/*
 * Simulate a SPI flash
 *
 * Copyright (c) 2011-2013 The Chromium OS Authors.
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * Licensed under the GPL-2 or later.
 */

#define LOG_CATEGORY UCLASS_SPI_FLASH

#include <common.h>
#include <dm.h>
#include <log.h>
#include <malloc.h>
#include <spi.h>
#include <os.h>

#include <spi_flash.h>
#include "sf_internal.h"

#include <asm/getopt.h>
#include <asm/spi.h>
#include <asm/state.h>
#include <dm/device-internal.h>
#include <dm/lists.h>
#include <dm/uclass-internal.h>

/*
 * The different states that our SPI flash transitions between.
 * We need to keep track of this across multiple xfer calls since
 * the SPI bus could possibly call down into us multiple times.
 */
enum sandbox_sf_state {
        SF_CMD,   /* default state -- we're awaiting a command */
        SF_ID,    /* read the flash's (jedec) ID code */
        SF_ADDR,  /* processing the offset in the flash to read/etc... */
        SF_READ,  /* reading data from the flash */
        SF_WRITE, /* writing data to the flash, i.e. page programming */
        SF_ERASE, /* erase the flash */
        SF_READ_STATUS, /* read the flash's status register */
        SF_READ_STATUS1, /* read the flash's status register upper 8 bits*/
        SF_WRITE_STATUS, /* write the flash's status register */
};

static const char *sandbox_sf_state_name(enum sandbox_sf_state state)
{
        static const char * const states[] = {
                "CMD", "ID", "ADDR", "READ", "WRITE", "ERASE", "READ_STATUS",
                "READ_STATUS1", "WRITE_STATUS",
        };
        return states[state];
}

/* Bits for the status register */
#define STAT_WIP        (1 << 0)
#define STAT_WEL        (1 << 1)
#define STAT_BP_SHIFT   2
#define STAT_BP_MASK    (7 << STAT_BP_SHIFT)

/* Assume all SPI flashes have 3 byte addresses since they do atm */
#define SF_ADDR_LEN     3

#define IDCODE_LEN 3

/* Used to quickly bulk erase backing store */
static u8 sandbox_sf_0xff[0x1000];

/* Internal state data for each SPI flash */
struct sandbox_spi_flash {
        unsigned int cs;        /* Chip select we are attached to */
        /*
         * As we receive data over the SPI bus, our flash transitions
         * between states.  For example, we start off in the SF_CMD
         * state where the first byte tells us what operation to perform
         * (such as read or write the flash).  But the operation itself
         * can go through a few states such as first reading in the
         * offset in the flash to perform the requested operation.
         * Thus "state" stores the exact state that our machine is in
         * while "cmd" stores the overall command we're processing.
         */
        enum sandbox_sf_state state;
        uint cmd;
        /* Erase size of current erase command */
        uint erase_size;
        /* Current position in the flash; used when reading/writing/etc... */
        uint off;
        /* How many address bytes we've consumed */
        uint addr_bytes, pad_addr_bytes;
        /* The current flash status (see STAT_XXX defines above) */
        u16 status;
        /* Data describing the flash we're emulating */
        const struct flash_info *data;
        /* The file on disk to serv up data from */
        int fd;
};

struct sandbox_spi_flash_plat_data {
        const char *filename;
        const char *device_name;
        int bus;
        int cs;
};

void sandbox_sf_set_block_protect(struct udevice *dev, int bp_mask)
{
        struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

        sbsf->status &= ~STAT_BP_MASK;
        sbsf->status |= bp_mask << STAT_BP_SHIFT;
}

/**
 * This is a very strange probe function. If it has platform data (which may
 * have come from the device tree) then this function gets the filename and
 * device type from there.
 */
static int sandbox_sf_probe(struct udevice *dev)
{
        /* spec = idcode:file */
        struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
        size_t len, idname_len;
        const struct flash_info *data;
        struct sandbox_spi_flash_plat_data *pdata = dev_get_plat(dev);
        struct sandbox_state *state = state_get_current();
        struct dm_spi_slave_plat *slave_plat;
        struct udevice *bus = dev->parent;
        const char *spec = NULL;
        struct udevice *emul;
        int ret = 0;
        int cs = -1;

        debug("%s: bus %d, looking for emul=%p: ", __func__, dev_seq(bus), dev);
        ret = sandbox_spi_get_emul(state, bus, dev, &emul);
        if (ret) {
                printf("Error: Unknown chip select for device '%s'\n",
                        dev->name);
                return ret;
        }
        slave_plat = dev_get_parent_plat(dev);
        cs = slave_plat->cs;
        debug("found at cs %d\n", cs);

        if (!pdata->filename) {
                printf("Error: No filename available\n");
                return -EINVAL;
        }
        spec = strchr(pdata->device_name, ',');
        if (spec)
                spec++;
        else
                spec = pdata->device_name;
        idname_len = strlen(spec);
        debug("%s: device='%s'\n", __func__, spec);

        for (data = spi_nor_ids; data->name; data++) {
                len = strlen(data->name);
                if (idname_len != len)
                        continue;
                if (!strncasecmp(spec, data->name, len))
                        break;
        }
        if (!data->name) {
                printf("%s: unknown flash '%*s'\n", __func__, (int)idname_len,
                       spec);
                ret = -EINVAL;
                goto error;
        }

        if (sandbox_sf_0xff[0] == 0x00)
                memset(sandbox_sf_0xff, 0xff, sizeof(sandbox_sf_0xff));

        sbsf->fd = os_open(pdata->filename, 02);
        if (sbsf->fd == -1) {
                printf("%s: unable to open file '%s'\n", __func__,
                       pdata->filename);
                ret = -EIO;
                goto error;
        }

        sbsf->data = data;
        sbsf->cs = cs;

        return 0;

 error:
        debug("%s: Got error %d\n", __func__, ret);
        return ret;
}

static int sandbox_sf_remove(struct udevice *dev)
{
        struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

        os_close(sbsf->fd);

        return 0;
}

static void sandbox_sf_cs_activate(struct udevice *dev)
{
        struct sandbox_spi_flash *sbsf = dev_get_priv(dev);

        log_content("sandbox_sf: CS activated; state is fresh!\n");

        /* CS is asserted, so reset state */
        sbsf->off = 0;
        sbsf->addr_bytes = 0;
        sbsf->pad_addr_bytes = 0;
        sbsf->state = SF_CMD;
        sbsf->cmd = SF_CMD;
}

static void sandbox_sf_cs_deactivate(struct udevice *dev)
{
        log_content("sandbox_sf: CS deactivated; cmd done processing!\n");
}

/*
 * There are times when the data lines are allowed to tristate.  What
 * is actually sensed on the line depends on the hardware.  It could
 * always be 0xFF/0x00 (if there are pull ups/downs), or things could
 * float and so we'd get garbage back.  This func encapsulates that
 * scenario so we can worry about the details here.
 */
static void sandbox_spi_tristate(u8 *buf, uint len)
{
        /* XXX: make this into a user config option ? */
        memset(buf, 0xff, len);
}

/* Figure out what command this stream is telling us to do */
static int sandbox_sf_process_cmd(struct sandbox_spi_flash *sbsf, const u8 *rx,
                                  u8 *tx)
{
        enum sandbox_sf_state oldstate = sbsf->state;

        /* We need to output a byte for the cmd byte we just ate */
        if (tx)
                sandbox_spi_tristate(tx, 1);

        sbsf->cmd = rx[0];
        switch (sbsf->cmd) {
        case SPINOR_OP_RDID:
                sbsf->state = SF_ID;
                sbsf->cmd = SF_ID;
                break;
        case SPINOR_OP_READ_FAST:
                sbsf->pad_addr_bytes = 1;
        case SPINOR_OP_READ:
        case SPINOR_OP_PP:
                sbsf->state = SF_ADDR;
                break;
        case SPINOR_OP_WRDI:
                debug(" write disabled\n");
                sbsf->status &= ~STAT_WEL;
                break;
        case SPINOR_OP_RDSR:
                sbsf->state = SF_READ_STATUS;
                break;
        case SPINOR_OP_RDSR2:
                sbsf->state = SF_READ_STATUS1;
                break;
        case SPINOR_OP_WREN:
                debug(" write enabled\n");
                sbsf->status |= STAT_WEL;
                break;
        case SPINOR_OP_WRSR:
                sbsf->state = SF_WRITE_STATUS;
                break;
        default: {
                int flags = sbsf->data->flags;

                /* we only support erase here */
                if (sbsf->cmd == SPINOR_OP_CHIP_ERASE) {
                        sbsf->erase_size = sbsf->data->sector_size *
                                sbsf->data->n_sectors;
                } else if (sbsf->cmd == SPINOR_OP_BE_4K && (flags & SECT_4K)) {
                        sbsf->erase_size = 4 << 10;
                } else if (sbsf->cmd == SPINOR_OP_SE && !(flags & SECT_4K)) {
                        sbsf->erase_size = 64 << 10;
                } else {
                        debug(" cmd unknown: %#x\n", sbsf->cmd);
                        return -EIO;
                }
                sbsf->state = SF_ADDR;
                break;
        }
        }

        if (oldstate != sbsf->state)
                log_content(" cmd: transition to %s state\n",
                            sandbox_sf_state_name(sbsf->state));

        return 0;
}

int sandbox_erase_part(struct sandbox_spi_flash *sbsf, int size)
{
        int todo;
        int ret;

        while (size > 0) {
                todo = min(size, (int)sizeof(sandbox_sf_0xff));
                ret = os_write(sbsf->fd, sandbox_sf_0xff, todo);
                if (ret != todo)
                        return ret;
                size -= todo;
        }

        return 0;
}

static int sandbox_sf_xfer(struct udevice *dev, unsigned int bitlen,
                           const void *rxp, void *txp, unsigned long flags)
{
        struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
        const uint8_t *rx = rxp;
        uint8_t *tx = txp;
        uint cnt, pos = 0;
        int bytes = bitlen / 8;
        int ret;

        log_content("sandbox_sf: state:%x(%s) bytes:%u\n", sbsf->state,
                    sandbox_sf_state_name(sbsf->state), bytes);

        if ((flags & SPI_XFER_BEGIN))
                sandbox_sf_cs_activate(dev);

        if (sbsf->state == SF_CMD) {
                /* Figure out the initial state */
                ret = sandbox_sf_process_cmd(sbsf, rx, tx);
                if (ret)
                        return ret;
                ++pos;
        }

        /* Process the remaining data */
        while (pos < bytes) {
                switch (sbsf->state) {
                case SF_ID: {
                        u8 id;

                        log_content(" id: off:%u tx:", sbsf->off);
                        if (sbsf->off < IDCODE_LEN) {
                                /* Extract correct byte from ID 0x00aabbcc */
                                id = ((JEDEC_MFR(sbsf->data) << 16) |
                                        JEDEC_ID(sbsf->data)) >>
                                        (8 * (IDCODE_LEN - 1 - sbsf->off));
                        } else {
                                id = 0;
                        }
                        log_content("%d %02x\n", sbsf->off, id);
                        tx[pos++] = id;
                        ++sbsf->off;
                        break;
                }
                case SF_ADDR:
                        log_content(" addr: bytes:%u rx:%02x ",
                                    sbsf->addr_bytes, rx[pos]);

                        if (sbsf->addr_bytes++ < SF_ADDR_LEN)
                                sbsf->off = (sbsf->off << 8) | rx[pos];
                        log_content("addr:%06x\n", sbsf->off);

                        if (tx)
                                sandbox_spi_tristate(&tx[pos], 1);
                        pos++;

                        /* See if we're done processing */
                        if (sbsf->addr_bytes <
                                        SF_ADDR_LEN + sbsf->pad_addr_bytes)
                                break;

                        /* Next state! */
                        if (os_lseek(sbsf->fd, sbsf->off, OS_SEEK_SET) < 0) {
                                puts("sandbox_sf: os_lseek() failed");
                                return -EIO;
                        }
                        switch (sbsf->cmd) {
                        case SPINOR_OP_READ_FAST:
                        case SPINOR_OP_READ:
                                sbsf->state = SF_READ;
                                break;
                        case SPINOR_OP_PP:
                                sbsf->state = SF_WRITE;
                                break;
                        default:
                                /* assume erase state ... */
                                sbsf->state = SF_ERASE;
                                goto case_sf_erase;
                        }
                        log_content(" cmd: transition to %s state\n",
                                    sandbox_sf_state_name(sbsf->state));
                        break;
                case SF_READ:
                        /*
                         * XXX: need to handle exotic behavior:
                         *      - reading past end of device
                         */

                        cnt = bytes - pos;
                        log_content(" tx: read(%u)\n", cnt);
                        assert(tx);
                        ret = os_read(sbsf->fd, tx + pos, cnt);
                        if (ret < 0) {
                                puts("sandbox_sf: os_read() failed\n");
                                return -EIO;
                        }
                        pos += ret;
                        break;
                case SF_READ_STATUS:
                        log_content(" read status: %#x\n", sbsf->status);
                        cnt = bytes - pos;
                        memset(tx + pos, sbsf->status, cnt);
                        pos += cnt;
                        break;
                case SF_READ_STATUS1:
                        log_content(" read status: %#x\n", sbsf->status);
                        cnt = bytes - pos;
                        memset(tx + pos, sbsf->status >> 8, cnt);
                        pos += cnt;
                        break;
                case SF_WRITE_STATUS:
                        log_content(" write status: %#x (ignored)\n", rx[pos]);
                        pos = bytes;
                        break;
                case SF_WRITE:
                        /*
                         * XXX: need to handle exotic behavior:
                         *      - unaligned addresses
                         *      - more than a page (256) worth of data
                         *      - reading past end of device
                         */
                        if (!(sbsf->status & STAT_WEL)) {
                                puts("sandbox_sf: write enable not set before write\n");
                                goto done;
                        }

                        cnt = bytes - pos;
                        log_content(" rx: write(%u)\n", cnt);
                        if (tx)
                                sandbox_spi_tristate(&tx[pos], cnt);
                        ret = os_write(sbsf->fd, rx + pos, cnt);
                        if (ret < 0) {
                                puts("sandbox_spi: os_write() failed\n");
                                return -EIO;
                        }
                        pos += ret;
                        sbsf->status &= ~STAT_WEL;
                        break;
                case SF_ERASE:
 case_sf_erase: {
                        if (!(sbsf->status & STAT_WEL)) {
                                puts("sandbox_sf: write enable not set before erase\n");
                                goto done;
                        }

                        /* verify address is aligned */
                        if (sbsf->off & (sbsf->erase_size - 1)) {
                                log_content(" sector erase: cmd:%#x needs align:%#x, but we got %#x\n",
                                            sbsf->cmd, sbsf->erase_size,
                                            sbsf->off);
                                sbsf->status &= ~STAT_WEL;
                                goto done;
                        }

                        log_content(" sector erase addr: %u, size: %u\n",
                                    sbsf->off, sbsf->erase_size);

                        cnt = bytes - pos;
                        if (tx)
                                sandbox_spi_tristate(&tx[pos], cnt);
                        pos += cnt;

                        /*
                         * TODO(vapier@gentoo.org): latch WIP in status, and
                         * delay before clearing it ?
                         */
                        ret = sandbox_erase_part(sbsf, sbsf->erase_size);
                        sbsf->status &= ~STAT_WEL;
                        if (ret) {
                                log_content("sandbox_sf: Erase failed\n");
                                goto done;
                        }
                        goto done;
                }
                default:
                        log_content(" ??? no idea what to do ???\n");
                        goto done;
                }
        }

 done:
        if (flags & SPI_XFER_END)
                sandbox_sf_cs_deactivate(dev);
        return pos == bytes ? 0 : -EIO;
}

int sandbox_sf_of_to_plat(struct udevice *dev)
{
        struct sandbox_spi_flash_plat_data *pdata = dev_get_plat(dev);

        pdata->filename = dev_read_string(dev, "sandbox,filename");
        pdata->device_name = dev_read_string(dev, "compatible");
        if (!pdata->filename || !pdata->device_name) {
                debug("%s: Missing properties, filename=%s, device_name=%s\n",
                      __func__, pdata->filename, pdata->device_name);
                return -EINVAL;
        }

        return 0;
}

static const struct dm_spi_emul_ops sandbox_sf_emul_ops = {
        .xfer          = sandbox_sf_xfer,
};

#ifdef CONFIG_SPI_FLASH
int sandbox_sf_bind_emul(struct sandbox_state *state, int busnum, int cs,
                         struct udevice *bus, ofnode node, const char *spec)
{
        struct udevice *emul;
        char name[20], *str;
        struct driver *drv;
        int ret;

        /* now the emulator */
        strncpy(name, spec, sizeof(name) - 6);
        name[sizeof(name) - 6] = '\0';
        strcat(name, "-emul");
        drv = lists_driver_lookup_name("sandbox_sf_emul");
        if (!drv) {
                puts("Cannot find sandbox_sf_emul driver\n");
                return -ENOENT;
        }
        str = strdup(name);
        if (!str)
                return -ENOMEM;
        ret = device_bind(bus, drv, str, NULL, node, &emul);
        if (ret) {
                free(str);
                printf("Cannot create emul device for spec '%s' (err=%d)\n",
                       spec, ret);
                return ret;
        }
        state->spi[busnum][cs].emul = emul;

        return 0;
}

void sandbox_sf_unbind_emul(struct sandbox_state *state, int busnum, int cs)
{
        struct udevice *dev;

        dev = state->spi[busnum][cs].emul;
        device_remove(dev, DM_REMOVE_NORMAL);
        device_unbind(dev);
        state->spi[busnum][cs].emul = NULL;
}

int sandbox_spi_get_emul(struct sandbox_state *state,
                         struct udevice *bus, struct udevice *slave,
                         struct udevice **emulp)
{
        struct sandbox_spi_info *info;
        int busnum = dev_seq(bus);
        int cs = spi_chip_select(slave);
        int ret;

        info = &state->spi[busnum][cs];
        if (!info->emul) {
                /* Use the same device tree node as the SPI flash device */
                debug("%s: busnum=%u, cs=%u: binding SPI flash emulation: ",
                      __func__, busnum, cs);
                ret = sandbox_sf_bind_emul(state, busnum, cs, bus,
                                           dev_ofnode(slave), slave->name);
                if (ret) {
                        debug("failed (err=%d)\n", ret);
                        return ret;
                }
                debug("OK\n");
        }
        *emulp = info->emul;

        return 0;
}
#endif

static const struct udevice_id sandbox_sf_ids[] = {
        { .compatible = "sandbox,spi-flash" },
        { }
};

U_BOOT_DRIVER(sandbox_sf_emul) = {
        .name           = "sandbox_sf_emul",
        .id             = UCLASS_SPI_EMUL,
        .of_match       = sandbox_sf_ids,
        .of_to_plat = sandbox_sf_of_to_plat,
        .probe          = sandbox_sf_probe,
        .remove         = sandbox_sf_remove,
        .priv_auto      = sizeof(struct sandbox_spi_flash),
        .plat_auto      = sizeof(struct sandbox_spi_flash_plat_data),
        .ops            = &sandbox_sf_emul_ops,
};