/*
 * 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/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 <mach/dma.h>
#include <mach/gpmc.h>
#include <mach/nand.h>

#define GPMC_IRQ_STATUS         0x18
#define GPMC_ECC_CONFIG         0x1F4
#define GPMC_ECC_CONTROL        0x1F8
#define GPMC_ECC_SIZE_CONFIG    0x1FC
#define GPMC_ECC1_RESULT        0x200

#define DRIVER_NAME     "omap2-nand"

/* size (4 KiB) for IO mapping */
#define NAND_IO_SIZE    SZ_4K

#define NAND_WP_OFF     0
#define NAND_WP_BIT     0x00000010
#define WR_RD_PIN_MONITORING    0x00600000

#define GPMC_BUF_FULL   0x00000001
#define GPMC_BUF_EMPTY  0x00000000

#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)

#ifdef CONFIG_MTD_PARTITIONS
static const char *part_probes[] = { "cmdlinepart", NULL };
#endif

#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
static int use_prefetch = 1;

/* "modprobe ... use_prefetch=0" etc */
module_param(use_prefetch, bool, 0);
MODULE_PARM_DESC(use_prefetch, "enable/disable use of PREFETCH");

#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH_DMA
static int use_dma = 1;

/* "modprobe ... use_dma=0" etc */
module_param(use_dma, bool, 0);
MODULE_PARM_DESC(use_dma, "enable/disable use of DMA");
#else
const int use_dma;
#endif
#else
const int use_prefetch;
const int use_dma;
#endif

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

        int                             gpmc_cs;
        unsigned long                   phys_base;
        void __iomem                    *gpmc_cs_baseaddr;
        void __iomem                    *gpmc_baseaddr;
        void __iomem                    *nand_pref_fifo_add;
        struct completion               comp;
        int                             dma_ch;
};

/**
 * omap_nand_wp - This function enable or disable the Write Protect feature
 * @mtd: MTD device structure
 * @mode: WP ON/OFF
 */
static void omap_nand_wp(struct mtd_info *mtd, int mode)
{
        struct omap_nand_info *info = container_of(mtd,
                                                struct omap_nand_info, mtd);

        unsigned long config = __raw_readl(info->gpmc_baseaddr + GPMC_CONFIG);

        if (mode)
                config &= ~(NAND_WP_BIT);       /* WP is ON */
        else
                config |= (NAND_WP_BIT);        /* WP is OFF */

        __raw_writel(config, (info->gpmc_baseaddr + GPMC_CONFIG));
}

/**
 * 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);
        switch (ctrl) {
        case NAND_CTRL_CHANGE | NAND_CTRL_CLE:
                info->nand.IO_ADDR_W = info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_COMMAND;
                info->nand.IO_ADDR_R = info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_DATA;
                break;

        case NAND_CTRL_CHANGE | NAND_CTRL_ALE:
                info->nand.IO_ADDR_W = info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_ADDRESS;
                info->nand.IO_ADDR_R = info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_DATA;
                break;

        case NAND_CTRL_CHANGE | NAND_NCE:
                info->nand.IO_ADDR_W = info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_DATA;
                info->nand.IO_ADDR_R = info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_DATA;
                break;
        }

        if (cmd != NAND_CMD_NONE)
                __raw_writeb(cmd, info->nand.IO_ADDR_W);
}

/**
 * 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;

        while (len--) {
                iowrite8(*p++, info->nand.IO_ADDR_W);
                while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
                                                GPMC_STATUS) & GPMC_BUF_FULL));
        }
}

/**
 * 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;

        /* FIXME try bursts of writesw() or DMA ... */
        len >>= 1;

        while (len--) {
                iowrite16(*p++, info->nand.IO_ADDR_W);

                while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
                                                GPMC_STATUS) & GPMC_BUF_FULL))
                        ;
        }
}

/**
 * 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 pfpw_status = 0, r_count = 0;
        int ret = 0;
        u32 *p = (u32 *)buf;

        /* take care of subpage reads */
        for (; len % 4 != 0; ) {
                *buf++ = __raw_readb(info->nand.IO_ADDR_R);
                len--;
        }
        p = (u32 *) buf;

        /* configure and start prefetch transfer */
        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
        if (ret) {
                /* PFPW engine is busy, use cpu copy method */
                if (info->nand.options & NAND_BUSWIDTH_16)
                        omap_read_buf16(mtd, buf, len);
                else
                        omap_read_buf8(mtd, buf, len);
        } else {
                do {
                        pfpw_status = gpmc_prefetch_status();
                        r_count = ((pfpw_status >> 24) & 0x7F) >> 2;
                        ioread32_rep(info->nand_pref_fifo_add, p, r_count);
                        p += r_count;
                        len -= r_count << 2;
                } while (len);

                /* disable and stop the PFPW engine */
                gpmc_prefetch_reset();
        }
}

/**
 * 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 pfpw_status = 0, w_count = 0;
        int i = 0, ret = 0;
        u16 *p = (u16 *) buf;

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

        /*  configure and start prefetch transfer */
        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
        if (ret) {
                /* PFPW engine is busy, use cpu copy method */
                if (info->nand.options & NAND_BUSWIDTH_16)
                        omap_write_buf16(mtd, buf, len);
                else
                        omap_write_buf8(mtd, buf, len);
        } else {
                pfpw_status = gpmc_prefetch_status();
                while (pfpw_status & 0x3FFF) {
                        w_count = ((pfpw_status >> 24) & 0x7F) >> 1;
                        for (i = 0; (i < w_count) && len; i++, len -= 2)
                                iowrite16(*p++, info->nand_pref_fifo_add);
                        pfpw_status = gpmc_prefetch_status();
                }

                /* disable and stop the PFPW engine */
                gpmc_prefetch_reset();
        }
}

#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH_DMA
/*
 * 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);
        uint32_t prefetch_status = 0;
        enum dma_data_direction dir = is_write ? DMA_TO_DEVICE :
                                                        DMA_FROM_DEVICE;
        dma_addr_t dma_addr;
        int ret;

        /* The fifo depth is 64 bytes. We have a sync at each frame and frame
         * length is 64 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, 0x1, len, is_write);
        if (ret)
                /* PFPW engine is busy, use cpu copy methode */
                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);

        while (0x3fff & (prefetch_status = gpmc_prefetch_status()))
                ;
        /* disable and stop the PFPW engine */
        gpmc_prefetch_reset();

        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;
}
#else
static void omap_nand_dma_cb(int lch, u16 ch_status, void *data) {}
static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
                                        unsigned int len, int is_write)
{
        return 0;
}
#endif

/**
 * 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, buf, len, 0x1);
}

/**
 * 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;
}

#ifdef CONFIG_MTD_NAND_OMAP_HWECC
/**
 * omap_hwecc_init - Initialize the HW ECC for NAND flash in GPMC controller
 * @mtd: MTD device structure
 */
static void omap_hwecc_init(struct mtd_info *mtd)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        struct nand_chip *chip = mtd->priv;
        unsigned long val = 0x0;

        /* Read from ECC Control Register */
        val = __raw_readl(info->gpmc_baseaddr + GPMC_ECC_CONTROL);
        /* Clear all ECC | Enable Reg1 */
        val = ((0x00000001<<8) | 0x00000001);
        __raw_writel(val, info->gpmc_baseaddr + GPMC_ECC_CONTROL);

        /* Read from ECC Size Config Register */
        val = __raw_readl(info->gpmc_baseaddr + GPMC_ECC_SIZE_CONFIG);
        /* ECCSIZE1=512 | Select eccResultsize[0-3] */
        val = ((((chip->ecc.size >> 1) - 1) << 22) | (0x0000000F));
        __raw_writel(val, info->gpmc_baseaddr + GPMC_ECC_SIZE_CONFIG);
}

/**
 * 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.
 */
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 */
                DEBUG(MTD_DEBUG_LEVEL0, "ECC UNCORRECTED_ERROR 1\n");
                return -1;

        case 11:
                /* UN-Correctable error */
                DEBUG(MTD_DEBUG_LEVEL0, "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];

                DEBUG(MTD_DEBUG_LEVEL0, "Correcting single bit ECC error at "
                                "offset: %d, bit: %d\n", find_byte, find_bit);

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

                return 0;
        default:
                if (isEccFF) {
                        if (ecc_data2[0] == 0 &&
                            ecc_data2[1] == 0 &&
                            ecc_data2[2] == 0)
                                return 0;
                }
                DEBUG(MTD_DEBUG_LEVEL0, "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 mismached, it will call 'omap_compare_ecc' for error detection
 * and correction.
 */
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;

        /* 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;
                }
                read_ecc += 3;
                calc_ecc += 3;
                dat      += 512;
        }
        return 0;
}

/**
 * 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);
        unsigned long val = 0x0;
        unsigned long reg;

        /* Start Reading from HW ECC1_Result = 0x200 */
        reg = (unsigned long)(info->gpmc_baseaddr + GPMC_ECC1_RESULT);
        val = __raw_readl(reg);
        *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);
        reg += 4;

        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;
        unsigned long val = __raw_readl(info->gpmc_baseaddr + GPMC_ECC_CONFIG);

        switch (mode) {
        case NAND_ECC_READ:
                __raw_writel(0x101, info->gpmc_baseaddr + GPMC_ECC_CONTROL);
                /* (ECC 16 or 8 bit col) | ( CS  )  | ECC Enable */
                val = (dev_width << 7) | (info->gpmc_cs << 1) | (0x1);
                break;
        case NAND_ECC_READSYN:
                 __raw_writel(0x100, info->gpmc_baseaddr + GPMC_ECC_CONTROL);
                /* (ECC 16 or 8 bit col) | ( CS  )  | ECC Enable */
                val = (dev_width << 7) | (info->gpmc_cs << 1) | (0x1);
                break;
        case NAND_ECC_WRITE:
                __raw_writel(0x101, info->gpmc_baseaddr + GPMC_ECC_CONTROL);
                /* (ECC 16 or 8 bit col) | ( CS  )  | ECC Enable */
                val = (dev_width << 7) | (info->gpmc_cs << 1) | (0x1);
                break;
        default:
                DEBUG(MTD_DEBUG_LEVEL0, "Error: Unrecognized Mode[%d]!\n",
                                        mode);
                break;
        }

        __raw_writel(val, info->gpmc_baseaddr + GPMC_ECC_CONFIG);
}
#endif

/**
 * 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;

        this->IO_ADDR_W = (void *) info->gpmc_cs_baseaddr +
                                                GPMC_CS_NAND_COMMAND;
        this->IO_ADDR_R = (void *) info->gpmc_cs_baseaddr + GPMC_CS_NAND_DATA;

        __raw_writeb(NAND_CMD_STATUS & 0xFF, this->IO_ADDR_W);

        while (time_before(jiffies, timeo)) {
                status = __raw_readb(this->IO_ADDR_R);
                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)
{
        struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
                                                        mtd);
        unsigned int val = __raw_readl(info->gpmc_baseaddr + GPMC_IRQ_STATUS);

        if ((val & 0x100) == 0x100) {
                /* Clear IRQ Interrupt */
                val |= 0x100;
                val &= ~(0x0);
                __raw_writel(val, info->gpmc_baseaddr + GPMC_IRQ_STATUS);
        } else {
                unsigned int cnt = 0;
                while (cnt++ < 0x1FF) {
                        if  ((val & 0x100) == 0x100)
                                return 0;
                        val = __raw_readl(info->gpmc_baseaddr +
                                                        GPMC_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;
        unsigned long                   val;


        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->gpmc_baseaddr     = pdata->gpmc_baseaddr;
        info->gpmc_cs_baseaddr  = pdata->gpmc_cs_baseaddr;

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

        err = gpmc_cs_request(info->gpmc_cs, NAND_IO_SIZE, &info->phys_base);
        if (err < 0) {
                dev_err(&pdev->dev, "Cannot request GPMC CS\n");
                goto out_free_info;
        }

        /* Enable RD PIN Monitoring Reg */
        if (pdata->dev_ready) {
                val  = gpmc_cs_read_reg(info->gpmc_cs, GPMC_CS_CONFIG1);
                val |= WR_RD_PIN_MONITORING;
                gpmc_cs_write_reg(info->gpmc_cs, GPMC_CS_CONFIG1, val);
        }

        val  = gpmc_cs_read_reg(info->gpmc_cs, GPMC_CS_CONFIG7);
        val &= ~(0xf << 8);
        val |=  (0xc & 0xf) << 8;
        gpmc_cs_write_reg(info->gpmc_cs, GPMC_CS_CONFIG7, val);

        /* NAND write protect off */
        omap_nand_wp(&info->mtd, NAND_WP_OFF);

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

        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;
        }

        info->nand.options  |= NAND_SKIP_BBTSCAN;
        if ((gpmc_cs_read_reg(info->gpmc_cs, GPMC_CS_CONFIG1) & 0x3000)
                                                                == 0x1000)
                info->nand.options  |= NAND_BUSWIDTH_16;

        if (use_prefetch) {
                /* copy the virtual address of nand base for fifo access */
                info->nand_pref_fifo_add = info->nand.IO_ADDR_R;

                info->nand.read_buf   = omap_read_buf_pref;
                info->nand.write_buf  = omap_write_buf_pref;
                if (use_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;
                                printk(KERN_WARNING "DMA request failed."
                                        " Non-dma data transfer mode\n");
                        } 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;
                        }
                }
        } else {
                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;

                }
        }
        info->nand.verify_buf = omap_verify_buf;

#ifdef CONFIG_MTD_NAND_OMAP_HWECC
        info->nand.ecc.bytes            = 3;
        info->nand.ecc.size             = 512;
        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;

        /* init HW ECC */
        omap_hwecc_init(&info->mtd);
#else
        info->nand.ecc.mode = NAND_ECC_SOFT;
#endif

        /* 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(&info->mtd, 1)) {
                info->nand.options ^= NAND_BUSWIDTH_16;
                if (nand_scan(&info->mtd, 1)) {
                        err = -ENXIO;
                        goto out_release_mem_region;
                }
        }

#ifdef CONFIG_MTD_PARTITIONS
        err = parse_mtd_partitions(&info->mtd, part_probes, &info->parts, 0);
        if (err > 0)
                add_mtd_partitions(&info->mtd, info->parts, err);
        else if (pdata->parts)
                add_mtd_partitions(&info->mtd, pdata->parts, pdata->nr_parts);
        else
#endif
                add_mtd_device(&info->mtd);

        platform_set_drvdata(pdev, &info->mtd);

        return 0;

out_release_mem_region:
        release_mem_region(info->phys_base, NAND_IO_SIZE);
out_free_cs:
        gpmc_cs_free(info->gpmc_cs);
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 = mtd->priv;

        platform_set_drvdata(pdev, NULL);
        if (use_dma)
                omap_free_dma(info->dma_ch);

        /* Release NAND device, its internal structures and partitions */
        nand_release(&info->mtd);
        iounmap(info->nand_pref_fifo_add);
        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,
        },
};

static int __init omap_nand_init(void)
{
        printk(KERN_INFO "%s driver initializing\n", DRIVER_NAME);

        /* This check is required if driver is being
         * loaded run time as a module
         */
        if ((1 == use_dma) && (0 == use_prefetch)) {
                printk(KERN_INFO"Wrong parameters: 'use_dma' can not be 1 "
                                "without use_prefetch'. Prefetch will not be"
                                " used in either mode (mpu or dma)\n");
        }
        return platform_driver_register(&omap_nand_driver);
}

static void __exit omap_nand_exit(void)
{
        platform_driver_unregister(&omap_nand_driver);
}

module_init(omap_nand_init);
module_exit(omap_nand_exit);

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