/*
 *  Copyright © 2003 Rick Bronson
 *
 *  Derived from drivers/mtd/nand/autcpu12.c
 *       Copyright © 2001 Thomas Gleixner (gleixner@autronix.de)
 *
 *  Derived from drivers/mtd/spia.c
 *       Copyright © 2000 Steven J. Hill (sjhill@cotw.com)
 *
 *
 *  Add Hardware ECC support for AT91SAM9260 / AT91SAM9263
 *     Richard Genoud (richard.genoud@gmail.com), Adeneo Copyright © 2007
 *
 *     Derived from Das U-Boot source code
 *              (u-boot-1.1.5/board/atmel/at91sam9263ek/nand.c)
 *     © Copyright 2006 ATMEL Rousset, Lacressonniere Nicolas
 *
 *  Add Programmable Multibit ECC support for various AT91 SoC
 *     © Copyright 2012 ATMEL, Hong Xu
 *
 *  Add Nand Flash Controller support for SAMA5 SoC
 *     © Copyright 2013 ATMEL, Josh Wu (josh.wu@atmel.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/of_mtd.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>

#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/platform_data/atmel.h>

static int use_dma = 1;
module_param(use_dma, int, 0);

static int on_flash_bbt = 0;
module_param(on_flash_bbt, int, 0);

/* Register access macros */
#define ecc_readl(add, reg)                             \
        __raw_readl(add + ATMEL_ECC_##reg)
#define ecc_writel(add, reg, value)                     \
        __raw_writel((value), add + ATMEL_ECC_##reg)

#include "atmel_nand_ecc.h"     /* Hardware ECC registers */
#include "atmel_nand_nfc.h"     /* Nand Flash Controller definition */

struct atmel_nand_caps {
        bool pmecc_correct_erase_page;
        uint8_t pmecc_max_correction;
};

struct atmel_nand_nfc_caps {
        uint32_t rb_mask;
};

/* oob layout for large page size
 * bad block info is on bytes 0 and 1
 * the bytes have to be consecutives to avoid
 * several NAND_CMD_RNDOUT during read
 */
static struct nand_ecclayout atmel_oobinfo_large = {
        .eccbytes = 4,
        .eccpos = {60, 61, 62, 63},
        .oobfree = {
                {2, 58}
        },
};

/* oob layout for small page size
 * bad block info is on bytes 4 and 5
 * the bytes have to be consecutives to avoid
 * several NAND_CMD_RNDOUT during read
 */
static struct nand_ecclayout atmel_oobinfo_small = {
        .eccbytes = 4,
        .eccpos = {0, 1, 2, 3},
        .oobfree = {
                {6, 10}
        },
};

struct atmel_nfc {
        void __iomem            *base_cmd_regs;
        void __iomem            *hsmc_regs;
        void                    *sram_bank0;
        dma_addr_t              sram_bank0_phys;
        bool                    use_nfc_sram;
        bool                    write_by_sram;

        struct clk              *clk;

        bool                    is_initialized;
        struct completion       comp_ready;
        struct completion       comp_cmd_done;
        struct completion       comp_xfer_done;

        /* Point to the sram bank which include readed data via NFC */
        void                    *data_in_sram;
        bool                    will_write_sram;
        const struct atmel_nand_nfc_caps *caps;
};
static struct atmel_nfc nand_nfc;

struct atmel_nand_host {
        struct nand_chip        nand_chip;
        void __iomem            *io_base;
        dma_addr_t              io_phys;
        struct atmel_nand_data  board;
        struct device           *dev;
        void __iomem            *ecc;

        struct completion       comp;
        struct dma_chan         *dma_chan;

        struct atmel_nfc        *nfc;

        const struct atmel_nand_caps    *caps;
        bool                    has_pmecc;
        u8                      pmecc_corr_cap;
        u16                     pmecc_sector_size;
        bool                    has_no_lookup_table;
        u32                     pmecc_lookup_table_offset;
        u32                     pmecc_lookup_table_offset_512;
        u32                     pmecc_lookup_table_offset_1024;

        int                     pmecc_degree;   /* Degree of remainders */
        int                     pmecc_cw_len;   /* Length of codeword */

        void __iomem            *pmerrloc_base;
        void __iomem            *pmerrloc_el_base;
        void __iomem            *pmecc_rom_base;

        /* lookup table for alpha_to and index_of */
        void __iomem            *pmecc_alpha_to;
        void __iomem            *pmecc_index_of;

        /* data for pmecc computation */
        int16_t                 *pmecc_partial_syn;
        int16_t                 *pmecc_si;
        int16_t                 *pmecc_smu;     /* Sigma table */
        int16_t                 *pmecc_lmu;     /* polynomal order */
        int                     *pmecc_mu;
        int                     *pmecc_dmu;
        int                     *pmecc_delta;
};

static struct nand_ecclayout atmel_pmecc_oobinfo;

/*
 * Enable NAND.
 */
static void atmel_nand_enable(struct atmel_nand_host *host)
{
        if (gpio_is_valid(host->board.enable_pin))
                gpio_set_value(host->board.enable_pin, 0);
}

/*
 * Disable NAND.
 */
static void atmel_nand_disable(struct atmel_nand_host *host)
{
        if (gpio_is_valid(host->board.enable_pin))
                gpio_set_value(host->board.enable_pin, 1);
}

/*
 * Hardware specific access to control-lines
 */
static void atmel_nand_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        if (ctrl & NAND_CTRL_CHANGE) {
                if (ctrl & NAND_NCE)
                        atmel_nand_enable(host);
                else
                        atmel_nand_disable(host);
        }
        if (cmd == NAND_CMD_NONE)
                return;

        if (ctrl & NAND_CLE)
                writeb(cmd, host->io_base + (1 << host->board.cle));
        else
                writeb(cmd, host->io_base + (1 << host->board.ale));
}

/*
 * Read the Device Ready pin.
 */
static int atmel_nand_device_ready(struct mtd_info *mtd)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        return gpio_get_value(host->board.rdy_pin) ^
                !!host->board.rdy_pin_active_low;
}

/* Set up for hardware ready pin and enable pin. */
static int atmel_nand_set_enable_ready_pins(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        int res = 0;

        if (gpio_is_valid(host->board.rdy_pin)) {
                res = devm_gpio_request(host->dev,
                                host->board.rdy_pin, "nand_rdy");
                if (res < 0) {
                        dev_err(host->dev,
                                "can't request rdy gpio %d\n",
                                host->board.rdy_pin);
                        return res;
                }

                res = gpio_direction_input(host->board.rdy_pin);
                if (res < 0) {
                        dev_err(host->dev,
                                "can't request input direction rdy gpio %d\n",
                                host->board.rdy_pin);
                        return res;
                }

                chip->dev_ready = atmel_nand_device_ready;
        }

        if (gpio_is_valid(host->board.enable_pin)) {
                res = devm_gpio_request(host->dev,
                                host->board.enable_pin, "nand_enable");
                if (res < 0) {
                        dev_err(host->dev,
                                "can't request enable gpio %d\n",
                                host->board.enable_pin);
                        return res;
                }

                res = gpio_direction_output(host->board.enable_pin, 1);
                if (res < 0) {
                        dev_err(host->dev,
                                "can't request output direction enable gpio %d\n",
                                host->board.enable_pin);
                        return res;
                }
        }

        return res;
}

/*
 * Minimal-overhead PIO for data access.
 */
static void atmel_read_buf8(struct mtd_info *mtd, u8 *buf, int len)
{
        struct nand_chip        *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        if (host->nfc && host->nfc->use_nfc_sram && host->nfc->data_in_sram) {
                memcpy(buf, host->nfc->data_in_sram, len);
                host->nfc->data_in_sram += len;
        } else {
                __raw_readsb(nand_chip->IO_ADDR_R, buf, len);
        }
}

static void atmel_read_buf16(struct mtd_info *mtd, u8 *buf, int len)
{
        struct nand_chip        *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        if (host->nfc && host->nfc->use_nfc_sram && host->nfc->data_in_sram) {
                memcpy(buf, host->nfc->data_in_sram, len);
                host->nfc->data_in_sram += len;
        } else {
                __raw_readsw(nand_chip->IO_ADDR_R, buf, len / 2);
        }
}

static void atmel_write_buf8(struct mtd_info *mtd, const u8 *buf, int len)
{
        struct nand_chip        *nand_chip = mtd_to_nand(mtd);

        __raw_writesb(nand_chip->IO_ADDR_W, buf, len);
}

static void atmel_write_buf16(struct mtd_info *mtd, const u8 *buf, int len)
{
        struct nand_chip        *nand_chip = mtd_to_nand(mtd);

        __raw_writesw(nand_chip->IO_ADDR_W, buf, len / 2);
}

static void dma_complete_func(void *completion)
{
        complete(completion);
}

static int nfc_set_sram_bank(struct atmel_nand_host *host, unsigned int bank)
{
        /* NFC only has two banks. Must be 0 or 1 */
        if (bank > 1)
                return -EINVAL;

        if (bank) {
                struct mtd_info *mtd = nand_to_mtd(&host->nand_chip);

                /* Only for a 2k-page or lower flash, NFC can handle 2 banks */
                if (mtd->writesize > 2048)
                        return -EINVAL;
                nfc_writel(host->nfc->hsmc_regs, BANK, ATMEL_HSMC_NFC_BANK1);
        } else {
                nfc_writel(host->nfc->hsmc_regs, BANK, ATMEL_HSMC_NFC_BANK0);
        }

        return 0;
}

static uint nfc_get_sram_off(struct atmel_nand_host *host)
{
        if (nfc_readl(host->nfc->hsmc_regs, BANK) & ATMEL_HSMC_NFC_BANK1)
                return NFC_SRAM_BANK1_OFFSET;
        else
                return 0;
}

static dma_addr_t nfc_sram_phys(struct atmel_nand_host *host)
{
        if (nfc_readl(host->nfc->hsmc_regs, BANK) & ATMEL_HSMC_NFC_BANK1)
                return host->nfc->sram_bank0_phys + NFC_SRAM_BANK1_OFFSET;
        else
                return host->nfc->sram_bank0_phys;
}

static int atmel_nand_dma_op(struct mtd_info *mtd, void *buf, int len,
                               int is_read)
{
        struct dma_device *dma_dev;
        enum dma_ctrl_flags flags;
        dma_addr_t dma_src_addr, dma_dst_addr, phys_addr;
        struct dma_async_tx_descriptor *tx = NULL;
        dma_cookie_t cookie;
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        void *p = buf;
        int err = -EIO;
        enum dma_data_direction dir = is_read ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
        struct atmel_nfc *nfc = host->nfc;

        if (buf >= high_memory)
                goto err_buf;

        dma_dev = host->dma_chan->device;

        flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;

        phys_addr = dma_map_single(dma_dev->dev, p, len, dir);
        if (dma_mapping_error(dma_dev->dev, phys_addr)) {
                dev_err(host->dev, "Failed to dma_map_single\n");
                goto err_buf;
        }

        if (is_read) {
                if (nfc && nfc->data_in_sram)
                        dma_src_addr = nfc_sram_phys(host) + (nfc->data_in_sram
                                - (nfc->sram_bank0 + nfc_get_sram_off(host)));
                else
                        dma_src_addr = host->io_phys;

                dma_dst_addr = phys_addr;
        } else {
                dma_src_addr = phys_addr;

                if (nfc && nfc->write_by_sram)
                        dma_dst_addr = nfc_sram_phys(host);
                else
                        dma_dst_addr = host->io_phys;
        }

        tx = dma_dev->device_prep_dma_memcpy(host->dma_chan, dma_dst_addr,
                                             dma_src_addr, len, flags);
        if (!tx) {
                dev_err(host->dev, "Failed to prepare DMA memcpy\n");
                goto err_dma;
        }

        init_completion(&host->comp);
        tx->callback = dma_complete_func;
        tx->callback_param = &host->comp;

        cookie = tx->tx_submit(tx);
        if (dma_submit_error(cookie)) {
                dev_err(host->dev, "Failed to do DMA tx_submit\n");
                goto err_dma;
        }

        dma_async_issue_pending(host->dma_chan);
        wait_for_completion(&host->comp);

        if (is_read && nfc && nfc->data_in_sram)
                /* After read data from SRAM, need to increase the position */
                nfc->data_in_sram += len;

        err = 0;

err_dma:
        dma_unmap_single(dma_dev->dev, phys_addr, len, dir);
err_buf:
        if (err != 0)
                dev_dbg(host->dev, "Fall back to CPU I/O\n");
        return err;
}

static void atmel_read_buf(struct mtd_info *mtd, u8 *buf, int len)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(chip);

        if (use_dma && len > mtd->oobsize)
                /* only use DMA for bigger than oob size: better performances */
                if (atmel_nand_dma_op(mtd, buf, len, 1) == 0)
                        return;

        if (host->board.bus_width_16)
                atmel_read_buf16(mtd, buf, len);
        else
                atmel_read_buf8(mtd, buf, len);
}

static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(chip);

        if (use_dma && len > mtd->oobsize)
                /* only use DMA for bigger than oob size: better performances */
                if (atmel_nand_dma_op(mtd, (void *)buf, len, 0) == 0)
                        return;

        if (host->board.bus_width_16)
                atmel_write_buf16(mtd, buf, len);
        else
                atmel_write_buf8(mtd, buf, len);
}

/*
 * Return number of ecc bytes per sector according to sector size and
 * correction capability
 *
 * Following table shows what at91 PMECC supported:
 * Correction Capability        Sector_512_bytes        Sector_1024_bytes
 * =====================        ================        =================
 *                2-bits                 4-bytes                  4-bytes
 *                4-bits                 7-bytes                  7-bytes
 *                8-bits                13-bytes                 14-bytes
 *               12-bits                20-bytes                 21-bytes
 *               24-bits                39-bytes                 42-bytes
 *               32-bits                52-bytes                 56-bytes
 */
static int pmecc_get_ecc_bytes(int cap, int sector_size)
{
        int m = 12 + sector_size / 512;
        return (m * cap + 7) / 8;
}

static void pmecc_config_ecc_layout(struct nand_ecclayout *layout,
                                    int oobsize, int ecc_len)
{
        int i;

        layout->eccbytes = ecc_len;

        /* ECC will occupy the last ecc_len bytes continuously */
        for (i = 0; i < ecc_len; i++)
                layout->eccpos[i] = oobsize - ecc_len + i;

        layout->oobfree[0].offset = PMECC_OOB_RESERVED_BYTES;
        layout->oobfree[0].length =
                oobsize - ecc_len - layout->oobfree[0].offset;
}

static void __iomem *pmecc_get_alpha_to(struct atmel_nand_host *host)
{
        int table_size;

        table_size = host->pmecc_sector_size == 512 ?
                PMECC_LOOKUP_TABLE_SIZE_512 : PMECC_LOOKUP_TABLE_SIZE_1024;

        return host->pmecc_rom_base + host->pmecc_lookup_table_offset +
                        table_size * sizeof(int16_t);
}

static int pmecc_data_alloc(struct atmel_nand_host *host)
{
        const int cap = host->pmecc_corr_cap;
        int size;

        size = (2 * cap + 1) * sizeof(int16_t);
        host->pmecc_partial_syn = devm_kzalloc(host->dev, size, GFP_KERNEL);
        host->pmecc_si = devm_kzalloc(host->dev, size, GFP_KERNEL);
        host->pmecc_lmu = devm_kzalloc(host->dev,
                        (cap + 1) * sizeof(int16_t), GFP_KERNEL);
        host->pmecc_smu = devm_kzalloc(host->dev,
                        (cap + 2) * size, GFP_KERNEL);

        size = (cap + 1) * sizeof(int);
        host->pmecc_mu = devm_kzalloc(host->dev, size, GFP_KERNEL);
        host->pmecc_dmu = devm_kzalloc(host->dev, size, GFP_KERNEL);
        host->pmecc_delta = devm_kzalloc(host->dev, size, GFP_KERNEL);

        if (!host->pmecc_partial_syn ||
                !host->pmecc_si ||
                !host->pmecc_lmu ||
                !host->pmecc_smu ||
                !host->pmecc_mu ||
                !host->pmecc_dmu ||
                !host->pmecc_delta)
                return -ENOMEM;

        return 0;
}

static void pmecc_gen_syndrome(struct mtd_info *mtd, int sector)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        int i;
        uint32_t value;

        /* Fill odd syndromes */
        for (i = 0; i < host->pmecc_corr_cap; i++) {
                value = pmecc_readl_rem_relaxed(host->ecc, sector, i / 2);
                if (i & 1)
                        value >>= 16;
                value &= 0xffff;
                host->pmecc_partial_syn[(2 * i) + 1] = (int16_t)value;
        }
}

static void pmecc_substitute(struct mtd_info *mtd)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        int16_t __iomem *alpha_to = host->pmecc_alpha_to;
        int16_t __iomem *index_of = host->pmecc_index_of;
        int16_t *partial_syn = host->pmecc_partial_syn;
        const int cap = host->pmecc_corr_cap;
        int16_t *si;
        int i, j;

        /* si[] is a table that holds the current syndrome value,
         * an element of that table belongs to the field
         */
        si = host->pmecc_si;

        memset(&si[1], 0, sizeof(int16_t) * (2 * cap - 1));

        /* Computation 2t syndromes based on S(x) */
        /* Odd syndromes */
        for (i = 1; i < 2 * cap; i += 2) {
                for (j = 0; j < host->pmecc_degree; j++) {
                        if (partial_syn[i] & ((unsigned short)0x1 << j))
                                si[i] = readw_relaxed(alpha_to + i * j) ^ si[i];
                }
        }
        /* Even syndrome = (Odd syndrome) ** 2 */
        for (i = 2, j = 1; j <= cap; i = ++j << 1) {
                if (si[j] == 0) {
                        si[i] = 0;
                } else {
                        int16_t tmp;

                        tmp = readw_relaxed(index_of + si[j]);
                        tmp = (tmp * 2) % host->pmecc_cw_len;
                        si[i] = readw_relaxed(alpha_to + tmp);
                }
        }

        return;
}

static void pmecc_get_sigma(struct mtd_info *mtd)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        int16_t *lmu = host->pmecc_lmu;
        int16_t *si = host->pmecc_si;
        int *mu = host->pmecc_mu;
        int *dmu = host->pmecc_dmu;     /* Discrepancy */
        int *delta = host->pmecc_delta; /* Delta order */
        int cw_len = host->pmecc_cw_len;
        const int16_t cap = host->pmecc_corr_cap;
        const int num = 2 * cap + 1;
        int16_t __iomem *index_of = host->pmecc_index_of;
        int16_t __iomem *alpha_to = host->pmecc_alpha_to;
        int i, j, k;
        uint32_t dmu_0_count, tmp;
        int16_t *smu = host->pmecc_smu;

        /* index of largest delta */
        int ro;
        int largest;
        int diff;

        dmu_0_count = 0;

        /* First Row */

        /* Mu */
        mu[0] = -1;

        memset(smu, 0, sizeof(int16_t) * num);
        smu[0] = 1;

        /* discrepancy set to 1 */
        dmu[0] = 1;
        /* polynom order set to 0 */
        lmu[0] = 0;
        delta[0] = (mu[0] * 2 - lmu[0]) >> 1;

        /* Second Row */

        /* Mu */
        mu[1] = 0;
        /* Sigma(x) set to 1 */
        memset(&smu[num], 0, sizeof(int16_t) * num);
        smu[num] = 1;

        /* discrepancy set to S1 */
        dmu[1] = si[1];

        /* polynom order set to 0 */
        lmu[1] = 0;

        delta[1] = (mu[1] * 2 - lmu[1]) >> 1;

        /* Init the Sigma(x) last row */
        memset(&smu[(cap + 1) * num], 0, sizeof(int16_t) * num);

        for (i = 1; i <= cap; i++) {
                mu[i + 1] = i << 1;
                /* Begin Computing Sigma (Mu+1) and L(mu) */
                /* check if discrepancy is set to 0 */
                if (dmu[i] == 0) {
                        dmu_0_count++;

                        tmp = ((cap - (lmu[i] >> 1) - 1) / 2);
                        if ((cap - (lmu[i] >> 1) - 1) & 0x1)
                                tmp += 2;
                        else
                                tmp += 1;

                        if (dmu_0_count == tmp) {
                                for (j = 0; j <= (lmu[i] >> 1) + 1; j++)
                                        smu[(cap + 1) * num + j] =
                                                        smu[i * num + j];

                                lmu[cap + 1] = lmu[i];
                                return;
                        }

                        /* copy polynom */
                        for (j = 0; j <= lmu[i] >> 1; j++)
                                smu[(i + 1) * num + j] = smu[i * num + j];

                        /* copy previous polynom order to the next */
                        lmu[i + 1] = lmu[i];
                } else {
                        ro = 0;
                        largest = -1;
                        /* find largest delta with dmu != 0 */
                        for (j = 0; j < i; j++) {
                                if ((dmu[j]) && (delta[j] > largest)) {
                                        largest = delta[j];
                                        ro = j;
                                }
                        }

                        /* compute difference */
                        diff = (mu[i] - mu[ro]);

                        /* Compute degree of the new smu polynomial */
                        if ((lmu[i] >> 1) > ((lmu[ro] >> 1) + diff))
                                lmu[i + 1] = lmu[i];
                        else
                                lmu[i + 1] = ((lmu[ro] >> 1) + diff) * 2;

                        /* Init smu[i+1] with 0 */
                        for (k = 0; k < num; k++)
                                smu[(i + 1) * num + k] = 0;

                        /* Compute smu[i+1] */
                        for (k = 0; k <= lmu[ro] >> 1; k++) {
                                int16_t a, b, c;

                                if (!(smu[ro * num + k] && dmu[i]))
                                        continue;
                                a = readw_relaxed(index_of + dmu[i]);
                                b = readw_relaxed(index_of + dmu[ro]);
                                c = readw_relaxed(index_of + smu[ro * num + k]);
                                tmp = a + (cw_len - b) + c;
                                a = readw_relaxed(alpha_to + tmp % cw_len);
                                smu[(i + 1) * num + (k + diff)] = a;
                        }

                        for (k = 0; k <= lmu[i] >> 1; k++)
                                smu[(i + 1) * num + k] ^= smu[i * num + k];
                }

                /* End Computing Sigma (Mu+1) and L(mu) */
                /* In either case compute delta */
                delta[i + 1] = (mu[i + 1] * 2 - lmu[i + 1]) >> 1;

                /* Do not compute discrepancy for the last iteration */
                if (i >= cap)
                        continue;

                for (k = 0; k <= (lmu[i + 1] >> 1); k++) {
                        tmp = 2 * (i - 1);
                        if (k == 0) {
                                dmu[i + 1] = si[tmp + 3];
                        } else if (smu[(i + 1) * num + k] && si[tmp + 3 - k]) {
                                int16_t a, b, c;
                                a = readw_relaxed(index_of +
                                                smu[(i + 1) * num + k]);
                                b = si[2 * (i - 1) + 3 - k];
                                c = readw_relaxed(index_of + b);
                                tmp = a + c;
                                tmp %= cw_len;
                                dmu[i + 1] = readw_relaxed(alpha_to + tmp) ^
                                        dmu[i + 1];
                        }
                }
        }

        return;
}

static int pmecc_err_location(struct mtd_info *mtd)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        unsigned long end_time;
        const int cap = host->pmecc_corr_cap;
        const int num = 2 * cap + 1;
        int sector_size = host->pmecc_sector_size;
        int err_nbr = 0;        /* number of error */
        int roots_nbr;          /* number of roots */
        int i;
        uint32_t val;
        int16_t *smu = host->pmecc_smu;

        pmerrloc_writel(host->pmerrloc_base, ELDIS, PMERRLOC_DISABLE);

        for (i = 0; i <= host->pmecc_lmu[cap + 1] >> 1; i++) {
                pmerrloc_writel_sigma_relaxed(host->pmerrloc_base, i,
                                      smu[(cap + 1) * num + i]);
                err_nbr++;
        }

        val = (err_nbr - 1) << 16;
        if (sector_size == 1024)
                val |= 1;

        pmerrloc_writel(host->pmerrloc_base, ELCFG, val);
        pmerrloc_writel(host->pmerrloc_base, ELEN,
                        sector_size * 8 + host->pmecc_degree * cap);

        end_time = jiffies + msecs_to_jiffies(PMECC_MAX_TIMEOUT_MS);
        while (!(pmerrloc_readl_relaxed(host->pmerrloc_base, ELISR)
                 & PMERRLOC_CALC_DONE)) {
                if (unlikely(time_after(jiffies, end_time))) {
                        dev_err(host->dev, "PMECC: Timeout to calculate error location.\n");
                        return -1;
                }
                cpu_relax();
        }

        roots_nbr = (pmerrloc_readl_relaxed(host->pmerrloc_base, ELISR)
                & PMERRLOC_ERR_NUM_MASK) >> 8;
        /* Number of roots == degree of smu hence <= cap */
        if (roots_nbr == host->pmecc_lmu[cap + 1] >> 1)
                return err_nbr - 1;

        /* Number of roots does not match the degree of smu
         * unable to correct error */
        return -1;
}

static void pmecc_correct_data(struct mtd_info *mtd, uint8_t *buf, uint8_t *ecc,
                int sector_num, int extra_bytes, int err_nbr)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        int i = 0;
        int byte_pos, bit_pos, sector_size, pos;
        uint32_t tmp;
        uint8_t err_byte;

        sector_size = host->pmecc_sector_size;

        while (err_nbr) {
                tmp = pmerrloc_readl_el_relaxed(host->pmerrloc_el_base, i) - 1;
                byte_pos = tmp / 8;
                bit_pos  = tmp % 8;

                if (byte_pos >= (sector_size + extra_bytes))
                        BUG();  /* should never happen */

                if (byte_pos < sector_size) {
                        err_byte = *(buf + byte_pos);
                        *(buf + byte_pos) ^= (1 << bit_pos);

                        pos = sector_num * host->pmecc_sector_size + byte_pos;
                        dev_dbg(host->dev, "Bit flip in data area, byte_pos: %d, bit_pos: %d, 0x%02x -> 0x%02x\n",
                                pos, bit_pos, err_byte, *(buf + byte_pos));
                } else {
                        /* Bit flip in OOB area */
                        tmp = sector_num * nand_chip->ecc.bytes
                                        + (byte_pos - sector_size);
                        err_byte = ecc[tmp];
                        ecc[tmp] ^= (1 << bit_pos);

                        pos = tmp + nand_chip->ecc.layout->eccpos[0];
                        dev_dbg(host->dev, "Bit flip in OOB, oob_byte_pos: %d, bit_pos: %d, 0x%02x -> 0x%02x\n",
                                pos, bit_pos, err_byte, ecc[tmp]);
                }

                i++;
                err_nbr--;
        }

        return;
}

static int pmecc_correction(struct mtd_info *mtd, u32 pmecc_stat, uint8_t *buf,
        u8 *ecc)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        int i, err_nbr;
        uint8_t *buf_pos;
        int max_bitflips = 0;

        /* If can correct bitfilps from erased page, do the normal check */
        if (host->caps->pmecc_correct_erase_page)
                goto normal_check;

        for (i = 0; i < nand_chip->ecc.total; i++)
                if (ecc[i] != 0xff)
                        goto normal_check;
        /* Erased page, return OK */
        return 0;

normal_check:
        for (i = 0; i < nand_chip->ecc.steps; i++) {
                err_nbr = 0;
                if (pmecc_stat & 0x1) {
                        buf_pos = buf + i * host->pmecc_sector_size;

                        pmecc_gen_syndrome(mtd, i);
                        pmecc_substitute(mtd);
                        pmecc_get_sigma(mtd);

                        err_nbr = pmecc_err_location(mtd);
                        if (err_nbr == -1) {
                                dev_err(host->dev, "PMECC: Too many errors\n");
                                mtd->ecc_stats.failed++;
                                return -EIO;
                        } else {
                                pmecc_correct_data(mtd, buf_pos, ecc, i,
                                        nand_chip->ecc.bytes, err_nbr);
                                mtd->ecc_stats.corrected += err_nbr;
                                max_bitflips = max_t(int, max_bitflips, err_nbr);
                        }
                }
                pmecc_stat >>= 1;
        }

        return max_bitflips;
}

static void pmecc_enable(struct atmel_nand_host *host, int ecc_op)
{
        u32 val;

        if (ecc_op != NAND_ECC_READ && ecc_op != NAND_ECC_WRITE) {
                dev_err(host->dev, "atmel_nand: wrong pmecc operation type!");
                return;
        }

        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_RST);
        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE);
        val = pmecc_readl_relaxed(host->ecc, CFG);

        if (ecc_op == NAND_ECC_READ)
                pmecc_writel(host->ecc, CFG, (val & ~PMECC_CFG_WRITE_OP)
                        | PMECC_CFG_AUTO_ENABLE);
        else
                pmecc_writel(host->ecc, CFG, (val | PMECC_CFG_WRITE_OP)
                        & ~PMECC_CFG_AUTO_ENABLE);

        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_ENABLE);
        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DATA);
}

static int atmel_nand_pmecc_read_page(struct mtd_info *mtd,
        struct nand_chip *chip, uint8_t *buf, int oob_required, int page)
{
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        int eccsize = chip->ecc.size * chip->ecc.steps;
        uint8_t *oob = chip->oob_poi;
        uint32_t *eccpos = chip->ecc.layout->eccpos;
        uint32_t stat;
        unsigned long end_time;
        int bitflips = 0;

        if (!host->nfc || !host->nfc->use_nfc_sram)
                pmecc_enable(host, NAND_ECC_READ);

        chip->read_buf(mtd, buf, eccsize);
        chip->read_buf(mtd, oob, mtd->oobsize);

        end_time = jiffies + msecs_to_jiffies(PMECC_MAX_TIMEOUT_MS);
        while ((pmecc_readl_relaxed(host->ecc, SR) & PMECC_SR_BUSY)) {
                if (unlikely(time_after(jiffies, end_time))) {
                        dev_err(host->dev, "PMECC: Timeout to get error status.\n");
                        return -EIO;
                }
                cpu_relax();
        }

        stat = pmecc_readl_relaxed(host->ecc, ISR);
        if (stat != 0) {
                bitflips = pmecc_correction(mtd, stat, buf, &oob[eccpos[0]]);
                if (bitflips < 0)
                        /* uncorrectable errors */
                        return 0;
        }

        return bitflips;
}

static int atmel_nand_pmecc_write_page(struct mtd_info *mtd,
                struct nand_chip *chip, const uint8_t *buf, int oob_required,
                int page)
{
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        uint32_t *eccpos = chip->ecc.layout->eccpos;
        int i, j;
        unsigned long end_time;

        if (!host->nfc || !host->nfc->write_by_sram) {
                pmecc_enable(host, NAND_ECC_WRITE);
                chip->write_buf(mtd, (u8 *)buf, mtd->writesize);
        }

        end_time = jiffies + msecs_to_jiffies(PMECC_MAX_TIMEOUT_MS);
        while ((pmecc_readl_relaxed(host->ecc, SR) & PMECC_SR_BUSY)) {
                if (unlikely(time_after(jiffies, end_time))) {
                        dev_err(host->dev, "PMECC: Timeout to get ECC value.\n");
                        return -EIO;
                }
                cpu_relax();
        }

        for (i = 0; i < chip->ecc.steps; i++) {
                for (j = 0; j < chip->ecc.bytes; j++) {
                        int pos;

                        pos = i * chip->ecc.bytes + j;
                        chip->oob_poi[eccpos[pos]] =
                                pmecc_readb_ecc_relaxed(host->ecc, i, j);
                }
        }
        chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);

        return 0;
}

static void atmel_pmecc_core_init(struct mtd_info *mtd)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        uint32_t val = 0;
        struct nand_ecclayout *ecc_layout;

        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_RST);
        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE);

        switch (host->pmecc_corr_cap) {
        case 2:
                val = PMECC_CFG_BCH_ERR2;
                break;
        case 4:
                val = PMECC_CFG_BCH_ERR4;
                break;
        case 8:
                val = PMECC_CFG_BCH_ERR8;
                break;
        case 12:
                val = PMECC_CFG_BCH_ERR12;
                break;
        case 24:
                val = PMECC_CFG_BCH_ERR24;
                break;
        case 32:
                val = PMECC_CFG_BCH_ERR32;
                break;
        }

        if (host->pmecc_sector_size == 512)
                val |= PMECC_CFG_SECTOR512;
        else if (host->pmecc_sector_size == 1024)
                val |= PMECC_CFG_SECTOR1024;

        switch (nand_chip->ecc.steps) {
        case 1:
                val |= PMECC_CFG_PAGE_1SECTOR;
                break;
        case 2:
                val |= PMECC_CFG_PAGE_2SECTORS;
                break;
        case 4:
                val |= PMECC_CFG_PAGE_4SECTORS;
                break;
        case 8:
                val |= PMECC_CFG_PAGE_8SECTORS;
                break;
        }

        val |= (PMECC_CFG_READ_OP | PMECC_CFG_SPARE_DISABLE
                | PMECC_CFG_AUTO_DISABLE);
        pmecc_writel(host->ecc, CFG, val);

        ecc_layout = nand_chip->ecc.layout;
        pmecc_writel(host->ecc, SAREA, mtd->oobsize - 1);
        pmecc_writel(host->ecc, SADDR, ecc_layout->eccpos[0]);
        pmecc_writel(host->ecc, EADDR,
                        ecc_layout->eccpos[ecc_layout->eccbytes - 1]);
        /* See datasheet about PMECC Clock Control Register */
        pmecc_writel(host->ecc, CLK, 2);
        pmecc_writel(host->ecc, IDR, 0xff);
        pmecc_writel(host->ecc, CTRL, PMECC_CTRL_ENABLE);
}

/*
 * Get minimum ecc requirements from NAND.
 * If pmecc-cap, pmecc-sector-size in DTS are not specified, this function
 * will set them according to minimum ecc requirement. Otherwise, use the
 * value in DTS file.
 * return 0 if success. otherwise return error code.
 */
static int pmecc_choose_ecc(struct atmel_nand_host *host,
                int *cap, int *sector_size)
{
        /* Get minimum ECC requirements */
        if (host->nand_chip.ecc_strength_ds) {
                *cap = host->nand_chip.ecc_strength_ds;
                *sector_size = host->nand_chip.ecc_step_ds;
                dev_info(host->dev, "minimum ECC: %d bits in %d bytes\n",
                                *cap, *sector_size);
        } else {
                *cap = 2;
                *sector_size = 512;
                dev_info(host->dev, "can't detect min. ECC, assume 2 bits in 512 bytes\n");
        }

        /* If device tree doesn't specify, use NAND's minimum ECC parameters */
        if (host->pmecc_corr_cap == 0) {
                if (*cap > host->caps->pmecc_max_correction)
                        return -EINVAL;

                /* use the most fitable ecc bits (the near bigger one ) */
                if (*cap <= 2)
                        host->pmecc_corr_cap = 2;
                else if (*cap <= 4)
                        host->pmecc_corr_cap = 4;
                else if (*cap <= 8)
                        host->pmecc_corr_cap = 8;
                else if (*cap <= 12)
                        host->pmecc_corr_cap = 12;
                else if (*cap <= 24)
                        host->pmecc_corr_cap = 24;
                else if (*cap <= 32)
                        host->pmecc_corr_cap = 32;
                else
                        return -EINVAL;
        }
        if (host->pmecc_sector_size == 0) {
                /* use the most fitable sector size (the near smaller one ) */
                if (*sector_size >= 1024)
                        host->pmecc_sector_size = 1024;
                else if (*sector_size >= 512)
                        host->pmecc_sector_size = 512;
                else
                        return -EINVAL;
        }
        return 0;
}

static inline int deg(unsigned int poly)
{
        /* polynomial degree is the most-significant bit index */
        return fls(poly) - 1;
}

static int build_gf_tables(int mm, unsigned int poly,
                int16_t *index_of, int16_t *alpha_to)
{
        unsigned int i, x = 1;
        const unsigned int k = 1 << deg(poly);
        unsigned int nn = (1 << mm) - 1;

        /* primitive polynomial must be of degree m */
        if (k != (1u << mm))
                return -EINVAL;

        for (i = 0; i < nn; i++) {
                alpha_to[i] = x;
                index_of[x] = i;
                if (i && (x == 1))
                        /* polynomial is not primitive (a^i=1 with 0<i<2^m-1) */
                        return -EINVAL;
                x <<= 1;
                if (x & k)
                        x ^= poly;
        }
        alpha_to[nn] = 1;
        index_of[0] = 0;

        return 0;
}

static uint16_t *create_lookup_table(struct device *dev, int sector_size)
{
        int degree = (sector_size == 512) ?
                        PMECC_GF_DIMENSION_13 :
                        PMECC_GF_DIMENSION_14;
        unsigned int poly = (sector_size == 512) ?
                        PMECC_GF_13_PRIMITIVE_POLY :
                        PMECC_GF_14_PRIMITIVE_POLY;
        int table_size = (sector_size == 512) ?
                        PMECC_LOOKUP_TABLE_SIZE_512 :
                        PMECC_LOOKUP_TABLE_SIZE_1024;

        int16_t *addr = devm_kzalloc(dev, 2 * table_size * sizeof(uint16_t),
                        GFP_KERNEL);
        if (addr && build_gf_tables(degree, poly, addr, addr + table_size))
                return NULL;

        return addr;
}

static int atmel_pmecc_nand_init_params(struct platform_device *pdev,
                                         struct atmel_nand_host *host)
{
        struct nand_chip *nand_chip = &host->nand_chip;
        struct mtd_info *mtd = nand_to_mtd(nand_chip);
        struct resource *regs, *regs_pmerr, *regs_rom;
        uint16_t *galois_table;
        int cap, sector_size, err_no;

        err_no = pmecc_choose_ecc(host, &cap, &sector_size);
        if (err_no) {
                dev_err(host->dev, "The NAND flash's ECC requirement are not support!");
                return err_no;
        }

        if (cap > host->pmecc_corr_cap ||
                        sector_size != host->pmecc_sector_size)
                dev_info(host->dev, "WARNING: Be Caution! Using different PMECC parameters from Nand ONFI ECC reqirement.\n");

        cap = host->pmecc_corr_cap;
        sector_size = host->pmecc_sector_size;
        host->pmecc_lookup_table_offset = (sector_size == 512) ?
                        host->pmecc_lookup_table_offset_512 :
                        host->pmecc_lookup_table_offset_1024;

        dev_info(host->dev, "Initialize PMECC params, cap: %d, sector: %d\n",
                 cap, sector_size);

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!regs) {
                dev_warn(host->dev,
                        "Can't get I/O resource regs for PMECC controller, rolling back on software ECC\n");
                nand_chip->ecc.mode = NAND_ECC_SOFT;
                return 0;
        }

        host->ecc = devm_ioremap_resource(&pdev->dev, regs);
        if (IS_ERR(host->ecc)) {
                err_no = PTR_ERR(host->ecc);
                goto err;
        }

        regs_pmerr = platform_get_resource(pdev, IORESOURCE_MEM, 2);
        host->pmerrloc_base = devm_ioremap_resource(&pdev->dev, regs_pmerr);
        if (IS_ERR(host->pmerrloc_base)) {
                err_no = PTR_ERR(host->pmerrloc_base);
                goto err;
        }
        host->pmerrloc_el_base = host->pmerrloc_base + ATMEL_PMERRLOC_SIGMAx +
                (host->caps->pmecc_max_correction + 1) * 4;

        if (!host->has_no_lookup_table) {
                regs_rom = platform_get_resource(pdev, IORESOURCE_MEM, 3);
                host->pmecc_rom_base = devm_ioremap_resource(&pdev->dev,
                                                                regs_rom);
                if (IS_ERR(host->pmecc_rom_base)) {
                        dev_err(host->dev, "Can not get I/O resource for ROM, will build a lookup table in runtime!\n");
                        host->has_no_lookup_table = true;
                }
        }

        if (host->has_no_lookup_table) {
                /* Build the look-up table in runtime */
                galois_table = create_lookup_table(host->dev, sector_size);
                if (!galois_table) {
                        dev_err(host->dev, "Failed to build a lookup table in runtime!\n");
                        err_no = -EINVAL;
                        goto err;
                }

                host->pmecc_rom_base = (void __iomem *)galois_table;
                host->pmecc_lookup_table_offset = 0;
        }

        nand_chip->ecc.size = sector_size;

        /* set ECC page size and oob layout */
        switch (mtd->writesize) {
        case 512:
        case 1024:
        case 2048:
        case 4096:
        case 8192:
                if (sector_size > mtd->writesize) {
                        dev_err(host->dev, "pmecc sector size is bigger than the page size!\n");
                        err_no = -EINVAL;
                        goto err;
                }

                host->pmecc_degree = (sector_size == 512) ?
                        PMECC_GF_DIMENSION_13 : PMECC_GF_DIMENSION_14;
                host->pmecc_cw_len = (1 << host->pmecc_degree) - 1;
                host->pmecc_alpha_to = pmecc_get_alpha_to(host);
                host->pmecc_index_of = host->pmecc_rom_base +
                        host->pmecc_lookup_table_offset;

                nand_chip->ecc.strength = cap;
                nand_chip->ecc.bytes = pmecc_get_ecc_bytes(cap, sector_size);
                nand_chip->ecc.steps = mtd->writesize / sector_size;
                nand_chip->ecc.total = nand_chip->ecc.bytes *
                        nand_chip->ecc.steps;
                if (nand_chip->ecc.total >
                                mtd->oobsize - PMECC_OOB_RESERVED_BYTES) {
                        dev_err(host->dev, "No room for ECC bytes\n");
                        err_no = -EINVAL;
                        goto err;
                }
                pmecc_config_ecc_layout(&atmel_pmecc_oobinfo,
                                        mtd->oobsize,
                                        nand_chip->ecc.total);

                nand_chip->ecc.layout = &atmel_pmecc_oobinfo;
                break;
        default:
                dev_warn(host->dev,
                        "Unsupported page size for PMECC, use Software ECC\n");
                /* page size not handled by HW ECC */
                /* switching back to soft ECC */
                nand_chip->ecc.mode = NAND_ECC_SOFT;
                return 0;
        }

        /* Allocate data for PMECC computation */
        err_no = pmecc_data_alloc(host);
        if (err_no) {
                dev_err(host->dev,
                                "Cannot allocate memory for PMECC computation!\n");
                goto err;
        }

        nand_chip->options |= NAND_NO_SUBPAGE_WRITE;
        nand_chip->ecc.read_page = atmel_nand_pmecc_read_page;
        nand_chip->ecc.write_page = atmel_nand_pmecc_write_page;

        atmel_pmecc_core_init(mtd);

        return 0;

err:
        return err_no;
}

/*
 * Calculate HW ECC
 *
 * function called after a write
 *
 * mtd:        MTD block structure
 * dat:        raw data (unused)
 * ecc_code:   buffer for ECC
 */
static int atmel_nand_calculate(struct mtd_info *mtd,
                const u_char *dat, unsigned char *ecc_code)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        unsigned int ecc_value;

        /* get the first 2 ECC bytes */
        ecc_value = ecc_readl(host->ecc, PR);

        ecc_code[0] = ecc_value & 0xFF;
        ecc_code[1] = (ecc_value >> 8) & 0xFF;

        /* get the last 2 ECC bytes */
        ecc_value = ecc_readl(host->ecc, NPR) & ATMEL_ECC_NPARITY;

        ecc_code[2] = ecc_value & 0xFF;
        ecc_code[3] = (ecc_value >> 8) & 0xFF;

        return 0;
}

/*
 * HW ECC read page function
 *
 * mtd:        mtd info structure
 * chip:       nand chip info structure
 * buf:        buffer to store read data
 * oob_required:    caller expects OOB data read to chip->oob_poi
 */
static int atmel_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf, int oob_required, int page)
{
        int eccsize = chip->ecc.size;
        int eccbytes = chip->ecc.bytes;
        uint32_t *eccpos = chip->ecc.layout->eccpos;
        uint8_t *p = buf;
        uint8_t *oob = chip->oob_poi;
        uint8_t *ecc_pos;
        int stat;
        unsigned int max_bitflips = 0;

        /*
         * Errata: ALE is incorrectly wired up to the ECC controller
         * on the AP7000, so it will include the address cycles in the
         * ECC calculation.
         *
         * Workaround: Reset the parity registers before reading the
         * actual data.
         */
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        if (host->board.need_reset_workaround)
                ecc_writel(host->ecc, CR, ATMEL_ECC_RST);

        /* read the page */
        chip->read_buf(mtd, p, eccsize);

        /* move to ECC position if needed */
        if (eccpos[0] != 0) {
                /* This only works on large pages
                 * because the ECC controller waits for
                 * NAND_CMD_RNDOUTSTART after the
                 * NAND_CMD_RNDOUT.
                 * anyway, for small pages, the eccpos[0] == 0
                 */
                chip->cmdfunc(mtd, NAND_CMD_RNDOUT,
                                mtd->writesize + eccpos[0], -1);
        }

        /* the ECC controller needs to read the ECC just after the data */
        ecc_pos = oob + eccpos[0];
        chip->read_buf(mtd, ecc_pos, eccbytes);

        /* check if there's an error */
        stat = chip->ecc.correct(mtd, p, oob, NULL);

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

        /* get back to oob start (end of page) */
        chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize, -1);

        /* read the oob */
        chip->read_buf(mtd, oob, mtd->oobsize);

        return max_bitflips;
}

/*
 * HW ECC Correction
 *
 * function called after a read
 *
 * mtd:        MTD block structure
 * dat:        raw data read from the chip
 * read_ecc:   ECC from the chip (unused)
 * isnull:     unused
 *
 * Detect and correct a 1 bit error for a page
 */
static int atmel_nand_correct(struct mtd_info *mtd, u_char *dat,
                u_char *read_ecc, u_char *isnull)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);
        unsigned int ecc_status;
        unsigned int ecc_word, ecc_bit;

        /* get the status from the Status Register */
        ecc_status = ecc_readl(host->ecc, SR);

        /* if there's no error */
        if (likely(!(ecc_status & ATMEL_ECC_RECERR)))
                return 0;

        /* get error bit offset (4 bits) */
        ecc_bit = ecc_readl(host->ecc, PR) & ATMEL_ECC_BITADDR;
        /* get word address (12 bits) */
        ecc_word = ecc_readl(host->ecc, PR) & ATMEL_ECC_WORDADDR;
        ecc_word >>= 4;

        /* if there are multiple errors */
        if (ecc_status & ATMEL_ECC_MULERR) {
                /* check if it is a freshly erased block
                 * (filled with 0xff) */
                if ((ecc_bit == ATMEL_ECC_BITADDR)
                                && (ecc_word == (ATMEL_ECC_WORDADDR >> 4))) {
                        /* the block has just been erased, return OK */
                        return 0;
                }
                /* it doesn't seems to be a freshly
                 * erased block.
                 * We can't correct so many errors */
                dev_dbg(host->dev, "atmel_nand : multiple errors detected."
                                " Unable to correct.\n");
                return -EBADMSG;
        }

        /* if there's a single bit error : we can correct it */
        if (ecc_status & ATMEL_ECC_ECCERR) {
                /* there's nothing much to do here.
                 * the bit error is on the ECC itself.
                 */
                dev_dbg(host->dev, "atmel_nand : one bit error on ECC code."
                                " Nothing to correct\n");
                return 0;
        }

        dev_dbg(host->dev, "atmel_nand : one bit error on data."
                        " (word offset in the page :"
                        " 0x%x bit offset : 0x%x)\n",
                        ecc_word, ecc_bit);
        /* correct the error */
        if (nand_chip->options & NAND_BUSWIDTH_16) {
                /* 16 bits words */
                ((unsigned short *) dat)[ecc_word] ^= (1 << ecc_bit);
        } else {
                /* 8 bits words */
                dat[ecc_word] ^= (1 << ecc_bit);
        }
        dev_dbg(host->dev, "atmel_nand : error corrected\n");
        return 1;
}

/*
 * Enable HW ECC : unused on most chips
 */
static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        if (host->board.need_reset_workaround)
                ecc_writel(host->ecc, CR, ATMEL_ECC_RST);
}

static int atmel_of_init_port(struct atmel_nand_host *host,
                              struct device_node *np)
{
        u32 val;
        u32 offset[2];
        int ecc_mode;
        struct atmel_nand_data *board = &host->board;
        enum of_gpio_flags flags = 0;

        host->caps = (struct atmel_nand_caps *)
                of_device_get_match_data(host->dev);

        if (of_property_read_u32(np, "atmel,nand-addr-offset", &val) == 0) {
                if (val >= 32) {
                        dev_err(host->dev, "invalid addr-offset %u\n", val);
                        return -EINVAL;
                }
                board->ale = val;
        }

        if (of_property_read_u32(np, "atmel,nand-cmd-offset", &val) == 0) {
                if (val >= 32) {
                        dev_err(host->dev, "invalid cmd-offset %u\n", val);
                        return -EINVAL;
                }
                board->cle = val;
        }

        ecc_mode = of_get_nand_ecc_mode(np);

        board->ecc_mode = ecc_mode < 0 ? NAND_ECC_SOFT : ecc_mode;

        board->on_flash_bbt = of_get_nand_on_flash_bbt(np);

        board->has_dma = of_property_read_bool(np, "atmel,nand-has-dma");

        if (of_get_nand_bus_width(np) == 16)
                board->bus_width_16 = 1;

        board->rdy_pin = of_get_gpio_flags(np, 0, &flags);
        board->rdy_pin_active_low = (flags == OF_GPIO_ACTIVE_LOW);

        board->enable_pin = of_get_gpio(np, 1);
        board->det_pin = of_get_gpio(np, 2);

        host->has_pmecc = of_property_read_bool(np, "atmel,has-pmecc");

        /* load the nfc driver if there is */
        of_platform_populate(np, NULL, NULL, host->dev);

        if (!(board->ecc_mode == NAND_ECC_HW) || !host->has_pmecc)
                return 0;       /* Not using PMECC */

        /* use PMECC, get correction capability, sector size and lookup
         * table offset.
         * If correction bits and sector size are not specified, then find
         * them from NAND ONFI parameters.
         */
        if (of_property_read_u32(np, "atmel,pmecc-cap", &val) == 0) {
                if (val > host->caps->pmecc_max_correction) {
                        dev_err(host->dev,
                                "Required ECC strength too high: %u max %u\n",
                                val, host->caps->pmecc_max_correction);
                        return -EINVAL;
                }
                if ((val != 2)  && (val != 4)  && (val != 8) &&
                    (val != 12) && (val != 24) && (val != 32)) {
                        dev_err(host->dev,
                                "Required ECC strength not supported: %u\n",
                                val);
                        return -EINVAL;
                }
                host->pmecc_corr_cap = (u8)val;
        }

        if (of_property_read_u32(np, "atmel,pmecc-sector-size", &val) == 0) {
                if ((val != 512) && (val != 1024)) {
                        dev_err(host->dev,
                                "Required ECC sector size not supported: %u\n",
                                val);
                        return -EINVAL;
                }
                host->pmecc_sector_size = (u16)val;
        }

        if (of_property_read_u32_array(np, "atmel,pmecc-lookup-table-offset",
                        offset, 2) != 0) {
                dev_err(host->dev, "Cannot get PMECC lookup table offset, will build a lookup table in runtime.\n");
                host->has_no_lookup_table = true;
                /* Will build a lookup table and initialize the offset later */
                return 0;
        }
        if (!offset[0] && !offset[1]) {
                dev_err(host->dev, "Invalid PMECC lookup table offset\n");
                return -EINVAL;
        }
        host->pmecc_lookup_table_offset_512 = offset[0];
        host->pmecc_lookup_table_offset_1024 = offset[1];

        return 0;
}

static int atmel_hw_nand_init_params(struct platform_device *pdev,
                                         struct atmel_nand_host *host)
{
        struct nand_chip *nand_chip = &host->nand_chip;
        struct mtd_info *mtd = nand_to_mtd(nand_chip);
        struct resource         *regs;

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!regs) {
                dev_err(host->dev,
                        "Can't get I/O resource regs, use software ECC\n");
                nand_chip->ecc.mode = NAND_ECC_SOFT;
                return 0;
        }

        host->ecc = devm_ioremap_resource(&pdev->dev, regs);
        if (IS_ERR(host->ecc))
                return PTR_ERR(host->ecc);

        /* ECC is calculated for the whole page (1 step) */
        nand_chip->ecc.size = mtd->writesize;

        /* set ECC page size and oob layout */
        switch (mtd->writesize) {
        case 512:
                nand_chip->ecc.layout = &atmel_oobinfo_small;
                ecc_writel(host->ecc, MR, ATMEL_ECC_PAGESIZE_528);
                break;
        case 1024:
                nand_chip->ecc.layout = &atmel_oobinfo_large;
                ecc_writel(host->ecc, MR, ATMEL_ECC_PAGESIZE_1056);
                break;
        case 2048:
                nand_chip->ecc.layout = &atmel_oobinfo_large;
                ecc_writel(host->ecc, MR, ATMEL_ECC_PAGESIZE_2112);
                break;
        case 4096:
                nand_chip->ecc.layout = &atmel_oobinfo_large;
                ecc_writel(host->ecc, MR, ATMEL_ECC_PAGESIZE_4224);
                break;
        default:
                /* page size not handled by HW ECC */
                /* switching back to soft ECC */
                nand_chip->ecc.mode = NAND_ECC_SOFT;
                return 0;
        }

        /* set up for HW ECC */
        nand_chip->ecc.calculate = atmel_nand_calculate;
        nand_chip->ecc.correct = atmel_nand_correct;
        nand_chip->ecc.hwctl = atmel_nand_hwctl;
        nand_chip->ecc.read_page = atmel_nand_read_page;
        nand_chip->ecc.bytes = 4;
        nand_chip->ecc.strength = 1;

        return 0;
}

static inline u32 nfc_read_status(struct atmel_nand_host *host)
{
        u32 err_flags = NFC_SR_DTOE | NFC_SR_UNDEF | NFC_SR_AWB | NFC_SR_ASE;
        u32 nfc_status = nfc_readl(host->nfc->hsmc_regs, SR);

        if (unlikely(nfc_status & err_flags)) {
                if (nfc_status & NFC_SR_DTOE)
                        dev_err(host->dev, "NFC: Waiting Nand R/B Timeout Error\n");
                else if (nfc_status & NFC_SR_UNDEF)
                        dev_err(host->dev, "NFC: Access Undefined Area Error\n");
                else if (nfc_status & NFC_SR_AWB)
                        dev_err(host->dev, "NFC: Access memory While NFC is busy\n");
                else if (nfc_status & NFC_SR_ASE)
                        dev_err(host->dev, "NFC: Access memory Size Error\n");
        }

        return nfc_status;
}

/* SMC interrupt service routine */
static irqreturn_t hsmc_interrupt(int irq, void *dev_id)
{
        struct atmel_nand_host *host = dev_id;
        u32 status, mask, pending;
        irqreturn_t ret = IRQ_NONE;

        status = nfc_read_status(host);
        mask = nfc_readl(host->nfc->hsmc_regs, IMR);
        pending = status & mask;

        if (pending & NFC_SR_XFR_DONE) {
                complete(&host->nfc->comp_xfer_done);
                nfc_writel(host->nfc->hsmc_regs, IDR, NFC_SR_XFR_DONE);
                ret = IRQ_HANDLED;
        }
        if (pending & host->nfc->caps->rb_mask) {
                complete(&host->nfc->comp_ready);
                nfc_writel(host->nfc->hsmc_regs, IDR, host->nfc->caps->rb_mask);
                ret = IRQ_HANDLED;
        }
        if (pending & NFC_SR_CMD_DONE) {
                complete(&host->nfc->comp_cmd_done);
                nfc_writel(host->nfc->hsmc_regs, IDR, NFC_SR_CMD_DONE);
                ret = IRQ_HANDLED;
        }

        return ret;
}

/* NFC(Nand Flash Controller) related functions */
static void nfc_prepare_interrupt(struct atmel_nand_host *host, u32 flag)
{
        if (flag & NFC_SR_XFR_DONE)
                init_completion(&host->nfc->comp_xfer_done);

        if (flag & host->nfc->caps->rb_mask)
                init_completion(&host->nfc->comp_ready);

        if (flag & NFC_SR_CMD_DONE)
                init_completion(&host->nfc->comp_cmd_done);

        /* Enable interrupt that need to wait for */
        nfc_writel(host->nfc->hsmc_regs, IER, flag);
}

static int nfc_wait_interrupt(struct atmel_nand_host *host, u32 flag)
{
        int i, index = 0;
        struct completion *comp[3];     /* Support 3 interrupt completion */

        if (flag & NFC_SR_XFR_DONE)
                comp[index++] = &host->nfc->comp_xfer_done;

        if (flag & host->nfc->caps->rb_mask)
                comp[index++] = &host->nfc->comp_ready;

        if (flag & NFC_SR_CMD_DONE)
                comp[index++] = &host->nfc->comp_cmd_done;

        if (index == 0) {
                dev_err(host->dev, "Unknown interrupt flag: 0x%08x\n", flag);
                return -EINVAL;
        }

        for (i = 0; i < index; i++) {
                if (wait_for_completion_timeout(comp[i],
                                msecs_to_jiffies(NFC_TIME_OUT_MS)))
                        continue;       /* wait for next completion */
                else
                        goto err_timeout;
        }

        return 0;

err_timeout:
        dev_err(host->dev, "Time out to wait for interrupt: 0x%08x\n", flag);
        /* Disable the interrupt as it is not handled by interrupt handler */
        nfc_writel(host->nfc->hsmc_regs, IDR, flag);
        return -ETIMEDOUT;
}

static int nfc_send_command(struct atmel_nand_host *host,
        unsigned int cmd, unsigned int addr, unsigned char cycle0)
{
        unsigned long timeout;
        u32 flag = NFC_SR_CMD_DONE;
        flag |= cmd & NFCADDR_CMD_DATAEN ? NFC_SR_XFR_DONE : 0;

        dev_dbg(host->dev,
                "nfc_cmd: 0x%08x, addr1234: 0x%08x, cycle0: 0x%02x\n",
                cmd, addr, cycle0);

        timeout = jiffies + msecs_to_jiffies(NFC_TIME_OUT_MS);
        while (nfc_readl(host->nfc->hsmc_regs, SR) & NFC_SR_BUSY) {
                if (time_after(jiffies, timeout)) {
                        dev_err(host->dev,
                                "Time out to wait for NFC ready!\n");
                        return -ETIMEDOUT;
                }
        }

        nfc_prepare_interrupt(host, flag);
        nfc_writel(host->nfc->hsmc_regs, CYCLE0, cycle0);
        nfc_cmd_addr1234_writel(cmd, addr, host->nfc->base_cmd_regs);
        return nfc_wait_interrupt(host, flag);
}

static int nfc_device_ready(struct mtd_info *mtd)
{
        u32 status, mask;
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        status = nfc_read_status(host);
        mask = nfc_readl(host->nfc->hsmc_regs, IMR);

        /* The mask should be 0. If not we may lost interrupts */
        if (unlikely(mask & status))
                dev_err(host->dev, "Lost the interrupt flags: 0x%08x\n",
                                mask & status);

        return status & host->nfc->caps->rb_mask;
}

static void nfc_select_chip(struct mtd_info *mtd, int chip)
{
        struct nand_chip *nand_chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(nand_chip);

        if (chip == -1)
                nfc_writel(host->nfc->hsmc_regs, CTRL, NFC_CTRL_DISABLE);
        else
                nfc_writel(host->nfc->hsmc_regs, CTRL, NFC_CTRL_ENABLE);
}

static int nfc_make_addr(struct mtd_info *mtd, int command, int column,
                int page_addr, unsigned int *addr1234, unsigned int *cycle0)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        int acycle = 0;
        unsigned char addr_bytes[8];
        int index = 0, bit_shift;

        BUG_ON(addr1234 == NULL || cycle0 == NULL);

        *cycle0 = 0;
        *addr1234 = 0;

        if (column != -1) {
                if (chip->options & NAND_BUSWIDTH_16 &&
                                !nand_opcode_8bits(command))
                        column >>= 1;
                addr_bytes[acycle++] = column & 0xff;
                if (mtd->writesize > 512)
                        addr_bytes[acycle++] = (column >> 8) & 0xff;
        }

        if (page_addr != -1) {
                addr_bytes[acycle++] = page_addr & 0xff;
                addr_bytes[acycle++] = (page_addr >> 8) & 0xff;
                if (chip->chipsize > (128 << 20))
                        addr_bytes[acycle++] = (page_addr >> 16) & 0xff;
        }

        if (acycle > 4)
                *cycle0 = addr_bytes[index++];

        for (bit_shift = 0; index < acycle; bit_shift += 8)
                *addr1234 += addr_bytes[index++] << bit_shift;

        /* return acycle in cmd register */
        return acycle << NFCADDR_CMD_ACYCLE_BIT_POS;
}

static void nfc_nand_command(struct mtd_info *mtd, unsigned int command,
                                int column, int page_addr)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        unsigned long timeout;
        unsigned int nfc_addr_cmd = 0;

        unsigned int cmd1 = command << NFCADDR_CMD_CMD1_BIT_POS;

        /* Set default settings: no cmd2, no addr cycle. read from nand */
        unsigned int cmd2 = 0;
        unsigned int vcmd2 = 0;
        int acycle = NFCADDR_CMD_ACYCLE_NONE;
        int csid = NFCADDR_CMD_CSID_3;
        int dataen = NFCADDR_CMD_DATADIS;
        int nfcwr = NFCADDR_CMD_NFCRD;
        unsigned int addr1234 = 0;
        unsigned int cycle0 = 0;
        bool do_addr = true;
        host->nfc->data_in_sram = NULL;

        dev_dbg(host->dev, "%s: cmd = 0x%02x, col = 0x%08x, page = 0x%08x\n",
             __func__, command, column, page_addr);

        switch (command) {
        case NAND_CMD_RESET:
                nfc_addr_cmd = cmd1 | acycle | csid | dataen | nfcwr;
                nfc_send_command(host, nfc_addr_cmd, addr1234, cycle0);
                udelay(chip->chip_delay);

                nfc_nand_command(mtd, NAND_CMD_STATUS, -1, -1);
                timeout = jiffies + msecs_to_jiffies(NFC_TIME_OUT_MS);
                while (!(chip->read_byte(mtd) & NAND_STATUS_READY)) {
                        if (time_after(jiffies, timeout)) {
                                dev_err(host->dev,
                                        "Time out to wait status ready!\n");
                                break;
                        }
                }
                return;
        case NAND_CMD_STATUS:
                do_addr = false;
                break;
        case NAND_CMD_PARAM:
        case NAND_CMD_READID:
                do_addr = false;
                acycle = NFCADDR_CMD_ACYCLE_1;
                if (column != -1)
                        addr1234 = column;
                break;
        case NAND_CMD_RNDOUT:
                cmd2 = NAND_CMD_RNDOUTSTART << NFCADDR_CMD_CMD2_BIT_POS;
                vcmd2 = NFCADDR_CMD_VCMD2;
                break;
        case NAND_CMD_READ0:
        case NAND_CMD_READOOB:
                if (command == NAND_CMD_READOOB) {
                        column += mtd->writesize;
                        command = NAND_CMD_READ0; /* only READ0 is valid */
                        cmd1 = command << NFCADDR_CMD_CMD1_BIT_POS;
                }
                if (host->nfc->use_nfc_sram) {
                        /* Enable Data transfer to sram */
                        dataen = NFCADDR_CMD_DATAEN;

                        /* Need enable PMECC now, since NFC will transfer
                         * data in bus after sending nfc read command.
                         */
                        if (chip->ecc.mode == NAND_ECC_HW && host->has_pmecc)
                                pmecc_enable(host, NAND_ECC_READ);
                }

                cmd2 = NAND_CMD_READSTART << NFCADDR_CMD_CMD2_BIT_POS;
                vcmd2 = NFCADDR_CMD_VCMD2;
                break;
        /* For prgramming command, the cmd need set to write enable */
        case NAND_CMD_PAGEPROG:
        case NAND_CMD_SEQIN:
        case NAND_CMD_RNDIN:
                nfcwr = NFCADDR_CMD_NFCWR;
                if (host->nfc->will_write_sram && command == NAND_CMD_SEQIN)
                        dataen = NFCADDR_CMD_DATAEN;
                break;
        default:
                break;
        }

        if (do_addr)
                acycle = nfc_make_addr(mtd, command, column, page_addr,
                                &addr1234, &cycle0);

        nfc_addr_cmd = cmd1 | cmd2 | vcmd2 | acycle | csid | dataen | nfcwr;
        nfc_send_command(host, nfc_addr_cmd, addr1234, cycle0);

        /*
         * Program and erase have their own busy handlers status, sequential
         * in, and deplete1 need no delay.
         */
        switch (command) {
        case NAND_CMD_CACHEDPROG:
        case NAND_CMD_PAGEPROG:
        case NAND_CMD_ERASE1:
        case NAND_CMD_ERASE2:
        case NAND_CMD_RNDIN:
        case NAND_CMD_STATUS:
        case NAND_CMD_RNDOUT:
        case NAND_CMD_SEQIN:
        case NAND_CMD_READID:
                return;

        case NAND_CMD_READ0:
                if (dataen == NFCADDR_CMD_DATAEN) {
                        host->nfc->data_in_sram = host->nfc->sram_bank0 +
                                nfc_get_sram_off(host);
                        return;
                }
                /* fall through */
        default:
                nfc_prepare_interrupt(host, host->nfc->caps->rb_mask);
                nfc_wait_interrupt(host, host->nfc->caps->rb_mask);
        }
}

static int nfc_sram_write_page(struct mtd_info *mtd, struct nand_chip *chip,
                        uint32_t offset, int data_len, const uint8_t *buf,
                        int oob_required, int page, int cached, int raw)
{
        int cfg, len;
        int status = 0;
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        void *sram = host->nfc->sram_bank0 + nfc_get_sram_off(host);

        /* Subpage write is not supported */
        if (offset || (data_len < mtd->writesize))
                return -EINVAL;

        len = mtd->writesize;
        /* Copy page data to sram that will write to nand via NFC */

        if (use_dma) {
                if (atmel_nand_dma_op(mtd, (void *)buf, len, 0) != 0)
                        /* Fall back to use cpu copy */
                        memcpy(sram, buf, len);
        } else {
                memcpy(sram, buf, len);
        }

        cfg = nfc_readl(host->nfc->hsmc_regs, CFG);
        if (unlikely(raw) && oob_required) {
                memcpy(sram + len, chip->oob_poi, mtd->oobsize);
                len += mtd->oobsize;
                nfc_writel(host->nfc->hsmc_regs, CFG, cfg | NFC_CFG_WSPARE);
        } else {
                nfc_writel(host->nfc->hsmc_regs, CFG, cfg & ~NFC_CFG_WSPARE);
        }

        if (chip->ecc.mode == NAND_ECC_HW && host->has_pmecc)
                /*
                 * When use NFC sram, need set up PMECC before send
                 * NAND_CMD_SEQIN command. Since when the nand command
                 * is sent, nfc will do transfer from sram and nand.
                 */
                pmecc_enable(host, NAND_ECC_WRITE);

        host->nfc->will_write_sram = true;
        chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page);
        host->nfc->will_write_sram = false;

        if (likely(!raw))
                /* Need to write ecc into oob */
                status = chip->ecc.write_page(mtd, chip, buf, oob_required,
                                              page);

        if (status < 0)
                return status;

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

        if ((status & NAND_STATUS_FAIL) && (chip->errstat))
                status = chip->errstat(mtd, chip, FL_WRITING, status, page);

        if (status & NAND_STATUS_FAIL)
                return -EIO;

        return 0;
}

static int nfc_sram_init(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct atmel_nand_host *host = nand_get_controller_data(chip);
        int res = 0;

        /* Initialize the NFC CFG register */
        unsigned int cfg_nfc = 0;

        /* set page size and oob layout */
        switch (mtd->writesize) {
        case 512:
                cfg_nfc = NFC_CFG_PAGESIZE_512;
                break;
        case 1024:
                cfg_nfc = NFC_CFG_PAGESIZE_1024;
                break;
        case 2048:
                cfg_nfc = NFC_CFG_PAGESIZE_2048;
                break;
        case 4096:
                cfg_nfc = NFC_CFG_PAGESIZE_4096;
                break;
        case 8192:
                cfg_nfc = NFC_CFG_PAGESIZE_8192;
                break;
        default:
                dev_err(host->dev, "Unsupported page size for NFC.\n");
                res = -ENXIO;
                return res;
        }

        /* oob bytes size = (NFCSPARESIZE + 1) * 4
         * Max support spare size is 512 bytes. */
        cfg_nfc |= (((mtd->oobsize / 4) - 1) << NFC_CFG_NFC_SPARESIZE_BIT_POS
                & NFC_CFG_NFC_SPARESIZE);
        /* default set a max timeout */
        cfg_nfc |= NFC_CFG_RSPARE |
                        NFC_CFG_NFC_DTOCYC | NFC_CFG_NFC_DTOMUL;

        nfc_writel(host->nfc->hsmc_regs, CFG, cfg_nfc);

        host->nfc->will_write_sram = false;
        nfc_set_sram_bank(host, 0);

        /* Use Write page with NFC SRAM only for PMECC or ECC NONE. */
        if (host->nfc->write_by_sram) {
                if ((chip->ecc.mode == NAND_ECC_HW && host->has_pmecc) ||
                                chip->ecc.mode == NAND_ECC_NONE)
                        chip->write_page = nfc_sram_write_page;
                else
                        host->nfc->write_by_sram = false;
        }

        dev_info(host->dev, "Using NFC Sram read %s\n",
                        host->nfc->write_by_sram ? "and write" : "");
        return 0;
}

static struct platform_driver atmel_nand_nfc_driver;
/*
 * Probe for the NAND device.
 */
static int atmel_nand_probe(struct platform_device *pdev)
{
        struct atmel_nand_host *host;
        struct mtd_info *mtd;
        struct nand_chip *nand_chip;
        struct resource *mem;
        int res, irq;

        /* Allocate memory for the device structure (and zero it) */
        host = devm_kzalloc(&pdev->dev, sizeof(*host), GFP_KERNEL);
        if (!host)
                return -ENOMEM;

        res = platform_driver_register(&atmel_nand_nfc_driver);
        if (res)
                dev_err(&pdev->dev, "atmel_nand: can't register NFC driver\n");

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        host->io_base = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(host->io_base)) {
                res = PTR_ERR(host->io_base);
                goto err_nand_ioremap;
        }
        host->io_phys = (dma_addr_t)mem->start;

        nand_chip = &host->nand_chip;
        mtd = nand_to_mtd(nand_chip);
        host->dev = &pdev->dev;
        if (IS_ENABLED(CONFIG_OF) && pdev->dev.of_node) {
                nand_set_flash_node(nand_chip, pdev->dev.of_node);
                /* Only when CONFIG_OF is enabled of_node can be parsed */
                res = atmel_of_init_port(host, pdev->dev.of_node);
                if (res)
                        goto err_nand_ioremap;
        } else {
                memcpy(&host->board, dev_get_platdata(&pdev->dev),
                       sizeof(struct atmel_nand_data));
        }

         /* link the private data structures */
        nand_set_controller_data(nand_chip, host);
        mtd->dev.parent = &pdev->dev;

        /* Set address of NAND IO lines */
        nand_chip->IO_ADDR_R = host->io_base;
        nand_chip->IO_ADDR_W = host->io_base;

        if (nand_nfc.is_initialized) {
                /* NFC driver is probed and initialized */
                host->nfc = &nand_nfc;

                nand_chip->select_chip = nfc_select_chip;
                nand_chip->dev_ready = nfc_device_ready;
                nand_chip->cmdfunc = nfc_nand_command;

                /* Initialize the interrupt for NFC */
                irq = platform_get_irq(pdev, 0);
                if (irq < 0) {
                        dev_err(host->dev, "Cannot get HSMC irq!\n");
                        res = irq;
                        goto err_nand_ioremap;
                }

                res = devm_request_irq(&pdev->dev, irq, hsmc_interrupt,
                                0, "hsmc", host);
                if (res) {
                        dev_err(&pdev->dev, "Unable to request HSMC irq %d\n",
                                irq);
                        goto err_nand_ioremap;
                }
        } else {
                res = atmel_nand_set_enable_ready_pins(mtd);
                if (res)
                        goto err_nand_ioremap;

                nand_chip->cmd_ctrl = atmel_nand_cmd_ctrl;
        }

        nand_chip->ecc.mode = host->board.ecc_mode;
        nand_chip->chip_delay = 40;             /* 40us command delay time */

        if (host->board.bus_width_16)   /* 16-bit bus width */
                nand_chip->options |= NAND_BUSWIDTH_16;

        nand_chip->read_buf = atmel_read_buf;
        nand_chip->write_buf = atmel_write_buf;

        platform_set_drvdata(pdev, host);
        atmel_nand_enable(host);

        if (gpio_is_valid(host->board.det_pin)) {
                res = devm_gpio_request(&pdev->dev,
                                host->board.det_pin, "nand_det");
                if (res < 0) {
                        dev_err(&pdev->dev,
                                "can't request det gpio %d\n",
                                host->board.det_pin);
                        goto err_no_card;
                }

                res = gpio_direction_input(host->board.det_pin);
                if (res < 0) {
                        dev_err(&pdev->dev,
                                "can't request input direction det gpio %d\n",
                                host->board.det_pin);
                        goto err_no_card;
                }

                if (gpio_get_value(host->board.det_pin)) {
                        dev_info(&pdev->dev, "No SmartMedia card inserted.\n");
                        res = -ENXIO;
                        goto err_no_card;
                }
        }

        if (host->board.on_flash_bbt || on_flash_bbt) {
                dev_info(&pdev->dev, "Use On Flash BBT\n");
                nand_chip->bbt_options |= NAND_BBT_USE_FLASH;
        }

        if (!host->board.has_dma)
                use_dma = 0;

        if (use_dma) {
                dma_cap_mask_t mask;

                dma_cap_zero(mask);
                dma_cap_set(DMA_MEMCPY, mask);
                host->dma_chan = dma_request_channel(mask, NULL, NULL);
                if (!host->dma_chan) {
                        dev_err(host->dev, "Failed to request DMA channel\n");
                        use_dma = 0;
                }
        }
        if (use_dma)
                dev_info(host->dev, "Using %s for DMA transfers.\n",
                                        dma_chan_name(host->dma_chan));
        else
                dev_info(host->dev, "No DMA support for NAND access.\n");

        /* first scan to find the device and get the page size */
        if (nand_scan_ident(mtd, 1, NULL)) {
                res = -ENXIO;
                goto err_scan_ident;
        }

        if (nand_chip->ecc.mode == NAND_ECC_HW) {
                if (host->has_pmecc)
                        res = atmel_pmecc_nand_init_params(pdev, host);
                else
                        res = atmel_hw_nand_init_params(pdev, host);

                if (res != 0)
                        goto err_hw_ecc;
        }

        /* initialize the nfc configuration register */
        if (host->nfc && host->nfc->use_nfc_sram) {
                res = nfc_sram_init(mtd);
                if (res) {
                        host->nfc->use_nfc_sram = false;
                        dev_err(host->dev, "Disable use nfc sram for data transfer.\n");
                }
        }

        /* second phase scan */
        if (nand_scan_tail(mtd)) {
                res = -ENXIO;
                goto err_scan_tail;
        }

        mtd->name = "atmel_nand";
        res = mtd_device_register(mtd, host->board.parts,
                                  host->board.num_parts);
        if (!res)
                return res;

err_scan_tail:
        if (host->has_pmecc && host->nand_chip.ecc.mode == NAND_ECC_HW)
                pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE);
err_hw_ecc:
err_scan_ident:
err_no_card:
        atmel_nand_disable(host);
        if (host->dma_chan)
                dma_release_channel(host->dma_chan);
err_nand_ioremap:
        return res;
}

/*
 * Remove a NAND device.
 */
static int atmel_nand_remove(struct platform_device *pdev)
{
        struct atmel_nand_host *host = platform_get_drvdata(pdev);
        struct mtd_info *mtd = nand_to_mtd(&host->nand_chip);

        nand_release(mtd);

        atmel_nand_disable(host);

        if (host->has_pmecc && host->nand_chip.ecc.mode == NAND_ECC_HW) {
                pmecc_writel(host->ecc, CTRL, PMECC_CTRL_DISABLE);
                pmerrloc_writel(host->pmerrloc_base, ELDIS,
                                PMERRLOC_DISABLE);
        }

        if (host->dma_chan)
                dma_release_channel(host->dma_chan);

        platform_driver_unregister(&atmel_nand_nfc_driver);

        return 0;
}

/*
 * AT91RM9200 does not have PMECC or PMECC Errloc peripherals for
 * BCH ECC. Combined with the "atmel,has-pmecc", it is used to describe
 * devices from the SAM9 family that have those.
 */
static const struct atmel_nand_caps at91rm9200_caps = {
        .pmecc_correct_erase_page = false,
        .pmecc_max_correction = 24,
};

static const struct atmel_nand_caps sama5d4_caps = {
        .pmecc_correct_erase_page = true,
        .pmecc_max_correction = 24,
};

/*
 * The PMECC Errloc controller starting in SAMA5D2 is not compatible,
 * as the increased correction strength requires more registers.
 */
static const struct atmel_nand_caps sama5d2_caps = {
        .pmecc_correct_erase_page = true,
        .pmecc_max_correction = 32,
};

static const struct of_device_id atmel_nand_dt_ids[] = {
        { .compatible = "atmel,at91rm9200-nand", .data = &at91rm9200_caps },
        { .compatible = "atmel,sama5d4-nand", .data = &sama5d4_caps },
        { .compatible = "atmel,sama5d2-nand", .data = &sama5d2_caps },
        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, atmel_nand_dt_ids);

static int atmel_nand_nfc_probe(struct platform_device *pdev)
{
        struct atmel_nfc *nfc = &nand_nfc;
        struct resource *nfc_cmd_regs, *nfc_hsmc_regs, *nfc_sram;
        int ret;

        nfc_cmd_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        nfc->base_cmd_regs = devm_ioremap_resource(&pdev->dev, nfc_cmd_regs);
        if (IS_ERR(nfc->base_cmd_regs))
                return PTR_ERR(nfc->base_cmd_regs);

        nfc_hsmc_regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        nfc->hsmc_regs = devm_ioremap_resource(&pdev->dev, nfc_hsmc_regs);
        if (IS_ERR(nfc->hsmc_regs))
                return PTR_ERR(nfc->hsmc_regs);

        nfc_sram = platform_get_resource(pdev, IORESOURCE_MEM, 2);
        if (nfc_sram) {
                nfc->sram_bank0 = (void * __force)
                                devm_ioremap_resource(&pdev->dev, nfc_sram);
                if (IS_ERR(nfc->sram_bank0)) {
                        dev_warn(&pdev->dev, "Fail to ioremap the NFC sram with error: %ld. So disable NFC sram.\n",
                                        PTR_ERR(nfc->sram_bank0));
                } else {
                        nfc->use_nfc_sram = true;
                        nfc->sram_bank0_phys = (dma_addr_t)nfc_sram->start;

                        if (pdev->dev.of_node)
                                nfc->write_by_sram = of_property_read_bool(
                                                pdev->dev.of_node,
                                                "atmel,write-by-sram");
                }
        }

        nfc->caps = (const struct atmel_nand_nfc_caps *)
                of_device_get_match_data(&pdev->dev);
        if (!nfc->caps)
                return -ENODEV;

        nfc_writel(nfc->hsmc_regs, IDR, 0xffffffff);
        nfc_readl(nfc->hsmc_regs, SR);  /* clear the NFC_SR */

        nfc->clk = devm_clk_get(&pdev->dev, NULL);
        if (!IS_ERR(nfc->clk)) {
                ret = clk_prepare_enable(nfc->clk);
                if (ret)
                        return ret;
        } else {
                dev_warn(&pdev->dev, "NFC clock missing, update your Device Tree");
        }

        nfc->is_initialized = true;
        dev_info(&pdev->dev, "NFC is probed.\n");

        return 0;
}

static int atmel_nand_nfc_remove(struct platform_device *pdev)
{
        struct atmel_nfc *nfc = &nand_nfc;

        if (!IS_ERR(nfc->clk))
                clk_disable_unprepare(nfc->clk);

        return 0;
}

static const struct atmel_nand_nfc_caps sama5d3_nfc_caps = {
        .rb_mask = NFC_SR_RB_EDGE0,
};

static const struct atmel_nand_nfc_caps sama5d4_nfc_caps = {
        .rb_mask = NFC_SR_RB_EDGE3,
};

static const struct of_device_id atmel_nand_nfc_match[] = {
        { .compatible = "atmel,sama5d3-nfc", .data = &sama5d3_nfc_caps },
        { .compatible = "atmel,sama5d4-nfc", .data = &sama5d4_nfc_caps },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, atmel_nand_nfc_match);

static struct platform_driver atmel_nand_nfc_driver = {
        .driver = {
                .name = "atmel_nand_nfc",
                .of_match_table = of_match_ptr(atmel_nand_nfc_match),
        },
        .probe = atmel_nand_nfc_probe,
        .remove = atmel_nand_nfc_remove,
};

static struct platform_driver atmel_nand_driver = {
        .probe          = atmel_nand_probe,
        .remove         = atmel_nand_remove,
        .driver         = {
                .name   = "atmel_nand",
                .of_match_table = of_match_ptr(atmel_nand_dt_ids),
        },
};

module_platform_driver(atmel_nand_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("NAND/SmartMedia driver for AT91 / AVR32");
MODULE_ALIAS("platform:atmel_nand");