/*
 * NAND Flash Controller Device Driver
 * Copyright © 2009-2010, Intel Corporation and its suppliers.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/mtd/mtd.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "denali.h"

MODULE_LICENSE("GPL");

#define DENALI_NAND_NAME    "denali-nand"

/* Host Data/Command Interface */
#define DENALI_HOST_ADDR        0x00
#define DENALI_HOST_DATA        0x10

#define DENALI_MAP00            (0 << 26)       /* direct access to buffer */
#define DENALI_MAP01            (1 << 26)       /* read/write pages in PIO */
#define DENALI_MAP10            (2 << 26)       /* high-level control plane */
#define DENALI_MAP11            (3 << 26)       /* direct controller access */

/* MAP11 access cycle type */
#define DENALI_MAP11_CMD        ((DENALI_MAP11) | 0)    /* command cycle */
#define DENALI_MAP11_ADDR       ((DENALI_MAP11) | 1)    /* address cycle */
#define DENALI_MAP11_DATA       ((DENALI_MAP11) | 2)    /* data cycle */

/* MAP10 commands */
#define DENALI_ERASE            0x01

#define DENALI_BANK(denali)     ((denali)->active_bank << 24)

#define DENALI_INVALID_BANK     -1
#define DENALI_NR_BANKS         4

/*
 * The bus interface clock, clk_x, is phase aligned with the core clock.  The
 * clk_x is an integral multiple N of the core clk.  The value N is configured
 * at IP delivery time, and its available value is 4, 5, or 6.  We need to align
 * to the largest value to make it work with any possible configuration.
 */
#define DENALI_CLK_X_MULT       6

/*
 * this macro allows us to convert from an MTD structure to our own
 * device context (denali) structure.
 */
static inline struct denali_nand_info *mtd_to_denali(struct mtd_info *mtd)
{
        return container_of(mtd_to_nand(mtd), struct denali_nand_info, nand);
}

static void denali_host_write(struct denali_nand_info *denali,
                              uint32_t addr, uint32_t data)
{
        iowrite32(addr, denali->host + DENALI_HOST_ADDR);
        iowrite32(data, denali->host + DENALI_HOST_DATA);
}

/*
 * Use the configuration feature register to determine the maximum number of
 * banks that the hardware supports.
 */
static void detect_max_banks(struct denali_nand_info *denali)
{
        uint32_t features = ioread32(denali->reg + FEATURES);

        denali->max_banks = 1 << (features & FEATURES__N_BANKS);

        /* the encoding changed from rev 5.0 to 5.1 */
        if (denali->revision < 0x0501)
                denali->max_banks <<= 1;
}

static void denali_enable_irq(struct denali_nand_info *denali)
{
        int i;

        for (i = 0; i < DENALI_NR_BANKS; i++)
                iowrite32(U32_MAX, denali->reg + INTR_EN(i));
        iowrite32(GLOBAL_INT_EN_FLAG, denali->reg + GLOBAL_INT_ENABLE);
}

static void denali_disable_irq(struct denali_nand_info *denali)
{
        int i;

        for (i = 0; i < DENALI_NR_BANKS; i++)
                iowrite32(0, denali->reg + INTR_EN(i));
        iowrite32(0, denali->reg + GLOBAL_INT_ENABLE);
}

static void denali_clear_irq(struct denali_nand_info *denali,
                             int bank, uint32_t irq_status)
{
        /* write one to clear bits */
        iowrite32(irq_status, denali->reg + INTR_STATUS(bank));
}

static void denali_clear_irq_all(struct denali_nand_info *denali)
{
        int i;

        for (i = 0; i < DENALI_NR_BANKS; i++)
                denali_clear_irq(denali, i, U32_MAX);
}

static irqreturn_t denali_isr(int irq, void *dev_id)
{
        struct denali_nand_info *denali = dev_id;
        irqreturn_t ret = IRQ_NONE;
        uint32_t irq_status;
        int i;

        spin_lock(&denali->irq_lock);

        for (i = 0; i < DENALI_NR_BANKS; i++) {
                irq_status = ioread32(denali->reg + INTR_STATUS(i));
                if (irq_status)
                        ret = IRQ_HANDLED;

                denali_clear_irq(denali, i, irq_status);

                if (i != denali->active_bank)
                        continue;

                denali->irq_status |= irq_status;

                if (denali->irq_status & denali->irq_mask)
                        complete(&denali->complete);
        }

        spin_unlock(&denali->irq_lock);

        return ret;
}

static void denali_reset_irq(struct denali_nand_info *denali)
{
        unsigned long flags;

        spin_lock_irqsave(&denali->irq_lock, flags);
        denali->irq_status = 0;
        denali->irq_mask = 0;
        spin_unlock_irqrestore(&denali->irq_lock, flags);
}

static uint32_t denali_wait_for_irq(struct denali_nand_info *denali,
                                    uint32_t irq_mask)
{
        unsigned long time_left, flags;
        uint32_t irq_status;

        spin_lock_irqsave(&denali->irq_lock, flags);

        irq_status = denali->irq_status;

        if (irq_mask & irq_status) {
                /* return immediately if the IRQ has already happened. */
                spin_unlock_irqrestore(&denali->irq_lock, flags);
                return irq_status;
        }

        denali->irq_mask = irq_mask;
        reinit_completion(&denali->complete);
        spin_unlock_irqrestore(&denali->irq_lock, flags);

        time_left = wait_for_completion_timeout(&denali->complete,
                                                msecs_to_jiffies(1000));
        if (!time_left) {
                dev_err(denali->dev, "timeout while waiting for irq 0x%x\n",
                        denali->irq_mask);
                return 0;
        }

        return denali->irq_status;
}

static uint32_t denali_check_irq(struct denali_nand_info *denali)
{
        unsigned long flags;
        uint32_t irq_status;

        spin_lock_irqsave(&denali->irq_lock, flags);
        irq_status = denali->irq_status;
        spin_unlock_irqrestore(&denali->irq_lock, flags);

        return irq_status;
}

/*
 * This helper function setups the registers for ECC and whether or not
 * the spare area will be transferred.
 */
static void setup_ecc_for_xfer(struct denali_nand_info *denali, bool ecc_en,
                                bool transfer_spare)
{
        int ecc_en_flag, transfer_spare_flag;

        /* set ECC, transfer spare bits if needed */
        ecc_en_flag = ecc_en ? ECC_ENABLE__FLAG : 0;
        transfer_spare_flag = transfer_spare ? TRANSFER_SPARE_REG__FLAG : 0;

        /* Enable spare area/ECC per user's request. */
        iowrite32(ecc_en_flag, denali->reg + ECC_ENABLE);
        iowrite32(transfer_spare_flag, denali->reg + TRANSFER_SPARE_REG);
}

static void denali_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        int i;

        iowrite32(DENALI_MAP11_DATA | DENALI_BANK(denali),
                  denali->host + DENALI_HOST_ADDR);

        for (i = 0; i < len; i++)
                buf[i] = ioread32(denali->host + DENALI_HOST_DATA);
}

static void denali_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        int i;

        iowrite32(DENALI_MAP11_DATA | DENALI_BANK(denali),
                  denali->host + DENALI_HOST_ADDR);

        for (i = 0; i < len; i++)
                iowrite32(buf[i], denali->host + DENALI_HOST_DATA);
}

static void denali_read_buf16(struct mtd_info *mtd, uint8_t *buf, int len)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint16_t *buf16 = (uint16_t *)buf;
        int i;

        iowrite32(DENALI_MAP11_DATA | DENALI_BANK(denali),
                  denali->host + DENALI_HOST_ADDR);

        for (i = 0; i < len / 2; i++)
                buf16[i] = ioread32(denali->host + DENALI_HOST_DATA);
}

static void denali_write_buf16(struct mtd_info *mtd, const uint8_t *buf,
                               int len)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        const uint16_t *buf16 = (const uint16_t *)buf;
        int i;

        iowrite32(DENALI_MAP11_DATA | DENALI_BANK(denali),
                  denali->host + DENALI_HOST_ADDR);

        for (i = 0; i < len / 2; i++)
                iowrite32(buf16[i], denali->host + DENALI_HOST_DATA);
}

static uint8_t denali_read_byte(struct mtd_info *mtd)
{
        uint8_t byte;

        denali_read_buf(mtd, &byte, 1);

        return byte;
}

static void denali_write_byte(struct mtd_info *mtd, uint8_t byte)
{
        denali_write_buf(mtd, &byte, 1);
}

static uint16_t denali_read_word(struct mtd_info *mtd)
{
        uint16_t word;

        denali_read_buf16(mtd, (uint8_t *)&word, 2);

        return word;
}

static void denali_cmd_ctrl(struct mtd_info *mtd, int dat, unsigned int ctrl)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint32_t type;

        if (ctrl & NAND_CLE)
                type = DENALI_MAP11_CMD;
        else if (ctrl & NAND_ALE)
                type = DENALI_MAP11_ADDR;
        else
                return;

        /*
         * Some commands are followed by chip->dev_ready or chip->waitfunc.
         * irq_status must be cleared here to catch the R/B# interrupt later.
         */
        if (ctrl & NAND_CTRL_CHANGE)
                denali_reset_irq(denali);

        denali_host_write(denali, DENALI_BANK(denali) | type, dat);
}

static int denali_dev_ready(struct mtd_info *mtd)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);

        return !!(denali_check_irq(denali) & INTR__INT_ACT);
}

static int denali_check_erased_page(struct mtd_info *mtd,
                                    struct nand_chip *chip, uint8_t *buf,
                                    unsigned long uncor_ecc_flags,
                                    unsigned int max_bitflips)
{
        uint8_t *ecc_code = chip->buffers->ecccode;
        int ecc_steps = chip->ecc.steps;
        int ecc_size = chip->ecc.size;
        int ecc_bytes = chip->ecc.bytes;
        int i, ret, stat;

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

        for (i = 0; i < ecc_steps; i++) {
                if (!(uncor_ecc_flags & BIT(i)))
                        continue;

                stat = nand_check_erased_ecc_chunk(buf, ecc_size,
                                                  ecc_code, 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);
                }

                buf += ecc_size;
                ecc_code += ecc_bytes;
        }

        return max_bitflips;
}

static int denali_hw_ecc_fixup(struct mtd_info *mtd,
                               struct denali_nand_info *denali,
                               unsigned long *uncor_ecc_flags)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        int bank = denali->active_bank;
        uint32_t ecc_cor;
        unsigned int max_bitflips;

        ecc_cor = ioread32(denali->reg + ECC_COR_INFO(bank));
        ecc_cor >>= ECC_COR_INFO__SHIFT(bank);

        if (ecc_cor & ECC_COR_INFO__UNCOR_ERR) {
                /*
                 * This flag is set when uncorrectable error occurs at least in
                 * one ECC sector.  We can not know "how many sectors", or
                 * "which sector(s)".  We need erase-page check for all sectors.
                 */
                *uncor_ecc_flags = GENMASK(chip->ecc.steps - 1, 0);
                return 0;
        }

        max_bitflips = ecc_cor & ECC_COR_INFO__MAX_ERRORS;

        /*
         * The register holds the maximum of per-sector corrected bitflips.
         * This is suitable for the return value of the ->read_page() callback.
         * Unfortunately, we can not know the total number of corrected bits in
         * the page.  Increase the stats by max_bitflips. (compromised solution)
         */
        mtd->ecc_stats.corrected += max_bitflips;

        return max_bitflips;
}

#define ECC_SECTOR(x)   (((x) & ECC_ERROR_ADDRESS__SECTOR_NR) >> 12)
#define ECC_BYTE(x)     (((x) & ECC_ERROR_ADDRESS__OFFSET))
#define ECC_CORRECTION_VALUE(x) ((x) & ERR_CORRECTION_INFO__BYTEMASK)
#define ECC_ERROR_UNCORRECTABLE(x) ((x) & ERR_CORRECTION_INFO__ERROR_TYPE)
#define ECC_ERR_DEVICE(x)       (((x) & ERR_CORRECTION_INFO__DEVICE_NR) >> 8)
#define ECC_LAST_ERR(x)         ((x) & ERR_CORRECTION_INFO__LAST_ERR_INFO)

static int denali_sw_ecc_fixup(struct mtd_info *mtd,
                               struct denali_nand_info *denali,
                               unsigned long *uncor_ecc_flags, uint8_t *buf)
{
        unsigned int ecc_size = denali->nand.ecc.size;
        unsigned int bitflips = 0;
        unsigned int max_bitflips = 0;
        uint32_t err_addr, err_cor_info;
        unsigned int err_byte, err_sector, err_device;
        uint8_t err_cor_value;
        unsigned int prev_sector = 0;
        uint32_t irq_status;

        denali_reset_irq(denali);

        do {
                err_addr = ioread32(denali->reg + ECC_ERROR_ADDRESS);
                err_sector = ECC_SECTOR(err_addr);
                err_byte = ECC_BYTE(err_addr);

                err_cor_info = ioread32(denali->reg + ERR_CORRECTION_INFO);
                err_cor_value = ECC_CORRECTION_VALUE(err_cor_info);
                err_device = ECC_ERR_DEVICE(err_cor_info);

                /* reset the bitflip counter when crossing ECC sector */
                if (err_sector != prev_sector)
                        bitflips = 0;

                if (ECC_ERROR_UNCORRECTABLE(err_cor_info)) {
                        /*
                         * Check later if this is a real ECC error, or
                         * an erased sector.
                         */
                        *uncor_ecc_flags |= BIT(err_sector);
                } else if (err_byte < ecc_size) {
                        /*
                         * If err_byte is larger than ecc_size, means error
                         * happened in OOB, so we ignore it. It's no need for
                         * us to correct it err_device is represented the NAND
                         * error bits are happened in if there are more than
                         * one NAND connected.
                         */
                        int offset;
                        unsigned int flips_in_byte;

                        offset = (err_sector * ecc_size + err_byte) *
                                        denali->devs_per_cs + err_device;

                        /* correct the ECC error */
                        flips_in_byte = hweight8(buf[offset] ^ err_cor_value);
                        buf[offset] ^= err_cor_value;
                        mtd->ecc_stats.corrected += flips_in_byte;
                        bitflips += flips_in_byte;

                        max_bitflips = max(max_bitflips, bitflips);
                }

                prev_sector = err_sector;
        } while (!ECC_LAST_ERR(err_cor_info));

        /*
         * Once handle all ecc errors, controller will trigger a
         * ECC_TRANSACTION_DONE interrupt, so here just wait for
         * a while for this interrupt
         */
        irq_status = denali_wait_for_irq(denali, INTR__ECC_TRANSACTION_DONE);
        if (!(irq_status & INTR__ECC_TRANSACTION_DONE))
                return -EIO;

        return max_bitflips;
}

/* programs the controller to either enable/disable DMA transfers */
static void denali_enable_dma(struct denali_nand_info *denali, bool en)
{
        iowrite32(en ? DMA_ENABLE__FLAG : 0, denali->reg + DMA_ENABLE);
        ioread32(denali->reg + DMA_ENABLE);
}

static void denali_setup_dma64(struct denali_nand_info *denali,
                               dma_addr_t dma_addr, int page, int write)
{
        uint32_t mode;
        const int page_count = 1;

        mode = DENALI_MAP10 | DENALI_BANK(denali) | page;

        /* DMA is a three step process */

        /*
         * 1. setup transfer type, interrupt when complete,
         *    burst len = 64 bytes, the number of pages
         */
        denali_host_write(denali, mode,
                          0x01002000 | (64 << 16) | (write << 8) | page_count);

        /* 2. set memory low address */
        denali_host_write(denali, mode, dma_addr);

        /* 3. set memory high address */
        denali_host_write(denali, mode, (uint64_t)dma_addr >> 32);
}

static void denali_setup_dma32(struct denali_nand_info *denali,
                               dma_addr_t dma_addr, int page, int write)
{
        uint32_t mode;
        const int page_count = 1;

        mode = DENALI_MAP10 | DENALI_BANK(denali);

        /* DMA is a four step process */

        /* 1. setup transfer type and # of pages */
        denali_host_write(denali, mode | page,
                          0x2000 | (write << 8) | page_count);

        /* 2. set memory high address bits 23:8 */
        denali_host_write(denali, mode | ((dma_addr >> 16) << 8), 0x2200);

        /* 3. set memory low address bits 23:8 */
        denali_host_write(denali, mode | ((dma_addr & 0xffff) << 8), 0x2300);

        /* 4. interrupt when complete, burst len = 64 bytes */
        denali_host_write(denali, mode | 0x14000, 0x2400);
}

static void denali_setup_dma(struct denali_nand_info *denali,
                             dma_addr_t dma_addr, int page, int write)
{
        if (denali->caps & DENALI_CAP_DMA_64BIT)
                denali_setup_dma64(denali, dma_addr, page, write);
        else
                denali_setup_dma32(denali, dma_addr, page, write);
}

static int denali_pio_read(struct denali_nand_info *denali, void *buf,
                           size_t size, int page, int raw)
{
        uint32_t addr = DENALI_BANK(denali) | page;
        uint32_t *buf32 = (uint32_t *)buf;
        uint32_t irq_status, ecc_err_mask;
        int i;

        if (denali->caps & DENALI_CAP_HW_ECC_FIXUP)
                ecc_err_mask = INTR__ECC_UNCOR_ERR;
        else
                ecc_err_mask = INTR__ECC_ERR;

        denali_reset_irq(denali);

        iowrite32(DENALI_MAP01 | addr, denali->host + DENALI_HOST_ADDR);
        for (i = 0; i < size / 4; i++)
                *buf32++ = ioread32(denali->host + DENALI_HOST_DATA);

        irq_status = denali_wait_for_irq(denali, INTR__PAGE_XFER_INC);
        if (!(irq_status & INTR__PAGE_XFER_INC))
                return -EIO;

        if (irq_status & INTR__ERASED_PAGE)
                memset(buf, 0xff, size);

        return irq_status & ecc_err_mask ? -EBADMSG : 0;
}

static int denali_pio_write(struct denali_nand_info *denali,
                            const void *buf, size_t size, int page, int raw)
{
        uint32_t addr = DENALI_BANK(denali) | page;
        const uint32_t *buf32 = (uint32_t *)buf;
        uint32_t irq_status;
        int i;

        denali_reset_irq(denali);

        iowrite32(DENALI_MAP01 | addr, denali->host + DENALI_HOST_ADDR);
        for (i = 0; i < size / 4; i++)
                iowrite32(*buf32++, denali->host + DENALI_HOST_DATA);

        irq_status = denali_wait_for_irq(denali,
                                INTR__PROGRAM_COMP | INTR__PROGRAM_FAIL);
        if (!(irq_status & INTR__PROGRAM_COMP))
                return -EIO;

        return 0;
}

static int denali_pio_xfer(struct denali_nand_info *denali, void *buf,
                           size_t size, int page, int raw, int write)
{
        if (write)
                return denali_pio_write(denali, buf, size, page, raw);
        else
                return denali_pio_read(denali, buf, size, page, raw);
}

static int denali_dma_xfer(struct denali_nand_info *denali, void *buf,
                           size_t size, int page, int raw, int write)
{
        dma_addr_t dma_addr;
        uint32_t irq_mask, irq_status, ecc_err_mask;
        enum dma_data_direction dir = write ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
        int ret = 0;

        dma_addr = dma_map_single(denali->dev, buf, size, dir);
        if (dma_mapping_error(denali->dev, dma_addr)) {
                dev_dbg(denali->dev, "Failed to DMA-map buffer. Trying PIO.\n");
                return denali_pio_xfer(denali, buf, size, page, raw, write);
        }

        if (write) {
                /*
                 * INTR__PROGRAM_COMP is never asserted for the DMA transfer.
                 * We can use INTR__DMA_CMD_COMP instead.  This flag is asserted
                 * when the page program is completed.
                 */
                irq_mask = INTR__DMA_CMD_COMP | INTR__PROGRAM_FAIL;
                ecc_err_mask = 0;
        } else if (denali->caps & DENALI_CAP_HW_ECC_FIXUP) {
                irq_mask = INTR__DMA_CMD_COMP;
                ecc_err_mask = INTR__ECC_UNCOR_ERR;
        } else {
                irq_mask = INTR__DMA_CMD_COMP;
                ecc_err_mask = INTR__ECC_ERR;
        }

        denali_enable_dma(denali, true);

        denali_reset_irq(denali);
        denali_setup_dma(denali, dma_addr, page, write);

        /* wait for operation to complete */
        irq_status = denali_wait_for_irq(denali, irq_mask);
        if (!(irq_status & INTR__DMA_CMD_COMP))
                ret = -EIO;
        else if (irq_status & ecc_err_mask)
                ret = -EBADMSG;

        denali_enable_dma(denali, false);
        dma_unmap_single(denali->dev, dma_addr, size, dir);

        if (irq_status & INTR__ERASED_PAGE)
                memset(buf, 0xff, size);

        return ret;
}

static int denali_data_xfer(struct denali_nand_info *denali, void *buf,
                            size_t size, int page, int raw, int write)
{
        setup_ecc_for_xfer(denali, !raw, raw);

        if (denali->dma_avail)
                return denali_dma_xfer(denali, buf, size, page, raw, write);
        else
                return denali_pio_xfer(denali, buf, size, page, raw, write);
}

static void denali_oob_xfer(struct mtd_info *mtd, struct nand_chip *chip,
                            int page, int write)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        unsigned int start_cmd = write ? NAND_CMD_SEQIN : NAND_CMD_READ0;
        unsigned int rnd_cmd = write ? NAND_CMD_RNDIN : NAND_CMD_RNDOUT;
        int writesize = mtd->writesize;
        int oobsize = mtd->oobsize;
        uint8_t *bufpoi = chip->oob_poi;
        int ecc_steps = chip->ecc.steps;
        int ecc_size = chip->ecc.size;
        int ecc_bytes = chip->ecc.bytes;
        int oob_skip = denali->oob_skip_bytes;
        size_t size = writesize + oobsize;
        int i, pos, len;

        /* BBM at the beginning of the OOB area */
        chip->cmdfunc(mtd, start_cmd, writesize, page);
        if (write)
                chip->write_buf(mtd, bufpoi, oob_skip);
        else
                chip->read_buf(mtd, bufpoi, oob_skip);
        bufpoi += oob_skip;

        /* OOB ECC */
        for (i = 0; i < ecc_steps; i++) {
                pos = ecc_size + i * (ecc_size + ecc_bytes);
                len = ecc_bytes;

                if (pos >= writesize)
                        pos += oob_skip;
                else if (pos + len > writesize)
                        len = writesize - pos;

                chip->cmdfunc(mtd, rnd_cmd, pos, -1);
                if (write)
                        chip->write_buf(mtd, bufpoi, len);
                else
                        chip->read_buf(mtd, bufpoi, len);
                bufpoi += len;
                if (len < ecc_bytes) {
                        len = ecc_bytes - len;
                        chip->cmdfunc(mtd, rnd_cmd, writesize + oob_skip, -1);
                        if (write)
                                chip->write_buf(mtd, bufpoi, len);
                        else
                                chip->read_buf(mtd, bufpoi, len);
                        bufpoi += len;
                }
        }

        /* OOB free */
        len = oobsize - (bufpoi - chip->oob_poi);
        chip->cmdfunc(mtd, rnd_cmd, size - len, -1);
        if (write)
                chip->write_buf(mtd, bufpoi, len);
        else
                chip->read_buf(mtd, bufpoi, len);
}

static int denali_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf, int oob_required, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        int writesize = mtd->writesize;
        int oobsize = mtd->oobsize;
        int ecc_steps = chip->ecc.steps;
        int ecc_size = chip->ecc.size;
        int ecc_bytes = chip->ecc.bytes;
        void *dma_buf = denali->buf;
        int oob_skip = denali->oob_skip_bytes;
        size_t size = writesize + oobsize;
        int ret, i, pos, len;

        ret = denali_data_xfer(denali, dma_buf, size, page, 1, 0);
        if (ret)
                return ret;

        /* Arrange the buffer for syndrome payload/ecc layout */
        if (buf) {
                for (i = 0; i < ecc_steps; i++) {
                        pos = i * (ecc_size + ecc_bytes);
                        len = ecc_size;

                        if (pos >= writesize)
                                pos += oob_skip;
                        else if (pos + len > writesize)
                                len = writesize - pos;

                        memcpy(buf, dma_buf + pos, len);
                        buf += len;
                        if (len < ecc_size) {
                                len = ecc_size - len;
                                memcpy(buf, dma_buf + writesize + oob_skip,
                                       len);
                                buf += len;
                        }
                }
        }

        if (oob_required) {
                uint8_t *oob = chip->oob_poi;

                /* BBM at the beginning of the OOB area */
                memcpy(oob, dma_buf + writesize, oob_skip);
                oob += oob_skip;

                /* OOB ECC */
                for (i = 0; i < ecc_steps; i++) {
                        pos = ecc_size + i * (ecc_size + ecc_bytes);
                        len = ecc_bytes;

                        if (pos >= writesize)
                                pos += oob_skip;
                        else if (pos + len > writesize)
                                len = writesize - pos;

                        memcpy(oob, dma_buf + pos, len);
                        oob += len;
                        if (len < ecc_bytes) {
                                len = ecc_bytes - len;
                                memcpy(oob, dma_buf + writesize + oob_skip,
                                       len);
                                oob += len;
                        }
                }

                /* OOB free */
                len = oobsize - (oob - chip->oob_poi);
                memcpy(oob, dma_buf + size - len, len);
        }

        return 0;
}

static int denali_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
                           int page)
{
        denali_oob_xfer(mtd, chip, page, 0);

        return 0;
}

static int denali_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
                            int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        int status;

        denali_reset_irq(denali);

        denali_oob_xfer(mtd, chip, page, 1);

        chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
        status = chip->waitfunc(mtd, chip);

        return status & NAND_STATUS_FAIL ? -EIO : 0;
}

static int denali_read_page(struct mtd_info *mtd, struct nand_chip *chip,
                            uint8_t *buf, int oob_required, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        unsigned long uncor_ecc_flags = 0;
        int stat = 0;
        int ret;

        ret = denali_data_xfer(denali, buf, mtd->writesize, page, 0, 0);
        if (ret && ret != -EBADMSG)
                return ret;

        if (denali->caps & DENALI_CAP_HW_ECC_FIXUP)
                stat = denali_hw_ecc_fixup(mtd, denali, &uncor_ecc_flags);
        else if (ret == -EBADMSG)
                stat = denali_sw_ecc_fixup(mtd, denali, &uncor_ecc_flags, buf);

        if (stat < 0)
                return stat;

        if (uncor_ecc_flags) {
                ret = denali_read_oob(mtd, chip, page);
                if (ret)
                        return ret;

                stat = denali_check_erased_page(mtd, chip, buf,
                                                uncor_ecc_flags, stat);
        }

        return stat;
}

static int denali_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
                                 const uint8_t *buf, int oob_required, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        int writesize = mtd->writesize;
        int oobsize = mtd->oobsize;
        int ecc_steps = chip->ecc.steps;
        int ecc_size = chip->ecc.size;
        int ecc_bytes = chip->ecc.bytes;
        void *dma_buf = denali->buf;
        int oob_skip = denali->oob_skip_bytes;
        size_t size = writesize + oobsize;
        int i, pos, len;

        /*
         * Fill the buffer with 0xff first except the full page transfer.
         * This simplifies the logic.
         */
        if (!buf || !oob_required)
                memset(dma_buf, 0xff, size);

        /* Arrange the buffer for syndrome payload/ecc layout */
        if (buf) {
                for (i = 0; i < ecc_steps; i++) {
                        pos = i * (ecc_size + ecc_bytes);
                        len = ecc_size;

                        if (pos >= writesize)
                                pos += oob_skip;
                        else if (pos + len > writesize)
                                len = writesize - pos;

                        memcpy(dma_buf + pos, buf, len);
                        buf += len;
                        if (len < ecc_size) {
                                len = ecc_size - len;
                                memcpy(dma_buf + writesize + oob_skip, buf,
                                       len);
                                buf += len;
                        }
                }
        }

        if (oob_required) {
                const uint8_t *oob = chip->oob_poi;

                /* BBM at the beginning of the OOB area */
                memcpy(dma_buf + writesize, oob, oob_skip);
                oob += oob_skip;

                /* OOB ECC */
                for (i = 0; i < ecc_steps; i++) {
                        pos = ecc_size + i * (ecc_size + ecc_bytes);
                        len = ecc_bytes;

                        if (pos >= writesize)
                                pos += oob_skip;
                        else if (pos + len > writesize)
                                len = writesize - pos;

                        memcpy(dma_buf + pos, oob, len);
                        oob += len;
                        if (len < ecc_bytes) {
                                len = ecc_bytes - len;
                                memcpy(dma_buf + writesize + oob_skip, oob,
                                       len);
                                oob += len;
                        }
                }

                /* OOB free */
                len = oobsize - (oob - chip->oob_poi);
                memcpy(dma_buf + size - len, oob, len);
        }

        return denali_data_xfer(denali, dma_buf, size, page, 1, 1);
}

static int denali_write_page(struct mtd_info *mtd, struct nand_chip *chip,
                             const uint8_t *buf, int oob_required, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);

        return denali_data_xfer(denali, (void *)buf, mtd->writesize,
                                page, 0, 1);
}

static void denali_select_chip(struct mtd_info *mtd, int chip)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);

        denali->active_bank = chip;
}

static int denali_waitfunc(struct mtd_info *mtd, struct nand_chip *chip)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint32_t irq_status;

        /* R/B# pin transitioned from low to high? */
        irq_status = denali_wait_for_irq(denali, INTR__INT_ACT);

        return irq_status & INTR__INT_ACT ? 0 : NAND_STATUS_FAIL;
}

static int denali_erase(struct mtd_info *mtd, int page)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        uint32_t irq_status;

        denali_reset_irq(denali);

        denali_host_write(denali, DENALI_MAP10 | DENALI_BANK(denali) | page,
                          DENALI_ERASE);

        /* wait for erase to complete or failure to occur */
        irq_status = denali_wait_for_irq(denali,
                                         INTR__ERASE_COMP | INTR__ERASE_FAIL);

        return irq_status & INTR__ERASE_COMP ? 0 : NAND_STATUS_FAIL;
}

static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr,
                                       const struct nand_data_interface *conf)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        const struct nand_sdr_timings *timings;
        unsigned long t_clk;
        int acc_clks, re_2_we, re_2_re, we_2_re, addr_2_data;
        int rdwr_en_lo, rdwr_en_hi, rdwr_en_lo_hi, cs_setup;
        int addr_2_data_mask;
        uint32_t tmp;

        timings = nand_get_sdr_timings(conf);
        if (IS_ERR(timings))
                return PTR_ERR(timings);

        /* clk_x period in picoseconds */
        t_clk = DIV_ROUND_DOWN_ULL(1000000000000ULL, denali->clk_x_rate);
        if (!t_clk)

                return -EINVAL;

        if (chipnr == NAND_DATA_IFACE_CHECK_ONLY)
                return 0;

        /* tREA -> ACC_CLKS */
        acc_clks = DIV_ROUND_UP(timings->tREA_max, t_clk);
        acc_clks = min_t(int, acc_clks, ACC_CLKS__VALUE);

        tmp = ioread32(denali->reg + ACC_CLKS);
        tmp &= ~ACC_CLKS__VALUE;
        tmp |= acc_clks;
        iowrite32(tmp, denali->reg + ACC_CLKS);

        /* tRWH -> RE_2_WE */
        re_2_we = DIV_ROUND_UP(timings->tRHW_min, t_clk);
        re_2_we = min_t(int, re_2_we, RE_2_WE__VALUE);

        tmp = ioread32(denali->reg + RE_2_WE);
        tmp &= ~RE_2_WE__VALUE;
        tmp |= re_2_we;
        iowrite32(tmp, denali->reg + RE_2_WE);

        /* tRHZ -> RE_2_RE */
        re_2_re = DIV_ROUND_UP(timings->tRHZ_max, t_clk);
        re_2_re = min_t(int, re_2_re, RE_2_RE__VALUE);

        tmp = ioread32(denali->reg + RE_2_RE);
        tmp &= ~RE_2_RE__VALUE;
        tmp |= re_2_re;
        iowrite32(tmp, denali->reg + RE_2_RE);

        /* tWHR -> WE_2_RE */
        we_2_re = DIV_ROUND_UP(timings->tWHR_min, t_clk);
        we_2_re = min_t(int, we_2_re, TWHR2_AND_WE_2_RE__WE_2_RE);

        tmp = ioread32(denali->reg + TWHR2_AND_WE_2_RE);
        tmp &= ~TWHR2_AND_WE_2_RE__WE_2_RE;
        tmp |= we_2_re;
        iowrite32(tmp, denali->reg + TWHR2_AND_WE_2_RE);

        /* tADL -> ADDR_2_DATA */

        /* for older versions, ADDR_2_DATA is only 6 bit wide */
        addr_2_data_mask = TCWAW_AND_ADDR_2_DATA__ADDR_2_DATA;
        if (denali->revision < 0x0501)
                addr_2_data_mask >>= 1;

        addr_2_data = DIV_ROUND_UP(timings->tADL_min, t_clk);
        addr_2_data = min_t(int, addr_2_data, addr_2_data_mask);

        tmp = ioread32(denali->reg + TCWAW_AND_ADDR_2_DATA);
        tmp &= ~addr_2_data_mask;
        tmp |= addr_2_data;
        iowrite32(tmp, denali->reg + TCWAW_AND_ADDR_2_DATA);

        /* tREH, tWH -> RDWR_EN_HI_CNT */
        rdwr_en_hi = DIV_ROUND_UP(max(timings->tREH_min, timings->tWH_min),
                                  t_clk);
        rdwr_en_hi = min_t(int, rdwr_en_hi, RDWR_EN_HI_CNT__VALUE);

        tmp = ioread32(denali->reg + RDWR_EN_HI_CNT);
        tmp &= ~RDWR_EN_HI_CNT__VALUE;
        tmp |= rdwr_en_hi;
        iowrite32(tmp, denali->reg + RDWR_EN_HI_CNT);

        /* tRP, tWP -> RDWR_EN_LO_CNT */
        rdwr_en_lo = DIV_ROUND_UP(max(timings->tRP_min, timings->tWP_min),
                                  t_clk);
        rdwr_en_lo_hi = DIV_ROUND_UP(max(timings->tRC_min, timings->tWC_min),
                                     t_clk);
        rdwr_en_lo_hi = max(rdwr_en_lo_hi, DENALI_CLK_X_MULT);
        rdwr_en_lo = max(rdwr_en_lo, rdwr_en_lo_hi - rdwr_en_hi);
        rdwr_en_lo = min_t(int, rdwr_en_lo, RDWR_EN_LO_CNT__VALUE);

        tmp = ioread32(denali->reg + RDWR_EN_LO_CNT);
        tmp &= ~RDWR_EN_LO_CNT__VALUE;
        tmp |= rdwr_en_lo;
        iowrite32(tmp, denali->reg + RDWR_EN_LO_CNT);

        /* tCS, tCEA -> CS_SETUP_CNT */
        cs_setup = max3((int)DIV_ROUND_UP(timings->tCS_min, t_clk) - rdwr_en_lo,
                        (int)DIV_ROUND_UP(timings->tCEA_max, t_clk) - acc_clks,
                        0);
        cs_setup = min_t(int, cs_setup, CS_SETUP_CNT__VALUE);

        tmp = ioread32(denali->reg + CS_SETUP_CNT);
        tmp &= ~CS_SETUP_CNT__VALUE;
        tmp |= cs_setup;
        iowrite32(tmp, denali->reg + CS_SETUP_CNT);

        return 0;
}

static void denali_reset_banks(struct denali_nand_info *denali)
{
        u32 irq_status;
        int i;

        for (i = 0; i < denali->max_banks; i++) {
                denali->active_bank = i;

                denali_reset_irq(denali);

                iowrite32(DEVICE_RESET__BANK(i),
                          denali->reg + DEVICE_RESET);

                irq_status = denali_wait_for_irq(denali,
                        INTR__RST_COMP | INTR__INT_ACT | INTR__TIME_OUT);
                if (!(irq_status & INTR__INT_ACT))
                        break;
        }

        dev_dbg(denali->dev, "%d chips connected\n", i);
        denali->max_banks = i;
}

static void denali_hw_init(struct denali_nand_info *denali)
{
        /*
         * The REVISION register may not be reliable.  Platforms are allowed to
         * override it.
         */
        if (!denali->revision)
                denali->revision = swab16(ioread32(denali->reg + REVISION));

        /*
         * tell driver how many bit controller will skip before
         * writing ECC code in OOB, this register may be already
         * set by firmware. So we read this value out.
         * if this value is 0, just let it be.
         */
        denali->oob_skip_bytes = ioread32(denali->reg + SPARE_AREA_SKIP_BYTES);
        detect_max_banks(denali);
        iowrite32(0x0F, denali->reg + RB_PIN_ENABLED);
        iowrite32(CHIP_EN_DONT_CARE__FLAG, denali->reg + CHIP_ENABLE_DONT_CARE);

        iowrite32(0xffff, denali->reg + SPARE_AREA_MARKER);

        /* Should set value for these registers when init */
        iowrite32(0, denali->reg + TWO_ROW_ADDR_CYCLES);
        iowrite32(1, denali->reg + ECC_ENABLE);
}

int denali_calc_ecc_bytes(int step_size, int strength)
{
        /* BCH code.  Denali requires ecc.bytes to be multiple of 2 */
        return DIV_ROUND_UP(strength * fls(step_size * 8), 16) * 2;
}
EXPORT_SYMBOL(denali_calc_ecc_bytes);

static int denali_ecc_setup(struct mtd_info *mtd, struct nand_chip *chip,
                            struct denali_nand_info *denali)
{
        int oobavail = mtd->oobsize - denali->oob_skip_bytes;
        int ret;

        /*
         * If .size and .strength are already set (usually by DT),
         * check if they are supported by this controller.
         */
        if (chip->ecc.size && chip->ecc.strength)
                return nand_check_ecc_caps(chip, denali->ecc_caps, oobavail);

        /*
         * We want .size and .strength closest to the chip's requirement
         * unless NAND_ECC_MAXIMIZE is requested.
         */
        if (!(chip->ecc.options & NAND_ECC_MAXIMIZE)) {
                ret = nand_match_ecc_req(chip, denali->ecc_caps, oobavail);
                if (!ret)
                        return 0;
        }

        /* Max ECC strength is the last thing we can do */
        return nand_maximize_ecc(chip, denali->ecc_caps, oobavail);
}

static int denali_ooblayout_ecc(struct mtd_info *mtd, int section,
                                struct mtd_oob_region *oobregion)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (section)
                return -ERANGE;

        oobregion->offset = denali->oob_skip_bytes;
        oobregion->length = chip->ecc.total;

        return 0;
}

static int denali_ooblayout_free(struct mtd_info *mtd, int section,
                                 struct mtd_oob_region *oobregion)
{
        struct denali_nand_info *denali = mtd_to_denali(mtd);
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (section)
                return -ERANGE;

        oobregion->offset = chip->ecc.total + denali->oob_skip_bytes;
        oobregion->length = mtd->oobsize - oobregion->offset;

        return 0;
}

static const struct mtd_ooblayout_ops denali_ooblayout_ops = {
        .ecc = denali_ooblayout_ecc,
        .free = denali_ooblayout_free,
};

/* initialize driver data structures */
static void denali_drv_init(struct denali_nand_info *denali)
{
        /*
         * the completion object will be used to notify
         * the callee that the interrupt is done
         */
        init_completion(&denali->complete);

        /*
         * the spinlock will be used to synchronize the ISR with any
         * element that might be access shared data (interrupt status)
         */
        spin_lock_init(&denali->irq_lock);
}

static int denali_multidev_fixup(struct denali_nand_info *denali)
{
        struct nand_chip *chip = &denali->nand;
        struct mtd_info *mtd = nand_to_mtd(chip);

        /*
         * Support for multi device:
         * When the IP configuration is x16 capable and two x8 chips are
         * connected in parallel, DEVICES_CONNECTED should be set to 2.
         * In this case, the core framework knows nothing about this fact,
         * so we should tell it the _logical_ pagesize and anything necessary.
         */
        denali->devs_per_cs = ioread32(denali->reg + DEVICES_CONNECTED);

        /*
         * On some SoCs, DEVICES_CONNECTED is not auto-detected.
         * For those, DEVICES_CONNECTED is left to 0.  Set 1 if it is the case.
         */
        if (denali->devs_per_cs == 0) {
                denali->devs_per_cs = 1;
                iowrite32(1, denali->reg + DEVICES_CONNECTED);
        }

        if (denali->devs_per_cs == 1)
                return 0;

        if (denali->devs_per_cs != 2) {
                dev_err(denali->dev, "unsupported number of devices %d\n",
                        denali->devs_per_cs);
                return -EINVAL;
        }

        /* 2 chips in parallel */
        mtd->size <<= 1;
        mtd->erasesize <<= 1;
        mtd->writesize <<= 1;
        mtd->oobsize <<= 1;
        chip->chipsize <<= 1;
        chip->page_shift += 1;
        chip->phys_erase_shift += 1;
        chip->bbt_erase_shift += 1;
        chip->chip_shift += 1;
        chip->pagemask <<= 1;
        chip->ecc.size <<= 1;
        chip->ecc.bytes <<= 1;
        chip->ecc.strength <<= 1;
        denali->oob_skip_bytes <<= 1;

        return 0;
}

int denali_init(struct denali_nand_info *denali)
{
        struct nand_chip *chip = &denali->nand;
        struct mtd_info *mtd = nand_to_mtd(chip);
        int ret;

        mtd->dev.parent = denali->dev;
        denali_hw_init(denali);
        denali_drv_init(denali);

        denali_clear_irq_all(denali);

        /* Request IRQ after all the hardware initialization is finished */
        ret = devm_request_irq(denali->dev, denali->irq, denali_isr,
                               IRQF_SHARED, DENALI_NAND_NAME, denali);
        if (ret) {
                dev_err(denali->dev, "Unable to request IRQ\n");
                return ret;
        }

        denali_enable_irq(denali);
        denali_reset_banks(denali);

        denali->active_bank = DENALI_INVALID_BANK;

        nand_set_flash_node(chip, denali->dev->of_node);
        /* Fallback to the default name if DT did not give "label" property */
        if (!mtd->name)
                mtd->name = "denali-nand";

        /* register the driver with the NAND core subsystem */
        chip->select_chip = denali_select_chip;
        chip->read_byte = denali_read_byte;
        chip->write_byte = denali_write_byte;
        chip->read_word = denali_read_word;
        chip->cmd_ctrl = denali_cmd_ctrl;
        chip->dev_ready = denali_dev_ready;
        chip->waitfunc = denali_waitfunc;

        /* clk rate info is needed for setup_data_interface */
        if (denali->clk_x_rate)
                chip->setup_data_interface = denali_setup_data_interface;

        /*
         * scan for NAND devices attached to the controller
         * this is the first stage in a two step process to register
         * with the nand subsystem
         */
        ret = nand_scan_ident(mtd, denali->max_banks, NULL);
        if (ret)
                goto disable_irq;

        if (ioread32(denali->reg + FEATURES) & FEATURES__DMA)
                denali->dma_avail = 1;

        if (denali->dma_avail) {
                int dma_bit = denali->caps & DENALI_CAP_DMA_64BIT ? 64 : 32;

                ret = dma_set_mask(denali->dev, DMA_BIT_MASK(dma_bit));
                if (ret) {
                        dev_info(denali->dev,
                                 "Failed to set DMA mask. Disabling DMA.\n");
                        denali->dma_avail = 0;
                }
        }

        if (denali->dma_avail) {
                chip->options |= NAND_USE_BOUNCE_BUFFER;
                chip->buf_align = 16;
        }

        /*
         * second stage of the NAND scan
         * this stage requires information regarding ECC and
         * bad block management.
         */

        chip->bbt_options |= NAND_BBT_USE_FLASH;
        chip->bbt_options |= NAND_BBT_NO_OOB;

        chip->ecc.mode = NAND_ECC_HW_SYNDROME;

        /* no subpage writes on denali */
        chip->options |= NAND_NO_SUBPAGE_WRITE;

        ret = denali_ecc_setup(mtd, chip, denali);
        if (ret) {
                dev_err(denali->dev, "Failed to setup ECC settings.\n");
                goto disable_irq;
        }

        dev_dbg(denali->dev,
                "chosen ECC settings: step=%d, strength=%d, bytes=%d\n",
                chip->ecc.size, chip->ecc.strength, chip->ecc.bytes);

        iowrite32(MAKE_ECC_CORRECTION(chip->ecc.strength, 1),
                  denali->reg + ECC_CORRECTION);
        iowrite32(mtd->erasesize / mtd->writesize,
                  denali->reg + PAGES_PER_BLOCK);
        iowrite32(chip->options & NAND_BUSWIDTH_16 ? 1 : 0,
                  denali->reg + DEVICE_WIDTH);
        iowrite32(mtd->writesize, denali->reg + DEVICE_MAIN_AREA_SIZE);
        iowrite32(mtd->oobsize, denali->reg + DEVICE_SPARE_AREA_SIZE);

        iowrite32(chip->ecc.size, denali->reg + CFG_DATA_BLOCK_SIZE);
        iowrite32(chip->ecc.size, denali->reg + CFG_LAST_DATA_BLOCK_SIZE);
        /* chip->ecc.steps is set by nand_scan_tail(); not available here */
        iowrite32(mtd->writesize / chip->ecc.size,
                  denali->reg + CFG_NUM_DATA_BLOCKS);

        mtd_set_ooblayout(mtd, &denali_ooblayout_ops);

        if (chip->options & NAND_BUSWIDTH_16) {
                chip->read_buf = denali_read_buf16;
                chip->write_buf = denali_write_buf16;
        } else {
                chip->read_buf = denali_read_buf;
                chip->write_buf = denali_write_buf;
        }
        chip->ecc.options |= NAND_ECC_CUSTOM_PAGE_ACCESS;
        chip->ecc.read_page = denali_read_page;
        chip->ecc.read_page_raw = denali_read_page_raw;
        chip->ecc.write_page = denali_write_page;
        chip->ecc.write_page_raw = denali_write_page_raw;
        chip->ecc.read_oob = denali_read_oob;
        chip->ecc.write_oob = denali_write_oob;
        chip->erase = denali_erase;

        ret = denali_multidev_fixup(denali);
        if (ret)
                goto disable_irq;

        /*
         * This buffer is DMA-mapped by denali_{read,write}_page_raw.  Do not
         * use devm_kmalloc() because the memory allocated by devm_ does not
         * guarantee DMA-safe alignment.
         */
        denali->buf = kmalloc(mtd->writesize + mtd->oobsize, GFP_KERNEL);
        if (!denali->buf) {
                ret = -ENOMEM;
                goto disable_irq;
        }

        ret = nand_scan_tail(mtd);
        if (ret)
                goto free_buf;

        ret = mtd_device_register(mtd, NULL, 0);
        if (ret) {
                dev_err(denali->dev, "Failed to register MTD: %d\n", ret);
                goto free_buf;
        }
        return 0;

free_buf:
        kfree(denali->buf);
disable_irq:
        denali_disable_irq(denali);

        return ret;
}
EXPORT_SYMBOL(denali_init);

/* driver exit point */
void denali_remove(struct denali_nand_info *denali)
{
        struct mtd_info *mtd = nand_to_mtd(&denali->nand);

        nand_release(mtd);
        kfree(denali->buf);
        denali_disable_irq(denali);
}
EXPORT_SYMBOL(denali_remove);