/*
 * 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/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/io.h>
#include <linux/slab.h>

#include <plat/dma.h>
#include <plat/gpmc.h>
#include <plat/nand.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)

/* 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;
        struct completion               comp;
        int                             dma_ch;
        int                             gpmc_irq;
        enum {
                OMAP_NAND_IO_READ = 0,  /* read */
                OMAP_NAND_IO_WRITE,     /* write */
        } iomode;
        u_char                          *buf;
        int                                     buf_len;
};

/**
 * 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)
                        gpmc_nand_write(info->gpmc_cs, GPMC_NAND_COMMAND, cmd);

                else if (ctrl & NAND_ALE)
                        gpmc_nand_write(info->gpmc_cs, GPMC_NAND_ADDRESS, cmd);

                else /* NAND_NCE */
                        gpmc_nand_write(info->gpmc_cs, GPMC_NAND_DATA, cmd);
        }
}

/**
 * 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 = gpmc_read_status(GPMC_STATUS_BUFFER);
                } 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 = gpmc_read_status(GPMC_STATUS_BUFFER);
                } 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 = gpmc_prefetch_enable(info->gpmc_cs,
                        PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x0);
        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 = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
                        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 */
                gpmc_prefetch_reset(info->gpmc_cs);
        }
}

/**
 * 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;

        /* 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 = gpmc_prefetch_enable(info->gpmc_cs,
                        PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x1);
        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 = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
                        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));
                while (gpmc_read_status(GPMC_PREFETCH_COUNT) && (tim++ < limit))
                        cpu_relax();

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

/*
 * omap_nand_dma_cb: callback on the completion of dma transfer
 * @lch: logical channel
 * @ch_satuts: channel status
 * @data: pointer to completion data structure
 */
static void omap_nand_dma_cb(int lch, u16 ch_status, void *data)
{
        complete((struct completion *) data);
}

/*
 * omap_nand_dma_transfer: configer 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);
        enum dma_data_direction dir = is_write ? DMA_TO_DEVICE :
                                                        DMA_FROM_DEVICE;
        dma_addr_t dma_addr;
        int ret;
        unsigned long tim, limit;

        /* The fifo depth is 64 bytes max.
         * But configure the FIFO-threahold to 32 to get a sync at each frame
         * and frame length is 32 bytes.
         */
        int buf_len = len >> 6;

        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);
        }

        dma_addr = dma_map_single(&info->pdev->dev, addr, len, dir);
        if (dma_mapping_error(&info->pdev->dev, dma_addr)) {
                dev_err(&info->pdev->dev,
                        "Couldn't DMA map a %d byte buffer\n", len);
                goto out_copy;
        }

        if (is_write) {
            omap_set_dma_dest_params(info->dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
                                                info->phys_base, 0, 0);
            omap_set_dma_src_params(info->dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
                                                        dma_addr, 0, 0);
            omap_set_dma_transfer_params(info->dma_ch, OMAP_DMA_DATA_TYPE_S32,
                                        0x10, buf_len, OMAP_DMA_SYNC_FRAME,
                                        OMAP24XX_DMA_GPMC, OMAP_DMA_DST_SYNC);
        } else {
            omap_set_dma_src_params(info->dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
                                                info->phys_base, 0, 0);
            omap_set_dma_dest_params(info->dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
                                                        dma_addr, 0, 0);
            omap_set_dma_transfer_params(info->dma_ch, OMAP_DMA_DATA_TYPE_S32,
                                        0x10, buf_len, OMAP_DMA_SYNC_FRAME,
                                        OMAP24XX_DMA_GPMC, OMAP_DMA_SRC_SYNC);
        }
        /*  configure and start prefetch transfer */
        ret = gpmc_prefetch_enable(info->gpmc_cs,
                        PREFETCH_FIFOTHRESHOLD_MAX, 0x1, len, is_write);
        if (ret)
                /* PFPW engine is busy, use cpu copy method */
                goto out_copy;

        init_completion(&info->comp);

        omap_start_dma(info->dma_ch);

        /* 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));
        while (gpmc_read_status(GPMC_PREFETCH_COUNT) && (tim++ < limit))
                cpu_relax();

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

        dma_unmap_single(&info->pdev->dev, dma_addr, len, dir);
        return 0;

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 - GMPC 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;
        u32 irq_stat;

        irq_stat = gpmc_read_status(GPMC_GET_IRQ_STATUS);
        bytes = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
        bytes = bytes  & 0xFFFC; /* io in multiple of 4 bytes */
        if (info->iomode == OMAP_NAND_IO_WRITE) { /* checks for write io */
                if (irq_stat & 0x2)
                        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 (irq_stat & 0x2)
                        goto done;
        }
        gpmc_cs_configure(info->gpmc_cs, GPMC_SET_IRQ_STATUS, irq_stat);

        return IRQ_HANDLED;

done:
        complete(&info->comp);
        /* disable irq */
        gpmc_cs_configure(info->gpmc_cs, GPMC_ENABLE_IRQ, 0);

        /* clear status */
        gpmc_cs_configure(info->gpmc_cs, GPMC_SET_IRQ_STATUS, irq_stat);

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

        info->buf_len = len;
        /* enable irq */
        gpmc_cs_configure(info->gpmc_cs, GPMC_ENABLE_IRQ,
                (GPMC_IRQ_FIFOEVENTENABLE | GPMC_IRQ_COUNT_EVENT));

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

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

        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 = gpmc_prefetch_enable(info->gpmc_cs,
                        (PREFETCH_FIFOTHRESHOLD_MAX * 3) / 8, 0x0, len, 0x1);
        if (ret)
                /* PFPW engine is busy, use cpu copy method */
                goto out_copy;

        info->buf_len = len;
        /* enable irq */
        gpmc_cs_configure(info->gpmc_cs, GPMC_ENABLE_IRQ,
                        (GPMC_IRQ_FIFOEVENTENABLE | GPMC_IRQ_COUNT_EVENT));

        /* 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));
        while (gpmc_read_status(GPMC_PREFETCH_COUNT) && (tim++ < limit))
                cpu_relax();

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

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

/**
 * omap_verify_buf - Verify chip data against buffer
 * @mtd: MTD device structure
 * @buf: buffer containing the data to compare
 * @len: number of bytes to compare
 */
static int omap_verify_buf(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;

        len >>= 1;
        while (len--) {
                if (*p++ != cpu_to_le16(readw(info->nand.IO_ADDR_R)))
                        return -EFAULT;
        }

        return 0;
}

/**
 * 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);
        return gpmc_calculate_ecc(info->gpmc_cs, dat, ecc_code);
}

/**
 * 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;

        gpmc_enable_hwecc(info->gpmc_cs, mode, dev_width, info->nand.ecc.size);
}

/**
 * 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 = NAND_STATUS_FAIL, state = this->state;

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

        gpmc_nand_write(info->gpmc_cs,
                        GPMC_NAND_COMMAND, (NAND_CMD_STATUS & 0xFF));
        while (time_before(jiffies, timeo)) {
                status = gpmc_nand_read(info->gpmc_cs, GPMC_NAND_DATA);
                if (status & NAND_STATUS_READY)
                        break;
                cond_resched();
        }
        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 = gpmc_read_status(GPMC_GET_IRQ_STATUS);
        if ((val & 0x100) == 0x100) {
                /* Clear IRQ Interrupt */
                val |= 0x100;
                val &= ~(0x0);
                gpmc_cs_configure(info->gpmc_cs, GPMC_SET_IRQ_STATUS, val);
        } else {
                unsigned int cnt = 0;
                while (cnt++ < 0x1FF) {
                        if  ((val & 0x100) == 0x100)
                                return 0;
                        val = gpmc_read_status(GPMC_GET_IRQ_STATUS);
                }
        }

        return 1;
}

static int __devinit omap_nand_probe(struct platform_device *pdev)
{
        struct omap_nand_info           *info;
        struct omap_nand_platform_data  *pdata;
        int                             err;
        int                             i, offset;

        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->phys_base         = pdata->phys_base;

        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;

        /* NAND write protect off */
        gpmc_cs_configure(info->gpmc_cs, GPMC_CONFIG_WP, 0);

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

        info->nand.IO_ADDR_R = ioremap(info->phys_base, NAND_IO_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
         * funcrtion 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:
                err = omap_request_dma(OMAP24XX_DMA_GPMC, "NAND",
                                omap_nand_dma_cb, &info->comp, &info->dma_ch);
                if (err < 0) {
                        info->dma_ch = -1;
                        dev_err(&pdev->dev, "DMA request failed!\n");
                        goto out_release_mem_region;
                } else {
                        omap_set_dma_dest_burst_mode(info->dma_ch,
                                        OMAP_DMA_DATA_BURST_16);
                        omap_set_dma_src_burst_mode(info->dma_ch,
                                        OMAP_DMA_DATA_BURST_16);

                        info->nand.read_buf   = omap_read_buf_dma_pref;
                        info->nand.write_buf  = omap_write_buf_dma_pref;
                }
                break;

        case NAND_OMAP_PREFETCH_IRQ:
                err = request_irq(pdata->gpmc_irq,
                                omap_nand_irq, IRQF_SHARED, "gpmc-nand", info);
                if (err) {
                        dev_err(&pdev->dev, "requesting irq(%d) error:%d",
                                                        pdata->gpmc_irq, err);
                        goto out_release_mem_region;
                } else {
                        info->gpmc_irq       = pdata->gpmc_irq;
                        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;
        }

        info->nand.verify_buf = omap_verify_buf;

        /* selsect 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;
        }

        /* 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;
        }

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

        mtd_device_parse_register(&info->mtd, NULL, NULL, pdata->parts,
                                  pdata->nr_parts);

        platform_set_drvdata(pdev, &info->mtd);

        return 0;

out_release_mem_region:
        release_mem_region(info->phys_base, NAND_IO_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);

        platform_set_drvdata(pdev, NULL);
        if (info->dma_ch != -1)
                omap_free_dma(info->dma_ch);

        if (info->gpmc_irq)
                free_irq(info->gpmc_irq, info);

        /* Release NAND device, its internal structures and partitions */
        nand_release(&info->mtd);
        iounmap(info->nand.IO_ADDR_R);
        kfree(&info->mtd);
        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");