// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2004-2008 Texas Instruments, <www.ti.com>
 * Rohit Choraria <rohitkc@ti.com>
 */

#include <common.h>
#include <log.h>
#include <asm/io.h>
#include <linux/errno.h>
#include <asm/arch/mem.h>
#include <linux/mtd/omap_gpmc.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/mtd/rawnand.h>
#include <linux/bch.h>
#include <linux/compiler.h>
#include <nand.h>
#include <linux/mtd/omap_elm.h>

#define BADBLOCK_MARKER_LENGTH  2
#define SECTOR_BYTES            512
#define ECCCLEAR                (0x1 << 8)
#define ECCRESULTREG1           (0x1 << 0)
/* 4 bit padding to make byte aligned, 56 = 52 + 4 */
#define BCH4_BIT_PAD            4

#ifdef CONFIG_BCH
static u8  bch8_polynomial[] = {0xef, 0x51, 0x2e, 0x09, 0xed, 0x93, 0x9a, 0xc2,
                                0x97, 0x79, 0xe5, 0x24, 0xb5};
#endif
static uint8_t cs_next;
static __maybe_unused struct nand_ecclayout omap_ecclayout;

#if defined(CONFIG_NAND_OMAP_GPMC_WSCFG)
static const int8_t wscfg[CONFIG_SYS_MAX_NAND_DEVICE] =
        { CONFIG_NAND_OMAP_GPMC_WSCFG };
#else
/* wscfg is preset to zero since its a static variable */
static const int8_t wscfg[CONFIG_SYS_MAX_NAND_DEVICE];
#endif

/*
 * Driver configurations
 */
struct omap_nand_info {
        struct bch_control *control;
        enum omap_ecc ecc_scheme;
        uint8_t cs;
        uint8_t ws;             /* wait status pin (0,1) */
};

/* We are wasting a bit of memory but al least we are safe */
static struct omap_nand_info omap_nand_info[GPMC_MAX_CS];

/*
 * 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_to_nand(mtd);
        struct omap_nand_info *info = nand_get_controller_data(this);
        int cs = info->cs;

        /*
         * 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);
}

/* Check wait pin as dev ready indicator */
static int omap_dev_ready(struct mtd_info *mtd)
{
        register struct nand_chip *this = mtd_to_nand(mtd);
        struct omap_nand_info *info = nand_get_controller_data(this);
        return gpmc_cfg->status & (1 << (8 + info->ws));
}

/*
 * 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 occurred
 * 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 -EBADMSG;
                }
        }
        return 0;
}

/*
 * omap_enable_hwecc - configures GPMC as per ECC scheme before read/write
 * @mtd:        MTD device structure
 * @mode:       Read/Write mode
 */
__maybe_unused
static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
{
        struct nand_chip        *nand   = mtd_to_nand(mtd);
        struct omap_nand_info   *info   = nand_get_controller_data(nand);
        unsigned int dev_width = (nand->options & NAND_BUSWIDTH_16) ? 1 : 0;
        unsigned int ecc_algo = 0;
        unsigned int bch_type = 0;
        unsigned int eccsize1 = 0x00, eccsize0 = 0x00, bch_wrapmode = 0x00;
        u32 ecc_size_config_val = 0;
        u32 ecc_config_val = 0;
        int cs = info->cs;

        /* configure GPMC for specific ecc-scheme */
        switch (info->ecc_scheme) {
        case OMAP_ECC_HAM1_CODE_SW:
                return;
        case OMAP_ECC_HAM1_CODE_HW:
                ecc_algo = 0x0;
                bch_type = 0x0;
                bch_wrapmode = 0x00;
                eccsize0 = 0xFF;
                eccsize1 = 0xFF;
                break;
        case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
        case OMAP_ECC_BCH8_CODE_HW:
                ecc_algo = 0x1;
                bch_type = 0x1;
                if (mode == NAND_ECC_WRITE) {
                        bch_wrapmode = 0x01;
                        eccsize0 = 0;  /* extra bits in nibbles per sector */
                        eccsize1 = 28; /* OOB bits in nibbles per sector */
                } else {
                        bch_wrapmode = 0x01;
                        eccsize0 = 26; /* ECC bits in nibbles per sector */
                        eccsize1 = 2;  /* non-ECC bits in nibbles per sector */
                }
                break;
        case OMAP_ECC_BCH16_CODE_HW:
                ecc_algo = 0x1;
                bch_type = 0x2;
                if (mode == NAND_ECC_WRITE) {
                        bch_wrapmode = 0x01;
                        eccsize0 = 0;  /* extra bits in nibbles per sector */
                        eccsize1 = 52; /* OOB bits in nibbles per sector */
                } else {
                        bch_wrapmode = 0x01;
                        eccsize0 = 52; /* ECC bits in nibbles per sector */
                        eccsize1 = 0;  /* non-ECC bits in nibbles per sector */
                }
                break;
        default:
                return;
        }
        /* Clear ecc and enable bits */
        writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
        /* Configure ecc size for BCH */
        ecc_size_config_val = (eccsize1 << 22) | (eccsize0 << 12);
        writel(ecc_size_config_val, &gpmc_cfg->ecc_size_config);

        /* Configure device details for BCH engine */
        ecc_config_val = ((ecc_algo << 16)      | /* HAM1 | BCHx */
                        (bch_type << 12)        | /* BCH4/BCH8/BCH16 */
                        (bch_wrapmode << 8)     | /* wrap mode */
                        (dev_width << 7)        | /* bus width */
                        (0x0 << 4)              | /* number of sectors */
                        (cs <<  1)              | /* ECC CS */
                        (0x1));                   /* enable ECC */
        writel(ecc_config_val, &gpmc_cfg->ecc_config);
}

/*
 *  omap_calculate_ecc - Read ECC result
 *  @mtd:       MTD structure
 *  @dat:       unused
 *  @ecc_code:  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.
 *  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.
 */
static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
                                uint8_t *ecc_code)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct omap_nand_info *info = nand_get_controller_data(chip);
        const uint32_t *ptr;
        uint32_t val = 0;
        int8_t i = 0, j;

        switch (info->ecc_scheme) {
        case OMAP_ECC_HAM1_CODE_HW:
                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);
                break;
#ifdef CONFIG_BCH
        case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
#endif
        case OMAP_ECC_BCH8_CODE_HW:
                ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[3];
                val = readl(ptr);
                ecc_code[i++] = (val >>  0) & 0xFF;
                ptr--;
                for (j = 0; j < 3; j++) {
                        val = readl(ptr);
                        ecc_code[i++] = (val >> 24) & 0xFF;
                        ecc_code[i++] = (val >> 16) & 0xFF;
                        ecc_code[i++] = (val >>  8) & 0xFF;
                        ecc_code[i++] = (val >>  0) & 0xFF;
                        ptr--;
                }
                break;
        case OMAP_ECC_BCH16_CODE_HW:
                val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[2]);
                ecc_code[i++] = (val >>  8) & 0xFF;
                ecc_code[i++] = (val >>  0) & 0xFF;
                val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[1]);
                ecc_code[i++] = (val >> 24) & 0xFF;
                ecc_code[i++] = (val >> 16) & 0xFF;
                ecc_code[i++] = (val >>  8) & 0xFF;
                ecc_code[i++] = (val >>  0) & 0xFF;
                val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[0]);
                ecc_code[i++] = (val >> 24) & 0xFF;
                ecc_code[i++] = (val >> 16) & 0xFF;
                ecc_code[i++] = (val >>  8) & 0xFF;
                ecc_code[i++] = (val >>  0) & 0xFF;
                for (j = 3; j >= 0; j--) {
                        val = readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[j]
                                                                        );
                        ecc_code[i++] = (val >> 24) & 0xFF;
                        ecc_code[i++] = (val >> 16) & 0xFF;
                        ecc_code[i++] = (val >>  8) & 0xFF;
                        ecc_code[i++] = (val >>  0) & 0xFF;
                }
                break;
        default:
                return -EINVAL;
        }
        /* ECC scheme specific syndrome customizations */
        switch (info->ecc_scheme) {
        case OMAP_ECC_HAM1_CODE_HW:
                break;
#ifdef CONFIG_BCH
        case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:

                for (i = 0; i < chip->ecc.bytes; i++)
                        *(ecc_code + i) = *(ecc_code + i) ^
                                                bch8_polynomial[i];
                break;
#endif
        case OMAP_ECC_BCH8_CODE_HW:
                ecc_code[chip->ecc.bytes - 1] = 0x00;
                break;
        case OMAP_ECC_BCH16_CODE_HW:
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

#ifdef CONFIG_NAND_OMAP_GPMC_PREFETCH

#define PREFETCH_CONFIG1_CS_SHIFT       24
#define PREFETCH_FIFOTHRESHOLD_MAX      0x40
#define PREFETCH_FIFOTHRESHOLD(val)     ((val) << 8)
#define PREFETCH_STATUS_COUNT(val)      (val & 0x00003fff)
#define PREFETCH_STATUS_FIFO_CNT(val)   ((val >> 24) & 0x7F)
#define ENABLE_PREFETCH                 (1 << 7)

/**
 * omap_prefetch_enable - configures and starts prefetch transfer
 * @fifo_th: fifo threshold to be used for read/ write
 * @count: number of bytes to be transferred
 * @is_write: prefetch read(0) or write post(1) mode
 * @cs: chip select to use
 */
static int omap_prefetch_enable(int fifo_th, unsigned int count, int is_write, int cs)
{
        uint32_t val;

        if (fifo_th > PREFETCH_FIFOTHRESHOLD_MAX)
                return -EINVAL;

        if (readl(&gpmc_cfg->prefetch_control))
                return -EBUSY;

        /* Set the amount of bytes to be prefetched */
        writel(count, &gpmc_cfg->prefetch_config2);

        val = (cs << PREFETCH_CONFIG1_CS_SHIFT) | (is_write & 1) |
                PREFETCH_FIFOTHRESHOLD(fifo_th) | ENABLE_PREFETCH;
        writel(val, &gpmc_cfg->prefetch_config1);

        /*  Start the prefetch engine */
        writel(1, &gpmc_cfg->prefetch_control);

        return 0;
}

/**
 * omap_prefetch_reset - disables and stops the prefetch engine
 */
static void omap_prefetch_reset(void)
{
        writel(0, &gpmc_cfg->prefetch_control);
        writel(0, &gpmc_cfg->prefetch_config1);
}

static int __read_prefetch_aligned(struct nand_chip *chip, uint32_t *buf, int len)
{
        int ret;
        uint32_t cnt;
        struct omap_nand_info *info = nand_get_controller_data(chip);

        ret = omap_prefetch_enable(PREFETCH_FIFOTHRESHOLD_MAX, len, 0, info->cs);
        if (ret < 0)
                return ret;

        do {
                int i;

                cnt = readl(&gpmc_cfg->prefetch_status);
                cnt = PREFETCH_STATUS_FIFO_CNT(cnt);

                for (i = 0; i < cnt / 4; i++) {
                        *buf++ = readl(CONFIG_SYS_NAND_BASE);
                        len -= 4;
                }
        } while (len);

        omap_prefetch_reset();

        return 0;
}

static inline void omap_nand_read(struct mtd_info *mtd, uint8_t *buf, int len)
{
        struct nand_chip *chip = mtd_to_nand(mtd);

        if (chip->options & NAND_BUSWIDTH_16)
                nand_read_buf16(mtd, buf, len);
        else
                nand_read_buf(mtd, buf, len);
}

static void omap_nand_read_prefetch(struct mtd_info *mtd, uint8_t *buf, int len)
{
        int ret;
        uint32_t head, tail;
        struct nand_chip *chip = mtd_to_nand(mtd);

        /*
         * If the destination buffer is unaligned, start with reading
         * the overlap byte-wise.
         */
        head = ((uint32_t) buf) % 4;
        if (head) {
                omap_nand_read(mtd, buf, head);
                buf += head;
                len -= head;
        }

        /*
         * Only transfer multiples of 4 bytes in a pre-fetched fashion.
         * If there's a residue, care for it byte-wise afterwards.
         */
        tail = len % 4;

        ret = __read_prefetch_aligned(chip, (uint32_t *)buf, len - tail);
        if (ret < 0) {
                /* fallback in case the prefetch engine is busy */
                omap_nand_read(mtd, buf, len);
        } else if (tail) {
                buf += len - tail;
                omap_nand_read(mtd, buf, tail);
        }
}
#endif /* CONFIG_NAND_OMAP_GPMC_PREFETCH */

#ifdef CONFIG_NAND_OMAP_ELM
/*
 * omap_reverse_list - re-orders list elements in reverse order [internal]
 * @list:       pointer to start of list
 * @length:     length of list
*/
static void omap_reverse_list(u8 *list, unsigned int length)
{
        unsigned int i, j;
        unsigned int half_length = length / 2;
        u8 tmp;
        for (i = 0, j = length - 1; i < half_length; i++, j--) {
                tmp = list[i];
                list[i] = list[j];
                list[j] = tmp;
        }
}

/*
 * omap_correct_data_bch - Compares the ecc read from nand spare area
 * with ECC registers values and corrects one bit error if it has occurred
 *
 * @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_to_nand(mtd);
        struct omap_nand_info *info = nand_get_controller_data(chip);
        struct nand_ecc_ctrl *ecc = &chip->ecc;
        uint32_t error_count = 0, error_max;
        uint32_t error_loc[ELM_MAX_ERROR_COUNT];
        enum bch_level bch_type;
        uint32_t i, ecc_flag = 0;
        uint8_t count;
        uint32_t byte_pos, bit_pos;
        int err = 0;

        /* check calculated ecc */
        for (i = 0; i < ecc->bytes && !ecc_flag; i++) {
                if (calc_ecc[i] != 0x00)
                        ecc_flag = 1;
        }
        if (!ecc_flag)
                return 0;

        /* check for whether its a erased-page */
        ecc_flag = 0;
        for (i = 0; i < ecc->bytes && !ecc_flag; i++) {
                if (read_ecc[i] != 0xff)
                        ecc_flag = 1;
        }
        if (!ecc_flag)
                return 0;

        /*
         * while reading ECC result we read it in big endian.
         * Hence while loading to ELM we have rotate to get the right endian.
         */
        switch (info->ecc_scheme) {
        case OMAP_ECC_BCH8_CODE_HW:
                bch_type = BCH_8_BIT;
                omap_reverse_list(calc_ecc, ecc->bytes - 1);
                break;
        case OMAP_ECC_BCH16_CODE_HW:
                bch_type = BCH_16_BIT;
                omap_reverse_list(calc_ecc, ecc->bytes);
                break;
        default:
                return -EINVAL;
        }
        /* use elm module to check for errors */
        elm_config(bch_type);
        err = elm_check_error(calc_ecc, bch_type, &error_count, error_loc);
        if (err)
                return err;

        /* correct bch error */
        for (count = 0; count < error_count; count++) {
                switch (info->ecc_scheme) {
                case OMAP_ECC_BCH8_CODE_HW:
                        /* 14th byte in ECC is reserved to match ROM layout */
                        error_max = SECTOR_BYTES + (ecc->bytes - 1);
                        break;
                case OMAP_ECC_BCH16_CODE_HW:
                        error_max = SECTOR_BYTES + ecc->bytes;
                        break;
                default:
                        return -EINVAL;
                }
                byte_pos = error_max - (error_loc[count] / 8) - 1;
                bit_pos  = error_loc[count] % 8;
                if (byte_pos < SECTOR_BYTES) {
                        dat[byte_pos] ^= 1 << bit_pos;
                        debug("nand: bit-flip corrected @data=%d\n", byte_pos);
                } else if (byte_pos < error_max) {
                        read_ecc[byte_pos - SECTOR_BYTES] ^= 1 << bit_pos;
                        debug("nand: bit-flip corrected @oob=%d\n", byte_pos -
                                                                SECTOR_BYTES);
                } else {
                        err = -EBADMSG;
                        printf("nand: error: invalid bit-flip location\n");
                }
        }
        return (err) ? err : error_count;
}

/**
 * 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
 * @oob_required: caller expects OOB data read to chip->oob_poi
 * @page:       page number to read
 *
 */
static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
                                uint8_t *buf, int oob_required, 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, -1);
                chip->read_buf(mtd, p, eccsize);

                /* read respective ecc from oob area */
                chip->cmdfunc(mtd, NAND_CMD_RNDOUT, oob_pos, -1);
                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_NAND_OMAP_ELM */

/*
 * OMAP3 BCH8 support (with BCH library)
 */
#ifdef CONFIG_BCH
/**
 * omap_correct_data_bch_sw - 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_sw(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_to_nand(mtd);
        struct omap_nand_info *info = nand_get_controller_data(chip);

        count = decode_bch(info->control, NULL, SECTOR_BYTES,
                                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] < SECTOR_BYTES << 3)
                                data[errloc[i] >> 3] ^= 1 << (errloc[i] & 7);
                        debug("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_to_nand(mtd);
        struct omap_nand_info *info = nand_get_controller_data(chip);

        if (info->control) {
                free_bch(info->control);
                info->control = NULL;
        }
}
#endif /* CONFIG_BCH */

/**
 * omap_select_ecc_scheme - configures driver for particular ecc-scheme
 * @nand: NAND chip device structure
 * @ecc_scheme: ecc scheme to configure
 * @pagesize: number of main-area bytes per page of NAND device
 * @oobsize: number of OOB/spare bytes per page of NAND device
 */
static int omap_select_ecc_scheme(struct nand_chip *nand,
        enum omap_ecc ecc_scheme, unsigned int pagesize, unsigned int oobsize) {
        struct omap_nand_info   *info           = nand_get_controller_data(nand);
        struct nand_ecclayout   *ecclayout      = &omap_ecclayout;
        int eccsteps = pagesize / SECTOR_BYTES;
        int i;

        switch (ecc_scheme) {
        case OMAP_ECC_HAM1_CODE_SW:
                debug("nand: selected OMAP_ECC_HAM1_CODE_SW\n");
                /* For this ecc-scheme, ecc.bytes, ecc.layout, ... are
                 * initialized in nand_scan_tail(), so just set ecc.mode */
                info->control           = NULL;
                nand->ecc.mode          = NAND_ECC_SOFT;
                nand->ecc.layout        = NULL;
                nand->ecc.size          = 0;
                break;

        case OMAP_ECC_HAM1_CODE_HW:
                debug("nand: selected OMAP_ECC_HAM1_CODE_HW\n");
                /* check ecc-scheme requirements before updating ecc info */
                if ((3 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
                        printf("nand: error: insufficient OOB: require=%d\n", (
                                (3 * eccsteps) + BADBLOCK_MARKER_LENGTH));
                        return -EINVAL;
                }
                info->control           = NULL;
                /* populate ecc specific fields */
                memset(&nand->ecc, 0, sizeof(struct nand_ecc_ctrl));
                nand->ecc.mode          = NAND_ECC_HW;
                nand->ecc.strength      = 1;
                nand->ecc.size          = SECTOR_BYTES;
                nand->ecc.bytes         = 3;
                nand->ecc.hwctl         = omap_enable_hwecc;
                nand->ecc.correct       = omap_correct_data;
                nand->ecc.calculate     = omap_calculate_ecc;
                /* define ecc-layout */
                ecclayout->eccbytes     = nand->ecc.bytes * eccsteps;
                for (i = 0; i < ecclayout->eccbytes; i++) {
                        if (nand->options & NAND_BUSWIDTH_16)
                                ecclayout->eccpos[i] = i + 2;
                        else
                                ecclayout->eccpos[i] = i + 1;
                }
                ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
                ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -
                                                BADBLOCK_MARKER_LENGTH;
                break;

        case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
#ifdef CONFIG_BCH
                debug("nand: selected OMAP_ECC_BCH8_CODE_HW_DETECTION_SW\n");
                /* check ecc-scheme requirements before updating ecc info */
                if ((13 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
                        printf("nand: error: insufficient OOB: require=%d\n", (
                                (13 * eccsteps) + BADBLOCK_MARKER_LENGTH));
                        return -EINVAL;
                }
                /* check if BCH S/W library can be used for error detection */
                info->control = init_bch(13, 8, 0x201b);
                if (!info->control) {
                        printf("nand: error: could not init_bch()\n");
                        return -ENODEV;
                }
                /* populate ecc specific fields */
                memset(&nand->ecc, 0, sizeof(struct nand_ecc_ctrl));
                nand->ecc.mode          = NAND_ECC_HW;
                nand->ecc.strength      = 8;
                nand->ecc.size          = SECTOR_BYTES;
                nand->ecc.bytes         = 13;
                nand->ecc.hwctl         = omap_enable_hwecc;
                nand->ecc.correct       = omap_correct_data_bch_sw;
                nand->ecc.calculate     = omap_calculate_ecc;
                /* define ecc-layout */
                ecclayout->eccbytes     = nand->ecc.bytes * eccsteps;
                ecclayout->eccpos[0]    = BADBLOCK_MARKER_LENGTH;
                for (i = 1; i < ecclayout->eccbytes; i++) {
                        if (i % nand->ecc.bytes)
                                ecclayout->eccpos[i] =
                                                ecclayout->eccpos[i - 1] + 1;
                        else
                                ecclayout->eccpos[i] =
                                                ecclayout->eccpos[i - 1] + 2;
                }
                ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
                ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -
                                                BADBLOCK_MARKER_LENGTH;
                break;
#else
                printf("nand: error: CONFIG_BCH required for ECC\n");
                return -EINVAL;
#endif

        case OMAP_ECC_BCH8_CODE_HW:
#ifdef CONFIG_NAND_OMAP_ELM
                debug("nand: selected OMAP_ECC_BCH8_CODE_HW\n");
                /* check ecc-scheme requirements before updating ecc info */
                if ((14 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
                        printf("nand: error: insufficient OOB: require=%d\n", (
                                (14 * eccsteps) + BADBLOCK_MARKER_LENGTH));
                        return -EINVAL;
                }
                /* intialize ELM for ECC error detection */
                elm_init();
                info->control           = NULL;
                /* populate ecc specific fields */
                memset(&nand->ecc, 0, sizeof(struct nand_ecc_ctrl));
                nand->ecc.mode          = NAND_ECC_HW;
                nand->ecc.strength      = 8;
                nand->ecc.size          = SECTOR_BYTES;
                nand->ecc.bytes         = 14;
                nand->ecc.hwctl         = omap_enable_hwecc;
                nand->ecc.correct       = omap_correct_data_bch;
                nand->ecc.calculate     = omap_calculate_ecc;
                nand->ecc.read_page     = omap_read_page_bch;
                /* define ecc-layout */
                ecclayout->eccbytes     = nand->ecc.bytes * eccsteps;
                for (i = 0; i < ecclayout->eccbytes; i++)
                        ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;
                ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
                ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -
                                                BADBLOCK_MARKER_LENGTH;
                break;
#else
                printf("nand: error: CONFIG_NAND_OMAP_ELM required for ECC\n");
                return -EINVAL;
#endif

        case OMAP_ECC_BCH16_CODE_HW:
#ifdef CONFIG_NAND_OMAP_ELM
                debug("nand: using OMAP_ECC_BCH16_CODE_HW\n");
                /* check ecc-scheme requirements before updating ecc info */
                if ((26 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
                        printf("nand: error: insufficient OOB: require=%d\n", (
                                (26 * eccsteps) + BADBLOCK_MARKER_LENGTH));
                        return -EINVAL;
                }
                /* intialize ELM for ECC error detection */
                elm_init();
                /* populate ecc specific fields */
                nand->ecc.mode          = NAND_ECC_HW;
                nand->ecc.size          = SECTOR_BYTES;
                nand->ecc.bytes         = 26;
                nand->ecc.strength      = 16;
                nand->ecc.hwctl         = omap_enable_hwecc;
                nand->ecc.correct       = omap_correct_data_bch;
                nand->ecc.calculate     = omap_calculate_ecc;
                nand->ecc.read_page     = omap_read_page_bch;
                /* define ecc-layout */
                ecclayout->eccbytes     = nand->ecc.bytes * eccsteps;
                for (i = 0; i < ecclayout->eccbytes; i++)
                        ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;
                ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
                ecclayout->oobfree[0].length = oobsize - nand->ecc.bytes -
                                                BADBLOCK_MARKER_LENGTH;
                break;
#else
                printf("nand: error: CONFIG_NAND_OMAP_ELM required for ECC\n");
                return -EINVAL;
#endif
        default:
                debug("nand: error: ecc scheme not enabled or supported\n");
                return -EINVAL;
        }

        /* nand_scan_tail() sets ham1 sw ecc; hw ecc layout is set by driver */
        if (ecc_scheme != OMAP_ECC_HAM1_CODE_SW)
                nand->ecc.layout = ecclayout;

        info->ecc_scheme = ecc_scheme;
        return 0;
}

#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)
 */
int __maybe_unused omap_nand_switch_ecc(uint32_t hardware, uint32_t eccstrength)
{
        struct nand_chip *nand;
        struct mtd_info *mtd = get_nand_dev_by_index(nand_curr_device);
        int err = 0;

        if (!mtd) {
                printf("nand: error: no NAND devices found\n");
                return -ENODEV;
        }

        nand = mtd_to_nand(mtd);
        nand->options |= NAND_OWN_BUFFERS;
        nand->options &= ~NAND_SUBPAGE_READ;
        /* Setup the ecc configurations again */
        if (hardware) {
                if (eccstrength == 1) {
                        err = omap_select_ecc_scheme(nand,
                                        OMAP_ECC_HAM1_CODE_HW,
                                        mtd->writesize, mtd->oobsize);
                } else if (eccstrength == 8) {
                        err = omap_select_ecc_scheme(nand,
                                        OMAP_ECC_BCH8_CODE_HW,
                                        mtd->writesize, mtd->oobsize);
                } else if (eccstrength == 16) {
                        err = omap_select_ecc_scheme(nand,
                                        OMAP_ECC_BCH16_CODE_HW,
                                        mtd->writesize, mtd->oobsize);
                } else {
                        printf("nand: error: unsupported ECC scheme\n");
                        return -EINVAL;
                }
        } else {
                if (eccstrength == 1) {
                        err = omap_select_ecc_scheme(nand,
                                        OMAP_ECC_HAM1_CODE_SW,
                                        mtd->writesize, mtd->oobsize);
                } else if (eccstrength == 8) {
                        err = omap_select_ecc_scheme(nand,
                                        OMAP_ECC_BCH8_CODE_HW_DETECTION_SW,
                                        mtd->writesize, mtd->oobsize);
                } else {
                        printf("nand: error: unsupported ECC scheme\n");
                        return -EINVAL;
                }
        }

        /* Update NAND handling after ECC mode switch */
        if (!err)
                err = nand_scan_tail(mtd);
        return err;
}
#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;
        int cs = cs_next++;
        int err = 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: error: 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;
        omap_nand_info[cs].control = NULL;
        omap_nand_info[cs].cs = cs;
        omap_nand_info[cs].ws = wscfg[cs];
        nand_set_controller_data(nand, &omap_nand_info[cs]);

        nand->cmd_ctrl  = omap_nand_hwcontrol;
        nand->options   |= NAND_NO_PADDING | NAND_CACHEPRG;
        nand->chip_delay = 100;
        nand->ecc.layout = &omap_ecclayout;

        /* configure driver and controller based on NAND device bus-width */
        gpmc_config = readl(&gpmc_cfg->cs[cs].config1);
#if defined(CONFIG_SYS_NAND_BUSWIDTH_16BIT)
        nand->options |= NAND_BUSWIDTH_16;
        writel(gpmc_config | (0x1 << 12), &gpmc_cfg->cs[cs].config1);
#else
        nand->options &= ~NAND_BUSWIDTH_16;
        writel(gpmc_config & ~(0x1 << 12), &gpmc_cfg->cs[cs].config1);
#endif
        /* select ECC scheme */
#if defined(CONFIG_NAND_OMAP_ECCSCHEME)
        err = omap_select_ecc_scheme(nand, CONFIG_NAND_OMAP_ECCSCHEME,
                        CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE);
#else
        /* pagesize and oobsize are not required to configure sw ecc-scheme */
        err = omap_select_ecc_scheme(nand, OMAP_ECC_HAM1_CODE_SW,
                        0, 0);
#endif
        if (err)
                return err;

#ifdef CONFIG_NAND_OMAP_GPMC_PREFETCH
        nand->read_buf = omap_nand_read_prefetch;
#else
        if (nand->options & NAND_BUSWIDTH_16)
                nand->read_buf = nand_read_buf16;
        else
                nand->read_buf = nand_read_buf;
#endif

        nand->dev_ready = omap_dev_ready;

        return 0;
}