/*
 *  CFI parallel flash with Intel command set emulation
 *
 *  Copyright (c) 2006 Thorsten Zitterell
 *  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, see <http://www.gnu.org/licenses/>.
 */

/*
 * 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
 * - CFI queries
 *
 * It does not support timings
 * It does not support flash interleaving
 * 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
 *
 * It does not implement much more ...
 */

#include "hw.h"
#include "flash.h"
#include "block.h"
#include "qemu-timer.h"

#define PFLASH_BUG(fmt, ...) \
do { \
    printf("PFLASH: Possible BUG - " fmt, ## __VA_ARGS__); \
    exit(1); \
} while(0)

/* #define PFLASH_DEBUG */
#ifdef PFLASH_DEBUG
#define DPRINTF(fmt, ...)                          \
do {                                               \
    printf("PFLASH: " fmt , ## __VA_ARGS__);       \
} while (0)
#else
#define DPRINTF(fmt, ...) do { } while (0)
#endif

struct pflash_t {
    BlockDriverState *bs;
    target_phys_addr_t base;
    target_phys_addr_t sector_len;
    target_phys_addr_t 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];
    target_phys_addr_t counter;
    unsigned int writeblock_size;
    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_phys_addr_t offset,
                             int width)
{
    target_phys_addr_t boff;
    uint32_t ret;
    uint8_t *p;

    ret = -1;
    boff = offset & 0xFF; /* why this here ?? */

    if (pfl->width == 2)
        boff = boff >> 1;
    else if (pfl->width == 4)
        boff = boff >> 2;

#if 0
    DPRINTF("%s: reading offset " TARGET_FMT_plx " under cmd %02x width %d\n",
            __func__, offset, pfl->cmd, width);
#endif
    switch (pfl->cmd) {
    case 0x00:
        /* Flash area read */
        p = pfl->storage;
        switch (width) {
        case 1:
            ret = p[offset];
            DPRINTF("%s: data offset " TARGET_FMT_plx " %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 " TARGET_FMT_plx " %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 + 1] << 8;
            ret |= p[offset + 2] << 16;
            ret |= p[offset + 3] << 24;
#endif
            DPRINTF("%s: data offset " TARGET_FMT_plx " %08x\n",
                    __func__, offset, ret);
            break;
        default:
            DPRINTF("BUG in %s\n", __func__);
        }

        break;
    case 0x20: /* Block erase */
    case 0x50: /* Clear status register */
    case 0x60: /* Block /un)lock */
    case 0x70: /* Status Register */
    case 0xe8: /* Write block */
        /* Status register read */
        ret = pfl->status;
        DPRINTF("%s: status %x\n", __func__, ret);
        break;
    case 0x98: /* Query mode */
        if (boff > pfl->cfi_len)
            ret = 0;
        else
            ret = pfl->cfi_table[boff];
        break;
    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;
    }
    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 inline void pflash_data_write(pflash_t *pfl, target_phys_addr_t offset,
                          uint32_t value, int width)
{
    uint8_t *p = pfl->storage;

    DPRINTF("%s: block write offset " TARGET_FMT_plx
            " value %x counter " TARGET_FMT_plx "\n",
            __func__, offset, value, pfl->counter);
    switch (width) {
    case 1:
        p[offset] = value;
        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
        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
        break;
    }

}

static void pflash_write(pflash_t *pfl, target_phys_addr_t offset,
                         uint32_t value, int width)
{
    uint8_t *p;
    uint8_t cmd;

    cmd = value;

    DPRINTF("%s: writing offset " TARGET_FMT_plx " value %08x width %d wcycle 0x%x\n",
            __func__, offset, value, width, pfl->wcycle);

    if (!pfl->wcycle) {
        /* Set the device in I/O access mode */
        cpu_register_physical_memory(pfl->base, pfl->total_len, pfl->fl_mem);
    }

    switch (pfl->wcycle) {
    case 0:
        /* read mode */
        switch (cmd) {
        case 0x00: /* ??? */
            goto reset_flash;
        case 0x10: /* Single Byte Program */
        case 0x40: /* Single Byte Program */
            DPRINTF("%s: Single Byte Program\n", __func__);
            break;
        case 0x20: /* Block erase */
            p = pfl->storage;
            offset &= ~(pfl->sector_len - 1);

            DPRINTF("%s: block erase at " TARGET_FMT_plx " bytes "
                    TARGET_FMT_plx "\n",
                    __func__, offset, pfl->sector_len);

            memset(p + offset, 0xff, pfl->sector_len);
            pflash_update(pfl, offset, pfl->sector_len);
            pfl->status |= 0x80; /* Ready! */
            break;
        case 0x50: /* Clear status bits */
            DPRINTF("%s: Clear status bits\n", __func__);
            pfl->status = 0x0;
            goto reset_flash;
        case 0x60: /* Block (un)lock */
            DPRINTF("%s: Block unlock\n", __func__);
            break;
        case 0x70: /* Status Register */
            DPRINTF("%s: Read status register\n", __func__);
            pfl->cmd = cmd;
            return;
        case 0x98: /* CFI query */
            DPRINTF("%s: CFI query\n", __func__);
            break;
        case 0xe8: /* Write to buffer */
            DPRINTF("%s: Write to buffer\n", __func__);
            pfl->status |= 0x80; /* Ready! */
            break;
        case 0xff: /* Read array mode */
            DPRINTF("%s: Read array mode\n", __func__);
            goto reset_flash;
        default:
            goto error_flash;
        }
        pfl->wcycle++;
        pfl->cmd = cmd;
        return;
    case 1:
        switch (pfl->cmd) {
        case 0x10: /* Single Byte Program */
        case 0x40: /* Single Byte Program */
            DPRINTF("%s: Single Byte Program\n", __func__);
            pflash_data_write(pfl, offset, value, width);
            pflash_update(pfl, offset, width);
            pfl->status |= 0x80; /* Ready! */
            pfl->wcycle = 0;
        break;
        case 0x20: /* Block erase */
        case 0x28:
            if (cmd == 0xd0) { /* confirm */
                pfl->wcycle = 0;
                pfl->status |= 0x80;
            } else if (cmd == 0xff) { /* read array mode */
                goto reset_flash;
            } else
                goto error_flash;

            break;
        case 0xe8:
            DPRINTF("%s: block write of %x bytes\n", __func__, value);
            pfl->counter = value;
            pfl->wcycle++;
            break;
        case 0x60:
            if (cmd == 0xd0) {
                pfl->wcycle = 0;
                pfl->status |= 0x80;
            } else if (cmd == 0x01) {
                pfl->wcycle = 0;
                pfl->status |= 0x80;
            } else if (cmd == 0xff) {
                goto reset_flash;
            } else {
                DPRINTF("%s: Unknown (un)locking command\n", __func__);
                goto reset_flash;
            }
            break;
        case 0x98:
            if (cmd == 0xff) {
                goto reset_flash;
            } else {
                DPRINTF("%s: leaving query mode\n", __func__);
            }
            break;
        default:
            goto error_flash;
        }
        return;
    case 2:
        switch (pfl->cmd) {
        case 0xe8: /* Block write */
            pflash_data_write(pfl, offset, value, width);

            pfl->status |= 0x80;

            if (!pfl->counter) {
                target_phys_addr_t mask = pfl->writeblock_size - 1;
                mask = ~mask;

                DPRINTF("%s: block write finished\n", __func__);
                pfl->wcycle++;
                /* Flush the entire write buffer onto backing storage.  */
                pflash_update(pfl, offset & mask, pfl->writeblock_size);
            }

            pfl->counter--;
            break;
        default:
            goto error_flash;
        }
        return;
    case 3: /* Confirm mode */
        switch (pfl->cmd) {
        case 0xe8: /* Block write */
            if (cmd == 0xd0) {
                pfl->wcycle = 0;
                pfl->status |= 0x80;
            } else {
                DPRINTF("%s: unknown command for \"write block\"\n", __func__);
                PFLASH_BUG("Write block confirm");
                goto reset_flash;
            }
            break;
        default:
            goto error_flash;
        }
        return;
    default:
        /* Should never happen */
        DPRINTF("%s: invalid write state\n",  __func__);
        goto reset_flash;
    }
    return;

 error_flash:
    printf("%s: Unimplemented flash cmd sequence "
           "(offset " TARGET_FMT_plx ", wcycle 0x%x cmd 0x%x value 0x%x)\n",
           __func__, offset, pfl->wcycle, pfl->cmd, value);

 reset_flash:
    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;
}


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 * const pflash_write_ops[] = {
    &pflash_writeb,
    &pflash_writew,
    &pflash_writel,
};

static CPUReadMemoryFunc * const 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_cfi01_register(target_phys_addr_t base, ram_addr_t off,
                                BlockDriverState *bs, uint32_t sector_len,
                                int nb_blocs, int width,
                                uint16_t id0, uint16_t id1,
                                uint16_t id2, uint16_t id3)
{
    pflash_t *pfl;
    target_phys_addr_t total_len;
    int ret;

    total_len = sector_len * nb_blocs;

    /* XXX: to be fixed */
#if 0
    if (total_len != (8 * 1024 * 1024) && total_len != (16 * 1024 * 1024) &&
        total_len != (32 * 1024 * 1024) && total_len != (64 * 1024 * 1024))
        return NULL;
#endif

    pfl = qemu_mallocz(sizeof(pflash_t));

    /* FIXME: Allocate ram ourselves.  */
    pfl->storage = qemu_get_ram_ptr(off);
    pfl->fl_mem = cpu_register_io_memory(
                    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 */
        ret = bdrv_read(pfl->bs, 0, pfl->storage, total_len >> 9);
        if (ret < 0) {
            cpu_unregister_io_memory(pfl->fl_mem);
            qemu_free(pfl);
            return NULL;
        }
    }
#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 */
    pfl->cfi_len = 0x52;
    /* Standard "QRY" string */
    pfl->cfi_table[0x10] = 'Q';
    pfl->cfi_table[0x11] = 'R';
    pfl->cfi_table[0x12] = 'Y';
    /* Command set (Intel) */
    pfl->cfi_table[0x13] = 0x01;
    pfl->cfi_table[0x14] = 0x00;
    /* Primary extended table address (none) */
    pfl->cfi_table[0x15] = 0x31;
    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] = 0x45;
    /* Vcc max */
    pfl->cfi_table[0x1C] = 0x55;
    /* 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 */
    pfl->cfi_table[0x20] = 0x07;
    /* Typical timeout for block erase */
    pfl->cfi_table[0x21] = 0x0a;
    /* Typical timeout for full chip erase (4096 ms) */
    pfl->cfi_table[0x22] = 0x00;
    /* Reserved */
    pfl->cfi_table[0x23] = 0x04;
    /* Max timeout for buffer write */
    pfl->cfi_table[0x24] = 0x04;
    /* Max timeout for block erase */
    pfl->cfi_table[0x25] = 0x04;
    /* Max timeout for chip erase */
    pfl->cfi_table[0x26] = 0x00;
    /* 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 */
    if (width == 1) {
        pfl->cfi_table[0x2A] = 0x08;
    } else {
        pfl->cfi_table[0x2A] = 0x0B;
    }
    pfl->writeblock_size = 1 << pfl->cfi_table[0x2A];

    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;

    /* Extended */
    pfl->cfi_table[0x31] = 'P';
    pfl->cfi_table[0x32] = 'R';
    pfl->cfi_table[0x33] = 'I';

    pfl->cfi_table[0x34] = '1';
    pfl->cfi_table[0x35] = '1';

    pfl->cfi_table[0x36] = 0x00;
    pfl->cfi_table[0x37] = 0x00;
    pfl->cfi_table[0x38] = 0x00;
    pfl->cfi_table[0x39] = 0x00;

    pfl->cfi_table[0x3a] = 0x00;

    pfl->cfi_table[0x3b] = 0x00;
    pfl->cfi_table[0x3c] = 0x00;

    return pfl;
}