/*
 *  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 "vl.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_ulong base;
    target_ulong sector_len;
    target_ulong total_len;
    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];
    uint8_t cfi_len;
    uint8_t cfi_table[0x52];
    QEMUTimer *timer;
    ram_addr_t off;
    int fl_mem;
    void *storage;
};

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 {
        cpu_register_physical_memory(pfl->base, pfl->total_len,
                                     pfl->off | IO_MEM_ROMD | pfl->fl_mem);
        pfl->wcycle = 0;
    }
    pfl->cmd = 0;
}

static uint32_t pflash_read (pflash_t *pfl, target_ulong offset, int width)
{
    target_ulong boff;
    uint32_t ret;
    uint8_t *p;

    DPRINTF("%s: offset " TARGET_FMT_lx "\n", __func__, offset);
    ret = -1;
    offset -= pfl->base;
    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, target_ulong offset, uint32_t value,
                          int width)
{
    target_ulong boff;
    uint8_t *p;
    uint8_t cmd;

    /* WARNING: when the memory area is in ROMD mode, the offset is a
       ram offset, not a physical address */
    if (pfl->wcycle == 0)
        offset -= (target_ulong)(long)pfl->storage;
    else
        offset -= pfl->base;
        
    cmd = value;
    DPRINTF("%s: offset " TARGET_FMT_lx " %08x %d\n", __func__,
            offset, value, width);
    if (pfl->cmd != 0xA0 && cmd == 0xF0) {
        DPRINTF("%s: flash reset asked (%02x %02x)\n",
                __func__, pfl->cmd, cmd);
        goto reset_flash;
    }
    /* Set the device in I/O access mode */
    cpu_register_physical_memory(pfl->base, pfl->total_len, pfl->fl_mem);
    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:
        /* 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 != 0x555 || cmd != 0xAA) {
            DPRINTF("%s: unlock0 failed " TARGET_FMT_lx " %02x %04x\n",
                    __func__, boff, cmd, 0x555);
            goto reset_flash;
        }
        DPRINTF("%s: unlock sequence started\n", __func__);
        break;
    case 1:
        /* We started an unlock sequence */
    check_unlock1:
        if (boff != 0x2AA || 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 != 0x555) {
            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 != 0x555) {
                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->total_len);
            pfl->status = 0x00;
            pflash_update(pfl, 0, pfl->total_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:
    if (pfl->wcycle != 0) {
        cpu_register_physical_memory(pfl->base, pfl->total_len,
                                     pfl->off | IO_MEM_ROMD | pfl->fl_mem);
    }
    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;
    }
    if (!(n & 0x1)) {
        ret++;
        n = n >> 1;
    }
#if 0 /* This is not necessary as n is never 0 */
    if (!n)
        ret++;
#endif

    return ret;
}

pflash_t *pflash_register (target_ulong base, ram_addr_t off,
                           BlockDriverState *bs,
                           target_ulong sector_len, int nb_blocs, int width,
                           uint16_t id0, uint16_t id1, 
                           uint16_t id2, uint16_t id3)
{
    pflash_t *pfl;
    target_long total_len;

    total_len = sector_len * nb_blocs;
    /* XXX: to be fixed */
    if (total_len != (8 * 1024 * 1024) && total_len != (16 * 1024 * 1024) &&
        total_len != (32 * 1024 * 1024) && total_len != (64 * 1024 * 1024))
        return NULL;
    pfl = qemu_mallocz(sizeof(pflash_t));
    if (pfl == NULL)
        return NULL;
    pfl->storage = phys_ram_base + off;
    pfl->fl_mem = cpu_register_io_memory(0, pflash_read_ops, pflash_write_ops, pfl);
    pfl->off = off;
    cpu_register_physical_memory(base, total_len,
                                 off | pfl->fl_mem | IO_MEM_ROMD);
    pfl->bs = bs;
    if (pfl->bs) {
        /* read the initial flash content */
        bdrv_read(pfl->bs, 0, pfl->storage, total_len >> 9);
    }
#if 0 /* XXX: there should be a bit to set up read-only,
       *      the same way the hardware does (with WP pin).
       */
    pfl->ro = 1;
#else
    pfl->ro = 0;
#endif
    pfl->timer = qemu_new_timer(vm_clock, pflash_timer, pfl);
    pfl->base = base;
    pfl->sector_len = sector_len;
    pfl->total_len = total_len;
    pfl->width = width;
    pfl->wcycle = 0;
    pfl->cmd = 0;
    pfl->status = 0;
    pfl->ident[0] = id0;
    pfl->ident[1] = id1;
    pfl->ident[2] = id2;
    pfl->ident[3] = id3;
    /* Hardcoded CFI table (mostly from SG29 Spansion flash) */
    pfl->cfi_len = 0x52;
    /* Standard "QRY" string */
    pfl->cfi_table[0x10] = 'Q';
    pfl->cfi_table[0x11] = 'R';
    pfl->cfi_table[0x12] = 'Y';
    /* Command set (AMD/Fujitsu) */
    pfl->cfi_table[0x13] = 0x02;
    pfl->cfi_table[0x14] = 0x00;
    /* Primary extended table address (none) */
    pfl->cfi_table[0x15] = 0x00;
    pfl->cfi_table[0x16] = 0x00;
    /* Alternate command set (none) */
    pfl->cfi_table[0x17] = 0x00;
    pfl->cfi_table[0x18] = 0x00;
    /* Alternate extended table (none) */
    pfl->cfi_table[0x19] = 0x00;
    pfl->cfi_table[0x1A] = 0x00;
    /* Vcc min */
    pfl->cfi_table[0x1B] = 0x27;
    /* Vcc max */
    pfl->cfi_table[0x1C] = 0x36;
    /* Vpp min (no Vpp pin) */
    pfl->cfi_table[0x1D] = 0x00;
    /* Vpp max (no Vpp pin) */
    pfl->cfi_table[0x1E] = 0x00;
    /* Reserved */
    pfl->cfi_table[0x1F] = 0x07;
    /* Timeout for min size buffer write (16 µs) */
    pfl->cfi_table[0x20] = 0x04;
    /* Typical timeout for block erase (512 ms) */
    pfl->cfi_table[0x21] = 0x09;
    /* Typical timeout for full chip erase (4096 ms) */
    pfl->cfi_table[0x22] = 0x0C;
    /* Reserved */
    pfl->cfi_table[0x23] = 0x01;
    /* Max timeout for buffer write */
    pfl->cfi_table[0x24] = 0x04;
    /* Max timeout for block erase */
    pfl->cfi_table[0x25] = 0x0A;
    /* Max timeout for chip erase */
    pfl->cfi_table[0x26] = 0x0D;
    /* Device size */
    pfl->cfi_table[0x27] = ctz32(total_len) + 1;
    /* Flash device interface (8 & 16 bits) */
    pfl->cfi_table[0x28] = 0x02;
    pfl->cfi_table[0x29] = 0x00;
    /* Max number of bytes in multi-bytes write */
    pfl->cfi_table[0x2A] = 0x05;
    pfl->cfi_table[0x2B] = 0x00;
    /* Number of erase block regions (uniform) */
    pfl->cfi_table[0x2C] = 0x01;
    /* Erase block region 1 */
    pfl->cfi_table[0x2D] = nb_blocs - 1;
    pfl->cfi_table[0x2E] = (nb_blocs - 1) >> 8;
    pfl->cfi_table[0x2F] = sector_len >> 8;
    pfl->cfi_table[0x30] = sector_len >> 16;

    return pfl;
}