/*
 * Copyright © 2004 Texas Instruments, Jian Zhang <jzhang@ti.com>
 * Copyright © 2004 Micron Technology Inc.
 * Copyright © 2004 David Brownell
 *
 * 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/platform_device.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/sched.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
#include <linux/omap-dma.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_device.h>

#ifdef CONFIG_MTD_NAND_OMAP_BCH
#include <linux/bch.h>
#include <linux/platform_data/elm.h>
#endif

#include <linux/platform_data/mtd-nand-omap2.h>

#define DRIVER_NAME     "omap2-nand"
#define OMAP_NAND_TIMEOUT_MS    5000

#define NAND_Ecc_P1e            (1 << 0)
#define NAND_Ecc_P2e            (1 << 1)
#define NAND_Ecc_P4e            (1 << 2)
#define NAND_Ecc_P8e            (1 << 3)
#define NAND_Ecc_P16e           (1 << 4)
#define NAND_Ecc_P32e           (1 << 5)
#define NAND_Ecc_P64e           (1 << 6)
#define NAND_Ecc_P128e          (1 << 7)
#define NAND_Ecc_P256e          (1 << 8)
#define NAND_Ecc_P512e          (1 << 9)
#define NAND_Ecc_P1024e         (1 << 10)
#define NAND_Ecc_P2048e         (1 << 11)

#define NAND_Ecc_P1o            (1 << 16)
#define NAND_Ecc_P2o            (1 << 17)
#define NAND_Ecc_P4o            (1 << 18)
#define NAND_Ecc_P8o            (1 << 19)
#define NAND_Ecc_P16o           (1 << 20)
#define NAND_Ecc_P32o           (1 << 21)
#define NAND_Ecc_P64o           (1 << 22)
#define NAND_Ecc_P128o          (1 << 23)
#define NAND_Ecc_P256o          (1 << 24)
#define NAND_Ecc_P512o          (1 << 25)
#define NAND_Ecc_P1024o         (1 << 26)
#define NAND_Ecc_P2048o         (1 << 27)

#define TF(value)       (value ? 1 : 0)

#define P2048e(a)       (TF(a & NAND_Ecc_P2048e)        << 0)
#define P2048o(a)       (TF(a & NAND_Ecc_P2048o)        << 1)
#define P1e(a)          (TF(a & NAND_Ecc_P1e)           << 2)
#define P1o(a)          (TF(a & NAND_Ecc_P1o)           << 3)
#define P2e(a)          (TF(a & NAND_Ecc_P2e)           << 4)
#define P2o(a)          (TF(a & NAND_Ecc_P2o)           << 5)
#define P4e(a)          (TF(a & NAND_Ecc_P4e)           << 6)
#define P4o(a)          (TF(a & NAND_Ecc_P4o)           << 7)

#define P8e(a)          (TF(a & NAND_Ecc_P8e)           << 0)
#define P8o(a)          (TF(a & NAND_Ecc_P8o)           << 1)
#define P16e(a)         (TF(a & NAND_Ecc_P16e)          << 2)
#define P16o(a)         (TF(a & NAND_Ecc_P16o)          << 3)
#define P32e(a)         (TF(a & NAND_Ecc_P32e)          << 4)
#define P32o(a)         (TF(a & NAND_Ecc_P32o)          << 5)
#define P64e(a)         (TF(a & NAND_Ecc_P64e)          << 6)
#define P64o(a)         (TF(a & NAND_Ecc_P64o)          << 7)

#define P128e(a)        (TF(a & NAND_Ecc_P128e)         << 0)
#define P128o(a)        (TF(a & NAND_Ecc_P128o)         << 1)
#define P256e(a)        (TF(a & NAND_Ecc_P256e)         << 2)
#define P256o(a)        (TF(a & NAND_Ecc_P256o)         << 3)
#define P512e(a)        (TF(a & NAND_Ecc_P512e)         << 4)
#define P512o(a)        (TF(a & NAND_Ecc_P512o)         << 5)
#define P1024e(a)       (TF(a & NAND_Ecc_P1024e)        << 6)
#define P1024o(a)       (TF(a & NAND_Ecc_P1024o)        << 7)

#define P8e_s(a)        (TF(a & NAND_Ecc_P8e)           << 0)
#define P8o_s(a)        (TF(a & NAND_Ecc_P8o)           << 1)
#define P16e_s(a)       (TF(a & NAND_Ecc_P16e)          << 2)
#define P16o_s(a)       (TF(a & NAND_Ecc_P16o)          << 3)
#define P1e_s(a)        (TF(a & NAND_Ecc_P1e)           << 4)
#define P1o_s(a)        (TF(a & NAND_Ecc_P1o)           << 5)
#define P2e_s(a)        (TF(a & NAND_Ecc_P2e)           << 6)
#define P2o_s(a)        (TF(a & NAND_Ecc_P2o)           << 7)

#define P4e_s(a)        (TF(a & NAND_Ecc_P4e)           << 0)
#define P4o_s(a)        (TF(a & NAND_Ecc_P4o)           << 1)

#define PREFETCH_CONFIG1_CS_SHIFT       24
#define ECC_CONFIG_CS_SHIFT             1
#define CS_MASK                         0x7
#define ENABLE_PREFETCH                 (0x1 << 7)
#define DMA_MPU_MODE_SHIFT              2
#define ECCSIZE0_SHIFT                  12
#define ECCSIZE1_SHIFT                  22
#define ECC1RESULTSIZE                  0x1
#define ECCCLEAR                        0x100
#define ECC1                            0x1
#define PREFETCH_FIFOTHRESHOLD_MAX      0x40
#define PREFETCH_FIFOTHRESHOLD(val)     ((val) << 8)
#define PREFETCH_STATUS_COUNT(val)      (val & 0x00003fff)
#define PREFETCH_STATUS_FIFO_CNT(val)   ((val >> 24) & 0x7F)
#define STATUS_BUFF_EMPTY               0x00000001

#define OMAP24XX_DMA_GPMC               4

#define BCH8_MAX_ERROR          8       /* upto 8 bit correctable */
#define BCH4_MAX_ERROR          4       /* upto 4 bit correctable */

#define SECTOR_BYTES            512
/* 4 bit padding to make byte aligned, 56 = 52 + 4 */
#define BCH4_BIT_PAD            4
#define BCH8_ECC_MAX            ((SECTOR_BYTES + BCH8_ECC_OOB_BYTES) * 8)
#define BCH4_ECC_MAX            ((SECTOR_BYTES + BCH4_ECC_OOB_BYTES) * 8)

/* GPMC ecc engine settings for read */
#define BCH_WRAPMODE_1          1       /* BCH wrap mode 1 */
#define BCH8R_ECC_SIZE0         0x1a    /* ecc_size0 = 26 */
#define BCH8R_ECC_SIZE1         0x2     /* ecc_size1 = 2 */
#define BCH4R_ECC_SIZE0         0xd     /* ecc_size0 = 13 */
#define BCH4R_ECC_SIZE1         0x3     /* ecc_size1 = 3 */

/* GPMC ecc engine settings for write */
#define BCH_WRAPMODE_6          6       /* BCH wrap mode 6 */
#define BCH_ECC_SIZE0           0x0     /* ecc_size0 = 0, no oob protection */
#define BCH_ECC_SIZE1           0x20    /* ecc_size1 = 32 */

#ifdef CONFIG_MTD_NAND_OMAP_BCH
static u_char bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2, 0xbe, 0xcc,
        0xac, 0x6b, 0xff, 0x99, 0x7b};
static u_char bch4_vector[] = {0x00, 0x6b, 0x31, 0xdd, 0x41, 0xbc, 0x10};
#endif

/* oob info generated runtime depending on ecc algorithm and layout selected */
static struct nand_ecclayout omap_oobinfo;
/* Define some generic bad / good block scan pattern which are used
 * while scanning a device for factory marked good / bad blocks
 */
static uint8_t scan_ff_pattern[] = { 0xff };
static struct nand_bbt_descr bb_descrip_flashbased = {
        .options = NAND_BBT_SCANEMPTY | NAND_BBT_SCANALLPAGES,
        .offs = 0,
        .len = 1,
        .pattern = scan_ff_pattern,
};


struct omap_nand_info {
        struct nand_hw_control          controller;
        struct omap_nand_platform_data  *pdata;
        struct mtd_info                 mtd;
        struct nand_chip                nand;
        struct platform_device          *pdev;

        int                             gpmc_cs;
        unsigned long                   phys_base;
        unsigned long                   mem_size;
        struct completion               comp;
        struct dma_chan                 *dma;
        int                             gpmc_irq_fifo;
        int                             gpmc_irq_count;
        enum {
                OMAP_NAND_IO_READ = 0,  /* read */
                OMAP_NAND_IO_WRITE,     /* write */
        } iomode;
        u_char                          *buf;
        int                                     buf_len;
        struct gpmc_nand_regs           reg;

#ifdef CONFIG_MTD_NAND_OMAP_BCH
        struct bch_control             *bch;
        struct nand_ecclayout           ecclayout;
        bool                            is_elm_used;
        struct device                   *elm_dev;
        struct device_node              *of_node;
#endif
};

/**
 * omap_prefetch_enable - configures and starts prefetch transfer
 * @cs: cs (chip select) number
 * @fifo_th: fifo threshold to be used for read/ write
 * @dma_mode: dma mode enable (1) or disable (0)
 * @u32_count: number of bytes to be transferred
 * @is_write: prefetch read(0) or write post(1) mode
 */
static int omap_prefetch_enable(int cs, int fifo_th, int dma_mode,
        unsigned int u32_count, int is_write, struct omap_nand_info *info)
{
        u32 val;

        if (fifo_th > PREFETCH_FIFOTHRESHOLD_MAX)
                return -1;

        if (readl(info->reg.gpmc_prefetch_control))
                return -EBUSY;

        /* Set the amount of bytes to be prefetched */
        writel(u32_count, info->reg.gpmc_prefetch_config2);

        /* Set dma/mpu mode, the prefetch read / post write and
         * enable the engine. Set which cs is has requested for.
         */
        val = ((cs << PREFETCH_CONFIG1_CS_SHIFT) |
                PREFETCH_FIFOTHRESHOLD(fifo_th) | ENABLE_PREFETCH |
                (dma_mode << DMA_MPU_MODE_SHIFT) | (0x1 & is_write));
        writel(val, info->reg.gpmc_prefetch_config1);

        /*  Start the prefetch engine */
        writel(0x1, info->reg.gpmc_prefetch_control);

        return 0;
}

/**
 * omap_prefetch_reset - disables and stops the prefetch engine
 */
static int omap_prefetch_reset(int cs, struct omap_nand_info *info)
{
        u32 config1;

        /* check if the same module/cs is trying to reset */
        config1 = readl(info->reg.gpmc_prefetch_config1);
        if (((config1 >> PREFETCH_CONFIG1_CS_SHIFT) & CS_MASK) != cs)
                return -EINVAL;

        /* Stop the PFPW engine */
        writel(0x0, info->reg.gpmc_prefetch_control);

        /* Reset/disable the PFPW engine */
        writel(0x0, info->reg.gpmc_prefetch_config1);

        return 0;
}

/**
 * omap_hwcontrol - hardware specific access to control-lines
 * @mtd: MTD device structure
 * @cmd: command to device
 * @ctrl:
 * NAND_NCE: bit 0 -> don't care
 * NAND_CLE: bit 1 -> Command Latch
 * NAND_ALE: bit 2 -> Address Latch
 *
 * NOTE: boards may use different bits for these!!
 */
static void omap_hwcontrol(struct mtd_info *mtd, int cmd, unsigned int ctrl)
{
        struct omap_nand_info *info = container_of(mtd,
                                        struct omap_nand_info, mtd);

        if (cmd != NAND_CMD_NONE) {
                if (ctrl & NAND_CLE)
                        writeb(cmd, info->reg.gpmc_nand_command);

                else if (ctrl & NAND_ALE)
                        writeb(cmd, info->reg.gpmc_nand_address);

                else /* NAND_NCE */
                        writeb(cmd, info->reg.gpmc_nand_data);
        }
}

/**
 * omap_read_buf8 - read data from NAND controller into buffer
 * @mtd: MTD device structure
 * @buf: buffer to store date
 * @len: number of bytes to read
 */
static void omap_read_buf8(struct mtd_info *mtd, u_char *buf, int len)
{
        struct nand_chip *nand = mtd->priv;

        ioread8_rep(nand->IO_ADDR_R, buf, len);
}

/**
 * omap_write_buf8 - write buffer to NAND controller
 * @mtd: MTD device structure
 * @buf: data buffer
 * @len: number of bytes to write
 */
static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);
        u_char *p = (u_char *)buf;
        u32     status = 0;

        while (len--) {
                iowrite8(*p++, info->nand.IO_ADDR_W);
                /* wait until buffer is available for write */
                do {
                        status = readl(info->reg.gpmc_status) &
                                        STATUS_BUFF_EMPTY;
                } while (!status);
        }
}

/**
 * omap_read_buf16 - read data from NAND controller into buffer
 * @mtd: MTD device structure
 * @buf: buffer to store date
 * @len: number of bytes to read
 */
static void omap_read_buf16(struct mtd_info *mtd, u_char *buf, int len)
{
        struct nand_chip *nand = mtd->priv;

        ioread16_rep(nand->IO_ADDR_R, buf, len / 2);
}

/**
 * omap_write_buf16 - write buffer to NAND controller
 * @mtd: MTD device structure
 * @buf: data buffer
 * @len: number of bytes to write
 */
static void omap_write_buf16(struct mtd_info *mtd, const u_char * buf, int len)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);
        u16 *p = (u16 *) buf;
        u32     status = 0;
        /* FIXME try bursts of writesw() or DMA ... */
        len >>= 1;

        while (len--) {
                iowrite16(*p++, info->nand.IO_ADDR_W);
                /* wait until buffer is available for write */
                do {
                        status = readl(info->reg.gpmc_status) &
                                        STATUS_BUFF_EMPTY;
                } while (!status);
        }
}

/**
 * omap_read_buf_pref - read data from NAND controller into buffer
 * @mtd: MTD device structure
 * @buf: buffer to store date
 * @len: number of bytes to read
 */
static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);
        uint32_t r_count = 0;
        int ret = 0;
        u32 *p = (u32 *)buf;

        /* take care of subpage reads */
        if (len % 4) {
                if (info->nand.options & NAND_BUSWIDTH_16)
                        omap_read_buf16(mtd, buf, len % 4);
                else
                        omap_read_buf8(mtd, buf, len % 4);
                p = (u32 *) (buf + len % 4);
                len -= len % 4;
        }

        /* configure and start prefetch transfer */
        ret = omap_prefetch_enable(info->gpmc_cs,
                        PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x0, info);
        if (ret) {
                /* PFPW engine is busy, use cpu copy method */
                if (info->nand.options & NAND_BUSWIDTH_16)
                        omap_read_buf16(mtd, (u_char *)p, len);
                else
                        omap_read_buf8(mtd, (u_char *)p, len);
        } else {
                do {
                        r_count = readl(info->reg.gpmc_prefetch_status);
                        r_count = PREFETCH_STATUS_FIFO_CNT(r_count);
                        r_count = r_count >> 2;
                        ioread32_rep(info->nand.IO_ADDR_R, p, r_count);
                        p += r_count;
                        len -= r_count << 2;
                } while (len);
                /* disable and stop the PFPW engine */
                omap_prefetch_reset(info->gpmc_cs, info);
        }
}

/**
 * omap_write_buf_pref - write buffer to NAND controller
 * @mtd: MTD device structure
 * @buf: data buffer
 * @len: number of bytes to write
 */
static void omap_write_buf_pref(struct mtd_info *mtd,
                                        const u_char *buf, int len)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);
        uint32_t w_count = 0;
        int i = 0, ret = 0;
        u16 *p = (u16 *)buf;
        unsigned long tim, limit;
        u32 val;

        /* take care of subpage writes */
        if (len % 2 != 0) {
                writeb(*buf, info->nand.IO_ADDR_W);
                p = (u16 *)(buf + 1);
                len--;
        }

        /*  configure and start prefetch transfer */
        ret = omap_prefetch_enable(info->gpmc_cs,
                        PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x1, info);
        if (ret) {
                /* PFPW engine is busy, use cpu copy method */
                if (info->nand.options & NAND_BUSWIDTH_16)
                        omap_write_buf16(mtd, (u_char *)p, len);
                else
                        omap_write_buf8(mtd, (u_char *)p, len);
        } else {
                while (len) {
                        w_count = readl(info->reg.gpmc_prefetch_status);
                        w_count = PREFETCH_STATUS_FIFO_CNT(w_count);
                        w_count = w_count >> 1;
                        for (i = 0; (i < w_count) && len; i++, len -= 2)
                                iowrite16(*p++, info->nand.IO_ADDR_W);
                }
                /* wait for data to flushed-out before reset the prefetch */
                tim = 0;
                limit = (loops_per_jiffy *
                                        msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));
                do {
                        cpu_relax();
                        val = readl(info->reg.gpmc_prefetch_status);
                        val = PREFETCH_STATUS_COUNT(val);
                } while (val && (tim++ < limit));

                /* disable and stop the PFPW engine */
                omap_prefetch_reset(info->gpmc_cs, info);
        }
}

/*
 * omap_nand_dma_callback: callback on the completion of dma transfer
 * @data: pointer to completion data structure
 */
static void omap_nand_dma_callback(void *data)
{
        complete((struct completion *) data);
}

/*
 * omap_nand_dma_transfer: configure and start dma transfer
 * @mtd: MTD device structure
 * @addr: virtual address in RAM of source/destination
 * @len: number of data bytes to be transferred
 * @is_write: flag for read/write operation
 */
static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
                                        unsigned int len, int is_write)
{
        struct omap_nand_info *info = container_of(mtd,
                                        struct omap_nand_info, mtd);
        struct dma_async_tx_descriptor *tx;
        enum dma_data_direction dir = is_write ? DMA_TO_DEVICE :
                                                        DMA_FROM_DEVICE;
        struct scatterlist sg;
        unsigned long tim, limit;
        unsigned n;
        int ret;
        u32 val;

        if (addr >= high_memory) {
                struct page *p1;

                if (((size_t)addr & PAGE_MASK) !=
                        ((size_t)(addr + len - 1) & PAGE_MASK))
                        goto out_copy;
                p1 = vmalloc_to_page(addr);
                if (!p1)
                        goto out_copy;
                addr = page_address(p1) + ((size_t)addr & ~PAGE_MASK);
        }

        sg_init_one(&sg, addr, len);
        n = dma_map_sg(info->dma->device->dev, &sg, 1, dir);
        if (n == 0) {
                dev_err(&info->pdev->dev,
                        "Couldn't DMA map a %d byte buffer\n", len);
                goto out_copy;
        }

        tx = dmaengine_prep_slave_sg(info->dma, &sg, n,
                is_write ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
                DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (!tx)
                goto out_copy_unmap;

        tx->callback = omap_nand_dma_callback;
        tx->callback_param = &info->comp;
        dmaengine_submit(tx);

        /*  configure and start prefetch transfer */
        ret = omap_prefetch_enable(info->gpmc_cs,
                PREFETCH_FIFOTHRESHOLD_MAX, 0x1, len, is_write, info);
        if (ret)
                /* PFPW engine is busy, use cpu copy method */
                goto out_copy_unmap;

        init_completion(&info->comp);
        dma_async_issue_pending(info->dma);

        /* setup and start DMA using dma_addr */
        wait_for_completion(&info->comp);
        tim = 0;
        limit = (loops_per_jiffy * msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));

        do {
                cpu_relax();
                val = readl(info->reg.gpmc_prefetch_status);
                val = PREFETCH_STATUS_COUNT(val);
        } while (val && (tim++ < limit));

        /* disable and stop the PFPW engine */
        omap_prefetch_reset(info->gpmc_cs, info);

        dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
        return 0;

out_copy_unmap:
        dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
out_copy:
        if (info->nand.options & NAND_BUSWIDTH_16)
                is_write == 0 ? omap_read_buf16(mtd, (u_char *) addr, len)
                        : omap_write_buf16(mtd, (u_char *) addr, len);
        else
                is_write == 0 ? omap_read_buf8(mtd, (u_char *) addr, len)
                        : omap_write_buf8(mtd, (u_char *) addr, len);
        return 0;
}

/**
 * omap_read_buf_dma_pref - read data from NAND controller into buffer
 * @mtd: MTD device structure
 * @buf: buffer to store date
 * @len: number of bytes to read
 */
static void omap_read_buf_dma_pref(struct mtd_info *mtd, u_char *buf, int len)
{
        if (len <= mtd->oobsize)
                omap_read_buf_pref(mtd, buf, len);
        else
                /* start transfer in DMA mode */
                omap_nand_dma_transfer(mtd, buf, len, 0x0);
}

/**
 * omap_write_buf_dma_pref - write buffer to NAND controller
 * @mtd: MTD device structure
 * @buf: data buffer
 * @len: number of bytes to write
 */
static void omap_write_buf_dma_pref(struct mtd_info *mtd,
                                        const u_char *buf, int len)
{
        if (len <= mtd->oobsize)
                omap_write_buf_pref(mtd, buf, len);
        else
                /* start transfer in DMA mode */
                omap_nand_dma_transfer(mtd, (u_char *) buf, len, 0x1);
}

/*
 * omap_nand_irq - GPMC irq handler
 * @this_irq: gpmc irq number
 * @dev: omap_nand_info structure pointer is passed here
 */
static irqreturn_t omap_nand_irq(int this_irq, void *dev)
{
        struct omap_nand_info *info = (struct omap_nand_info *) dev;
        u32 bytes;

        bytes = readl(info->reg.gpmc_prefetch_status);
        bytes = PREFETCH_STATUS_FIFO_CNT(bytes);
        bytes = bytes  & 0xFFFC; /* io in multiple of 4 bytes */
        if (info->iomode == OMAP_NAND_IO_WRITE) { /* checks for write io */
                if (this_irq == info->gpmc_irq_count)
                        goto done;

                if (info->buf_len && (info->buf_len < bytes))
                        bytes = info->buf_len;
                else if (!info->buf_len)
                        bytes = 0;
                iowrite32_rep(info->nand.IO_ADDR_W,
                                                (u32 *)info->buf, bytes >> 2);
                info->buf = info->buf + bytes;
                info->buf_len -= bytes;

        } else {
                ioread32_rep(info->nand.IO_ADDR_R,
                                                (u32 *)info->buf, bytes >> 2);
                info->buf = info->buf + bytes;

                if (this_irq == info->gpmc_irq_count)
                        goto done;
        }

        return IRQ_HANDLED;

done:
        complete(&info->comp);

        disable_irq_nosync(info->gpmc_irq_fifo);
        disable_irq_nosync(info->gpmc_irq_count);

        return IRQ_HANDLED;
}

/*
 * omap_read_buf_irq_pref - read data from NAND controller into buffer
 * @mtd: MTD device structure
 * @buf: buffer to store date
 * @len: number of bytes to read
 */
static void omap_read_buf_irq_pref(struct mtd_info *mtd, u_char *buf, int len)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);
        int ret = 0;

        if (len <= mtd->oobsize) {
                omap_read_buf_pref(mtd, buf, len);
                return;
        }

        info->iomode = OMAP_NAND_IO_READ;
        info->buf = buf;
        init_completion(&info->comp);

        /*  configure and start prefetch transfer */
        ret = omap_prefetch_enable(info->gpmc_cs,
                        PREFETCH_FIFOTHRESHOLD_MAX/2, 0x0, len, 0x0, info);
        if (ret)
                /* PFPW engine is busy, use cpu copy method */
                goto out_copy;

        info->buf_len = len;

        enable_irq(info->gpmc_irq_count);
        enable_irq(info->gpmc_irq_fifo);

        /* waiting for read to complete */
        wait_for_completion(&info->comp);

        /* disable and stop the PFPW engine */
        omap_prefetch_reset(info->gpmc_cs, info);
        return;

out_copy:
        if (info->nand.options & NAND_BUSWIDTH_16)
                omap_read_buf16(mtd, buf, len);
        else
                omap_read_buf8(mtd, buf, len);
}

/*
 * omap_write_buf_irq_pref - write buffer to NAND controller
 * @mtd: MTD device structure
 * @buf: data buffer
 * @len: number of bytes to write
 */
static void omap_write_buf_irq_pref(struct mtd_info *mtd,
                                        const u_char *buf, int len)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);
        int ret = 0;
        unsigned long tim, limit;
        u32 val;

        if (len <= mtd->oobsize) {
                omap_write_buf_pref(mtd, buf, len);
                return;
        }

        info->iomode = OMAP_NAND_IO_WRITE;
        info->buf = (u_char *) buf;
        init_completion(&info->comp);

        /* configure and start prefetch transfer : size=24 */
        ret = omap_prefetch_enable(info->gpmc_cs,
                (PREFETCH_FIFOTHRESHOLD_MAX * 3) / 8, 0x0, len, 0x1, info);
        if (ret)
                /* PFPW engine is busy, use cpu copy method */
                goto out_copy;

        info->buf_len = len;

        enable_irq(info->gpmc_irq_count);
        enable_irq(info->gpmc_irq_fifo);

        /* waiting for write to complete */
        wait_for_completion(&info->comp);

        /* wait for data to flushed-out before reset the prefetch */
        tim = 0;
        limit = (loops_per_jiffy *  msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));
        do {
                val = readl(info->reg.gpmc_prefetch_status);
                val = PREFETCH_STATUS_COUNT(val);
                cpu_relax();
        } while (val && (tim++ < limit));

        /* disable and stop the PFPW engine */
        omap_prefetch_reset(info->gpmc_cs, info);
        return;

out_copy:
        if (info->nand.options & NAND_BUSWIDTH_16)
                omap_write_buf16(mtd, buf, len);
        else
                omap_write_buf8(mtd, buf, len);
}

/**
 * gen_true_ecc - This function will generate true ECC value
 * @ecc_buf: buffer to store ecc code
 *
 * This generated true ECC value can be used when correcting
 * data read from NAND flash memory core
 */
static void gen_true_ecc(u8 *ecc_buf)
{
        u32 tmp = ecc_buf[0] | (ecc_buf[1] << 16) |
                ((ecc_buf[2] & 0xF0) << 20) | ((ecc_buf[2] & 0x0F) << 8);

        ecc_buf[0] = ~(P64o(tmp) | P64e(tmp) | P32o(tmp) | P32e(tmp) |
                        P16o(tmp) | P16e(tmp) | P8o(tmp) | P8e(tmp));
        ecc_buf[1] = ~(P1024o(tmp) | P1024e(tmp) | P512o(tmp) | P512e(tmp) |
                        P256o(tmp) | P256e(tmp) | P128o(tmp) | P128e(tmp));
        ecc_buf[2] = ~(P4o(tmp) | P4e(tmp) | P2o(tmp) | P2e(tmp) | P1o(tmp) |
                        P1e(tmp) | P2048o(tmp) | P2048e(tmp));
}

/**
 * omap_compare_ecc - Detect (2 bits) and correct (1 bit) error in data
 * @ecc_data1:  ecc code from nand spare area
 * @ecc_data2:  ecc code from hardware register obtained from hardware ecc
 * @page_data:  page data
 *
 * This function compares two ECC's and indicates if there is an error.
 * If the error can be corrected it will be corrected to the buffer.
 * If there is no error, %0 is returned. If there is an error but it
 * was corrected, %1 is returned. Otherwise, %-1 is returned.
 */
static int omap_compare_ecc(u8 *ecc_data1,      /* read from NAND memory */
                            u8 *ecc_data2,      /* read from register */
                            u8 *page_data)
{
        uint    i;
        u8      tmp0_bit[8], tmp1_bit[8], tmp2_bit[8];
        u8      comp0_bit[8], comp1_bit[8], comp2_bit[8];
        u8      ecc_bit[24];
        u8      ecc_sum = 0;
        u8      find_bit = 0;
        uint    find_byte = 0;
        int     isEccFF;

        isEccFF = ((*(u32 *)ecc_data1 & 0xFFFFFF) == 0xFFFFFF);

        gen_true_ecc(ecc_data1);
        gen_true_ecc(ecc_data2);

        for (i = 0; i <= 2; i++) {
                *(ecc_data1 + i) = ~(*(ecc_data1 + i));
                *(ecc_data2 + i) = ~(*(ecc_data2 + i));
        }

        for (i = 0; i < 8; i++) {
                tmp0_bit[i]     = *ecc_data1 % 2;
                *ecc_data1      = *ecc_data1 / 2;
        }

        for (i = 0; i < 8; i++) {
                tmp1_bit[i]      = *(ecc_data1 + 1) % 2;
                *(ecc_data1 + 1) = *(ecc_data1 + 1) / 2;
        }

        for (i = 0; i < 8; i++) {
                tmp2_bit[i]      = *(ecc_data1 + 2) % 2;
                *(ecc_data1 + 2) = *(ecc_data1 + 2) / 2;
        }

        for (i = 0; i < 8; i++) {
                comp0_bit[i]     = *ecc_data2 % 2;
                *ecc_data2       = *ecc_data2 / 2;
        }

        for (i = 0; i < 8; i++) {
                comp1_bit[i]     = *(ecc_data2 + 1) % 2;
                *(ecc_data2 + 1) = *(ecc_data2 + 1) / 2;
        }

        for (i = 0; i < 8; i++) {
                comp2_bit[i]     = *(ecc_data2 + 2) % 2;
                *(ecc_data2 + 2) = *(ecc_data2 + 2) / 2;
        }

        for (i = 0; i < 6; i++)
                ecc_bit[i] = tmp2_bit[i + 2] ^ comp2_bit[i + 2];

        for (i = 0; i < 8; i++)
                ecc_bit[i + 6] = tmp0_bit[i] ^ comp0_bit[i];

        for (i = 0; i < 8; i++)
                ecc_bit[i + 14] = tmp1_bit[i] ^ comp1_bit[i];

        ecc_bit[22] = tmp2_bit[0] ^ comp2_bit[0];
        ecc_bit[23] = tmp2_bit[1] ^ comp2_bit[1];

        for (i = 0; i < 24; i++)
                ecc_sum += ecc_bit[i];

        switch (ecc_sum) {
        case 0:
                /* Not reached because this function is not called if
                 *  ECC values are equal
                 */
                return 0;

        case 1:
                /* Uncorrectable error */
                pr_debug("ECC UNCORRECTED_ERROR 1\n");
                return -1;

        case 11:
                /* UN-Correctable error */
                pr_debug("ECC UNCORRECTED_ERROR B\n");
                return -1;

        case 12:
                /* Correctable error */
                find_byte = (ecc_bit[23] << 8) +
                            (ecc_bit[21] << 7) +
                            (ecc_bit[19] << 6) +
                            (ecc_bit[17] << 5) +
                            (ecc_bit[15] << 4) +
                            (ecc_bit[13] << 3) +
                            (ecc_bit[11] << 2) +
                            (ecc_bit[9]  << 1) +
                            ecc_bit[7];

                find_bit = (ecc_bit[5] << 2) + (ecc_bit[3] << 1) + ecc_bit[1];

                pr_debug("Correcting single bit ECC error at offset: "
                                "%d, bit: %d\n", find_byte, find_bit);

                page_data[find_byte] ^= (1 << find_bit);

                return 1;
        default:
                if (isEccFF) {
                        if (ecc_data2[0] == 0 &&
                            ecc_data2[1] == 0 &&
                            ecc_data2[2] == 0)
                                return 0;
                }
                pr_debug("UNCORRECTED_ERROR default\n");
                return -1;
        }
}

/**
 * omap_correct_data - Compares the ECC read with HW generated ECC
 * @mtd: MTD device structure
 * @dat: page data
 * @read_ecc: ecc read from nand flash
 * @calc_ecc: ecc read from HW ECC registers
 *
 * Compares the ecc read from nand spare area with ECC registers values
 * and if ECC's mismatched, it will call 'omap_compare_ecc' for error
 * detection and correction. If there are no errors, %0 is returned. If
 * there were errors and all of the errors were corrected, the number of
 * corrected errors is returned. If uncorrectable errors exist, %-1 is
 * returned.
 */
static int omap_correct_data(struct mtd_info *mtd, u_char *dat,
                                u_char *read_ecc, u_char *calc_ecc)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        int blockCnt = 0, i = 0, ret = 0;
        int stat = 0;

        /* Ex NAND_ECC_HW12_2048 */
        if ((info->nand.ecc.mode == NAND_ECC_HW) &&
                        (info->nand.ecc.size  == 2048))
                blockCnt = 4;
        else
                blockCnt = 1;

        for (i = 0; i < blockCnt; i++) {
                if (memcmp(read_ecc, calc_ecc, 3) != 0) {
                        ret = omap_compare_ecc(read_ecc, calc_ecc, dat);
                        if (ret < 0)
                                return ret;
                        /* keep track of the number of corrected errors */
                        stat += ret;
                }
                read_ecc += 3;
                calc_ecc += 3;
                dat      += 512;
        }
        return stat;
}

/**
 * omap_calcuate_ecc - Generate non-inverted ECC bytes.
 * @mtd: MTD device structure
 * @dat: The pointer to data on which ecc is computed
 * @ecc_code: The ecc_code buffer
 *
 * Using noninverted ECC can be considered ugly since writing a blank
 * page ie. padding will clear the ECC bytes. This is no problem as long
 * nobody is trying to write data on the seemingly unused page. Reading
 * an erased page will produce an ECC mismatch between generated and read
 * ECC bytes that has to be dealt with separately.
 */
static int omap_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
                                u_char *ecc_code)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        u32 val;

        val = readl(info->reg.gpmc_ecc_config);
        if (((val >> ECC_CONFIG_CS_SHIFT)  & ~CS_MASK) != info->gpmc_cs)
                return -EINVAL;

        /* read ecc result */
        val = readl(info->reg.gpmc_ecc1_result);
        *ecc_code++ = val;          /* P128e, ..., P1e */
        *ecc_code++ = val >> 16;    /* P128o, ..., P1o */
        /* P2048o, P1024o, P512o, P256o, P2048e, P1024e, P512e, P256e */
        *ecc_code++ = ((val >> 8) & 0x0f) | ((val >> 20) & 0xf0);

        return 0;
}

/**
 * omap_enable_hwecc - This function enables the hardware ecc functionality
 * @mtd: MTD device structure
 * @mode: Read/Write mode
 */
static void omap_enable_hwecc(struct mtd_info *mtd, int mode)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        struct nand_chip *chip = mtd->priv;
        unsigned int dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : 0;
        u32 val;

        /* clear ecc and enable bits */
        val = ECCCLEAR | ECC1;
        writel(val, info->reg.gpmc_ecc_control);

        /* program ecc and result sizes */
        val = ((((info->nand.ecc.size >> 1) - 1) << ECCSIZE1_SHIFT) |
                         ECC1RESULTSIZE);
        writel(val, info->reg.gpmc_ecc_size_config);

        switch (mode) {
        case NAND_ECC_READ:
        case NAND_ECC_WRITE:
                writel(ECCCLEAR | ECC1, info->reg.gpmc_ecc_control);
                break;
        case NAND_ECC_READSYN:
                writel(ECCCLEAR, info->reg.gpmc_ecc_control);
                break;
        default:
                dev_info(&info->pdev->dev,
                        "error: unrecognized Mode[%d]!\n", mode);
                break;
        }

        /* (ECC 16 or 8 bit col) | ( CS  )  | ECC Enable */

        val = (dev_width << 7) | (info->gpmc_cs << 1) | (0x1);
        writel(val, info->reg.gpmc_ecc_config);
}

/**
 * omap_wait - wait until the command is done
 * @mtd: MTD device structure
 * @chip: NAND Chip structure
 *
 * Wait function is called during Program and erase operations and
 * the way it is called from MTD layer, we should wait till the NAND
 * chip is ready after the programming/erase operation has completed.
 *
 * Erase can take up to 400ms and program up to 20ms according to
 * general NAND and SmartMedia specs
 */
static int omap_wait(struct mtd_info *mtd, struct nand_chip *chip)
{
        struct nand_chip *this = mtd->priv;
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        unsigned long timeo = jiffies;
        int status, state = this->state;

        if (state == FL_ERASING)
                timeo += (HZ * 400) / 1000;
        else
                timeo += (HZ * 20) / 1000;

        writeb(NAND_CMD_STATUS & 0xFF, info->reg.gpmc_nand_command);
        while (time_before(jiffies, timeo)) {
                status = readb(info->reg.gpmc_nand_data);
                if (status & NAND_STATUS_READY)
                        break;
                cond_resched();
        }

        status = readb(info->reg.gpmc_nand_data);
        return status;
}

/**
 * omap_dev_ready - calls the platform specific dev_ready function
 * @mtd: MTD device structure
 */
static int omap_dev_ready(struct mtd_info *mtd)
{
        unsigned int val = 0;
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);

        val = readl(info->reg.gpmc_status);

        if ((val & 0x100) == 0x100) {
                return 1;
        } else {
                return 0;
        }
}

#ifdef CONFIG_MTD_NAND_OMAP_BCH

/**
 * omap3_enable_hwecc_bch - Program OMAP3 GPMC to perform BCH ECC correction
 * @mtd: MTD device structure
 * @mode: Read/Write mode
 *
 * When using BCH, sector size is hardcoded to 512 bytes.
 * Using wrapping mode 6 both for reading and writing if ELM module not uses
 * for error correction.
 * On writing,
 * eccsize0 = 0  (no additional protected byte in spare area)
 * eccsize1 = 32 (skip 32 nibbles = 16 bytes per sector in spare area)
 */
static void omap3_enable_hwecc_bch(struct mtd_info *mtd, int mode)
{
        int nerrors;
        unsigned int dev_width, nsectors;
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
        struct nand_chip *chip = mtd->priv;
        u32 val, wr_mode;
        unsigned int ecc_size1, ecc_size0;

        /* Using wrapping mode 6 for writing */
        wr_mode = BCH_WRAPMODE_6;

        /*
         * ECC engine enabled for valid ecc_size0 nibbles
         * and disabled for ecc_size1 nibbles.
         */
        ecc_size0 = BCH_ECC_SIZE0;
        ecc_size1 = BCH_ECC_SIZE1;

        /* Perform ecc calculation on 512-byte sector */
        nsectors = 1;

        /* Update number of error correction */
        nerrors = info->nand.ecc.strength;

        /* Multi sector reading/writing for NAND flash with page size < 4096 */
        if (info->is_elm_used && (mtd->writesize <= 4096)) {
                if (mode == NAND_ECC_READ) {
                        /* Using wrapping mode 1 for reading */
                        wr_mode = BCH_WRAPMODE_1;

                        /*
                         * ECC engine enabled for ecc_size0 nibbles
                         * and disabled for ecc_size1 nibbles.
                         */
                        ecc_size0 = (nerrors == 8) ?
                                BCH8R_ECC_SIZE0 : BCH4R_ECC_SIZE0;
                        ecc_size1 = (nerrors == 8) ?
                                BCH8R_ECC_SIZE1 : BCH4R_ECC_SIZE1;
                }

                /* Perform ecc calculation for one page (< 4096) */
                nsectors = info->nand.ecc.steps;
        }

        writel(ECC1, info->reg.gpmc_ecc_control);

        /* Configure ecc size for BCH */
        val = (ecc_size1 << ECCSIZE1_SHIFT) | (ecc_size0 << ECCSIZE0_SHIFT);
        writel(val, info->reg.gpmc_ecc_size_config);

        dev_width = (chip->options & NAND_BUSWIDTH_16) ? 1 : 0;

        /* BCH configuration */
        val = ((1                        << 16) | /* enable BCH */
               (((nerrors == 8) ? 1 : 0) << 12) | /* 8 or 4 bits */
               (wr_mode                  <<  8) | /* wrap mode */
               (dev_width                <<  7) | /* bus width */
               (((nsectors-1) & 0x7)     <<  4) | /* number of sectors */
               (info->gpmc_cs            <<  1) | /* ECC CS */
               (0x1));                            /* enable ECC */

        writel(val, info->reg.gpmc_ecc_config);

        /* Clear ecc and enable bits */
        writel(ECCCLEAR | ECC1, info->reg.gpmc_ecc_control);
}

/**
 * omap3_calculate_ecc_bch4 - Generate 7 bytes of ECC bytes
 * @mtd: MTD device structure
 * @dat: The pointer to data on which ecc is computed
 * @ecc_code: The ecc_code buffer
 */
static int omap3_calculate_ecc_bch4(struct mtd_info *mtd, const u_char *dat,
                                    u_char *ecc_code)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
        unsigned long nsectors, val1, val2;
        int i;

        nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;

        for (i = 0; i < nsectors; i++) {

                /* Read hw-computed remainder */
                val1 = readl(info->reg.gpmc_bch_result0[i]);
                val2 = readl(info->reg.gpmc_bch_result1[i]);

                /*
                 * Add constant polynomial to remainder, in order to get an ecc
                 * sequence of 0xFFs for a buffer filled with 0xFFs; and
                 * left-justify the resulting polynomial.
                 */
                *ecc_code++ = 0x28 ^ ((val2 >> 12) & 0xFF);
                *ecc_code++ = 0x13 ^ ((val2 >>  4) & 0xFF);
                *ecc_code++ = 0xcc ^ (((val2 & 0xF) << 4)|((val1 >> 28) & 0xF));
                *ecc_code++ = 0x39 ^ ((val1 >> 20) & 0xFF);
                *ecc_code++ = 0x96 ^ ((val1 >> 12) & 0xFF);
                *ecc_code++ = 0xac ^ ((val1 >> 4) & 0xFF);
                *ecc_code++ = 0x7f ^ ((val1 & 0xF) << 4);
        }

        return 0;
}

/**
 * omap3_calculate_ecc_bch8 - Generate 13 bytes of ECC bytes
 * @mtd: MTD device structure
 * @dat: The pointer to data on which ecc is computed
 * @ecc_code: The ecc_code buffer
 */
static int omap3_calculate_ecc_bch8(struct mtd_info *mtd, const u_char *dat,
                                    u_char *ecc_code)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
        unsigned long nsectors, val1, val2, val3, val4;
        int i;

        nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;

        for (i = 0; i < nsectors; i++) {

                /* Read hw-computed remainder */
                val1 = readl(info->reg.gpmc_bch_result0[i]);
                val2 = readl(info->reg.gpmc_bch_result1[i]);
                val3 = readl(info->reg.gpmc_bch_result2[i]);
                val4 = readl(info->reg.gpmc_bch_result3[i]);

                /*
                 * Add constant polynomial to remainder, in order to get an ecc
                 * sequence of 0xFFs for a buffer filled with 0xFFs.
                 */
                *ecc_code++ = 0xef ^ (val4 & 0xFF);
                *ecc_code++ = 0x51 ^ ((val3 >> 24) & 0xFF);
                *ecc_code++ = 0x2e ^ ((val3 >> 16) & 0xFF);
                *ecc_code++ = 0x09 ^ ((val3 >> 8) & 0xFF);
                *ecc_code++ = 0xed ^ (val3 & 0xFF);
                *ecc_code++ = 0x93 ^ ((val2 >> 24) & 0xFF);
                *ecc_code++ = 0x9a ^ ((val2 >> 16) & 0xFF);
                *ecc_code++ = 0xc2 ^ ((val2 >> 8) & 0xFF);
                *ecc_code++ = 0x97 ^ (val2 & 0xFF);
                *ecc_code++ = 0x79 ^ ((val1 >> 24) & 0xFF);
                *ecc_code++ = 0xe5 ^ ((val1 >> 16) & 0xFF);
                *ecc_code++ = 0x24 ^ ((val1 >> 8) & 0xFF);
                *ecc_code++ = 0xb5 ^ (val1 & 0xFF);
        }

        return 0;
}

/**
 * omap3_calculate_ecc_bch - Generate bytes of ECC bytes
 * @mtd:        MTD device structure
 * @dat:        The pointer to data on which ecc is computed
 * @ecc_code:   The ecc_code buffer
 *
 * Support calculating of BCH4/8 ecc vectors for the page
 */
static int omap3_calculate_ecc_bch(struct mtd_info *mtd, const u_char *dat,
                                    u_char *ecc_code)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
        unsigned long nsectors, bch_val1, bch_val2, bch_val3, bch_val4;
        int i, eccbchtsel;

        nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;
        /*
         * find BCH scheme used
         * 0 -> BCH4
         * 1 -> BCH8
         */
        eccbchtsel = ((readl(info->reg.gpmc_ecc_config) >> 12) & 0x3);

        for (i = 0; i < nsectors; i++) {

                /* Read hw-computed remainder */
                bch_val1 = readl(info->reg.gpmc_bch_result0[i]);
                bch_val2 = readl(info->reg.gpmc_bch_result1[i]);
                if (eccbchtsel) {
                        bch_val3 = readl(info->reg.gpmc_bch_result2[i]);
                        bch_val4 = readl(info->reg.gpmc_bch_result3[i]);
                }

                if (eccbchtsel) {
                        /* BCH8 ecc scheme */
                        *ecc_code++ = (bch_val4 & 0xFF);
                        *ecc_code++ = ((bch_val3 >> 24) & 0xFF);
                        *ecc_code++ = ((bch_val3 >> 16) & 0xFF);
                        *ecc_code++ = ((bch_val3 >> 8) & 0xFF);
                        *ecc_code++ = (bch_val3 & 0xFF);
                        *ecc_code++ = ((bch_val2 >> 24) & 0xFF);
                        *ecc_code++ = ((bch_val2 >> 16) & 0xFF);
                        *ecc_code++ = ((bch_val2 >> 8) & 0xFF);
                        *ecc_code++ = (bch_val2 & 0xFF);
                        *ecc_code++ = ((bch_val1 >> 24) & 0xFF);
                        *ecc_code++ = ((bch_val1 >> 16) & 0xFF);
                        *ecc_code++ = ((bch_val1 >> 8) & 0xFF);
                        *ecc_code++ = (bch_val1 & 0xFF);
                        /*
                         * Setting 14th byte to zero to handle
                         * erased page & maintain compatibility
                         * with RBL
                         */
                        *ecc_code++ = 0x0;
                } else {
                        /* BCH4 ecc scheme */
                        *ecc_code++ = ((bch_val2 >> 12) & 0xFF);
                        *ecc_code++ = ((bch_val2 >> 4) & 0xFF);
                        *ecc_code++ = ((bch_val2 & 0xF) << 4) |
                                ((bch_val1 >> 28) & 0xF);
                        *ecc_code++ = ((bch_val1 >> 20) & 0xFF);
                        *ecc_code++ = ((bch_val1 >> 12) & 0xFF);
                        *ecc_code++ = ((bch_val1 >> 4) & 0xFF);
                        *ecc_code++ = ((bch_val1 & 0xF) << 4);
                        /*
                         * Setting 8th byte to zero to handle
                         * erased page
                         */
                        *ecc_code++ = 0x0;
                }
        }

        return 0;
}

/**
 * erased_sector_bitflips - count bit flips
 * @data:       data sector buffer
 * @oob:        oob buffer
 * @info:       omap_nand_info
 *
 * Check the bit flips in erased page falls below correctable level.
 * If falls below, report the page as erased with correctable bit
 * flip, else report as uncorrectable page.
 */
static int erased_sector_bitflips(u_char *data, u_char *oob,
                struct omap_nand_info *info)
{
        int flip_bits = 0, i;

        for (i = 0; i < info->nand.ecc.size; i++) {
                flip_bits += hweight8(~data[i]);
                if (flip_bits > info->nand.ecc.strength)
                        return 0;
        }

        for (i = 0; i < info->nand.ecc.bytes - 1; i++) {
                flip_bits += hweight8(~oob[i]);
                if (flip_bits > info->nand.ecc.strength)
                        return 0;
        }

        /*
         * Bit flips falls in correctable level.
         * Fill data area with 0xFF
         */
        if (flip_bits) {
                memset(data, 0xFF, info->nand.ecc.size);
                memset(oob, 0xFF, info->nand.ecc.bytes);
        }

        return flip_bits;
}

/**
 * omap_elm_correct_data - corrects page data area in case error reported
 * @mtd:        MTD device structure
 * @data:       page data
 * @read_ecc:   ecc read from nand flash
 * @calc_ecc:   ecc read from HW ECC registers
 *
 * Calculated ecc vector reported as zero in case of non-error pages.
 * In case of error/erased pages non-zero error vector is reported.
 * In case of non-zero ecc vector, check read_ecc at fixed offset
 * (x = 13/7 in case of BCH8/4 == 0) to find page programmed or not.
 * To handle bit flips in this data, count the number of 0's in
 * read_ecc[x] and check if it greater than 4. If it is less, it is
 * programmed page, else erased page.
 *
 * 1. If page is erased, check with standard ecc vector (ecc vector
 * for erased page to find any bit flip). If check fails, bit flip
 * is present in erased page. Count the bit flips in erased page and
 * if it falls under correctable level, report page with 0xFF and
 * update the correctable bit information.
 * 2. If error is reported on programmed page, update elm error
 * vector and correct the page with ELM error correction routine.
 *
 */
static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
                                u_char *read_ecc, u_char *calc_ecc)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                        mtd);
        int eccsteps = info->nand.ecc.steps;
        int i , j, stat = 0;
        int eccsize, eccflag, ecc_vector_size;
        struct elm_errorvec err_vec[ERROR_VECTOR_MAX];
        u_char *ecc_vec = calc_ecc;
        u_char *spare_ecc = read_ecc;
        u_char *erased_ecc_vec;
        enum bch_ecc type;
        bool is_error_reported = false;

        /* Initialize elm error vector to zero */
        memset(err_vec, 0, sizeof(err_vec));

        if (info->nand.ecc.strength == BCH8_MAX_ERROR) {
                type = BCH8_ECC;
                erased_ecc_vec = bch8_vector;
        } else {
                type = BCH4_ECC;
                erased_ecc_vec = bch4_vector;
        }

        ecc_vector_size = info->nand.ecc.bytes;

        /*
         * Remove extra byte padding for BCH8 RBL
         * compatibility and erased page handling
         */
        eccsize = ecc_vector_size - 1;

        for (i = 0; i < eccsteps ; i++) {
                eccflag = 0;    /* initialize eccflag */

                /*
                 * Check any error reported,
                 * In case of error, non zero ecc reported.
                 */

                for (j = 0; (j < eccsize); j++) {
                        if (calc_ecc[j] != 0) {
                                eccflag = 1; /* non zero ecc, error present */
                                break;
                        }
                }

                if (eccflag == 1) {
                        /*
                         * Set threshold to minimum of 4, half of ecc.strength/2
                         * to allow max bit flip in byte to 4
                         */
                        unsigned int threshold = min_t(unsigned int, 4,
                                        info->nand.ecc.strength / 2);

                        /*
                         * Check data area is programmed by counting
                         * number of 0's at fixed offset in spare area.
                         * Checking count of 0's against threshold.
                         * In case programmed page expects at least threshold
                         * zeros in byte.
                         * If zeros are less than threshold for programmed page/
                         * zeros are more than threshold erased page, either
                         * case page reported as uncorrectable.
                         */
                        if (hweight8(~read_ecc[eccsize]) >= threshold) {
                                /*
                                 * Update elm error vector as
                                 * data area is programmed
                                 */
                                err_vec[i].error_reported = true;
                                is_error_reported = true;
                        } else {
                                /* Error reported in erased page */
                                int bitflip_count;
                                u_char *buf = &data[info->nand.ecc.size * i];

                                if (memcmp(calc_ecc, erased_ecc_vec, eccsize)) {
                                        bitflip_count = erased_sector_bitflips(
                                                        buf, read_ecc, info);

                                        if (bitflip_count)
                                                stat += bitflip_count;
                                        else
                                                return -EINVAL;
                                }
                        }
                }

                /* Update the ecc vector */
                calc_ecc += ecc_vector_size;
                read_ecc += ecc_vector_size;
        }

        /* Check if any error reported */
        if (!is_error_reported)
                return 0;

        /* Decode BCH error using ELM module */
        elm_decode_bch_error_page(info->elm_dev, ecc_vec, err_vec);

        for (i = 0; i < eccsteps; i++) {
                if (err_vec[i].error_reported) {
                        for (j = 0; j < err_vec[i].error_count; j++) {
                                u32 bit_pos, byte_pos, error_max, pos;

                                if (type == BCH8_ECC)
                                        error_max = BCH8_ECC_MAX;
                                else
                                        error_max = BCH4_ECC_MAX;

                                if (info->nand.ecc.strength == BCH8_MAX_ERROR)
                                        pos = err_vec[i].error_loc[j];
                                else
                                        /* Add 4 to take care 4 bit padding */
                                        pos = err_vec[i].error_loc[j] +
                                                BCH4_BIT_PAD;

                                /* Calculate bit position of error */
                                bit_pos = pos % 8;

                                /* Calculate byte position of error */
                                byte_pos = (error_max - pos - 1) / 8;

                                if (pos < error_max) {
                                        if (byte_pos < 512)
                                                data[byte_pos] ^= 1 << bit_pos;
                                        else
                                                spare_ecc[byte_pos - 512] ^=
                                                        1 << bit_pos;
                                }
                                /* else, not interested to correct ecc */
                        }
                }

                /* Update number of correctable errors */
                stat += err_vec[i].error_count;

                /* Update page data with sector size */
                data += info->nand.ecc.size;
                spare_ecc += ecc_vector_size;
        }

        for (i = 0; i < eccsteps; i++)
                /* Return error if uncorrectable error present */
                if (err_vec[i].error_uncorrectable)
                        return -EINVAL;

        return stat;
}

/**
 * omap3_correct_data_bch - Decode received data and correct errors
 * @mtd: MTD device structure
 * @data: page data
 * @read_ecc: ecc read from nand flash
 * @calc_ecc: ecc read from HW ECC registers
 */
static int omap3_correct_data_bch(struct mtd_info *mtd, u_char *data,
                                  u_char *read_ecc, u_char *calc_ecc)
{
        int i, count;
        /* cannot correct more than 8 errors */
        unsigned int errloc[8];
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);

        count = decode_bch(info->bch, NULL, 512, read_ecc, calc_ecc, NULL,
                           errloc);
        if (count > 0) {
                /* correct errors */
                for (i = 0; i < count; i++) {
                        /* correct data only, not ecc bytes */
                        if (errloc[i] < 8*512)
                                data[errloc[i]/8] ^= 1 << (errloc[i] & 7);
                        pr_debug("corrected bitflip %u\n", errloc[i]);
                }
        } else if (count < 0) {
                pr_err("ecc unrecoverable error\n");
        }
        return count;
}

/**
 * omap_write_page_bch - BCH ecc based write page function for entire page
 * @mtd:                mtd info structure
 * @chip:               nand chip info structure
 * @buf:                data buffer
 * @oob_required:       must write chip->oob_poi to OOB
 *
 * Custom write page method evolved to support multi sector writing in one shot
 */
static int omap_write_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
                                  const uint8_t *buf, int oob_required)
{
        int i;
        uint8_t *ecc_calc = chip->buffers->ecccalc;
        uint32_t *eccpos = chip->ecc.layout->eccpos;

        /* Enable GPMC ecc engine */
        chip->ecc.hwctl(mtd, NAND_ECC_WRITE);

        /* Write data */
        chip->write_buf(mtd, buf, mtd->writesize);

        /* Update ecc vector from GPMC result registers */
        chip->ecc.calculate(mtd, buf, &ecc_calc[0]);

        for (i = 0; i < chip->ecc.total; i++)
                chip->oob_poi[eccpos[i]] = ecc_calc[i];

        /* Write ecc vector to OOB area */
        chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
        return 0;
}

/**
 * omap_read_page_bch - BCH ecc based page read function for entire page
 * @mtd:                mtd info structure
 * @chip:               nand chip info structure
 * @buf:                buffer to store read data
 * @oob_required:       caller requires OOB data read to chip->oob_poi
 * @page:               page number to read
 *
 * For BCH ecc scheme, GPMC used for syndrome calculation and ELM module
 * used for error correction.
 * Custom method evolved to support ELM error correction & multi sector
 * reading. On reading page data area is read along with OOB data with
 * ecc engine enabled. ecc vector updated after read of OOB data.
 * For non error pages ecc vector reported as zero.
 */
static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf, int oob_required, int page)
{
        uint8_t *ecc_calc = chip->buffers->ecccalc;
        uint8_t *ecc_code = chip->buffers->ecccode;
        uint32_t *eccpos = chip->ecc.layout->eccpos;
        uint8_t *oob = &chip->oob_poi[eccpos[0]];
        uint32_t oob_pos = mtd->writesize + chip->ecc.layout->eccpos[0];
        int stat;
        unsigned int max_bitflips = 0;

        /* Enable GPMC ecc engine */
        chip->ecc.hwctl(mtd, NAND_ECC_READ);

        /* Read data */
        chip->read_buf(mtd, buf, mtd->writesize);

        /* Read oob bytes */
        chip->cmdfunc(mtd, NAND_CMD_RNDOUT, oob_pos, -1);
        chip->read_buf(mtd, oob, chip->ecc.total);

        /* Calculate ecc bytes */
        chip->ecc.calculate(mtd, buf, ecc_calc);

        memcpy(ecc_code, &chip->oob_poi[eccpos[0]], chip->ecc.total);

        stat = chip->ecc.correct(mtd, buf, ecc_code, ecc_calc);

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

        return max_bitflips;
}

/**
 * omap3_free_bch - Release BCH ecc resources
 * @mtd: MTD device structure
 */
static void omap3_free_bch(struct mtd_info *mtd)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
        if (info->bch) {
                free_bch(info->bch);
                info->bch = NULL;
        }
}

/**
 * omap3_init_bch - Initialize BCH ECC
 * @mtd: MTD device structure
 * @ecc_opt: OMAP ECC mode (OMAP_ECC_BCH4_CODE_HW or OMAP_ECC_BCH8_CODE_HW)
 */
static int omap3_init_bch(struct mtd_info *mtd, int ecc_opt)
{
        int max_errors;
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
#ifdef CONFIG_MTD_NAND_OMAP_BCH8
        const int hw_errors = BCH8_MAX_ERROR;
#else
        const int hw_errors = BCH4_MAX_ERROR;
#endif
        enum bch_ecc bch_type;
        const __be32 *parp;
        int lenp;
        struct device_node *elm_node;

        info->bch = NULL;

        max_errors = (ecc_opt == OMAP_ECC_BCH8_CODE_HW) ?
                BCH8_MAX_ERROR : BCH4_MAX_ERROR;
        if (max_errors != hw_errors) {
                pr_err("cannot configure %d-bit BCH ecc, only %d-bit supported",
                       max_errors, hw_errors);
                goto fail;
        }

        info->nand.ecc.size = 512;
        info->nand.ecc.hwctl = omap3_enable_hwecc_bch;
        info->nand.ecc.mode = NAND_ECC_HW;
        info->nand.ecc.strength = max_errors;

        if (hw_errors == BCH8_MAX_ERROR)
                bch_type = BCH8_ECC;
        else
                bch_type = BCH4_ECC;

        /* Detect availability of ELM module */
        parp = of_get_property(info->of_node, "elm_id", &lenp);
        if ((parp == NULL) && (lenp != (sizeof(void *) * 2))) {
                pr_err("Missing elm_id property, fall back to Software BCH\n");
                info->is_elm_used = false;
        } else {
                struct platform_device *pdev;

                elm_node = of_find_node_by_phandle(be32_to_cpup(parp));
                pdev = of_find_device_by_node(elm_node);
                info->elm_dev = &pdev->dev;
                elm_config(info->elm_dev, bch_type);
                info->is_elm_used = true;
        }

        if (info->is_elm_used && (mtd->writesize <= 4096)) {

                if (hw_errors == BCH8_MAX_ERROR)
                        info->nand.ecc.bytes = BCH8_SIZE;
                else
                        info->nand.ecc.bytes = BCH4_SIZE;

                info->nand.ecc.correct = omap_elm_correct_data;
                info->nand.ecc.calculate = omap3_calculate_ecc_bch;
                info->nand.ecc.read_page = omap_read_page_bch;
                info->nand.ecc.write_page = omap_write_page_bch;
        } else {
                /*
                 * software bch library is only used to detect and
                 * locate errors
                 */
                info->bch = init_bch(13, max_errors,
                                0x201b /* hw polynomial */);
                if (!info->bch)
                        goto fail;

                info->nand.ecc.correct = omap3_correct_data_bch;

                /*
                 * The number of corrected errors in an ecc block that will
                 * trigger block scrubbing defaults to the ecc strength (4 or 8)
                 * Set mtd->bitflip_threshold here to define a custom threshold.
                 */

                if (max_errors == 8) {
                        info->nand.ecc.bytes = 13;
                        info->nand.ecc.calculate = omap3_calculate_ecc_bch8;
                } else {
                        info->nand.ecc.bytes = 7;
                        info->nand.ecc.calculate = omap3_calculate_ecc_bch4;
                }
        }

        pr_info("enabling NAND BCH ecc with %d-bit correction\n", max_errors);
        return 0;
fail:
        omap3_free_bch(mtd);
        return -1;
}

/**
 * omap3_init_bch_tail - Build an oob layout for BCH ECC correction.
 * @mtd: MTD device structure
 */
static int omap3_init_bch_tail(struct mtd_info *mtd)
{
        int i, steps, offset;
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                   mtd);
        struct nand_ecclayout *layout = &info->ecclayout;

        /* build oob layout */
        steps = mtd->writesize/info->nand.ecc.size;
        layout->eccbytes = steps*info->nand.ecc.bytes;

        /* do not bother creating special oob layouts for small page devices */
        if (mtd->oobsize < 64) {
                pr_err("BCH ecc is not supported on small page devices\n");
                goto fail;
        }

        /* reserve 2 bytes for bad block marker */
        if (layout->eccbytes+2 > mtd->oobsize) {
                pr_err("no oob layout available for oobsize %d eccbytes %u\n",
                       mtd->oobsize, layout->eccbytes);
                goto fail;
        }

        /* ECC layout compatible with RBL for BCH8 */
        if (info->is_elm_used && (info->nand.ecc.bytes == BCH8_SIZE))
                offset = 2;
        else
                offset = mtd->oobsize - layout->eccbytes;

        /* put ecc bytes at oob tail */
        for (i = 0; i < layout->eccbytes; i++)
                layout->eccpos[i] = offset + i;

        if (info->is_elm_used && (info->nand.ecc.bytes == BCH8_SIZE))
                layout->oobfree[0].offset = 2 + layout->eccbytes * steps;
        else
                layout->oobfree[0].offset = 2;

        layout->oobfree[0].length = mtd->oobsize-2-layout->eccbytes;
        info->nand.ecc.layout = layout;

        if (!(info->nand.options & NAND_BUSWIDTH_16))
                info->nand.badblock_pattern = &bb_descrip_flashbased;
        return 0;
fail:
        omap3_free_bch(mtd);
        return -1;
}

#else
static int omap3_init_bch(struct mtd_info *mtd, int ecc_opt)
{
        pr_err("CONFIG_MTD_NAND_OMAP_BCH is not enabled\n");
        return -1;
}
static int omap3_init_bch_tail(struct mtd_info *mtd)
{
        return -1;
}
static void omap3_free_bch(struct mtd_info *mtd)
{
}
#endif /* CONFIG_MTD_NAND_OMAP_BCH */

static int omap_nand_probe(struct platform_device *pdev)
{
        struct omap_nand_info           *info;
        struct omap_nand_platform_data  *pdata;
        int                             err;
        int                             i, offset;
        dma_cap_mask_t mask;
        unsigned sig;
        struct resource                 *res;
        struct mtd_part_parser_data     ppdata = {};

        pdata = pdev->dev.platform_data;
        if (pdata == NULL) {
                dev_err(&pdev->dev, "platform data missing\n");
                return -ENODEV;
        }

        info = kzalloc(sizeof(struct omap_nand_info), GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        platform_set_drvdata(pdev, info);

        spin_lock_init(&info->controller.lock);
        init_waitqueue_head(&info->controller.wq);

        info->pdev = pdev;

        info->gpmc_cs           = pdata->cs;
        info->reg               = pdata->reg;

        info->mtd.priv          = &info->nand;
        info->mtd.name          = dev_name(&pdev->dev);
        info->mtd.owner         = THIS_MODULE;

        info->nand.options      = pdata->devsize;
        info->nand.options      |= NAND_SKIP_BBTSCAN;
#ifdef CONFIG_MTD_NAND_OMAP_BCH
        info->of_node           = pdata->of_node;
#endif

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (res == NULL) {
                err = -EINVAL;
                dev_err(&pdev->dev, "error getting memory resource\n");
                goto out_free_info;
        }

        info->phys_base = res->start;
        info->mem_size = resource_size(res);

        if (!request_mem_region(info->phys_base, info->mem_size,
                                pdev->dev.driver->name)) {
                err = -EBUSY;
                goto out_free_info;
        }

        info->nand.IO_ADDR_R = ioremap(info->phys_base, info->mem_size);
        if (!info->nand.IO_ADDR_R) {
                err = -ENOMEM;
                goto out_release_mem_region;
        }

        info->nand.controller = &info->controller;

        info->nand.IO_ADDR_W = info->nand.IO_ADDR_R;
        info->nand.cmd_ctrl  = omap_hwcontrol;

        /*
         * If RDY/BSY line is connected to OMAP then use the omap ready
         * function and the generic nand_wait function which reads the status
         * register after monitoring the RDY/BSY line. Otherwise use a standard
         * chip delay which is slightly more than tR (AC Timing) of the NAND
         * device and read status register until you get a failure or success
         */
        if (pdata->dev_ready) {
                info->nand.dev_ready = omap_dev_ready;
                info->nand.chip_delay = 0;
        } else {
                info->nand.waitfunc = omap_wait;
                info->nand.chip_delay = 50;
        }

        switch (pdata->xfer_type) {
        case NAND_OMAP_PREFETCH_POLLED:
                info->nand.read_buf   = omap_read_buf_pref;
                info->nand.write_buf  = omap_write_buf_pref;
                break;

        case NAND_OMAP_POLLED:
                if (info->nand.options & NAND_BUSWIDTH_16) {
                        info->nand.read_buf   = omap_read_buf16;
                        info->nand.write_buf  = omap_write_buf16;
                } else {
                        info->nand.read_buf   = omap_read_buf8;
                        info->nand.write_buf  = omap_write_buf8;
                }
                break;

        case NAND_OMAP_PREFETCH_DMA:
                dma_cap_zero(mask);
                dma_cap_set(DMA_SLAVE, mask);
                sig = OMAP24XX_DMA_GPMC;
                info->dma = dma_request_channel(mask, omap_dma_filter_fn, &sig);
                if (!info->dma) {
                        dev_err(&pdev->dev, "DMA engine request failed\n");
                        err = -ENXIO;
                        goto out_release_mem_region;
                } else {
                        struct dma_slave_config cfg;

                        memset(&cfg, 0, sizeof(cfg));
                        cfg.src_addr = info->phys_base;
                        cfg.dst_addr = info->phys_base;
                        cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                        cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                        cfg.src_maxburst = 16;
                        cfg.dst_maxburst = 16;
                        err = dmaengine_slave_config(info->dma, &cfg);
                        if (err) {
                                dev_err(&pdev->dev, "DMA engine slave config failed: %d\n",
                                        err);
                                goto out_release_mem_region;
                        }
                        info->nand.read_buf   = omap_read_buf_dma_pref;
                        info->nand.write_buf  = omap_write_buf_dma_pref;
                }
                break;

        case NAND_OMAP_PREFETCH_IRQ:
                info->gpmc_irq_fifo = platform_get_irq(pdev, 0);
                if (info->gpmc_irq_fifo <= 0) {
                        dev_err(&pdev->dev, "error getting fifo irq\n");
                        err = -ENODEV;
                        goto out_release_mem_region;
                }
                err = request_irq(info->gpmc_irq_fifo,  omap_nand_irq,
                                        IRQF_SHARED, "gpmc-nand-fifo", info);
                if (err) {
                        dev_err(&pdev->dev, "requesting irq(%d) error:%d",
                                                info->gpmc_irq_fifo, err);
                        info->gpmc_irq_fifo = 0;
                        goto out_release_mem_region;
                }

                info->gpmc_irq_count = platform_get_irq(pdev, 1);
                if (info->gpmc_irq_count <= 0) {
                        dev_err(&pdev->dev, "error getting count irq\n");
                        err = -ENODEV;
                        goto out_release_mem_region;
                }
                err = request_irq(info->gpmc_irq_count, omap_nand_irq,
                                        IRQF_SHARED, "gpmc-nand-count", info);
                if (err) {
                        dev_err(&pdev->dev, "requesting irq(%d) error:%d",
                                                info->gpmc_irq_count, err);
                        info->gpmc_irq_count = 0;
                        goto out_release_mem_region;
                }

                info->nand.read_buf  = omap_read_buf_irq_pref;
                info->nand.write_buf = omap_write_buf_irq_pref;

                break;

        default:
                dev_err(&pdev->dev,
                        "xfer_type(%d) not supported!\n", pdata->xfer_type);
                err = -EINVAL;
                goto out_release_mem_region;
        }

        /* select the ecc type */
        if (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_DEFAULT)
                info->nand.ecc.mode = NAND_ECC_SOFT;
        else if ((pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW) ||
                (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW_ROMCODE)) {
                info->nand.ecc.bytes            = 3;
                info->nand.ecc.size             = 512;

                info->nand.ecc.strength         = 1;
                info->nand.ecc.calculate        = omap_calculate_ecc;
                info->nand.ecc.hwctl            = omap_enable_hwecc;
                info->nand.ecc.correct          = omap_correct_data;
                info->nand.ecc.mode             = NAND_ECC_HW;
        } else if ((pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW) ||
                   (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW)) {
                err = omap3_init_bch(&info->mtd, pdata->ecc_opt);
                if (err) {
                        err = -EINVAL;
                        goto out_release_mem_region;
                }
        }

        /* DIP switches on some boards change between 8 and 16 bit
         * bus widths for flash.  Try the other width if the first try fails.
         */
        if (nand_scan_ident(&info->mtd, 1, NULL)) {
                info->nand.options ^= NAND_BUSWIDTH_16;
                if (nand_scan_ident(&info->mtd, 1, NULL)) {
                        err = -ENXIO;
                        goto out_release_mem_region;
                }
        }

        /* rom code layout */
        if (pdata->ecc_opt == OMAP_ECC_HAMMING_CODE_HW_ROMCODE) {

                if (info->nand.options & NAND_BUSWIDTH_16)
                        offset = 2;
                else {
                        offset = 1;
                        info->nand.badblock_pattern = &bb_descrip_flashbased;
                }
                omap_oobinfo.eccbytes = 3 * (info->mtd.oobsize/16);
                for (i = 0; i < omap_oobinfo.eccbytes; i++)
                        omap_oobinfo.eccpos[i] = i+offset;

                omap_oobinfo.oobfree->offset = offset + omap_oobinfo.eccbytes;
                omap_oobinfo.oobfree->length = info->mtd.oobsize -
                                        (offset + omap_oobinfo.eccbytes);

                info->nand.ecc.layout = &omap_oobinfo;
        } else if ((pdata->ecc_opt == OMAP_ECC_BCH4_CODE_HW) ||
                   (pdata->ecc_opt == OMAP_ECC_BCH8_CODE_HW)) {
                /* build OOB layout for BCH ECC correction */
                err = omap3_init_bch_tail(&info->mtd);
                if (err) {
                        err = -EINVAL;
                        goto out_release_mem_region;
                }
        }

        /* second phase scan */
        if (nand_scan_tail(&info->mtd)) {
                err = -ENXIO;
                goto out_release_mem_region;
        }

        ppdata.of_node = pdata->of_node;
        mtd_device_parse_register(&info->mtd, NULL, &ppdata, pdata->parts,
                                  pdata->nr_parts);

        platform_set_drvdata(pdev, &info->mtd);

        return 0;

out_release_mem_region:
        if (info->dma)
                dma_release_channel(info->dma);
        if (info->gpmc_irq_count > 0)
                free_irq(info->gpmc_irq_count, info);
        if (info->gpmc_irq_fifo > 0)
                free_irq(info->gpmc_irq_fifo, info);
        release_mem_region(info->phys_base, info->mem_size);
out_free_info:
        kfree(info);

        return err;
}

static int omap_nand_remove(struct platform_device *pdev)
{
        struct mtd_info *mtd = platform_get_drvdata(pdev);
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        omap3_free_bch(&info->mtd);

        platform_set_drvdata(pdev, NULL);
        if (info->dma)
                dma_release_channel(info->dma);

        if (info->gpmc_irq_count > 0)
                free_irq(info->gpmc_irq_count, info);
        if (info->gpmc_irq_fifo > 0)
                free_irq(info->gpmc_irq_fifo, info);

        /* Release NAND device, its internal structures and partitions */
        nand_release(&info->mtd);
        iounmap(info->nand.IO_ADDR_R);
        release_mem_region(info->phys_base, info->mem_size);
        kfree(info);
        return 0;
}

static struct platform_driver omap_nand_driver = {
        .probe          = omap_nand_probe,
        .remove         = omap_nand_remove,
        .driver         = {
                .name   = DRIVER_NAME,
                .owner  = THIS_MODULE,
        },
};

module_platform_driver(omap_nand_driver);

MODULE_ALIAS("platform:" DRIVER_NAME);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Glue layer for NAND flash on TI OMAP boards");