struct nand_controller_ops *ops = chip->controller->ops;
        int ret;

        if (!nand_controller_can_setup_interface(chip))
                return 0;

        /*
         * The ONFI specification says:
         * "
         * To transition from NV-DDR or NV-DDR2 to the SDR data
         * interface, the host shall use the Reset (FFh) command
         * using SDR timing mode 0. A device in any timing mode is
         * required to recognize Reset (FFh) command issued in SDR
         * timing mode 0.
         * "
         *
         * Configure the data interface in SDR mode and set the
         * timings to timing mode 0.
         */

        chip->current_interface_config = nand_get_reset_interface_config();
        ret = ops->setup_interface(chip, chipnr,
                                   chip->current_interface_config);
        if (ret)
                pr_err("Failed to configure data interface to SDR timing mode 0\n");

        return ret;
}

/**
 * nand_setup_interface - Setup the best data interface and timings
 * @chip: The NAND chip
 * @chipnr: Internal die id
 *
 * Configure what has been reported to be the best data interface and NAND
 * timings supported by the chip and the driver.
 *
 * Returns 0 for success or negative error code otherwise.
 */
static int nand_setup_interface(struct nand_chip *chip, int chipnr)
{
        const struct nand_controller_ops *ops = chip->controller->ops;
        u8 tmode_param[ONFI_SUBFEATURE_PARAM_LEN] = { };
        int ret;

        if (!nand_controller_can_setup_interface(chip))
                return 0;

        /*
         * A nand_reset_interface() put both the NAND chip and the NAND
         * controller in timings mode 0. If the default mode for this chip is
         * also 0, no need to proceed to the change again. Plus, at probe time,
         * nand_setup_interface() uses ->set/get_features() which would
         * fail anyway as the parameter page is not available yet.
         */
        if (!chip->best_interface_config)
                return 0;

        tmode_param[0] = chip->best_interface_config->timings.mode;

        /* Change the mode on the chip side (if supported by the NAND chip) */
        if (nand_supports_set_features(chip, ONFI_FEATURE_ADDR_TIMING_MODE)) {
                nand_select_target(chip, chipnr);
                ret = nand_set_features(chip, ONFI_FEATURE_ADDR_TIMING_MODE,
                                        tmode_param);
                nand_deselect_target(chip);
                if (ret)
                        return ret;
        }

        /* Change the mode on the controller side */
        ret = ops->setup_interface(chip, chipnr, chip->best_interface_config);
        if (ret)
                return ret;

        /* Check the mode has been accepted by the chip, if supported */
        if (!nand_supports_get_features(chip, ONFI_FEATURE_ADDR_TIMING_MODE))
                goto update_interface_config;

        memset(tmode_param, 0, ONFI_SUBFEATURE_PARAM_LEN);
        nand_select_target(chip, chipnr);
        ret = nand_get_features(chip, ONFI_FEATURE_ADDR_TIMING_MODE,
                                tmode_param);
        nand_deselect_target(chip);
        if (ret)
                goto err_reset_chip;

        if (tmode_param[0] != chip->best_interface_config->timings.mode) {
                pr_warn("timing mode %d not acknowledged by the NAND chip\n",
                        chip->best_interface_config->timings.mode);

                goto err_reset_chip;
        }

update_interface_config:
        chip->current_interface_config = chip->best_interface_config;

        return 0;

err_reset_chip:
        /*
         * Fallback to mode 0 if the chip explicitly did not ack the chosen
         * timing mode.
         */
        nand_reset_interface(chip, chipnr);
        nand_select_target(chip, chipnr);
        nand_reset_op(chip);
        nand_deselect_target(chip);

        return ret;
}

/**
 * nand_choose_best_sdr_timings - Pick up the best SDR timings that both the
 *                                NAND controller and the NAND chip support
 * @chip: the NAND chip
 * @iface: the interface configuration (can eventually be updated)
 * @spec_timings: specific timings, when not fitting the ONFI specification
 *
 * If specific timings are provided, use them. Otherwise, retrieve supported
 * timing modes from ONFI information.
 */
int nand_choose_best_sdr_timings(struct nand_chip *chip,
                                 struct nand_interface_config *iface,
                                 struct nand_sdr_timings *spec_timings)
{
        const struct nand_controller_ops *ops = chip->controller->ops;
        int best_mode = 0, mode, ret;

        iface->type = NAND_SDR_IFACE;

        if (spec_timings) {
                iface->timings.sdr = *spec_timings;
                iface->timings.mode = onfi_find_closest_sdr_mode(spec_timings);

                /* Verify the controller supports the requested interface */
                ret = ops->setup_interface(chip, NAND_DATA_IFACE_CHECK_ONLY,
                                           iface);
                if (!ret) {
                        chip->best_interface_config = iface;
                        return ret;
                }

                /* Fallback to slower modes */
                best_mode = iface->timings.mode;
        } else if (chip->parameters.onfi) {
                best_mode = fls(chip->parameters.onfi->async_timing_mode) - 1;
        }

        for (mode = best_mode; mode >= 0; mode--) {
                onfi_fill_interface_config(chip, iface, NAND_SDR_IFACE, mode);

                ret = ops->setup_interface(chip, NAND_DATA_IFACE_CHECK_ONLY,
                                           iface);
                if (!ret)
                        break;
        }

        chip->best_interface_config = iface;

        return 0;
}

/**
 * nand_choose_interface_config - find the best data interface and timings
 * @chip: The NAND chip
 *
 * Find the best data interface and NAND timings supported by the chip
 * and the driver. Eventually let the NAND manufacturer driver propose his own
 * set of timings.
 *
 * After this function nand_chip->interface_config is initialized with the best
 * timing mode available.
 *
 * Returns 0 for success or negative error code otherwise.
 */
static int nand_choose_interface_config(struct nand_chip *chip)
{
        struct nand_interface_config *iface;
        int ret;

        if (!nand_controller_can_setup_interface(chip))
                return 0;

        iface = kzalloc(sizeof(*iface), GFP_KERNEL);
        if (!iface)
                return -ENOMEM;

        if (chip->ops.choose_interface_config)
                ret = chip->ops.choose_interface_config(chip, iface);
        else
                ret = nand_choose_best_sdr_timings(chip, iface, NULL);

        if (ret)
                kfree(iface);

        return ret;
}

/**
 * nand_fill_column_cycles - fill the column cycles of an address
 * @chip: The NAND chip
 * @addrs: Array of address cycles to fill
 * @offset_in_page: The offset in the page
 *
 * Fills the first or the first two bytes of the @addrs field depending
 * on the NAND bus width and the page size.
 *
 * Returns the number of cycles needed to encode the column, or a negative
 * error code in case one of the arguments is invalid.
 */
static int nand_fill_column_cycles(struct nand_chip *chip, u8 *addrs,
                                   unsigned int offset_in_page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        /* Make sure the offset is less than the actual page size. */
        if (offset_in_page > mtd->writesize + mtd->oobsize)
                return -EINVAL;

        /*
         * On small page NANDs, there's a dedicated command to access the OOB
         * area, and the column address is relative to the start of the OOB
         * area, not the start of the page. Asjust the address accordingly.
         */
        if (mtd->writesize <= 512 && offset_in_page >= mtd->writesize)
                offset_in_page -= mtd->writesize;

        /*
         * The offset in page is expressed in bytes, if the NAND bus is 16-bit
         * wide, then it must be divided by 2.
         */
        if (chip->options & NAND_BUSWIDTH_16) {
                if (WARN_ON(offset_in_page % 2))
                        return -EINVAL;

                offset_in_page /= 2;
        }

        addrs[0] = offset_in_page;

        /*
         * Small page NANDs use 1 cycle for the columns, while large page NANDs
         * need 2
         */
        if (mtd->writesize <= 512)
                return 1;

        addrs[1] = offset_in_page >> 8;

        return 2;
}

static int nand_sp_exec_read_page_op(struct nand_chip *chip, unsigned int page,
                                     unsigned int offset_in_page, void *buf,
                                     unsigned int len)
{
        const struct nand_sdr_timings *sdr =
                nand_get_sdr_timings(nand_get_interface_config(chip));
        struct mtd_info *mtd = nand_to_mtd(chip);
        u8 addrs[4];
        struct nand_op_instr instrs[] = {
                NAND_OP_CMD(NAND_CMD_READ0, 0),
                NAND_OP_ADDR(3, addrs, PSEC_TO_NSEC(sdr->tWB_max)),
                NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tR_max),
                                 PSEC_TO_NSEC(sdr->tRR_min)),
                NAND_OP_DATA_IN(len, buf, 0),
        };
        struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);
        int ret;

        /* Drop the DATA_IN instruction if len is set to 0. */
        if (!len)
                op.ninstrs--;

        if (offset_in_page >= mtd->writesize)
                instrs[0].ctx.cmd.opcode = NAND_CMD_READOOB;
        else if (offset_in_page >= 256 &&
                 !(chip->options & NAND_BUSWIDTH_16))
                instrs[0].ctx.cmd.opcode = NAND_CMD_READ1;

        ret = nand_fill_column_cycles(chip, addrs, offset_in_page);
        if (ret < 0)
                return ret;

        addrs[1] = page;
        addrs[2] = page >> 8;

        if (chip->options & NAND_ROW_ADDR_3) {
                addrs[3] = page >> 16;
                instrs[1].ctx.addr.naddrs++;
        }

        return nand_exec_op(chip, &op);
}

static int nand_lp_exec_read_page_op(struct nand_chip *chip, unsigned int page,
                                     unsigned int offset_in_page, void *buf,
                                     unsigned int len)
{
        const struct nand_sdr_timings *sdr =
                nand_get_sdr_timings(nand_get_interface_config(chip));
        u8 addrs[5];
        struct nand_op_instr instrs[] = {
                NAND_OP_CMD(NAND_CMD_READ0, 0),
                NAND_OP_ADDR(4, addrs, 0),
                NAND_OP_CMD(NAND_CMD_READSTART, PSEC_TO_NSEC(sdr->tWB_max)),
                NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tR_max),
                                 PSEC_TO_NSEC(sdr->tRR_min)),
                NAND_OP_DATA_IN(len, buf, 0),
        };
        struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);
        int ret;

        /* Drop the DATA_IN instruction if len is set to 0. */
        if (!len)
                op.ninstrs--;

        ret = nand_fill_column_cycles(chip, addrs, offset_in_page);
        if (ret < 0)
                return ret;

        addrs[2] = page;
        addrs[3] = page >> 8;

        if (chip->options & NAND_ROW_ADDR_3) {
                addrs[4] = page >> 16;
                instrs[1].ctx.addr.naddrs++;
        }

        return nand_exec_op(chip, &op);
}

/**
 * nand_read_page_op - Do a READ PAGE operation
 * @chip: The NAND chip
 * @page: page to read
 * @offset_in_page: offset within the page
 * @buf: buffer used to store the data
 * @len: length of the buffer
 *
 * This function issues a READ PAGE operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_read_page_op(struct nand_chip *chip, unsigned int page,
                      unsigned int offset_in_page, void *buf, unsigned int len)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        if (len && !buf)
                return -EINVAL;

        if (offset_in_page + len > mtd->writesize + mtd->oobsize)
                return -EINVAL;

        if (nand_has_exec_op(chip)) {
                if (mtd->writesize > 512)
                        return nand_lp_exec_read_page_op(chip, page,
                                                         offset_in_page, buf,
                                                         len);

                return nand_sp_exec_read_page_op(chip, page, offset_in_page,
                                                 buf, len);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_READ0, offset_in_page, page);
        if (len)
                chip->legacy.read_buf(chip, buf, len);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_read_page_op);

/**
 * nand_read_param_page_op - Do a READ PARAMETER PAGE operation
 * @chip: The NAND chip
 * @page: parameter page to read
 * @buf: buffer used to store the data
 * @len: length of the buffer
 *
 * This function issues a READ PARAMETER PAGE operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_read_param_page_op(struct nand_chip *chip, u8 page, void *buf,
                            unsigned int len)
{
        unsigned int i;
        u8 *p = buf;

        if (len && !buf)
                return -EINVAL;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_PARAM, 0),
                        NAND_OP_ADDR(1, &page, PSEC_TO_NSEC(sdr->tWB_max)),
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tR_max),
                                         PSEC_TO_NSEC(sdr->tRR_min)),
                        NAND_OP_8BIT_DATA_IN(len, buf, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                /* Drop the DATA_IN instruction if len is set to 0. */
                if (!len)
                        op.ninstrs--;

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_PARAM, page, -1);
        for (i = 0; i < len; i++)
                p[i] = chip->legacy.read_byte(chip);

        return 0;
}

/**
 * nand_change_read_column_op - Do a CHANGE READ COLUMN operation
 * @chip: The NAND chip
 * @offset_in_page: offset within the page
 * @buf: buffer used to store the data
 * @len: length of the buffer
 * @force_8bit: force 8-bit bus access
 *
 * This function issues a CHANGE READ COLUMN operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_change_read_column_op(struct nand_chip *chip,
                               unsigned int offset_in_page, void *buf,
                               unsigned int len, bool force_8bit)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        if (len && !buf)
                return -EINVAL;

        if (offset_in_page + len > mtd->writesize + mtd->oobsize)
                return -EINVAL;

        /* Small page NANDs do not support column change. */
        if (mtd->writesize <= 512)
                return -ENOTSUPP;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                u8 addrs[2] = {};
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_RNDOUT, 0),
                        NAND_OP_ADDR(2, addrs, 0),
                        NAND_OP_CMD(NAND_CMD_RNDOUTSTART,
                                    PSEC_TO_NSEC(sdr->tCCS_min)),
                        NAND_OP_DATA_IN(len, buf, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);
                int ret;

                ret = nand_fill_column_cycles(chip, addrs, offset_in_page);
                if (ret < 0)
                        return ret;

                /* Drop the DATA_IN instruction if len is set to 0. */
                if (!len)
                        op.ninstrs--;

                instrs[3].ctx.data.force_8bit = force_8bit;

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_RNDOUT, offset_in_page, -1);
        if (len)
                chip->legacy.read_buf(chip, buf, len);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_change_read_column_op);

/**
 * nand_read_oob_op - Do a READ OOB operation
 * @chip: The NAND chip
 * @page: page to read
 * @offset_in_oob: offset within the OOB area
 * @buf: buffer used to store the data
 * @len: length of the buffer
 *
 * This function issues a READ OOB operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_read_oob_op(struct nand_chip *chip, unsigned int page,
                     unsigned int offset_in_oob, void *buf, unsigned int len)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        if (len && !buf)
                return -EINVAL;

        if (offset_in_oob + len > mtd->oobsize)
                return -EINVAL;

        if (nand_has_exec_op(chip))
                return nand_read_page_op(chip, page,
                                         mtd->writesize + offset_in_oob,
                                         buf, len);

        chip->legacy.cmdfunc(chip, NAND_CMD_READOOB, offset_in_oob, page);
        if (len)
                chip->legacy.read_buf(chip, buf, len);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_read_oob_op);

static int nand_exec_prog_page_op(struct nand_chip *chip, unsigned int page,
                                  unsigned int offset_in_page, const void *buf,
                                  unsigned int len, bool prog)
{
        const struct nand_sdr_timings *sdr =
                nand_get_sdr_timings(nand_get_interface_config(chip));
        struct mtd_info *mtd = nand_to_mtd(chip);
        u8 addrs[5] = {};
        struct nand_op_instr instrs[] = {
                /*
                 * The first instruction will be dropped if we're dealing
                 * with a large page NAND and adjusted if we're dealing
                 * with a small page NAND and the page offset is > 255.
                 */
                NAND_OP_CMD(NAND_CMD_READ0, 0),
                NAND_OP_CMD(NAND_CMD_SEQIN, 0),
                NAND_OP_ADDR(0, addrs, PSEC_TO_NSEC(sdr->tADL_min)),
                NAND_OP_DATA_OUT(len, buf, 0),
                NAND_OP_CMD(NAND_CMD_PAGEPROG, PSEC_TO_NSEC(sdr->tWB_max)),
                NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tPROG_max), 0),
        };
        struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);
        int naddrs = nand_fill_column_cycles(chip, addrs, offset_in_page);
        int ret;
        u8 status;

        if (naddrs < 0)
                return naddrs;

        addrs[naddrs++] = page;
        addrs[naddrs++] = page >> 8;
        if (chip->options & NAND_ROW_ADDR_3)
                addrs[naddrs++] = page >> 16;

        instrs[2].ctx.addr.naddrs = naddrs;

        /* Drop the last two instructions if we're not programming the page. */
        if (!prog) {
                op.ninstrs -= 2;
                /* Also drop the DATA_OUT instruction if empty. */
                if (!len)
                        op.ninstrs--;
        }

        if (mtd->writesize <= 512) {
                /*
                 * Small pages need some more tweaking: we have to adjust the
                 * first instruction depending on the page offset we're trying
                 * to access.
                 */
                if (offset_in_page >= mtd->writesize)
                        instrs[0].ctx.cmd.opcode = NAND_CMD_READOOB;
                else if (offset_in_page >= 256 &&
                         !(chip->options & NAND_BUSWIDTH_16))
                        instrs[0].ctx.cmd.opcode = NAND_CMD_READ1;
        } else {
                /*
                 * Drop the first command if we're dealing with a large page
                 * NAND.
                 */
                op.instrs++;
                op.ninstrs--;
        }

        ret = nand_exec_op(chip, &op);
        if (!prog || ret)
                return ret;

        ret = nand_status_op(chip, &status);
        if (ret)
                return ret;

        return status;
}

/**
 * nand_prog_page_begin_op - starts a PROG PAGE operation
 * @chip: The NAND chip
 * @page: page to write
 * @offset_in_page: offset within the page
 * @buf: buffer containing the data to write to the page
 * @len: length of the buffer
 *
 * This function issues the first half of a PROG PAGE operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_prog_page_begin_op(struct nand_chip *chip, unsigned int page,
                            unsigned int offset_in_page, const void *buf,
                            unsigned int len)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        if (len && !buf)
                return -EINVAL;

        if (offset_in_page + len > mtd->writesize + mtd->oobsize)
                return -EINVAL;

        if (nand_has_exec_op(chip))
                return nand_exec_prog_page_op(chip, page, offset_in_page, buf,
                                              len, false);

        chip->legacy.cmdfunc(chip, NAND_CMD_SEQIN, offset_in_page, page);

        if (buf)
                chip->legacy.write_buf(chip, buf, len);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_prog_page_begin_op);

/**
 * nand_prog_page_end_op - ends a PROG PAGE operation
 * @chip: The NAND chip
 *
 * This function issues the second half of a PROG PAGE operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_prog_page_end_op(struct nand_chip *chip)
{
        int ret;
        u8 status;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_PAGEPROG,
                                    PSEC_TO_NSEC(sdr->tWB_max)),
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tPROG_max), 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                ret = nand_exec_op(chip, &op);
                if (ret)
                        return ret;

                ret = nand_status_op(chip, &status);
                if (ret)
                        return ret;
        } else {
                chip->legacy.cmdfunc(chip, NAND_CMD_PAGEPROG, -1, -1);
                ret = chip->legacy.waitfunc(chip);
                if (ret < 0)
                        return ret;

                status = ret;
        }

        if (status & NAND_STATUS_FAIL)
                return -EIO;

        return 0;
}
EXPORT_SYMBOL_GPL(nand_prog_page_end_op);

/**
 * nand_prog_page_op - Do a full PROG PAGE operation
 * @chip: The NAND chip
 * @page: page to write
 * @offset_in_page: offset within the page
 * @buf: buffer containing the data to write to the page
 * @len: length of the buffer
 *
 * This function issues a full PROG PAGE operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_prog_page_op(struct nand_chip *chip, unsigned int page,
                      unsigned int offset_in_page, const void *buf,
                      unsigned int len)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int status;

        if (!len || !buf)
                return -EINVAL;

        if (offset_in_page + len > mtd->writesize + mtd->oobsize)
                return -EINVAL;

        if (nand_has_exec_op(chip)) {
                status = nand_exec_prog_page_op(chip, page, offset_in_page, buf,
                                                len, true);
        } else {
                chip->legacy.cmdfunc(chip, NAND_CMD_SEQIN, offset_in_page,
                                     page);
                chip->legacy.write_buf(chip, buf, len);
                chip->legacy.cmdfunc(chip, NAND_CMD_PAGEPROG, -1, -1);
                status = chip->legacy.waitfunc(chip);
        }

        if (status & NAND_STATUS_FAIL)
                return -EIO;

        return 0;
}
EXPORT_SYMBOL_GPL(nand_prog_page_op);

/**
 * nand_change_write_column_op - Do a CHANGE WRITE COLUMN operation
 * @chip: The NAND chip
 * @offset_in_page: offset within the page
 * @buf: buffer containing the data to send to the NAND
 * @len: length of the buffer
 * @force_8bit: force 8-bit bus access
 *
 * This function issues a CHANGE WRITE COLUMN operation.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_change_write_column_op(struct nand_chip *chip,
                                unsigned int offset_in_page,
                                const void *buf, unsigned int len,
                                bool force_8bit)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        if (len && !buf)
                return -EINVAL;

        if (offset_in_page + len > mtd->writesize + mtd->oobsize)
                return -EINVAL;

        /* Small page NANDs do not support column change. */
        if (mtd->writesize <= 512)
                return -ENOTSUPP;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                u8 addrs[2];
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_RNDIN, 0),
                        NAND_OP_ADDR(2, addrs, PSEC_TO_NSEC(sdr->tCCS_min)),
                        NAND_OP_DATA_OUT(len, buf, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);
                int ret;

                ret = nand_fill_column_cycles(chip, addrs, offset_in_page);
                if (ret < 0)
                        return ret;

                instrs[2].ctx.data.force_8bit = force_8bit;

                /* Drop the DATA_OUT instruction if len is set to 0. */
                if (!len)
                        op.ninstrs--;

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_RNDIN, offset_in_page, -1);
        if (len)
                chip->legacy.write_buf(chip, buf, len);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_change_write_column_op);

/**
 * nand_readid_op - Do a READID operation
 * @chip: The NAND chip
 * @addr: address cycle to pass after the READID command
 * @buf: buffer used to store the ID
 * @len: length of the buffer
 *
 * This function sends a READID command and reads back the ID returned by the
 * NAND.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_readid_op(struct nand_chip *chip, u8 addr, void *buf,
                   unsigned int len)
{
        unsigned int i;
        u8 *id = buf;

        if (len && !buf)
                return -EINVAL;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_READID, 0),
                        NAND_OP_ADDR(1, &addr, PSEC_TO_NSEC(sdr->tADL_min)),
                        NAND_OP_8BIT_DATA_IN(len, buf, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                /* Drop the DATA_IN instruction if len is set to 0. */
                if (!len)
                        op.ninstrs--;

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_READID, addr, -1);

        for (i = 0; i < len; i++)
                id[i] = chip->legacy.read_byte(chip);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_readid_op);

/**
 * nand_status_op - Do a STATUS operation
 * @chip: The NAND chip
 * @status: out variable to store the NAND status
 *
 * This function sends a STATUS command and reads back the status returned by
 * the NAND.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_status_op(struct nand_chip *chip, u8 *status)
{
        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_STATUS,
                                    PSEC_TO_NSEC(sdr->tADL_min)),
                        NAND_OP_8BIT_DATA_IN(1, status, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                if (!status)
                        op.ninstrs--;

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_STATUS, -1, -1);
        if (status)
                *status = chip->legacy.read_byte(chip);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_status_op);

/**
 * nand_exit_status_op - Exit a STATUS operation
 * @chip: The NAND chip
 *
 * This function sends a READ0 command to cancel the effect of the STATUS
 * command to avoid reading only the status until a new read command is sent.
 *
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_exit_status_op(struct nand_chip *chip)
{
        if (nand_has_exec_op(chip)) {
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_READ0, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_READ0, -1, -1);

        return 0;
}

/**
 * nand_erase_op - Do an erase operation
 * @chip: The NAND chip
 * @eraseblock: block to erase
 *
 * This function sends an ERASE command and waits for the NAND to be ready
 * before returning.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_erase_op(struct nand_chip *chip, unsigned int eraseblock)
{
        unsigned int page = eraseblock <<
                            (chip->phys_erase_shift - chip->page_shift);
        int ret;
        u8 status;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                u8 addrs[3] = { page, page >> 8, page >> 16 };
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_ERASE1, 0),
                        NAND_OP_ADDR(2, addrs, 0),
                        NAND_OP_CMD(NAND_CMD_ERASE2,
                                    PSEC_TO_MSEC(sdr->tWB_max)),
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tBERS_max), 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                if (chip->options & NAND_ROW_ADDR_3)
                        instrs[1].ctx.addr.naddrs++;

                ret = nand_exec_op(chip, &op);
                if (ret)
                        return ret;

                ret = nand_status_op(chip, &status);
                if (ret)
                        return ret;
        } else {
                chip->legacy.cmdfunc(chip, NAND_CMD_ERASE1, -1, page);
                chip->legacy.cmdfunc(chip, NAND_CMD_ERASE2, -1, -1);

                ret = chip->legacy.waitfunc(chip);
                if (ret < 0)
                        return ret;

                status = ret;
        }

        if (status & NAND_STATUS_FAIL)
                return -EIO;

        return 0;
}
EXPORT_SYMBOL_GPL(nand_erase_op);

/**
 * nand_set_features_op - Do a SET FEATURES operation
 * @chip: The NAND chip
 * @feature: feature id
 * @data: 4 bytes of data
 *
 * This function sends a SET FEATURES command and waits for the NAND to be
 * ready before returning.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
static int nand_set_features_op(struct nand_chip *chip, u8 feature,
                                const void *data)
{
        const u8 *params = data;
        int i, ret;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_SET_FEATURES, 0),
                        NAND_OP_ADDR(1, &feature, PSEC_TO_NSEC(sdr->tADL_min)),
                        NAND_OP_8BIT_DATA_OUT(ONFI_SUBFEATURE_PARAM_LEN, data,
                                              PSEC_TO_NSEC(sdr->tWB_max)),
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tFEAT_max), 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_SET_FEATURES, feature, -1);
        for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
                chip->legacy.write_byte(chip, params[i]);

        ret = chip->legacy.waitfunc(chip);
        if (ret < 0)
                return ret;

        if (ret & NAND_STATUS_FAIL)
                return -EIO;

        return 0;
}

/**
 * nand_get_features_op - Do a GET FEATURES operation
 * @chip: The NAND chip
 * @feature: feature id
 * @data: 4 bytes of data
 *
 * This function sends a GET FEATURES command and waits for the NAND to be
 * ready before returning.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
static int nand_get_features_op(struct nand_chip *chip, u8 feature,
                                void *data)
{
        u8 *params = data;
        int i;

        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_GET_FEATURES, 0),
                        NAND_OP_ADDR(1, &feature, PSEC_TO_NSEC(sdr->tWB_max)),
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tFEAT_max),
                                         PSEC_TO_NSEC(sdr->tRR_min)),
                        NAND_OP_8BIT_DATA_IN(ONFI_SUBFEATURE_PARAM_LEN,
                                             data, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_GET_FEATURES, feature, -1);
        for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
                params[i] = chip->legacy.read_byte(chip);

        return 0;
}

static int nand_wait_rdy_op(struct nand_chip *chip, unsigned int timeout_ms,
                            unsigned int delay_ns)
{
        if (nand_has_exec_op(chip)) {
                struct nand_op_instr instrs[] = {
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(timeout_ms),
                                         PSEC_TO_NSEC(delay_ns)),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                return nand_exec_op(chip, &op);
        }

        /* Apply delay or wait for ready/busy pin */
        if (!chip->legacy.dev_ready)
                udelay(chip->legacy.chip_delay);
        else
                nand_wait_ready(chip);

        return 0;
}

/**
 * nand_reset_op - Do a reset operation
 * @chip: The NAND chip
 *
 * This function sends a RESET command and waits for the NAND to be ready
 * before returning.
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_reset_op(struct nand_chip *chip)
{
        if (nand_has_exec_op(chip)) {
                const struct nand_sdr_timings *sdr =
                        nand_get_sdr_timings(nand_get_interface_config(chip));
                struct nand_op_instr instrs[] = {
                        NAND_OP_CMD(NAND_CMD_RESET, PSEC_TO_NSEC(sdr->tWB_max)),
                        NAND_OP_WAIT_RDY(PSEC_TO_MSEC(sdr->tRST_max), 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                return nand_exec_op(chip, &op);
        }

        chip->legacy.cmdfunc(chip, NAND_CMD_RESET, -1, -1);

        return 0;
}
EXPORT_SYMBOL_GPL(nand_reset_op);

/**
 * nand_read_data_op - Read data from the NAND
 * @chip: The NAND chip
 * @buf: buffer used to store the data
 * @len: length of the buffer
 * @force_8bit: force 8-bit bus access
 * @check_only: do not actually run the command, only checks if the
 *              controller driver supports it
 *
 * This function does a raw data read on the bus. Usually used after launching
 * another NAND operation like nand_read_page_op().
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_read_data_op(struct nand_chip *chip, void *buf, unsigned int len,
                      bool force_8bit, bool check_only)
{
        if (!len || !buf)
                return -EINVAL;

        if (nand_has_exec_op(chip)) {
                struct nand_op_instr instrs[] = {
                        NAND_OP_DATA_IN(len, buf, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                instrs[0].ctx.data.force_8bit = force_8bit;

                if (check_only)
                        return nand_check_op(chip, &op);

                return nand_exec_op(chip, &op);
        }

        if (check_only)
                return 0;

        if (force_8bit) {
                u8 *p = buf;
                unsigned int i;

                for (i = 0; i < len; i++)
                        p[i] = chip->legacy.read_byte(chip);
        } else {
                chip->legacy.read_buf(chip, buf, len);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(nand_read_data_op);

/**
 * nand_write_data_op - Write data from the NAND
 * @chip: The NAND chip
 * @buf: buffer containing the data to send on the bus
 * @len: length of the buffer
 * @force_8bit: force 8-bit bus access
 *
 * This function does a raw data write on the bus. Usually used after launching
 * another NAND operation like nand_write_page_begin_op().
 * This function does not select/unselect the CS line.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_write_data_op(struct nand_chip *chip, const void *buf,
                       unsigned int len, bool force_8bit)
{
        if (!len || !buf)
                return -EINVAL;

        if (nand_has_exec_op(chip)) {
                struct nand_op_instr instrs[] = {
                        NAND_OP_DATA_OUT(len, buf, 0),
                };
                struct nand_operation op = NAND_OPERATION(chip->cur_cs, instrs);

                instrs[0].ctx.data.force_8bit = force_8bit;

                return nand_exec_op(chip, &op);
        }

        if (force_8bit) {
                const u8 *p = buf;
                unsigned int i;

                for (i = 0; i < len; i++)
                        chip->legacy.write_byte(chip, p[i]);
        } else {
                chip->legacy.write_buf(chip, buf, len);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(nand_write_data_op);

/**
 * struct nand_op_parser_ctx - Context used by the parser
 * @instrs: array of all the instructions that must be addressed
 * @ninstrs: length of the @instrs array
 * @subop: Sub-operation to be passed to the NAND controller
 *
 * This structure is used by the core to split NAND operations into
 * sub-operations that can be handled by the NAND controller.
 */
struct nand_op_parser_ctx {
        const struct nand_op_instr *instrs;
        unsigned int ninstrs;
        struct nand_subop subop;
};

/**
 * nand_op_parser_must_split_instr - Checks if an instruction must be split
 * @pat: the parser pattern element that matches @instr
 * @instr: pointer to the instruction to check
 * @start_offset: this is an in/out parameter. If @instr has already been
 *                split, then @start_offset is the offset from which to start
 *                (either an address cycle or an offset in the data buffer).
 *                Conversely, if the function returns true (ie. instr must be
 *                split), this parameter is updated to point to the first
 *                data/address cycle that has not been taken care of.
 *
 * Some NAND controllers are limited and cannot send X address cycles with a
 * unique operation, or cannot read/write more than Y bytes at the same time.
 * In this case, split the instruction that does not fit in a single
 * controller-operation into two or more chunks.
 *
 * Returns true if the instruction must be split, false otherwise.
 * The @start_offset parameter is also updated to the offset at which the next
 * bundle of instruction must start (if an address or a data instruction).
 */
static bool
nand_op_parser_must_split_instr(const struct nand_op_parser_pattern_elem *pat,
                                const struct nand_op_instr *instr,
                                unsigned int *start_offset)
{
        switch (pat->type) {
        case NAND_OP_ADDR_INSTR:
                if (!pat->ctx.addr.maxcycles)
                        break;

                if (instr->ctx.addr.naddrs - *start_offset >
                    pat->ctx.addr.maxcycles) {
                        *start_offset += pat->ctx.addr.maxcycles;
                        return true;
                }
                break;

        case NAND_OP_DATA_IN_INSTR:
        case NAND_OP_DATA_OUT_INSTR:
                if (!pat->ctx.data.maxlen)
                        break;

                if (instr->ctx.data.len - *start_offset >
                    pat->ctx.data.maxlen) {
                        *start_offset += pat->ctx.data.maxlen;
                        return true;
                }
                break;

        default:
                break;
        }

        return false;
}

/**
 * nand_op_parser_match_pat - Checks if a pattern matches the instructions
 *                            remaining in the parser context
 * @pat: the pattern to test
 * @ctx: the parser context structure to match with the pattern @pat
 *
 * Check if @pat matches the set or a sub-set of instructions remaining in @ctx.
 * Returns true if this is the case, false ortherwise. When true is returned,
 * @ctx->subop is updated with the set of instructions to be passed to the
 * controller driver.
 */
static bool
nand_op_parser_match_pat(const struct nand_op_parser_pattern *pat,
                         struct nand_op_parser_ctx *ctx)
{
        unsigned int instr_offset = ctx->subop.first_instr_start_off;
        const struct nand_op_instr *end = ctx->instrs + ctx->ninstrs;
        const struct nand_op_instr *instr = ctx->subop.instrs;
        unsigned int i, ninstrs;

        for (i = 0, ninstrs = 0; i < pat->nelems && instr < end; i++) {
                /*
                 * The pattern instruction does not match the operation
                 * instruction. If the instruction is marked optional in the
                 * pattern definition, we skip the pattern element and continue
                 * to the next one. If the element is mandatory, there's no
                 * match and we can return false directly.
                 */
                if (instr->type != pat->elems[i].type) {
                        if (!pat->elems[i].optional)
                                return false;

                        continue;
                }

                /*
                 * Now check the pattern element constraints. If the pattern is
                 * not able to handle the whole instruction in a single step,
                 * we have to split it.
                 * The last_instr_end_off value comes back updated to point to
                 * the position where we have to split the instruction (the
                 * start of the next subop chunk).
                 */
                if (nand_op_parser_must_split_instr(&pat->elems[i], instr,
                                                    &instr_offset)) {
                        ninstrs++;
                        i++;
                        break;
                }

                instr++;
                ninstrs++;
                instr_offset = 0;
        }

        /*
         * This can happen if all instructions of a pattern are optional.
         * Still, if there's not at least one instruction handled by this
         * pattern, this is not a match, and we should try the next one (if
         * any).
         */
        if (!ninstrs)
                return false;

        /*
         * We had a match on the pattern head, but the pattern may be longer
         * than the instructions we're asked to execute. We need to make sure
         * there's no mandatory elements in the pattern tail.
         */
        for (; i < pat->nelems; i++) {
                if (!pat->elems[i].optional)
                        return false;
        }

        /*
         * We have a match: update the subop structure accordingly and return
         * true.
         */
        ctx->subop.ninstrs = ninstrs;
        ctx->subop.last_instr_end_off = instr_offset;

        return true;
}

#if IS_ENABLED(CONFIG_DYNAMIC_DEBUG) || defined(DEBUG)
static void nand_op_parser_trace(const struct nand_op_parser_ctx *ctx)
{
        const struct nand_op_instr *instr;
        char *prefix = "      ";
        unsigned int i;

        pr_debug("executing subop (CS%d):\n", ctx->subop.cs);

        for (i = 0; i < ctx->ninstrs; i++) {
                instr = &ctx->instrs[i];

                if (instr == &ctx->subop.instrs[0])
                        prefix = "    ->";

                nand_op_trace(prefix, instr);

                if (instr == &ctx->subop.instrs[ctx->subop.ninstrs - 1])
                        prefix = "      ";
        }
}
#else
static void nand_op_parser_trace(const struct nand_op_parser_ctx *ctx)
{
        /* NOP */
}
#endif

static int nand_op_parser_cmp_ctx(const struct nand_op_parser_ctx *a,
                                  const struct nand_op_parser_ctx *b)
{
        if (a->subop.ninstrs < b->subop.ninstrs)
                return -1;
        else if (a->subop.ninstrs > b->subop.ninstrs)
                return 1;

        if (a->subop.last_instr_end_off < b->subop.last_instr_end_off)
                return -1;
        else if (a->subop.last_instr_end_off > b->subop.last_instr_end_off)
                return 1;

        return 0;
}

/**
 * nand_op_parser_exec_op - exec_op parser
 * @chip: the NAND chip
 * @parser: patterns description provided by the controller driver
 * @op: the NAND operation to address
 * @check_only: when true, the function only checks if @op can be handled but
 *              does not execute the operation
 *
 * Helper function designed to ease integration of NAND controller drivers that
 * only support a limited set of instruction sequences. The supported sequences
 * are described in @parser, and the framework takes care of splitting @op into
 * multiple sub-operations (if required) and pass them back to the ->exec()
 * callback of the matching pattern if @check_only is set to false.
 *
 * NAND controller drivers should call this function from their own ->exec_op()
 * implementation.
 *
 * Returns 0 on success, a negative error code otherwise. A failure can be
 * caused by an unsupported operation (none of the supported patterns is able
 * to handle the requested operation), or an error returned by one of the
 * matching pattern->exec() hook.
 */
int nand_op_parser_exec_op(struct nand_chip *chip,
                           const struct nand_op_parser *parser,
                           const struct nand_operation *op, bool check_only)
{
        struct nand_op_parser_ctx ctx = {
                .subop.cs = op->cs,
                .subop.instrs = op->instrs,
                .instrs = op->instrs,
                .ninstrs = op->ninstrs,
        };
        unsigned int i;

        while (ctx.subop.instrs < op->instrs + op->ninstrs) {
                const struct nand_op_parser_pattern *pattern;
                struct nand_op_parser_ctx best_ctx;
                int ret, best_pattern = -1;

                for (i = 0; i < parser->npatterns; i++) {
                        struct nand_op_parser_ctx test_ctx = ctx;

                        pattern = &parser->patterns[i];
                        if (!nand_op_parser_match_pat(pattern, &test_ctx))
                                continue;

                        if (best_pattern >= 0 &&
                            nand_op_parser_cmp_ctx(&test_ctx, &best_ctx) <= 0)
                                continue;

                        best_pattern = i;
                        best_ctx = test_ctx;
                }

                if (best_pattern < 0) {
                        pr_debug("->exec_op() parser: pattern not found!\n");
                        return -ENOTSUPP;
                }

                ctx = best_ctx;
                nand_op_parser_trace(&ctx);

                if (!check_only) {
                        pattern = &parser->patterns[best_pattern];
                        ret = pattern->exec(chip, &ctx.subop);
                        if (ret)
                                return ret;
                }

                /*
                 * Update the context structure by pointing to the start of the
                 * next subop.
                 */
                ctx.subop.instrs = ctx.subop.instrs + ctx.subop.ninstrs;
                if (ctx.subop.last_instr_end_off)
                        ctx.subop.instrs -= 1;

                ctx.subop.first_instr_start_off = ctx.subop.last_instr_end_off;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(nand_op_parser_exec_op);

static bool nand_instr_is_data(const struct nand_op_instr *instr)
{
        return instr && (instr->type == NAND_OP_DATA_IN_INSTR ||
                         instr->type == NAND_OP_DATA_OUT_INSTR);
}

static bool nand_subop_instr_is_valid(const struct nand_subop *subop,
                                      unsigned int instr_idx)
{
        return subop && instr_idx < subop->ninstrs;
}

static unsigned int nand_subop_get_start_off(const struct nand_subop *subop,
                                             unsigned int instr_idx)
{
        if (instr_idx)
                return 0;

        return subop->first_instr_start_off;
}

/**
 * nand_subop_get_addr_start_off - Get the start offset in an address array
 * @subop: The entire sub-operation
 * @instr_idx: Index of the instruction inside the sub-operation
 *
 * During driver development, one could be tempted to directly use the
 * ->addr.addrs field of address instructions. This is wrong as address
 * instructions might be split.
 *
 * Given an address instruction, returns the offset of the first cycle to issue.
 */
unsigned int nand_subop_get_addr_start_off(const struct nand_subop *subop,
                                           unsigned int instr_idx)
{
        if (WARN_ON(!nand_subop_instr_is_valid(subop, instr_idx) ||
                    subop->instrs[instr_idx].type != NAND_OP_ADDR_INSTR))
                return 0;

        return nand_subop_get_start_off(subop, instr_idx);
}
EXPORT_SYMBOL_GPL(nand_subop_get_addr_start_off);

/**
 * nand_subop_get_num_addr_cyc - Get the remaining address cycles to assert
 * @subop: The entire sub-operation
 * @instr_idx: Index of the instruction inside the sub-operation
 *
 * During driver development, one could be tempted to directly use the
 * ->addr->naddrs field of a data instruction. This is wrong as instructions
 * might be split.
 *
 * Given an address instruction, returns the number of address cycle to issue.
 */
unsigned int nand_subop_get_num_addr_cyc(const struct nand_subop *subop,
                                         unsigned int instr_idx)
{
        int start_off, end_off;

        if (WARN_ON(!nand_subop_instr_is_valid(subop, instr_idx) ||
                    subop->instrs[instr_idx].type != NAND_OP_ADDR_INSTR))
                return 0;

        start_off = nand_subop_get_addr_start_off(subop, instr_idx);

        if (instr_idx == subop->ninstrs - 1 &&
            subop->last_instr_end_off)
                end_off = subop->last_instr_end_off;
        else
                end_off = subop->instrs[instr_idx].ctx.addr.naddrs;

        return end_off - start_off;
}
EXPORT_SYMBOL_GPL(nand_subop_get_num_addr_cyc);

/**
 * nand_subop_get_data_start_off - Get the start offset in a data array
 * @subop: The entire sub-operation
 * @instr_idx: Index of the instruction inside the sub-operation
 *
 * During driver development, one could be tempted to directly use the
 * ->data->buf.{in,out} field of data instructions. This is wrong as data
 * instructions might be split.
 *
 * Given a data instruction, returns the offset to start from.
 */
unsigned int nand_subop_get_data_start_off(const struct nand_subop *subop,
                                           unsigned int instr_idx)
{
        if (WARN_ON(!nand_subop_instr_is_valid(subop, instr_idx) ||
                    !nand_instr_is_data(&subop->instrs[instr_idx])))
                return 0;

        return nand_subop_get_start_off(subop, instr_idx);
}
EXPORT_SYMBOL_GPL(nand_subop_get_data_start_off);

/**
 * nand_subop_get_data_len - Get the number of bytes to retrieve
 * @subop: The entire sub-operation
 * @instr_idx: Index of the instruction inside the sub-operation
 *
 * During driver development, one could be tempted to directly use the
 * ->data->len field of a data instruction. This is wrong as data instructions
 * might be split.
 *
 * Returns the length of the chunk of data to send/receive.
 */
unsigned int nand_subop_get_data_len(const struct nand_subop *subop,
                                     unsigned int instr_idx)
{
        int start_off = 0, end_off;

        if (WARN_ON(!nand_subop_instr_is_valid(subop, instr_idx) ||
                    !nand_instr_is_data(&subop->instrs[instr_idx])))
                return 0;

        start_off = nand_subop_get_data_start_off(subop, instr_idx);

        if (instr_idx == subop->ninstrs - 1 &&
            subop->last_instr_end_off)
                end_off = subop->last_instr_end_off;
        else
                end_off = subop->instrs[instr_idx].ctx.data.len;

        return end_off - start_off;
}
EXPORT_SYMBOL_GPL(nand_subop_get_data_len);

/**
 * nand_reset - Reset and initialize a NAND device
 * @chip: The NAND chip
 * @chipnr: Internal die id
 *
 * Save the timings data structure, then apply SDR timings mode 0 (see
 * nand_reset_interface for details), do the reset operation, and apply
 * back the previous timings.
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int nand_reset(struct nand_chip *chip, int chipnr)
{
        int ret;

        ret = nand_reset_interface(chip, chipnr);
        if (ret)
                return ret;

        /*
         * The CS line has to be released before we can apply the new NAND
         * interface settings, hence this weird nand_select_target()
         * nand_deselect_target() dance.
         */
        nand_select_target(chip, chipnr);
        ret = nand_reset_op(chip);
        nand_deselect_target(chip);
        if (ret)
                return ret;

        ret = nand_setup_interface(chip, chipnr);
        if (ret)
                return ret;

        return 0;
}
EXPORT_SYMBOL_GPL(nand_reset);

/**
 * nand_get_features - wrapper to perform a GET_FEATURE
 * @chip: NAND chip info structure
 * @addr: feature address
 * @subfeature_param: the subfeature parameters, a four bytes array
 *
 * Returns 0 for success, a negative error otherwise. Returns -ENOTSUPP if the
 * operation cannot be handled.
 */
int nand_get_features(struct nand_chip *chip, int addr,
                      u8 *subfeature_param)
{
        if (!nand_supports_get_features(chip, addr))
                return -ENOTSUPP;

        if (chip->legacy.get_features)
                return chip->legacy.get_features(chip, addr, subfeature_param);

        return nand_get_features_op(chip, addr, subfeature_param);
}

/**
 * nand_set_features - wrapper to perform a SET_FEATURE
 * @chip: NAND chip info structure
 * @addr: feature address
 * @subfeature_param: the subfeature parameters, a four bytes array
 *
 * Returns 0 for success, a negative error otherwise. Returns -ENOTSUPP if the
 * operation cannot be handled.
 */
int nand_set_features(struct nand_chip *chip, int addr,
                      u8 *subfeature_param)
{
        if (!nand_supports_set_features(chip, addr))
                return -ENOTSUPP;

        if (chip->legacy.set_features)
                return chip->legacy.set_features(chip, addr, subfeature_param);

        return nand_set_features_op(chip, addr, subfeature_param);
}

/**
 * nand_check_erased_buf - check if a buffer contains (almost) only 0xff data
 * @buf: buffer to test
 * @len: buffer length
 * @bitflips_threshold: maximum number of bitflips
 *
 * Check if a buffer contains only 0xff, which means the underlying region
 * has been erased and is ready to be programmed.
 * The bitflips_threshold specify the maximum number of bitflips before
 * considering the region is not erased.
 * Note: The logic of this function has been extracted from the memweight
 * implementation, except that nand_check_erased_buf function exit before
 * testing the whole buffer if the number of bitflips exceed the
 * bitflips_threshold value.
 *
 * Returns a positive number of bitflips less than or equal to
 * bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
 * threshold.
 */
static int nand_check_erased_buf(void *buf, int len, int bitflips_threshold)
{
        const unsigned char *bitmap = buf;
        int bitflips = 0;
        int weight;

        for (; len && ((uintptr_t)bitmap) % sizeof(long);
             len--, bitmap++) {
                weight = hweight8(*bitmap);
                bitflips += BITS_PER_BYTE - weight;
                if (unlikely(bitflips > bitflips_threshold))
                        return -EBADMSG;
        }

        for (; len >= sizeof(long);
             len -= sizeof(long), bitmap += sizeof(long)) {
                unsigned long d = *((unsigned long *)bitmap);
                if (d == ~0UL)
                        continue;
                weight = hweight_long(d);
                bitflips += BITS_PER_LONG - weight;
                if (unlikely(bitflips > bitflips_threshold))
                        return -EBADMSG;
        }

        for (; len > 0; len--, bitmap++) {
                weight = hweight8(*bitmap);
                bitflips += BITS_PER_BYTE - weight;
                if (unlikely(bitflips > bitflips_threshold))
                        return -EBADMSG;
        }

        return bitflips;
}

/**
 * nand_check_erased_ecc_chunk - check if an ECC chunk contains (almost) only
 *                               0xff data
 * @data: data buffer to test
 * @datalen: data length
 * @ecc: ECC buffer
 * @ecclen: ECC length
 * @extraoob: extra OOB buffer
 * @extraooblen: extra OOB length
 * @bitflips_threshold: maximum number of bitflips
 *
 * Check if a data buffer and its associated ECC and OOB data contains only
 * 0xff pattern, which means the underlying region has been erased and is
 * ready to be programmed.
 * The bitflips_threshold specify the maximum number of bitflips before
 * considering the region as not erased.
 *
 * Note:
 * 1/ ECC algorithms are working on pre-defined block sizes which are usually
 *    different from the NAND page size. When fixing bitflips, ECC engines will
 *    report the number of errors per chunk, and the NAND core infrastructure
 *    expect you to return the maximum number of bitflips for the whole page.
 *    This is why you should always use this function on a single chunk and
 *    not on the whole page. After checking each chunk you should update your
 *    max_bitflips value accordingly.
 * 2/ When checking for bitflips in erased pages you should not only check
 *    the payload data but also their associated ECC data, because a user might
 *    have programmed almost all bits to 1 but a few. In this case, we
 *    shouldn't consider the chunk as erased, and checking ECC bytes prevent
 *    this case.
 * 3/ The extraoob argument is optional, and should be used if some of your OOB
 *    data are protected by the ECC engine.
 *    It could also be used if you support subpages and want to attach some
 *    extra OOB data to an ECC chunk.
 *
 * Returns a positive number of bitflips less than or equal to
 * bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
 * threshold. In case of success, the passed buffers are filled with 0xff.
 */
int nand_check_erased_ecc_chunk(void *data, int datalen,
                                void *ecc, int ecclen,
                                void *extraoob, int extraooblen,
                                int bitflips_threshold)
{
        int data_bitflips = 0, ecc_bitflips = 0, extraoob_bitflips = 0;

        data_bitflips = nand_check_erased_buf(data, datalen,
                                              bitflips_threshold);
        if (data_bitflips < 0)
                return data_bitflips;

        bitflips_threshold -= data_bitflips;

        ecc_bitflips = nand_check_erased_buf(ecc, ecclen, bitflips_threshold);
        if (ecc_bitflips < 0)
                return ecc_bitflips;

        bitflips_threshold -= ecc_bitflips;

        extraoob_bitflips = nand_check_erased_buf(extraoob, extraooblen,
                                                  bitflips_threshold);
        if (extraoob_bitflips < 0)
                return extraoob_bitflips;

        if (data_bitflips)
                memset(data, 0xff, datalen);

        if (ecc_bitflips)
                memset(ecc, 0xff, ecclen);

        if (extraoob_bitflips)
                memset(extraoob, 0xff, extraooblen);

        return data_bitflips + ecc_bitflips + extraoob_bitflips;
}
EXPORT_SYMBOL(nand_check_erased_ecc_chunk);

/**
 * nand_read_page_raw_notsupp - dummy read raw page function
 * @chip: nand chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 *
 * Returns -ENOTSUPP unconditionally.
 */
int nand_read_page_raw_notsupp(struct nand_chip *chip, u8 *buf,
                               int oob_required, int page)
{
        return -ENOTSUPP;
}

/**
 * nand_read_page_raw - [INTERN] read raw page data without ecc
 * @chip: nand chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 *
 * Not for syndrome calculating ECC controllers, which use a special oob layout.
 */
int nand_read_page_raw(struct nand_chip *chip, uint8_t *buf, int oob_required,
                       int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;

        ret = nand_read_page_op(chip, page, 0, buf, mtd->writesize);
        if (ret)
                return ret;

        if (oob_required) {
                ret = nand_read_data_op(chip, chip->oob_poi, mtd->oobsize,
                                        false, false);
                if (ret)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL(nand_read_page_raw);

/**
 * nand_monolithic_read_page_raw - Monolithic page read in raw mode
 * @chip: NAND chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 *
 * This is a raw page read, ie. without any error detection/correction.
 * Monolithic means we are requesting all the relevant data (main plus
 * eventually OOB) to be loaded in the NAND cache and sent over the
 * bus (from the NAND chip to the NAND controller) in a single
 * operation. This is an alternative to nand_read_page_raw(), which
 * first reads the main data, and if the OOB data is requested too,
 * then reads more data on the bus.
 */
int nand_monolithic_read_page_raw(struct nand_chip *chip, u8 *buf,
                                  int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        unsigned int size = mtd->writesize;
        u8 *read_buf = buf;
        int ret;

        if (oob_required) {
                size += mtd->oobsize;

                if (buf != chip->data_buf)
                        read_buf = nand_get_data_buf(chip);
        }

        ret = nand_read_page_op(chip, page, 0, read_buf, size);
        if (ret)
                return ret;

        if (buf != chip->data_buf)
                memcpy(buf, read_buf, mtd->writesize);

        return 0;
}
EXPORT_SYMBOL(nand_monolithic_read_page_raw);

/**
 * nand_read_page_raw_syndrome - [INTERN] read raw page data without ecc
 * @chip: nand chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 *
 * We need a special oob layout and handling even when OOB isn't used.
 */
static int nand_read_page_raw_syndrome(struct nand_chip *chip, uint8_t *buf,
                                       int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int eccsize = chip->ecc.size;
        int eccbytes = chip->ecc.bytes;
        uint8_t *oob = chip->oob_poi;
        int steps, size, ret;

        ret = nand_read_page_op(chip, page, 0, NULL, 0);
        if (ret)
                return ret;

        for (steps = chip->ecc.steps; steps > 0; steps--) {
                ret = nand_read_data_op(chip, buf, eccsize, false, false);
                if (ret)
                        return ret;

                buf += eccsize;

                if (chip->ecc.prepad) {
                        ret = nand_read_data_op(chip, oob, chip->ecc.prepad,
                                                false, false);
                        if (ret)
                                return ret;

                        oob += chip->ecc.prepad;
                }

                ret = nand_read_data_op(chip, oob, eccbytes, false, false);
                if (ret)
                        return ret;

                oob += eccbytes;

                if (chip->ecc.postpad) {
                        ret = nand_read_data_op(chip, oob, chip->ecc.postpad,
                                                false, false);
                        if (ret)
                                return ret;

                        oob += chip->ecc.postpad;
                }
        }

        size = mtd->oobsize - (oob - chip->oob_poi);
        if (size) {
                ret = nand_read_data_op(chip, oob, size, false, false);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * nand_read_page_swecc - [REPLACEABLE] software ECC based page read function
 * @chip: nand chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 */
static int nand_read_page_swecc(struct nand_chip *chip, uint8_t *buf,
                                int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int i, eccsize = chip->ecc.size, ret;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        uint8_t *p = buf;
        uint8_t *ecc_calc = chip->ecc.calc_buf;
        uint8_t *ecc_code = chip->ecc.code_buf;
        unsigned int max_bitflips = 0;

        chip->ecc.read_page_raw(chip, buf, 1, page);

        for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize)
                chip->ecc.calculate(chip, p, &ecc_calc[i]);

        ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
                                         chip->ecc.total);
        if (ret)
                return ret;

        eccsteps = chip->ecc.steps;
        p = buf;

        for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
                int stat;

                stat = chip->ecc.correct(chip, p, &ecc_code[i], &ecc_calc[i]);
                if (stat < 0) {
                        mtd->ecc_stats.failed++;
                } else {
                        mtd->ecc_stats.corrected += stat;
                        max_bitflips = max_t(unsigned int, max_bitflips, stat);
                }
        }
        return max_bitflips;
}

/**
 * nand_read_subpage - [REPLACEABLE] ECC based sub-page read function
 * @chip: nand chip info structure
 * @data_offs: offset of requested data within the page
 * @readlen: data length
 * @bufpoi: buffer to store read data
 * @page: page number to read
 */
static int nand_read_subpage(struct nand_chip *chip, uint32_t data_offs,
                             uint32_t readlen, uint8_t *bufpoi, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int start_step, end_step, num_steps, ret;
        uint8_t *p;
        int data_col_addr, i, gaps = 0;
        int datafrag_len, eccfrag_len, aligned_len, aligned_pos;
        int busw = (chip->options & NAND_BUSWIDTH_16) ? 2 : 1;
        int index, section = 0;
        unsigned int max_bitflips = 0;
        struct mtd_oob_region oobregion = { };

        /* Column address within the page aligned to ECC size (256bytes) */
        start_step = data_offs / chip->ecc.size;
        end_step = (data_offs + readlen - 1) / chip->ecc.size;
        num_steps = end_step - start_step + 1;
        index = start_step * chip->ecc.bytes;

        /* Data size aligned to ECC ecc.size */
        datafrag_len = num_steps * chip->ecc.size;
        eccfrag_len = num_steps * chip->ecc.bytes;

        data_col_addr = start_step * chip->ecc.size;
        /* If we read not a page aligned data */
        p = bufpoi + data_col_addr;
        ret = nand_read_page_op(chip, page, data_col_addr, p, datafrag_len);
        if (ret)
                return ret;

        /* Calculate ECC */
        for (i = 0; i < eccfrag_len ; i += chip->ecc.bytes, p += chip->ecc.size)
                chip->ecc.calculate(chip, p, &chip->ecc.calc_buf[i]);

        /*
         * The performance is faster if we position offsets according to
         * ecc.pos. Let's make sure that there are no gaps in ECC positions.
         */
        ret = mtd_ooblayout_find_eccregion(mtd, index, &section, &oobregion);
        if (ret)
                return ret;

        if (oobregion.length < eccfrag_len)
                gaps = 1;

        if (gaps) {
                ret = nand_change_read_column_op(chip, mtd->writesize,
                                                 chip->oob_poi, mtd->oobsize,
                                                 false);
                if (ret)
                        return ret;
        } else {
                /*
                 * Send the command to read the particular ECC bytes take care
                 * about buswidth alignment in read_buf.
                 */
                aligned_pos = oobregion.offset & ~(busw - 1);
                aligned_len = eccfrag_len;
                if (oobregion.offset & (busw - 1))
                        aligned_len++;
                if ((oobregion.offset + (num_steps * chip->ecc.bytes)) &
                    (busw - 1))
                        aligned_len++;

                ret = nand_change_read_column_op(chip,
                                                 mtd->writesize + aligned_pos,
                                                 &chip->oob_poi[aligned_pos],

                                                 aligned_len, false);
                if (ret)
                        return ret;
        }

        ret = mtd_ooblayout_get_eccbytes(mtd, chip->ecc.code_buf,
                                         chip->oob_poi, index, eccfrag_len);
        if (ret)
                return ret;

        p = bufpoi + data_col_addr;
        for (i = 0; i < eccfrag_len ; i += chip->ecc.bytes, p += chip->ecc.size) {
                int stat;

                stat = chip->ecc.correct(chip, p, &chip->ecc.code_buf[i],
                                         &chip->ecc.calc_buf[i]);
                if (stat == -EBADMSG &&
                    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
                        /* check for empty pages with bitflips */
                        stat = nand_check_erased_ecc_chunk(p, chip->ecc.size,
                                                &chip->ecc.code_buf[i],
                                                chip->ecc.bytes,
                                                NULL, 0,
                                                chip->ecc.strength);
                }

                if (stat < 0) {
                        mtd->ecc_stats.failed++;
                } else {
                        mtd->ecc_stats.corrected += stat;
                        max_bitflips = max_t(unsigned int, max_bitflips, stat);
                }
        }
        return max_bitflips;
}

/**
 * nand_read_page_hwecc - [REPLACEABLE] hardware ECC based page read function
 * @chip: nand chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 *
 * Not for syndrome calculating ECC controllers which need a special oob layout.
 */
static int nand_read_page_hwecc(struct nand_chip *chip, uint8_t *buf,
                                int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int i, eccsize = chip->ecc.size, ret;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        uint8_t *p = buf;
        uint8_t *ecc_calc = chip->ecc.calc_buf;
        uint8_t *ecc_code = chip->ecc.code_buf;
        unsigned int max_bitflips = 0;

        ret = nand_read_page_op(chip, page, 0, NULL, 0);
        if (ret)
                return ret;

        for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
                chip->ecc.hwctl(chip, NAND_ECC_READ);

                ret = nand_read_data_op(chip, p, eccsize, false, false);
                if (ret)
                        return ret;

                chip->ecc.calculate(chip, p, &ecc_calc[i]);
        }

        ret = nand_read_data_op(chip, chip->oob_poi, mtd->oobsize, false,
                                false);
        if (ret)
                return ret;

        ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
                                         chip->ecc.total);
        if (ret)
                return ret;

        eccsteps = chip->ecc.steps;
        p = buf;

        for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
                int stat;

                stat = chip->ecc.correct(chip, p, &ecc_code[i], &ecc_calc[i]);
                if (stat == -EBADMSG &&
                    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
                        /* check for empty pages with bitflips */
                        stat = nand_check_erased_ecc_chunk(p, eccsize,
                                                &ecc_code[i], eccbytes,
                                                NULL, 0,
                                                chip->ecc.strength);
                }

                if (stat < 0) {
                        mtd->ecc_stats.failed++;
                } else {
                        mtd->ecc_stats.corrected += stat;
                        max_bitflips = max_t(unsigned int, max_bitflips, stat);
                }
        }
        return max_bitflips;
}

/**
 * nand_read_page_syndrome - [REPLACEABLE] hardware ECC syndrome based page read
 * @chip: nand chip info structure
 * @buf: buffer to store read data
 * @oob_required: caller requires OOB data read to chip->oob_poi
 * @page: page number to read
 *
 * The hw generator calculates the error syndrome automatically. Therefore we
 * need a special oob layout and handling.
 */
static int nand_read_page_syndrome(struct nand_chip *chip, uint8_t *buf,
                                   int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret, i, eccsize = chip->ecc.size;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        int eccpadbytes = eccbytes + chip->ecc.prepad + chip->ecc.postpad;
        uint8_t *p = buf;
        uint8_t *oob = chip->oob_poi;
        unsigned int max_bitflips = 0;

        ret = nand_read_page_op(chip, page, 0, NULL, 0);
        if (ret)
                return ret;

        for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
                int stat;

                chip->ecc.hwctl(chip, NAND_ECC_READ);

                ret = nand_read_data_op(chip, p, eccsize, false, false);
                if (ret)
                        return ret;

                if (chip->ecc.prepad) {
                        ret = nand_read_data_op(chip, oob, chip->ecc.prepad,
                                                false, false);
                        if (ret)
                                return ret;

                        oob += chip->ecc.prepad;
                }

                chip->ecc.hwctl(chip, NAND_ECC_READSYN);

                ret = nand_read_data_op(chip, oob, eccbytes, false, false);
                if (ret)
                        return ret;

                stat = chip->ecc.correct(chip, p, oob, NULL);

                oob += eccbytes;

                if (chip->ecc.postpad) {
                        ret = nand_read_data_op(chip, oob, chip->ecc.postpad,
                                                false, false);
                        if (ret)
                                return ret;

                        oob += chip->ecc.postpad;
                }

                if (stat == -EBADMSG &&
                    (chip->ecc.options & NAND_ECC_GENERIC_ERASED_CHECK)) {
                        /* check for empty pages with bitflips */
                        stat = nand_check_erased_ecc_chunk(p, chip->ecc.size,
                                                           oob - eccpadbytes,
                                                           eccpadbytes,
                                                           NULL, 0,
                                                           chip->ecc.strength);
                }

                if (stat < 0) {
                        mtd->ecc_stats.failed++;
                } else {
                        mtd->ecc_stats.corrected += stat;
                        max_bitflips = max_t(unsigned int, max_bitflips, stat);
                }
        }

        /* Calculate remaining oob bytes */
        i = mtd->oobsize - (oob - chip->oob_poi);
        if (i) {
                ret = nand_read_data_op(chip, oob, i, false, false);
                if (ret)
                        return ret;
        }

        return max_bitflips;
}

/**
 * nand_transfer_oob - [INTERN] Transfer oob to client buffer
 * @chip: NAND chip object
 * @oob: oob destination address
 * @ops: oob ops structure
 * @len: size of oob to transfer
 */
static uint8_t *nand_transfer_oob(struct nand_chip *chip, uint8_t *oob,
                                  struct mtd_oob_ops *ops, size_t len)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;

        switch (ops->mode) {

        case MTD_OPS_PLACE_OOB:
        case MTD_OPS_RAW:
                memcpy(oob, chip->oob_poi + ops->ooboffs, len);
                return oob + len;

        case MTD_OPS_AUTO_OOB:
                ret = mtd_ooblayout_get_databytes(mtd, oob, chip->oob_poi,
                                                  ops->ooboffs, len);
                BUG_ON(ret);
                return oob + len;

        default:
                BUG();
        }
        return NULL;
}

/**
 * nand_setup_read_retry - [INTERN] Set the READ RETRY mode
 * @chip: NAND chip object
 * @retry_mode: the retry mode to use
 *
 * Some vendors supply a special command to shift the Vt threshold, to be used
 * when there are too many bitflips in a page (i.e., ECC error). After setting
 * a new threshold, the host should retry reading the page.
 */
static int nand_setup_read_retry(struct nand_chip *chip, int retry_mode)
{
        pr_debug("setting READ RETRY mode %d\n", retry_mode);

        if (retry_mode >= chip->read_retries)
                return -EINVAL;

        if (!chip->ops.setup_read_retry)
                return -EOPNOTSUPP;

        return chip->ops.setup_read_retry(chip, retry_mode);
}

static void nand_wait_readrdy(struct nand_chip *chip)
{
        const struct nand_sdr_timings *sdr;

        if (!(chip->options & NAND_NEED_READRDY))
                return;

        sdr = nand_get_sdr_timings(nand_get_interface_config(chip));
        WARN_ON(nand_wait_rdy_op(chip, PSEC_TO_MSEC(sdr->tR_max), 0));
}

/**
 * nand_do_read_ops - [INTERN] Read data with ECC
 * @chip: NAND chip object
 * @from: offset to read from
 * @ops: oob ops structure
 *
 * Internal function. Called with chip held.
 */
static int nand_do_read_ops(struct nand_chip *chip, loff_t from,
                            struct mtd_oob_ops *ops)
{
        int chipnr, page, realpage, col, bytes, aligned, oob_required;
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret = 0;
        uint32_t readlen = ops->len;
        uint32_t oobreadlen = ops->ooblen;
        uint32_t max_oobsize = mtd_oobavail(mtd, ops);

        uint8_t *bufpoi, *oob, *buf;
        int use_bounce_buf;
        unsigned int max_bitflips = 0;
        int retry_mode = 0;
        bool ecc_fail = false;

        chipnr = (int)(from >> chip->chip_shift);
        nand_select_target(chip, chipnr);

        realpage = (int)(from >> chip->page_shift);
        page = realpage & chip->pagemask;

        col = (int)(from & (mtd->writesize - 1));

        buf = ops->datbuf;
        oob = ops->oobbuf;
        oob_required = oob ? 1 : 0;

        while (1) {
                struct mtd_ecc_stats ecc_stats = mtd->ecc_stats;

                bytes = min(mtd->writesize - col, readlen);
                aligned = (bytes == mtd->writesize);

                if (!aligned)
                        use_bounce_buf = 1;
                else if (chip->options & NAND_USES_DMA)
                        use_bounce_buf = !virt_addr_valid(buf) ||
                                         !IS_ALIGNED((unsigned long)buf,
                                                     chip->buf_align);
                else
                        use_bounce_buf = 0;

                /* Is the current page in the buffer? */
                if (realpage != chip->pagecache.page || oob) {
                        bufpoi = use_bounce_buf ? chip->data_buf : buf;

                        if (use_bounce_buf && aligned)
                                pr_debug("%s: using read bounce buffer for buf@%p\n",
                                                 __func__, buf);

read_retry:
                        /*
                         * Now read the page into the buffer.  Absent an error,
                         * the read methods return max bitflips per ecc step.
                         */
                        if (unlikely(ops->mode == MTD_OPS_RAW))
                                ret = chip->ecc.read_page_raw(chip, bufpoi,
                                                              oob_required,
                                                              page);
                        else if (!aligned && NAND_HAS_SUBPAGE_READ(chip) &&
                                 !oob)
                                ret = chip->ecc.read_subpage(chip, col, bytes,
                                                             bufpoi, page);
                        else
                                ret = chip->ecc.read_page(chip, bufpoi,
                                                          oob_required, page);
                        if (ret < 0) {
                                if (use_bounce_buf)
                                        /* Invalidate page cache */
                                        chip->pagecache.page = -1;
                                break;
                        }

                        /*
                         * Copy back the data in the initial buffer when reading
                         * partial pages or when a bounce buffer is required.
                         */
                        if (use_bounce_buf) {
                                if (!NAND_HAS_SUBPAGE_READ(chip) && !oob &&
                                    !(mtd->ecc_stats.failed - ecc_stats.failed) &&
                                    (ops->mode != MTD_OPS_RAW)) {
                                        chip->pagecache.page = realpage;
                                        chip->pagecache.bitflips = ret;
                                } else {
                                        /* Invalidate page cache */
                                        chip->pagecache.page = -1;
                                }
                                memcpy(buf, bufpoi + col, bytes);
                        }

                        if (unlikely(oob)) {
                                int toread = min(oobreadlen, max_oobsize);

                                if (toread) {
                                        oob = nand_transfer_oob(chip, oob, ops,
                                                                toread);
                                        oobreadlen -= toread;
                                }
                        }

                        nand_wait_readrdy(chip);

                        if (mtd->ecc_stats.failed - ecc_stats.failed) {
                                if (retry_mode + 1 < chip->read_retries) {
                                        retry_mode++;
                                        ret = nand_setup_read_retry(chip,
                                                        retry_mode);
                                        if (ret < 0)
                                                break;

                                        /* Reset ecc_stats; retry */
                                        mtd->ecc_stats = ecc_stats;
                                        goto read_retry;
                                } else {
                                        /* No more retry modes; real failure */
                                        ecc_fail = true;
                                }
                        }

                        buf += bytes;
                        max_bitflips = max_t(unsigned int, max_bitflips, ret);
                } else {
                        memcpy(buf, chip->data_buf + col, bytes);
                        buf += bytes;
                        max_bitflips = max_t(unsigned int, max_bitflips,
                                             chip->pagecache.bitflips);
                }

                readlen -= bytes;

                /* Reset to retry mode 0 */
                if (retry_mode) {
                        ret = nand_setup_read_retry(chip, 0);
                        if (ret < 0)
                                break;
                        retry_mode = 0;
                }

                if (!readlen)
                        break;

                /* For subsequent reads align to page boundary */
                col = 0;
                /* Increment page address */
                realpage++;

                page = realpage & chip->pagemask;
                /* Check, if we cross a chip boundary */
                if (!page) {
                        chipnr++;
                        nand_deselect_target(chip);
                        nand_select_target(chip, chipnr);
                }
        }
        nand_deselect_target(chip);

        ops->retlen = ops->len - (size_t) readlen;
        if (oob)
                ops->oobretlen = ops->ooblen - oobreadlen;

        if (ret < 0)
                return ret;

        if (ecc_fail)
                return -EBADMSG;

        return max_bitflips;
}

/**
 * nand_read_oob_std - [REPLACEABLE] the most common OOB data read function
 * @chip: nand chip info structure
 * @page: page number to read
 */
int nand_read_oob_std(struct nand_chip *chip, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        return nand_read_oob_op(chip, page, 0, chip->oob_poi, mtd->oobsize);
}
EXPORT_SYMBOL(nand_read_oob_std);

/**
 * nand_read_oob_syndrome - [REPLACEABLE] OOB data read function for HW ECC
 *                          with syndromes
 * @chip: nand chip info structure
 * @page: page number to read
 */
static int nand_read_oob_syndrome(struct nand_chip *chip, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int length = mtd->oobsize;
        int chunk = chip->ecc.bytes + chip->ecc.prepad + chip->ecc.postpad;
        int eccsize = chip->ecc.size;
        uint8_t *bufpoi = chip->oob_poi;
        int i, toread, sndrnd = 0, pos, ret;

        ret = nand_read_page_op(chip, page, chip->ecc.size, NULL, 0);
        if (ret)
                return ret;

        for (i = 0; i < chip->ecc.steps; i++) {
                if (sndrnd) {
                        int ret;

                        pos = eccsize + i * (eccsize + chunk);
                        if (mtd->writesize > 512)
                                ret = nand_change_read_column_op(chip, pos,
                                                                 NULL, 0,
                                                                 false);
                        else
                                ret = nand_read_page_op(chip, page, pos, NULL,
                                                        0);

                        if (ret)
                                return ret;
                } else
                        sndrnd = 1;
                toread = min_t(int, length, chunk);

                ret = nand_read_data_op(chip, bufpoi, toread, false, false);
                if (ret)
                        return ret;

                bufpoi += toread;
                length -= toread;
        }
        if (length > 0) {
                ret = nand_read_data_op(chip, bufpoi, length, false, false);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * nand_write_oob_std - [REPLACEABLE] the most common OOB data write function
 * @chip: nand chip info structure
 * @page: page number to write
 */
int nand_write_oob_std(struct nand_chip *chip, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);

        return nand_prog_page_op(chip, page, mtd->writesize, chip->oob_poi,
                                 mtd->oobsize);
}
EXPORT_SYMBOL(nand_write_oob_std);

/**
 * nand_write_oob_syndrome - [REPLACEABLE] OOB data write function for HW ECC
 *                           with syndrome - only for large page flash
 * @chip: nand chip info structure
 * @page: page number to write
 */
static int nand_write_oob_syndrome(struct nand_chip *chip, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int chunk = chip->ecc.bytes + chip->ecc.prepad + chip->ecc.postpad;
        int eccsize = chip->ecc.size, length = mtd->oobsize;
        int ret, i, len, pos, sndcmd = 0, steps = chip->ecc.steps;
        const uint8_t *bufpoi = chip->oob_poi;

        /*
         * data-ecc-data-ecc ... ecc-oob
         * or
         * data-pad-ecc-pad-data-pad .... ecc-pad-oob
         */
        if (!chip->ecc.prepad && !chip->ecc.postpad) {
                pos = steps * (eccsize + chunk);
                steps = 0;
        } else
                pos = eccsize;

        ret = nand_prog_page_begin_op(chip, page, pos, NULL, 0);
        if (ret)
                return ret;

        for (i = 0; i < steps; i++) {
                if (sndcmd) {
                        if (mtd->writesize <= 512) {
                                uint32_t fill = 0xFFFFFFFF;

                                len = eccsize;
                                while (len > 0) {
                                        int num = min_t(int, len, 4);

                                        ret = nand_write_data_op(chip, &fill,
                                                                 num, false);
                                        if (ret)
                                                return ret;

                                        len -= num;
                                }
                        } else {
                                pos = eccsize + i * (eccsize + chunk);
                                ret = nand_change_write_column_op(chip, pos,
                                                                  NULL, 0,
                                                                  false);
                                if (ret)
                                        return ret;
                        }
                } else
                        sndcmd = 1;
                len = min_t(int, length, chunk);

                ret = nand_write_data_op(chip, bufpoi, len, false);
                if (ret)
                        return ret;

                bufpoi += len;
                length -= len;
        }
        if (length > 0) {
                ret = nand_write_data_op(chip, bufpoi, length, false);
                if (ret)
                        return ret;
        }

        return nand_prog_page_end_op(chip);
}

/**
 * nand_do_read_oob - [INTERN] NAND read out-of-band
 * @chip: NAND chip object
 * @from: offset to read from
 * @ops: oob operations description structure
 *
 * NAND read out-of-band data from the spare area.
 */
static int nand_do_read_oob(struct nand_chip *chip, loff_t from,
                            struct mtd_oob_ops *ops)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        unsigned int max_bitflips = 0;
        int page, realpage, chipnr;
        struct mtd_ecc_stats stats;
        int readlen = ops->ooblen;
        int len;
        uint8_t *buf = ops->oobbuf;
        int ret = 0;

        pr_debug("%s: from = 0x%08Lx, len = %i\n",
                        __func__, (unsigned long long)from, readlen);

        stats = mtd->ecc_stats;

        len = mtd_oobavail(mtd, ops);

        chipnr = (int)(from >> chip->chip_shift);
        nand_select_target(chip, chipnr);

        /* Shift to get page */
        realpage = (int)(from >> chip->page_shift);
        page = realpage & chip->pagemask;

        while (1) {
                if (ops->mode == MTD_OPS_RAW)
                        ret = chip->ecc.read_oob_raw(chip, page);
                else
                        ret = chip->ecc.read_oob(chip, page);

                if (ret < 0)
                        break;

                len = min(len, readlen);
                buf = nand_transfer_oob(chip, buf, ops, len);

                nand_wait_readrdy(chip);

                max_bitflips = max_t(unsigned int, max_bitflips, ret);

                readlen -= len;
                if (!readlen)
                        break;

                /* Increment page address */
                realpage++;

                page = realpage & chip->pagemask;
                /* Check, if we cross a chip boundary */
                if (!page) {
                        chipnr++;
                        nand_deselect_target(chip);
                        nand_select_target(chip, chipnr);
                }
        }
        nand_deselect_target(chip);

        ops->oobretlen = ops->ooblen - readlen;

        if (ret < 0)
                return ret;

        if (mtd->ecc_stats.failed - stats.failed)
                return -EBADMSG;

        return max_bitflips;
}

/**
 * nand_read_oob - [MTD Interface] NAND read data and/or out-of-band
 * @mtd: MTD device structure
 * @from: offset to read from
 * @ops: oob operation description structure
 *
 * NAND read data and/or out-of-band data.
 */
static int nand_read_oob(struct mtd_info *mtd, loff_t from,
                         struct mtd_oob_ops *ops)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        int ret;

        ops->retlen = 0;

        if (ops->mode != MTD_OPS_PLACE_OOB &&
            ops->mode != MTD_OPS_AUTO_OOB &&
            ops->mode != MTD_OPS_RAW)
                return -ENOTSUPP;

        ret = nand_get_device(chip);
        if (ret)
                return ret;

        if (!ops->datbuf)
                ret = nand_do_read_oob(chip, from, ops);
        else
                ret = nand_do_read_ops(chip, from, ops);

        nand_release_device(chip);
        return ret;
}

/**
 * nand_write_page_raw_notsupp - dummy raw page write function
 * @chip: nand chip info structure
 * @buf: data buffer
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 *
 * Returns -ENOTSUPP unconditionally.
 */
int nand_write_page_raw_notsupp(struct nand_chip *chip, const u8 *buf,
                                int oob_required, int page)
{
        return -ENOTSUPP;
}

/**
 * nand_write_page_raw - [INTERN] raw page write function
 * @chip: nand chip info structure
 * @buf: data buffer
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 *
 * Not for syndrome calculating ECC controllers, which use a special oob layout.
 */
int nand_write_page_raw(struct nand_chip *chip, const uint8_t *buf,
                        int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;

        ret = nand_prog_page_begin_op(chip, page, 0, buf, mtd->writesize);
        if (ret)
                return ret;

        if (oob_required) {
                ret = nand_write_data_op(chip, chip->oob_poi, mtd->oobsize,
                                         false);
                if (ret)
                        return ret;
        }

        return nand_prog_page_end_op(chip);
}
EXPORT_SYMBOL(nand_write_page_raw);

/**
 * nand_monolithic_write_page_raw - Monolithic page write in raw mode
 * @chip: NAND chip info structure
 * @buf: data buffer to write
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 *
 * This is a raw page write, ie. without any error detection/correction.
 * Monolithic means we are requesting all the relevant data (main plus
 * eventually OOB) to be sent over the bus and effectively programmed
 * into the NAND chip arrays in a single operation. This is an
 * alternative to nand_write_page_raw(), which first sends the main
 * data, then eventually send the OOB data by latching more data
 * cycles on the NAND bus, and finally sends the program command to
 * synchronyze the NAND chip cache.
 */
int nand_monolithic_write_page_raw(struct nand_chip *chip, const u8 *buf,
                                   int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        unsigned int size = mtd->writesize;
        u8 *write_buf = (u8 *)buf;

        if (oob_required) {
                size += mtd->oobsize;

                if (buf != chip->data_buf) {
                        write_buf = nand_get_data_buf(chip);
                        memcpy(write_buf, buf, mtd->writesize);
                }
        }

        return nand_prog_page_op(chip, page, 0, write_buf, size);
}
EXPORT_SYMBOL(nand_monolithic_write_page_raw);

/**
 * nand_write_page_raw_syndrome - [INTERN] raw page write function
 * @chip: nand chip info structure
 * @buf: data buffer
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 *
 * We need a special oob layout and handling even when ECC isn't checked.
 */
static int nand_write_page_raw_syndrome(struct nand_chip *chip,
                                        const uint8_t *buf, int oob_required,
                                        int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int eccsize = chip->ecc.size;
        int eccbytes = chip->ecc.bytes;
        uint8_t *oob = chip->oob_poi;
        int steps, size, ret;

        ret = nand_prog_page_begin_op(chip, page, 0, NULL, 0);
        if (ret)
                return ret;

        for (steps = chip->ecc.steps; steps > 0; steps--) {
                ret = nand_write_data_op(chip, buf, eccsize, false);
                if (ret)
                        return ret;

                buf += eccsize;

                if (chip->ecc.prepad) {
                        ret = nand_write_data_op(chip, oob, chip->ecc.prepad,
                                                 false);
                        if (ret)
                                return ret;

                        oob += chip->ecc.prepad;
                }

                ret = nand_write_data_op(chip, oob, eccbytes, false);
                if (ret)
                        return ret;

                oob += eccbytes;

                if (chip->ecc.postpad) {
                        ret = nand_write_data_op(chip, oob, chip->ecc.postpad,
                                                 false);
                        if (ret)
                                return ret;

                        oob += chip->ecc.postpad;
                }
        }

        size = mtd->oobsize - (oob - chip->oob_poi);
        if (size) {
                ret = nand_write_data_op(chip, oob, size, false);
                if (ret)
                        return ret;
        }

        return nand_prog_page_end_op(chip);
}
/**
 * nand_write_page_swecc - [REPLACEABLE] software ECC based page write function
 * @chip: nand chip info structure
 * @buf: data buffer
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 */
static int nand_write_page_swecc(struct nand_chip *chip, const uint8_t *buf,
                                 int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int i, eccsize = chip->ecc.size, ret;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        uint8_t *ecc_calc = chip->ecc.calc_buf;
        const uint8_t *p = buf;

        /* Software ECC calculation */
        for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize)
                chip->ecc.calculate(chip, p, &ecc_calc[i]);

        ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
                                         chip->ecc.total);
        if (ret)
                return ret;

        return chip->ecc.write_page_raw(chip, buf, 1, page);
}

/**
 * nand_write_page_hwecc - [REPLACEABLE] hardware ECC based page write function
 * @chip: nand chip info structure
 * @buf: data buffer
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 */
static int nand_write_page_hwecc(struct nand_chip *chip, const uint8_t *buf,
                                 int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        int i, eccsize = chip->ecc.size, ret;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        uint8_t *ecc_calc = chip->ecc.calc_buf;
        const uint8_t *p = buf;

        ret = nand_prog_page_begin_op(chip, page, 0, NULL, 0);
        if (ret)
                return ret;

        for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
                chip->ecc.hwctl(chip, NAND_ECC_WRITE);

                ret = nand_write_data_op(chip, p, eccsize, false);
                if (ret)
                        return ret;

                chip->ecc.calculate(chip, p, &ecc_calc[i]);
        }

        ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
                                         chip->ecc.total);
        if (ret)
                return ret;

        ret = nand_write_data_op(chip, chip->oob_poi, mtd->oobsize, false);
        if (ret)
                return ret;

        return nand_prog_page_end_op(chip);
}


/**
 * nand_write_subpage_hwecc - [REPLACEABLE] hardware ECC based subpage write
 * @chip:       nand chip info structure
 * @offset:     column address of subpage within the page
 * @data_len:   data length
 * @buf:        data buffer
 * @oob_required: must write chip->oob_poi to OOB
 * @page: page number to write
 */
static int nand_write_subpage_hwecc(struct nand_chip *chip, uint32_t offset,
                                    uint32_t data_len, const uint8_t *buf,
                                    int oob_required, int page)
{
        struct mtd_info *mtd = nand_to_mtd(chip);
        uint8_t *oob_buf  = chip->oob_poi;
        uint8_t *ecc_calc = chip->ecc.calc_buf;
        int ecc_size      = chip->ecc.size;
        int ecc_bytes     = chip->ecc.bytes;
        int ecc_steps     = chip->ecc.steps;
        uint32_t start_step = offset / ecc_size;
        uint32_t end_step   = (offset + data_len - 1) / ecc_size;
        int oob_bytes       = mtd->oobsize / ecc_steps;
        int step, ret;

        ret = nand_prog_page_begin_op(chip, page, 0, NULL, 0);
        if (ret)
                return ret;

        for (step = 0; step < ecc_steps; step++) {
                /* configure controller for WRITE access */
                chip->ecc.hwctl(chip, NAND_ECC_WRITE);

                /* write data (untouched subpages already masked by 0xFF) */
                ret = nand_write_data_op(chip, buf, ecc_size, false);
                if (ret)
                        return ret;

                /* mask ECC of un-touched subpages by padding 0xFF */
                if ((step < start_step) || (step > end_step))
                        memset(ecc_calc, 0xff, ecc_bytes);
                else
                        chip->ecc.calculate(chip, buf, ecc_calc);

                /* mask OOB of un-touched subpages by padding 0xFF */
                /* if oob_required, preserve OOB metadata of written subpage */
                if (!oob_required || (step < start_step) || (step > end_step))
                        memset(oob_buf, 0xff, oob_bytes);

                buf += ecc_size;
                ecc_calc += ecc_bytes;
                oob_buf  += oob_bytes;
        }

        /* copy calculated ECC for whole page to chip->buffer->oob */
        /* this include masked-value(0xFF) for unwritten subpages */
        ecc_calc = chip->ecc.calc_buf;
        ret = mtd_ooblayout_set_eccbytes(mtd, ecc_calc, chip->oob_poi, 0,
                                         chip->ecc.total);
        if (ret)
                return ret;

        /* write OOB buffer to NAND device */
        ret = nand_write_data_op(chip, chip->oob_poi, mtd->oobsize, false);
        if (ret)
                return ret;

        return nand_prog_page_end_op(chip);
}


/**
 * nand_write_page_syndrome - [REPLACEABLE] hardware ECC syndrome based page write
 * @chip: nand chip info structure
 * @buf: data buffer