/*
 * (C) Copyright 2004-2008 Texas Instruments, <www.ti.com>
 * Rohit Choraria <rohitkc@ti.com>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <asm/io.h>
#include <asm/errno.h>
#include <asm/arch/mem.h>
#include <asm/arch/cpu.h>
#include <asm/omap_gpmc.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/bch.h>
#include <linux/compiler.h>
#include <nand.h>
#ifdef CONFIG_AM33XX
#include <asm/arch/elm.h>
#endif

static uint8_t cs;
static __maybe_unused struct nand_ecclayout hw_nand_oob =
        GPMC_NAND_HW_ECC_LAYOUT;
static __maybe_unused struct nand_ecclayout hw_bch8_nand_oob =
        GPMC_NAND_HW_BCH8_ECC_LAYOUT;

/*
 * omap_nand_hwcontrol - Set the address pointers corretly for the
 *                      following address/data/command operation
 */
static void omap_nand_hwcontrol(struct mtd_info *mtd, int32_t cmd,
                                uint32_t ctrl)
{
        register struct nand_chip *this = mtd->priv;

        /*
         * Point the IO_ADDR to DATA and ADDRESS registers instead
         * of chip address
         */
        switch (ctrl) {
        case NAND_CTRL_CHANGE | NAND_CTRL_CLE:
                this->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_cmd;
                break;
        case NAND_CTRL_CHANGE | NAND_CTRL_ALE:
                this->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_adr;
                break;
        case NAND_CTRL_CHANGE | NAND_NCE:
                this->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_dat;
                break;
        }

        if (cmd != NAND_CMD_NONE)
                writeb(cmd, this->IO_ADDR_W);
}

#ifdef CONFIG_SPL_BUILD
/* Check wait pin as dev ready indicator */
int omap_spl_dev_ready(struct mtd_info *mtd)
{
        return gpmc_cfg->status & (1 << 8);
}
#endif

/*
 * omap_hwecc_init - Initialize the Hardware ECC for NAND flash in
 *                   GPMC controller
 * @mtd:        MTD device structure
 *
 */
static void __maybe_unused omap_hwecc_init(struct nand_chip *chip)
{
        /*
         * Init ECC Control Register
         * Clear all ECC | Enable Reg1
         */
        writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
        writel(ECCSIZE1 | ECCSIZE0 | ECCSIZE0SEL, &gpmc_cfg->ecc_size_config);
}

/*
 * gen_true_ecc - This function will generate true ECC value, which
 * can be used when correcting data read from NAND flash memory core
 *
 * @ecc_buf:    buffer to store ecc code
 *
 * @return:     re-formatted ECC value
 */
static uint32_t gen_true_ecc(uint8_t *ecc_buf)
{
        return ecc_buf[0] | (ecc_buf[1] << 16) | ((ecc_buf[2] & 0xF0) << 20) |
                ((ecc_buf[2] & 0x0F) << 8);
}

/*
 * omap_correct_data - Compares the ecc read from nand spare area with ECC
 * registers values and corrects one bit error if it has occured
 * Further details can be had from OMAP TRM and the following selected links:
 * http://en.wikipedia.org/wiki/Hamming_code
 * http://www.cs.utexas.edu/users/plaxton/c/337/05f/slides/ErrorCorrection-4.pdf
 *
 * @mtd:                 MTD device structure
 * @dat:                 page data
 * @read_ecc:            ecc read from nand flash
 * @calc_ecc:            ecc read from ECC registers
 *
 * @return 0 if data is OK or corrected, else returns -1
 */
static int __maybe_unused omap_correct_data(struct mtd_info *mtd, uint8_t *dat,
                                uint8_t *read_ecc, uint8_t *calc_ecc)
{
        uint32_t orig_ecc, new_ecc, res, hm;
        uint16_t parity_bits, byte;
        uint8_t bit;

        /* Regenerate the orginal ECC */
        orig_ecc = gen_true_ecc(read_ecc);
        new_ecc = gen_true_ecc(calc_ecc);
        /* Get the XOR of real ecc */
        res = orig_ecc ^ new_ecc;
        if (res) {
                /* Get the hamming width */
                hm = hweight32(res);
                /* Single bit errors can be corrected! */
                if (hm == 12) {
                        /* Correctable data! */
                        parity_bits = res >> 16;
                        bit = (parity_bits & 0x7);
                        byte = (parity_bits >> 3) & 0x1FF;
                        /* Flip the bit to correct */
                        dat[byte] ^= (0x1 << bit);
                } else if (hm == 1) {
                        printf("Error: Ecc is wrong\n");
                        /* ECC itself is corrupted */
                        return 2;
                } else {
                        /*
                         * hm distance != parity pairs OR one, could mean 2 bit
                         * error OR potentially be on a blank page..
                         * orig_ecc: contains spare area data from nand flash.
                         * new_ecc: generated ecc while reading data area.
                         * Note: if the ecc = 0, all data bits from which it was
                         * generated are 0xFF.
                         * The 3 byte(24 bits) ecc is generated per 512byte
                         * chunk of a page. If orig_ecc(from spare area)
                         * is 0xFF && new_ecc(computed now from data area)=0x0,
                         * this means that data area is 0xFF and spare area is
                         * 0xFF. A sure sign of a erased page!
                         */
                        if ((orig_ecc == 0x0FFF0FFF) && (new_ecc == 0x00000000))
                                return 0;
                        printf("Error: Bad compare! failed\n");
                        /* detected 2 bit error */
                        return -1;
                }
        }
        return 0;
}

/*
 *  omap_calculate_ecc - Generate non-inverted ECC bytes.
 *
 *  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.
 *  E.g. if page is 0xFF (fresh erased), and if HW ECC engine within GPMC
 *  is used, the result of read will be 0x0 while the ECC offsets of the
 *  spare area will be 0xFF which will result in an ECC mismatch.
 *  @mtd:       MTD structure
 *  @dat:       unused
 *  @ecc_code:  ecc_code buffer
 */
static int __maybe_unused omap_calculate_ecc(struct mtd_info *mtd,
                const uint8_t *dat, uint8_t *ecc_code)
{
        u_int32_t val;

        /* Start Reading from HW ECC1_Result = 0x200 */
        val = readl(&gpmc_cfg->ecc1_result);

        ecc_code[0] = val & 0xFF;
        ecc_code[1] = (val >> 16) & 0xFF;
        ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);

        /*
         * Stop reading anymore ECC vals and clear old results
         * enable will be called if more reads are required
         */
        writel(0x000, &gpmc_cfg->ecc_config);

        return 0;
}

/*
 * omap_enable_ecc - This function enables the hardware ecc functionality
 * @mtd:        MTD device structure
 * @mode:       Read/Write mode
 */
static void __maybe_unused omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
{
        struct nand_chip *chip = mtd->priv;
        uint32_t val, dev_width = (chip->options & NAND_BUSWIDTH_16) >> 1;

        switch (mode) {
        case NAND_ECC_READ:
        case NAND_ECC_WRITE:
                /* Clear the ecc result registers, select ecc reg as 1 */
                writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);

                /*
                 * Size 0 = 0xFF, Size1 is 0xFF - both are 512 bytes
                 * tell all regs to generate size0 sized regs
                 * we just have a single ECC engine for all CS
                 */
                writel(ECCSIZE1 | ECCSIZE0 | ECCSIZE0SEL,
                        &gpmc_cfg->ecc_size_config);
                val = (dev_width << 7) | (cs << 1) | (0x1);
                writel(val, &gpmc_cfg->ecc_config);
                break;
        default:
                printf("Error: Unrecognized Mode[%d]!\n", mode);
                break;
        }
}

/*
 * Generic BCH interface
 */
struct nand_bch_priv {
        uint8_t mode;
        uint8_t type;
        uint8_t nibbles;
        struct bch_control *control;
};

/* bch types */
#define ECC_BCH4        0
#define ECC_BCH8        1
#define ECC_BCH16       2

/* GPMC ecc engine settings */
#define BCH_WRAPMODE_1          1       /* BCH wrap mode 1 */
#define BCH_WRAPMODE_6          6       /* BCH wrap mode 6 */

/* BCH nibbles for diff bch levels */
#define NAND_ECC_HW_BCH ((uint8_t)(NAND_ECC_HW_OOB_FIRST) + 1)
#define ECC_BCH4_NIBBLES        13
#define ECC_BCH8_NIBBLES        26
#define ECC_BCH16_NIBBLES       52

/*
 * This can be a single instance cause all current users have only one NAND
 * with nearly the same setup (BCH8, some with ELM and others with sw BCH
 * library).
 * When some users with other BCH strength will exists this have to change!
 */
static __maybe_unused struct nand_bch_priv bch_priv = {
        .mode = NAND_ECC_HW_BCH,
        .type = ECC_BCH8,
        .nibbles = ECC_BCH8_NIBBLES,
        .control = NULL
};

/*
 * omap_hwecc_init_bch - Initialize the BCH Hardware ECC for NAND flash in
 *                              GPMC controller
 * @mtd:        MTD device structure
 * @mode:       Read/Write mode
 */
__maybe_unused
static void omap_hwecc_init_bch(struct nand_chip *chip, int32_t mode)
{
        uint32_t val;
        uint32_t dev_width = (chip->options & NAND_BUSWIDTH_16) >> 1;
#ifdef CONFIG_AM33XX
        uint32_t unused_length = 0;
#endif
        uint32_t wr_mode = BCH_WRAPMODE_6;
        struct nand_bch_priv *bch = chip->priv;

        /* Clear the ecc result registers, select ecc reg as 1 */
        writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);

#ifdef CONFIG_AM33XX
        wr_mode = BCH_WRAPMODE_1;

        switch (bch->nibbles) {
        case ECC_BCH4_NIBBLES:
                unused_length = 3;
                break;
        case ECC_BCH8_NIBBLES:
                unused_length = 2;
                break;
        case ECC_BCH16_NIBBLES:
                unused_length = 0;
                break;
        }

        /*
         * This is ecc_size_config for ELM mode.
         * Here we are using different settings for read and write access and
         * also depending on BCH strength.
         */
        switch (mode) {
        case NAND_ECC_WRITE:
                /* write access only setup eccsize1 config */
                val = ((unused_length + bch->nibbles) << 22);
                break;

        case NAND_ECC_READ:
        default:
                /*
                 * by default eccsize0 selected for ecc1resultsize
                 * eccsize0 config.
                 */
                val  = (bch->nibbles << 12);
                /* eccsize1 config */
                val |= (unused_length << 22);
                break;
        }
#else
        /*
         * This ecc_size_config setting is for BCH sw library.
         *
         * Note: we only support BCH8 currently with BCH sw library!
         * Should be really easy to adobt to BCH4, however some omap3 have
         * flaws with BCH4.
         *
         * Here we are using wrapping mode 6 both for reading and writing, with:
         *  size0 = 0  (no additional protected byte in spare area)
         *  size1 = 32 (skip 32 nibbles = 16 bytes per sector in spare area)
         */
        val = (32 << 22) | (0 << 12);
#endif
        /* ecc size configuration */
        writel(val, &gpmc_cfg->ecc_size_config);

        /*
         * Configure the ecc engine in gpmc
         * We assume 512 Byte sector pages for access to NAND.
         */
        val  = (1 << 16);               /* enable BCH mode */
        val |= (bch->type << 12);       /* setup BCH type */
        val |= (wr_mode << 8);          /* setup wrapping mode */
        val |= (dev_width << 7);        /* setup device width (16 or 8 bit) */
        val |= (cs << 1);               /* setup chip select to work on */
        debug("set ECC_CONFIG=0x%08x\n", val);
        writel(val, &gpmc_cfg->ecc_config);
}

/*
 * omap_enable_ecc_bch - This function enables the bch h/w ecc functionality
 * @mtd:        MTD device structure
 * @mode:       Read/Write mode
 */
__maybe_unused
static void omap_enable_ecc_bch(struct mtd_info *mtd, int32_t mode)
{
        struct nand_chip *chip = mtd->priv;

        omap_hwecc_init_bch(chip, mode);
        /* enable ecc */
        writel((readl(&gpmc_cfg->ecc_config) | 0x1), &gpmc_cfg->ecc_config);
}

/*
 * omap_ecc_disable - Disable H/W ECC calculation
 *
 * @mtd:        MTD device structure
 */
static void __maybe_unused omap_ecc_disable(struct mtd_info *mtd)
{
        writel((readl(&gpmc_cfg->ecc_config) & ~0x1), &gpmc_cfg->ecc_config);
}

/*
 * BCH8 support (needs ELM and thus AM33xx-only)
 */
#ifdef CONFIG_AM33XX
/*
 * omap_read_bch8_result - Read BCH result for BCH8 level
 *
 * @mtd:        MTD device structure
 * @big_endian: When set read register 3 first
 * @ecc_code:   Read syndrome from BCH result registers
 */
static void omap_read_bch8_result(struct mtd_info *mtd, uint8_t big_endian,
                                uint8_t *ecc_code)
{
        uint32_t *ptr;
        int8_t i = 0, j;

        if (big_endian) {
                ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[3];
                ecc_code[i++] = readl(ptr) & 0xFF;
                ptr--;
                for (j = 0; j < 3; j++) {
                        ecc_code[i++] = (readl(ptr) >> 24) & 0xFF;
                        ecc_code[i++] = (readl(ptr) >> 16) & 0xFF;
                        ecc_code[i++] = (readl(ptr) >>  8) & 0xFF;
                        ecc_code[i++] = readl(ptr) & 0xFF;
                        ptr--;
                }
        } else {
                ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[0];
                for (j = 0; j < 3; j++) {
                        ecc_code[i++] = readl(ptr) & 0xFF;
                        ecc_code[i++] = (readl(ptr) >>  8) & 0xFF;
                        ecc_code[i++] = (readl(ptr) >> 16) & 0xFF;
                        ecc_code[i++] = (readl(ptr) >> 24) & 0xFF;
                        ptr++;
                }
                ecc_code[i++] = readl(ptr) & 0xFF;
                ecc_code[i++] = 0;      /* 14th byte is always zero */
        }
}

/*
 * omap_rotate_ecc_bch - Rotate the syndrome bytes
 *
 * @mtd:        MTD device structure
 * @calc_ecc:   ECC read from ECC registers
 * @syndrome:   Rotated syndrome will be retuned in this array
 *
 */
static void omap_rotate_ecc_bch(struct mtd_info *mtd, uint8_t *calc_ecc,
                uint8_t *syndrome)
{
        struct nand_chip *chip = mtd->priv;
        struct nand_bch_priv *bch = chip->priv;
        uint8_t n_bytes = 0;
        int8_t i, j;

        switch (bch->type) {
        case ECC_BCH4:
                n_bytes = 8;
                break;

        case ECC_BCH16:
                n_bytes = 28;
                break;

        case ECC_BCH8:
        default:
                n_bytes = 13;
                break;
        }

        for (i = 0, j = (n_bytes-1); i < n_bytes; i++, j--)
                syndrome[i] =  calc_ecc[j];
}

/*
 *  omap_calculate_ecc_bch - Read BCH ECC result
 *
 *  @mtd:       MTD structure
 *  @dat:       unused
 *  @ecc_code:  ecc_code buffer
 */
static int omap_calculate_ecc_bch(struct mtd_info *mtd, const uint8_t *dat,
                                uint8_t *ecc_code)
{
        struct nand_chip *chip = mtd->priv;
        struct nand_bch_priv *bch = chip->priv;
        uint8_t big_endian = 1;
        int8_t ret = 0;

        if (bch->type == ECC_BCH8)
                omap_read_bch8_result(mtd, big_endian, ecc_code);
        else /* BCH4 and BCH16 currently not supported */
                ret = -1;

        /*
         * Stop reading anymore ECC vals and clear old results
         * enable will be called if more reads are required
         */
        omap_ecc_disable(mtd);

        return ret;
}

/*
 * omap_fix_errors_bch - Correct bch error in the data
 *
 * @mtd:        MTD device structure
 * @data:       Data read from flash
 * @error_count:Number of errors in data
 * @error_loc:  Locations of errors in the data
 *
 */
static void omap_fix_errors_bch(struct mtd_info *mtd, uint8_t *data,
                uint32_t error_count, uint32_t *error_loc)
{
        struct nand_chip *chip = mtd->priv;
        struct nand_bch_priv *bch = chip->priv;
        uint8_t count = 0;
        uint32_t error_byte_pos;
        uint32_t error_bit_mask;
        uint32_t last_bit = (bch->nibbles * 4) - 1;

        /* Flip all bits as specified by the error location array. */
        /* FOR( each found error location flip the bit ) */
        for (count = 0; count < error_count; count++) {
                if (error_loc[count] > last_bit) {
                        /* Remove the ECC spare bits from correction. */
                        error_loc[count] -= (last_bit + 1);
                        /* Offset bit in data region */
                        error_byte_pos = ((512 * 8) -
                                        (error_loc[count]) - 1) / 8;
                        /* Error Bit mask */
                        error_bit_mask = 0x1 << (error_loc[count] % 8);
                        /* Toggle the error bit to make the correction. */
                        data[error_byte_pos] ^= error_bit_mask;
                }
        }
}

/*
 * omap_correct_data_bch - Compares the ecc read from nand spare area
 * with ECC registers values and corrects one bit error if it has occured
 *
 * @mtd:        MTD device structure
 * @dat:        page data
 * @read_ecc:   ecc read from nand flash (ignored)
 * @calc_ecc:   ecc read from ECC registers
 *
 * @return 0 if data is OK or corrected, else returns -1
 */
static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat,
                                uint8_t *read_ecc, uint8_t *calc_ecc)
{
        struct nand_chip *chip = mtd->priv;
        struct nand_bch_priv *bch = chip->priv;
        uint8_t syndrome[28];
        uint32_t error_count = 0;
        uint32_t error_loc[8];
        uint32_t i, ecc_flag;

        ecc_flag = 0;
        for (i = 0; i < chip->ecc.bytes; i++)
                if (read_ecc[i] != 0xff)
                        ecc_flag = 1;

        if (!ecc_flag)
                return 0;

        elm_reset();
        elm_config((enum bch_level)(bch->type));

        /*
         * while reading ECC result we read it in big endian.
         * Hence while loading to ELM we have rotate to get the right endian.
         */
        omap_rotate_ecc_bch(mtd, calc_ecc, syndrome);

        /* use elm module to check for errors */
        if (elm_check_error(syndrome, bch->nibbles, &error_count,
                                error_loc) != 0) {
                printf("ECC: uncorrectable.\n");
                return -1;
        }

        /* correct bch error */
        if (error_count > 0)
                omap_fix_errors_bch(mtd, dat, error_count, error_loc);

        return 0;
}

/**
 * omap_read_page_bch - hardware ecc based page read function
 * @mtd:        mtd info structure
 * @chip:       nand chip info structure
 * @buf:        buffer to store read data
 * @page:       page number to read
 *
 */
static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf, int page)
{
        int i, eccsize = chip->ecc.size;
        int eccbytes = chip->ecc.bytes;
        int eccsteps = chip->ecc.steps;
        uint8_t *p = buf;
        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;
        uint32_t data_pos;
        uint32_t oob_pos;

        data_pos = 0;
        /* oob area start */
        oob_pos = (eccsize * eccsteps) + chip->ecc.layout->eccpos[0];
        oob += chip->ecc.layout->eccpos[0];

        for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize,
                                oob += eccbytes) {
                chip->ecc.hwctl(mtd, NAND_ECC_READ);
                /* read data */
                chip->cmdfunc(mtd, NAND_CMD_RNDOUT, data_pos, page);
                chip->read_buf(mtd, p, eccsize);

                /* read respective ecc from oob area */
                chip->cmdfunc(mtd, NAND_CMD_RNDOUT, oob_pos, page);
                chip->read_buf(mtd, oob, eccbytes);
                /* read syndrome */
                chip->ecc.calculate(mtd, p, &ecc_calc[i]);

                data_pos += eccsize;
                oob_pos += eccbytes;
        }

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

        eccsteps = chip->ecc.steps;
        p = buf;

        for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
                int stat;

                stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
                if (stat < 0)
                        mtd->ecc_stats.failed++;
                else
                        mtd->ecc_stats.corrected += stat;
        }
        return 0;
}
#endif /* CONFIG_AM33XX */

/*
 * OMAP3 BCH8 support (with BCH library)
 */
#ifdef CONFIG_NAND_OMAP_BCH8
/*
 *  omap_calculate_ecc_bch - Read BCH ECC result
 *
 *  @mtd:       MTD device structure
 *  @dat:       The pointer to data on which ecc is computed (unused here)
 *  @ecc:       The ECC output buffer
 */
static int omap_calculate_ecc_bch(struct mtd_info *mtd, const uint8_t *dat,
                                uint8_t *ecc)
{
        int ret = 0;
        size_t i;
        unsigned long nsectors, val1, val2, val3, val4;

        nsectors = ((readl(&gpmc_cfg->ecc_config) >> 4) & 0x7) + 1;

        for (i = 0; i < nsectors; i++) {
                /* Read hw-computed remainder */
                val1 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[0]);
                val2 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[1]);
                val3 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[2]);
                val4 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[3]);

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

        /*
         * Stop reading anymore ECC vals and clear old results
         * enable will be called if more reads are required
         */
        omap_ecc_disable(mtd);

        return ret;
}

/**
 * omap_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 omap_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 nand_chip *chip = mtd->priv;
        struct nand_bch_priv *chip_priv = chip->priv;
        struct bch_control *bch = chip_priv->control;

        count = decode_bch(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);
                        printf("corrected bitflip %u\n", errloc[i]);
#ifdef DEBUG
                        puts("read_ecc: ");
                        /*
                         * BCH8 have 13 bytes of ECC; BCH4 needs adoption
                         * here!
                         */
                        for (i = 0; i < 13; i++)
                                printf("%02x ", read_ecc[i]);
                        puts("\n");
                        puts("calc_ecc: ");
                        for (i = 0; i < 13; i++)
                                printf("%02x ", calc_ecc[i]);
                        puts("\n");
#endif
                }
        } else if (count < 0) {
                puts("ecc unrecoverable error\n");
        }
        return count;
}

/**
 * omap_free_bch - Release BCH ecc resources
 * @mtd: MTD device structure
 */
static void __maybe_unused omap_free_bch(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd->priv;
        struct nand_bch_priv *chip_priv = chip->priv;
        struct bch_control *bch = NULL;

        if (chip_priv)
                bch = chip_priv->control;

        if (bch) {
                free_bch(bch);
                chip_priv->control = NULL;
        }
}
#endif /* CONFIG_NAND_OMAP_BCH8 */

#ifndef CONFIG_SPL_BUILD
/*
 * omap_nand_switch_ecc - switch the ECC operation between different engines
 * (h/w and s/w) and different algorithms (hamming and BCHx)
 *
 * @hardware            - true if one of the HW engines should be used
 * @eccstrength         - the number of bits that could be corrected
 *                        (1 - hamming, 4 - BCH4, 8 - BCH8, 16 - BCH16)
 */
void omap_nand_switch_ecc(uint32_t hardware, uint32_t eccstrength)
{
        struct nand_chip *nand;
        struct mtd_info *mtd;

        if (nand_curr_device < 0 ||
            nand_curr_device >= CONFIG_SYS_MAX_NAND_DEVICE ||
            !nand_info[nand_curr_device].name) {
                printf("Error: Can't switch ecc, no devices available\n");
                return;
        }

        mtd = &nand_info[nand_curr_device];
        nand = mtd->priv;

        nand->options |= NAND_OWN_BUFFERS;

        /* Reset ecc interface */
        nand->ecc.mode = NAND_ECC_NONE;
        nand->ecc.read_page = NULL;
        nand->ecc.write_page = NULL;
        nand->ecc.read_oob = NULL;
        nand->ecc.write_oob = NULL;
        nand->ecc.hwctl = NULL;
        nand->ecc.correct = NULL;
        nand->ecc.calculate = NULL;

        /* Setup the ecc configurations again */
        if (hardware) {
                if (eccstrength == 1) {
                        nand->ecc.mode = NAND_ECC_HW;
                        nand->ecc.layout = &hw_nand_oob;
                        nand->ecc.size = 512;
                        nand->ecc.bytes = 3;
                        nand->ecc.hwctl = omap_enable_hwecc;
                        nand->ecc.correct = omap_correct_data;
                        nand->ecc.calculate = omap_calculate_ecc;
                        omap_hwecc_init(nand);
                        printf("1-bit hamming HW ECC selected\n");
                }
#if defined(CONFIG_AM33XX) || defined(CONFIG_NAND_OMAP_BCH8)
                else if (eccstrength == 8) {
                        nand->ecc.mode = NAND_ECC_HW;
                        nand->ecc.layout = &hw_bch8_nand_oob;
                        nand->ecc.size = 512;
#ifdef CONFIG_AM33XX
                        nand->ecc.bytes = 14;
                        nand->ecc.read_page = omap_read_page_bch;
#else
                        nand->ecc.bytes = 13;
#endif
                        nand->ecc.hwctl = omap_enable_ecc_bch;
                        nand->ecc.correct = omap_correct_data_bch;
                        nand->ecc.calculate = omap_calculate_ecc_bch;
                        omap_hwecc_init_bch(nand, NAND_ECC_READ);
                        printf("8-bit BCH HW ECC selected\n");
                }
#endif
        } else {
                nand->ecc.mode = NAND_ECC_SOFT;
                /* Use mtd default settings */
                nand->ecc.layout = NULL;
                nand->ecc.size = 0;
                printf("SW ECC selected\n");
        }

        /* Update NAND handling after ECC mode switch */
        nand_scan_tail(mtd);

        nand->options &= ~NAND_OWN_BUFFERS;
}
#endif /* CONFIG_SPL_BUILD */

/*
 * Board-specific NAND initialization. The following members of the
 * argument are board-specific:
 * - IO_ADDR_R: address to read the 8 I/O lines of the flash device
 * - IO_ADDR_W: address to write the 8 I/O lines of the flash device
 * - cmd_ctrl: hardwarespecific function for accesing control-lines
 * - waitfunc: hardwarespecific function for accesing device ready/busy line
 * - ecc.hwctl: function to enable (reset) hardware ecc generator
 * - ecc.mode: mode of ecc, see defines
 * - chip_delay: chip dependent delay for transfering data from array to
 *   read regs (tR)
 * - options: various chip options. They can partly be set to inform
 *   nand_scan about special functionality. See the defines for further
 *   explanation
 */
int board_nand_init(struct nand_chip *nand)
{
        int32_t gpmc_config = 0;
        cs = 0;

        /*
         * xloader/Uboot's gpmc configuration would have configured GPMC for
         * nand type of memory. The following logic scans and latches on to the
         * first CS with NAND type memory.
         * TBD: need to make this logic generic to handle multiple CS NAND
         * devices.
         */
        while (cs < GPMC_MAX_CS) {
                /* Check if NAND type is set */
                if ((readl(&gpmc_cfg->cs[cs].config1) & 0xC00) == 0x800) {
                        /* Found it!! */
                        break;
                }
                cs++;
        }
        if (cs >= GPMC_MAX_CS) {
                printf("NAND: Unable to find NAND settings in "
                        "GPMC Configuration - quitting\n");
                return -ENODEV;
        }

        gpmc_config = readl(&gpmc_cfg->config);
        /* Disable Write protect */
        gpmc_config |= 0x10;
        writel(gpmc_config, &gpmc_cfg->config);

        nand->IO_ADDR_R = (void __iomem *)&gpmc_cfg->cs[cs].nand_dat;
        nand->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_cmd;

        nand->cmd_ctrl = omap_nand_hwcontrol;
        nand->options = NAND_NO_PADDING | NAND_CACHEPRG | NAND_NO_AUTOINCR;
        /* If we are 16 bit dev, our gpmc config tells us that */
        if ((readl(&gpmc_cfg->cs[cs].config1) & 0x3000) == 0x1000)
                nand->options |= NAND_BUSWIDTH_16;

        nand->chip_delay = 100;

#if defined(CONFIG_AM33XX) || defined(CONFIG_NAND_OMAP_BCH8)
#ifdef CONFIG_AM33XX
        /* AM33xx uses the ELM */
        /* required in case of BCH */
        elm_init();
#else
        /*
         * Whereas other OMAP based SoC do not have the ELM, they use the BCH
         * SW library.
         */
        bch_priv.control = init_bch(13, 8, 0x201b /* hw polynominal */);
        if (!bch_priv.control) {
                puts("Could not init_bch()\n");
                return -ENODEV;
        }
#endif
        /* BCH info that will be correct for SPL or overridden otherwise. */
        nand->priv = &bch_priv;
#endif

        /* Default ECC mode */
#if defined(CONFIG_AM33XX) || defined(CONFIG_NAND_OMAP_BCH8)
        nand->ecc.mode = NAND_ECC_HW;
        nand->ecc.layout = &hw_bch8_nand_oob;
        nand->ecc.size = CONFIG_SYS_NAND_ECCSIZE;
        nand->ecc.bytes = CONFIG_SYS_NAND_ECCBYTES;
        nand->ecc.hwctl = omap_enable_ecc_bch;
        nand->ecc.correct = omap_correct_data_bch;
        nand->ecc.calculate = omap_calculate_ecc_bch;
#ifdef CONFIG_AM33XX
        nand->ecc.read_page = omap_read_page_bch;
#endif
        omap_hwecc_init_bch(nand, NAND_ECC_READ);
#else
#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_NAND_SOFTECC)
        nand->ecc.mode = NAND_ECC_SOFT;
#else
        nand->ecc.mode = NAND_ECC_HW;
        nand->ecc.layout = &hw_nand_oob;
        nand->ecc.size = CONFIG_SYS_NAND_ECCSIZE;
        nand->ecc.bytes = CONFIG_SYS_NAND_ECCBYTES;
        nand->ecc.hwctl = omap_enable_hwecc;
        nand->ecc.correct = omap_correct_data;
        nand->ecc.calculate = omap_calculate_ecc;
        omap_hwecc_init(nand);
#endif
#endif

#ifdef CONFIG_SPL_BUILD
        if (nand->options & NAND_BUSWIDTH_16)
                nand->read_buf = nand_read_buf16;
        else
                nand->read_buf = nand_read_buf;
        nand->dev_ready = omap_spl_dev_ready;
#endif

        return 0;
}