/*
 * (C) Copyright 2007 STMicroelectronics, <www.st.com>
 * (C) Copyright 2009 Alessandro Rubini <rubini@unipv.it>
 *
 * 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 <nand.h>
#include <asm/io.h>

static inline int parity(int b) /* b is really a byte; returns 0 or ~0 */
{
        __asm__ __volatile__(
                "eor   %0, %0, %0, lsr #4\n\t"
                "eor   %0, %0, %0, lsr #2\n\t"
                "eor   %0, %0, %0, lsr #1\n\t"
                "ands  %0, %0, #1\n\t"
                "subne %0, %0, #2\t"
                : "=r" (b) : "0" (b));
        return b;
}

/*
 * This is the ECC routine used in hardware, according to the manual.
 * HW claims to make the calculation but not the correction; so we must
 * recalculate the bytes for a comparison.
 */
static int ecc512(const unsigned char *data, unsigned char *ecc)
{
        int gpar = 0;
        int i, val, par;
        int pbits = 0;          /* P8, P16, ... P2048 */
        int pprime = 0;         /* P8', P16', ... P2048' */
        int lowbits;            /* P1, P2, P4 and primes */

        for (i = 0; i < 512; i++) {
                par = parity((val = data[i]));
                gpar ^= val;
                pbits ^= (i & par);
        }
        /*
         * Ok, now gpar is global parity (xor of all bytes)
         * pbits are all the parity bits (non-prime ones)
         */
        par = parity(gpar);
        pprime = pbits ^ par;
        /* Put low bits in the right position for ecc[2] (bits 7..2) */
        lowbits = 0
                | (parity(gpar & 0xf0) & 0x80)  /* P4  */
                | (parity(gpar & 0x0f) & 0x40)  /* P4' */
                | (parity(gpar & 0xcc) & 0x20)  /* P2  */
                | (parity(gpar & 0x33) & 0x10)  /* P2' */
                | (parity(gpar & 0xaa) & 0x08)  /* P1  */
                | (parity(gpar & 0x55) & 0x04); /* P1' */

        ecc[2] = ~(lowbits | ((pbits & 0x100) >> 7) | ((pprime & 0x100) >> 8));
        /* now intermix bits for ecc[1] (P1024..P128') and ecc[0] (P64..P8') */
        ecc[1] = ~(    (pbits & 0x80) >> 0  | ((pprime & 0x80) >> 1)
                    | ((pbits & 0x40) >> 1) | ((pprime & 0x40) >> 2)
                    | ((pbits & 0x20) >> 2) | ((pprime & 0x20) >> 3)
                    | ((pbits & 0x10) >> 3) | ((pprime & 0x10) >> 4));

        ecc[0] = ~(    (pbits & 0x8) << 4  | ((pprime & 0x8) << 3)
                    | ((pbits & 0x4) << 3) | ((pprime & 0x4) << 2)
                    | ((pbits & 0x2) << 2) | ((pprime & 0x2) << 1)
                    | ((pbits & 0x1) << 1) | ((pprime & 0x1) << 0));
        return 0;
}

/* This is the method in the chip->ecc field */
static int nomadik_ecc_calculate(struct mtd_info *mtd, const uint8_t *dat,
                                 uint8_t *ecc_code)
{
        return ecc512(dat, ecc_code);
}

static int nomadik_ecc_correct(struct mtd_info *mtd, uint8_t *dat,
                                uint8_t *r_ecc, uint8_t *c_ecc)
{
        struct nand_chip *chip = mtd->priv;
        uint32_t r, c, d, diff; /*read, calculated, xor of them */

        if (!memcmp(r_ecc, c_ecc, chip->ecc.bytes))
                return 0;

        /* Reorder the bytes into ascending-order 24 bits -- see manual */
        r = r_ecc[2] << 22 | r_ecc[1] << 14 | r_ecc[0] << 6 | r_ecc[2] >> 2;
        c = c_ecc[2] << 22 | c_ecc[1] << 14 | c_ecc[0] << 6 | c_ecc[2] >> 2;
        diff = (r ^ c) & ((1<<24)-1); /* use 24 bits only */

        /* If 12 bits are different, one per pair, it's correctable */
        if (((diff | (diff>>1)) & 0x555555) == 0x555555) {
                int bit = ((diff & 2) >> 1)
                        | ((diff & 0x8) >> 2) | ((diff & 0x20) >> 3);
                int byte;

                d = diff >> 6; /* remove bit-order info */
                byte =  ((d & 2) >> 1)
                        | ((d & 0x8) >> 2) | ((d & 0x20) >> 3)
                        | ((d & 0x80) >> 4) | ((d & 0x200) >> 5)
                        | ((d & 0x800) >> 6) | ((d & 0x2000) >> 7)
                        | ((d & 0x8000) >> 8) | ((d & 0x20000) >> 9);
                /* correct the single bit */
                dat[byte] ^= 1<<bit;
                return 0;
        }
        /* If 1 bit only differs, it's one bit error in ECC, ignore */
        if ((diff ^ (1 << (ffs(diff) - 1))) == 0)
                return 0;
        /* Otherwise, uncorrectable */
        return -1;
}

static void nomadik_ecc_hwctl(struct mtd_info *mtd, int mode)
{ /* mandatory in the structure but not used here */ }


/* This is the layout used by older installations, we keep compatible */
struct nand_ecclayout nomadik_ecc_layout = {
        .eccbytes = 3 * 4,
        .eccpos = { /* each subpage has 16 bytes: pos 2,3,4 hosts ECC */
                0x02, 0x03, 0x04,
                0x12, 0x13, 0x14,
                0x22, 0x23, 0x24,
                0x32, 0x33, 0x34},
        .oobfree = { {0x08, 0x08}, {0x18, 0x08}, {0x28, 0x08}, {0x38, 0x08} },
};

#define MASK_ALE        (1 << 24)       /* our ALE is AD21 */
#define MASK_CLE        (1 << 23)       /* our CLE is AD22 */

/* This is copied from the AT91SAM9 devices (Stelian Pop, Lead Tech Design) */
static void nomadik_nand_hwcontrol(struct mtd_info *mtd,
                                   int cmd, unsigned int ctrl)
{
        struct nand_chip *this = mtd->priv;
        u32 pcr0 = readl(REG_FSMC_PCR0);

        if (ctrl & NAND_CTRL_CHANGE) {
                ulong IO_ADDR_W = (ulong) this->IO_ADDR_W;
                IO_ADDR_W &= ~(MASK_ALE | MASK_CLE);

                if (ctrl & NAND_CLE)
                        IO_ADDR_W |= MASK_CLE;
                if (ctrl & NAND_ALE)
                        IO_ADDR_W |= MASK_ALE;

                if (ctrl & NAND_NCE)
                        writel(pcr0 | 0x4, REG_FSMC_PCR0);
                else
                        writel(pcr0 & ~0x4, REG_FSMC_PCR0);

                this->IO_ADDR_W = (void *) IO_ADDR_W;
                this->IO_ADDR_R = (void *) IO_ADDR_W;
        }

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

/* Returns 1 when ready; upper layers timeout at 20ms with timer routines */
static int nomadik_nand_ready(struct mtd_info *mtd)
{
        return 1; /* The ready bit is handled in hardware */
}

/* Copy a buffer 32bits at a time: faster than defualt method which is 8bit */
static void nomadik_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
        int i;
        struct nand_chip *chip = mtd->priv;
        u32 *p = (u32 *) buf;

        len >>= 2;
        writel(0, REG_FSMC_ECCR0);
        for (i = 0; i < len; i++)
                p[i] = readl(chip->IO_ADDR_R);
}

int board_nand_init(struct nand_chip *chip)
{
        /* Set up the FSMC_PCR0 for nand access*/
        writel(0x0000004a, REG_FSMC_PCR0);
        /* Set up FSMC_PMEM0, FSMC_PATT0 with timing data for access */
        writel(0x00020401, REG_FSMC_PMEM0);
        writel(0x00020404, REG_FSMC_PATT0);

        chip->options = NAND_COPYBACK | NAND_CACHEPRG | NAND_NO_PADDING;
        chip->cmd_ctrl = nomadik_nand_hwcontrol;
        chip->dev_ready = nomadik_nand_ready;
        /* The chip allows 32bit reads, so avoid the default 8bit copy */
        chip->read_buf = nomadik_nand_read_buf;

        /* ECC: follow the hardware-defined rulse, but do it in sw */
        chip->ecc.mode = NAND_ECC_HW;
        chip->ecc.bytes = 3;
        chip->ecc.size = 512;
        chip->ecc.layout = &nomadik_ecc_layout;
        chip->ecc.calculate = nomadik_ecc_calculate;
        chip->ecc.hwctl = nomadik_ecc_hwctl;
        chip->ecc.correct = nomadik_ecc_correct;

        return 0;
}