/*

 *  CFI parallel flash with AMD command set emulation

 *

 *  Copyright (c) 2005 Jocelyn Mayer

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

/*

 * For now, this code can emulate flashes of 1, 2 or 4 bytes width.

 * Supported commands/modes are:

 * - flash read

 * - flash write

 * - flash ID read

 * - sector erase

 * - chip erase

 * - unlock bypass command

 * - CFI queries

 *

 * It does not support flash interleaving.

 * It does not implement boot blocs with reduced size

 * It does not implement software data protection as found in many real chips

 * It does not implement erase suspend/resume commands

 * It does not implement multiple sectors erase

 */

#include "hw.h"

#include "flash.h"

#include "qemu-timer.h"

#include "block.h"

//#define PFLASH_DEBUG

#ifdef PFLASH_DEBUG

#define DPRINTF(fmt, args...)                      \

do {                                               \

        printf("PFLASH: " fmt , ##args);           \

} while (0)

#else

#define DPRINTF(fmt, args...) do { } while (0)

#endif

struct pflash_t {

    BlockDriverState *bs;

    target_phys_addr_t base;

    uint32_t sector_len;

    uint32_t chip_len;

    int mappings;

    int width;

    int wcycle; /* if 0, the flash is read normally */

    int bypass;

    int ro;

    uint8_t cmd;

    uint8_t status;

    uint16_t ident[4];

    uint16_t unlock_addr[2];

    uint8_t cfi_len;

    uint8_t cfi_table[0x52];

    QEMUTimer *timer;

    ram_addr_t off;

    int fl_mem;

    int rom_mode;

    void *storage;

};

static void pflash_register_memory(pflash_t *pfl, int rom_mode)

{

    unsigned long phys_offset = pfl->fl_mem;

    int i;

    if (rom_mode)

        phys_offset |= pfl->off | IO_MEM_ROMD;

    pfl->rom_mode = rom_mode;

    for (i = 0; i < pfl->mappings; i++)

        cpu_register_physical_memory(pfl->base + i * pfl->chip_len,

                                     pfl->chip_len, phys_offset);

}

static void pflash_timer (void *opaque)

{

    pflash_t *pfl = opaque;

    DPRINTF("%s: command %02x done\n", __func__, pfl->cmd);

    /* Reset flash */

    pfl->status ^= 0x80;

    if (pfl->bypass) {

        pfl->wcycle = 2;

    } else {

        pflash_register_memory(pfl, 1);

        pfl->wcycle = 0;

    }

    pfl->cmd = 0;

}

static uint32_t pflash_read (pflash_t *pfl, uint32_t offset, int width)

{

    uint32_t boff;

    uint32_t ret;

    uint8_t *p;

    DPRINTF("%s: offset " TARGET_FMT_lx "\n", __func__, offset);

    ret = -1;

    if (pfl->rom_mode) {

        /* Lazy reset of to ROMD mode */

        if (pfl->wcycle == 0)

            pflash_register_memory(pfl, 1);

    }

    offset &= pfl->chip_len - 1;

    boff = offset & 0xFF;

    if (pfl->width == 2)

        boff = boff >> 1;

    else if (pfl->width == 4)

        boff = boff >> 2;

    switch (pfl->cmd) {

    default:

        /* This should never happen : reset state & treat it as a read*/

        DPRINTF("%s: unknown command state: %x\n", __func__, pfl->cmd);

        pfl->wcycle = 0;

        pfl->cmd = 0;

    case 0x80:

        /* We accept reads during second unlock sequence... */

    case 0x00:

    flash_read:

        /* Flash area read */

        p = pfl->storage;

        switch (width) {

        case 1:

            ret = p[offset];

//            DPRINTF("%s: data offset %08x %02x\n", __func__, offset, ret);

            break;

        case 2:

#if defined(TARGET_WORDS_BIGENDIAN)

            ret = p[offset] << 8;

            ret |= p[offset + 1];

#else

            ret = p[offset];

            ret |= p[offset + 1] << 8;

#endif

//            DPRINTF("%s: data offset %08x %04x\n", __func__, offset, ret);

            break;

        case 4:

#if defined(TARGET_WORDS_BIGENDIAN)

            ret = p[offset] << 24;

            ret |= p[offset + 1] << 16;

            ret |= p[offset + 2] << 8;

            ret |= p[offset + 3];

#else

            ret = p[offset];

            ret |= p[offset + 1] << 8;

            ret |= p[offset + 2] << 16;

            ret |= p[offset + 3] << 24;

#endif

//            DPRINTF("%s: data offset %08x %08x\n", __func__, offset, ret);

            break;

        }

        break;

    case 0x90:

        /* flash ID read */

        switch (boff) {

        case 0x00:

        case 0x01:

            ret = pfl->ident[boff & 0x01];

            break;

        case 0x02:

            ret = 0x00; /* Pretend all sectors are unprotected */

            break;

        case 0x0E:

        case 0x0F:

            if (pfl->ident[2 + (boff & 0x01)] == (uint8_t)-1)

                goto flash_read;

            ret = pfl->ident[2 + (boff & 0x01)];

            break;

        default:

            goto flash_read;

        }

        DPRINTF("%s: ID " TARGET_FMT_ld " %x\n", __func__, boff, ret);

        break;

    case 0xA0:

    case 0x10:

    case 0x30:

        /* Status register read */

        ret = pfl->status;

        DPRINTF("%s: status %x\n", __func__, ret);

        /* Toggle bit 6 */

        pfl->status ^= 0x40;

        break;

    case 0x98:

        /* CFI query mode */

        if (boff > pfl->cfi_len)

            ret = 0;

        else

            ret = pfl->cfi_table[boff];

        break;

    }

    return ret;

}

/* update flash content on disk */

static void pflash_update(pflash_t *pfl, int offset,

                          int size)

{

    int offset_end;

    if (pfl->bs) {

        offset_end = offset + size;

        /* round to sectors */

        offset = offset >> 9;

        offset_end = (offset_end + 511) >> 9;

        bdrv_write(pfl->bs, offset, pfl->storage + (offset << 9),

                   offset_end - offset);

    }

}

static void pflash_write (pflash_t *pfl, uint32_t offset, uint32_t value,

                          int width)

{

    uint32_t boff;

    uint8_t *p;

    uint8_t cmd;

    cmd = value;

    if (pfl->cmd != 0xA0 && cmd == 0xF0) {

#if 0

        DPRINTF("%s: flash reset asked (%02x %02x)\n",

                __func__, pfl->cmd, cmd);

#endif

        goto reset_flash;

    }

    DPRINTF("%s: offset " TARGET_FMT_lx " %08x %d %d\n", __func__,

            offset, value, width, pfl->wcycle);

    offset &= pfl->chip_len - 1;

    DPRINTF("%s: offset " TARGET_FMT_lx " %08x %d\n", __func__,

            offset, value, width);

    boff = offset & (pfl->sector_len - 1);

    if (pfl->width == 2)

        boff = boff >> 1;

    else if (pfl->width == 4)

        boff = boff >> 2;

    switch (pfl->wcycle) {

    case 0:

        /* Set the device in I/O access mode if required */

        if (pfl->rom_mode)

            pflash_register_memory(pfl, 0);

        /* We're in read mode */

    check_unlock0:

        if (boff == 0x55 && cmd == 0x98) {

        enter_CFI_mode:

            /* Enter CFI query mode */

            pfl->wcycle = 7;

            pfl->cmd = 0x98;

            return;

        }

        if (boff != pfl->unlock_addr[0] || cmd != 0xAA) {

            DPRINTF("%s: unlock0 failed " TARGET_FMT_lx " %02x %04x\n",

                    __func__, boff, cmd, pfl->unlock_addr[0]);

            goto reset_flash;

        }

        DPRINTF("%s: unlock sequence started\n", __func__);

        break;

    case 1:

        /* We started an unlock sequence */

    check_unlock1:

        if (boff != pfl->unlock_addr[1] || cmd != 0x55) {

            DPRINTF("%s: unlock1 failed " TARGET_FMT_lx " %02x\n", __func__,

                    boff, cmd);

            goto reset_flash;

        }

        DPRINTF("%s: unlock sequence done\n", __func__);

        break;

    case 2:

        /* We finished an unlock sequence */

        if (!pfl->bypass && boff != pfl->unlock_addr[0]) {

            DPRINTF("%s: command failed " TARGET_FMT_lx " %02x\n", __func__,

                    boff, cmd);

            goto reset_flash;

        }

        switch (cmd) {

        case 0x20:

            pfl->bypass = 1;

            goto do_bypass;

        case 0x80:

        case 0x90:

        case 0xA0:

            pfl->cmd = cmd;

            DPRINTF("%s: starting command %02x\n", __func__, cmd);

            break;

        default:

            DPRINTF("%s: unknown command %02x\n", __func__, cmd);

            goto reset_flash;

        }

        break;

    case 3:

        switch (pfl->cmd) {

        case 0x80:

            /* We need another unlock sequence */

            goto check_unlock0;

        case 0xA0:

            DPRINTF("%s: write data offset " TARGET_FMT_lx " %08x %d\n",

                    __func__, offset, value, width);

            p = pfl->storage;

            switch (width) {

            case 1:

                p[offset] &= value;

                pflash_update(pfl, offset, 1);

                break;

            case 2:

#if defined(TARGET_WORDS_BIGENDIAN)

                p[offset] &= value >> 8;

                p[offset + 1] &= value;

#else

                p[offset] &= value;

                p[offset + 1] &= value >> 8;

#endif

                pflash_update(pfl, offset, 2);

                break;

            case 4:

#if defined(TARGET_WORDS_BIGENDIAN)

                p[offset] &= value >> 24;

                p[offset + 1] &= value >> 16;

                p[offset + 2] &= value >> 8;

                p[offset + 3] &= value;

#else

                p[offset] &= value;

                p[offset + 1] &= value >> 8;

                p[offset + 2] &= value >> 16;

                p[offset + 3] &= value >> 24;

#endif

                pflash_update(pfl, offset, 4);

                break;

            }

            pfl->status = 0x00 | ~(value & 0x80);

            /* Let's pretend write is immediate */

            if (pfl->bypass)

                goto do_bypass;

            goto reset_flash;

        case 0x90:

            if (pfl->bypass && cmd == 0x00) {

                /* Unlock bypass reset */

                goto reset_flash;

            }

            /* We can enter CFI query mode from autoselect mode */

            if (boff == 0x55 && cmd == 0x98)

                goto enter_CFI_mode;

            /* No break here */

        default:

            DPRINTF("%s: invalid write for command %02x\n",

                    __func__, pfl->cmd);

            goto reset_flash;

        }

    case 4:

        switch (pfl->cmd) {

        case 0xA0:

            /* Ignore writes while flash data write is occuring */

            /* As we suppose write is immediate, this should never happen */

            return;

        case 0x80:

            goto check_unlock1;

        default:

            /* Should never happen */

            DPRINTF("%s: invalid command state %02x (wc 4)\n",

                    __func__, pfl->cmd);

            goto reset_flash;

        }

        break;

    case 5:

        switch (cmd) {

        case 0x10:

            if (boff != pfl->unlock_addr[0]) {

                DPRINTF("%s: chip erase: invalid address " TARGET_FMT_lx "\n",

                        __func__, offset);

                goto reset_flash;

            }

            /* Chip erase */

            DPRINTF("%s: start chip erase\n", __func__);

            memset(pfl->storage, 0xFF, pfl->chip_len);

            pfl->status = 0x00;

            pflash_update(pfl, 0, pfl->chip_len);

            /* Let's wait 5 seconds before chip erase is done */

            qemu_mod_timer(pfl->timer,

                           qemu_get_clock(vm_clock) + (ticks_per_sec * 5));

            break;

        case 0x30:

            /* Sector erase */

            p = pfl->storage;

            offset &= ~(pfl->sector_len - 1);

            DPRINTF("%s: start sector erase at " TARGET_FMT_lx "\n", __func__,

                    offset);

            memset(p + offset, 0xFF, pfl->sector_len);

            pflash_update(pfl, offset, pfl->sector_len);

            pfl->status = 0x00;

            /* Let's wait 1/2 second before sector erase is done */

            qemu_mod_timer(pfl->timer,

                           qemu_get_clock(vm_clock) + (ticks_per_sec / 2));

            break;

        default:

            DPRINTF("%s: invalid command %02x (wc 5)\n", __func__, cmd);

            goto reset_flash;

        }

        pfl->cmd = cmd;

        break;

    case 6:

        switch (pfl->cmd) {

        case 0x10:

            /* Ignore writes during chip erase */

            return;

        case 0x30:

            /* Ignore writes during sector erase */

            return;

        default:

            /* Should never happen */

            DPRINTF("%s: invalid command state %02x (wc 6)\n",

                    __func__, pfl->cmd);

            goto reset_flash;

        }

        break;

    case 7: /* Special value for CFI queries */

        DPRINTF("%s: invalid write in CFI query mode\n", __func__);

        goto reset_flash;

    default:

        /* Should never happen */

        DPRINTF("%s: invalid write state (wc 7)\n",  __func__);

        goto reset_flash;

    }

    pfl->wcycle++;

    return;

    /* Reset flash */

 reset_flash:

    pfl->bypass = 0;

    pfl->wcycle = 0;

    pfl->cmd = 0;

    return;

 do_bypass:

    pfl->wcycle = 2;

    pfl->cmd = 0;

    return;

}

static uint32_t pflash_readb (void *opaque, target_phys_addr_t addr)

{

    return pflash_read(opaque, addr, 1);

}

static uint32_t pflash_readw (void *opaque, target_phys_addr_t addr)

{

    pflash_t *pfl = opaque;

    return pflash_read(pfl, addr, 2);

}

static uint32_t pflash_readl (void *opaque, target_phys_addr_t addr)

{

    pflash_t *pfl = opaque;

    return pflash_read(pfl, addr, 4);

}

static void pflash_writeb (void *opaque, target_phys_addr_t addr,

                           uint32_t value)

{

    pflash_write(opaque, addr, value, 1);

}

static void pflash_writew (void *opaque, target_phys_addr_t addr,

                           uint32_t value)

{

    pflash_t *pfl = opaque;

    pflash_write(pfl, addr, value, 2);

}

static void pflash_writel (void *opaque, target_phys_addr_t addr,

                           uint32_t value)

{

    pflash_t *pfl = opaque;

    pflash_write(pfl, addr, value, 4);

}

static CPUWriteMemoryFunc *pflash_write_ops[] = {

    &pflash_writeb,

    &pflash_writew,

    &pflash_writel,

};

static CPUReadMemoryFunc *pflash_read_ops[] = {

    &pflash_readb,

    &pflash_readw,

    &pflash_readl,

};

/* Count trailing zeroes of a 32 bits quantity */

static int ctz32 (uint32_t n)

{

    int ret;

    ret = 0;

    if (!(n & 0xFFFF)) {

        ret += 16;

        n = n >> 16;

    }

    if (!(n & 0xFF)) {

        ret += 8;

        n = n >> 8;

    }

    if (!(n & 0xF)) {

        ret += 4;

        n = n >> 4;

    }

    if (!(n & 0x3)) {

        ret += 2;

        n = n >> 2;