Archipelago » qemu

/*

 * SD Memory Card emulation as defined in the "SD Memory Card Physical

 * layer specification, Version 1.10."

 *

 * Copyright (c) 2006 Andrzej Zaborowski  <balrog@zabor.org>

 * Copyright (c) 2007 CodeSourcery

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "hw.h"

#include "block.h"

#include "block_int.h"

#include "sd.h"

//#define DEBUG_SD 1

#ifdef DEBUG_SD

#define DPRINTF(fmt, ...) \

do { fprintf(stderr, "SD: " fmt , ## __VA_ARGS__); } while (0)

#else

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

#endif

typedef enum {

    sd_r0 = 0,    /* no response */

    sd_r1,        /* normal response command */

    sd_r2_i,      /* CID register */

    sd_r2_s,      /* CSD register */

    sd_r3,        /* OCR register */

    sd_r6 = 6,    /* Published RCA response */

    sd_r7,        /* Operating voltage */

    sd_r1b = -1,

} sd_rsp_type_t;

struct SDState {

    enum {

        sd_inactive,

        sd_card_identification_mode,

        sd_data_transfer_mode,

    } mode;

    enum {

        sd_inactive_state = -1,

        sd_idle_state = 0,

        sd_ready_state,

        sd_identification_state,

        sd_standby_state,

        sd_transfer_state,

        sd_sendingdata_state,

        sd_receivingdata_state,

        sd_programming_state,

        sd_disconnect_state,

    } state;

    uint32_t ocr;

    uint8_t scr[8];

    uint8_t cid[16];

    uint8_t csd[16];

    uint16_t rca;

    uint32_t card_status;

    uint8_t sd_status[64];

    uint32_t vhs;

    int wp_switch;

    int *wp_groups;

    uint64_t size;

    int blk_len;

    uint32_t erase_start;

    uint32_t erase_end;

    uint8_t pwd[16];

    int pwd_len;

    int function_group[6];

    int spi;

    int current_cmd;

    int blk_written;

    uint64_t data_start;

    uint32_t data_offset;

    uint8_t data[512];

    qemu_irq readonly_cb;

    qemu_irq inserted_cb;

    BlockDriverState *bdrv;

    uint8_t *buf;

    int enable;

};

static void sd_set_status(SDState *sd)

{

    switch (sd->state) {

    case sd_inactive_state:

        sd->mode = sd_inactive;

        break;

    case sd_idle_state:

    case sd_ready_state:

    case sd_identification_state:

        sd->mode = sd_card_identification_mode;

        break;

    case sd_standby_state:

    case sd_transfer_state:

    case sd_sendingdata_state:

    case sd_receivingdata_state:

    case sd_programming_state:

    case sd_disconnect_state:

        sd->mode = sd_data_transfer_mode;

        break;

    }

    sd->card_status &= ~CURRENT_STATE;

    sd->card_status |= sd->state << 9;

}

static const sd_cmd_type_t sd_cmd_type[64] = {

    sd_bc,   sd_none, sd_bcr,  sd_bcr,  sd_none, sd_none, sd_none, sd_ac,

    sd_bcr,  sd_ac,   sd_ac,   sd_adtc, sd_ac,   sd_ac,   sd_none, sd_ac,

    sd_ac,   sd_adtc, sd_adtc, sd_none, sd_none, sd_none, sd_none, sd_none,

    sd_adtc, sd_adtc, sd_adtc, sd_adtc, sd_ac,   sd_ac,   sd_adtc, sd_none,

    sd_ac,   sd_ac,   sd_none, sd_none, sd_none, sd_none, sd_ac,   sd_none,

    sd_none, sd_none, sd_bc,   sd_none, sd_none, sd_none, sd_none, sd_none,

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_ac,

    sd_adtc, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none,

};

static const sd_cmd_type_t sd_acmd_type[64] = {

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_ac,   sd_none,

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_adtc, sd_none, sd_none,

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_adtc, sd_ac,

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none,

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none,

    sd_none, sd_bcr,  sd_ac,   sd_none, sd_none, sd_none, sd_none, sd_none,

    sd_none, sd_none, sd_none, sd_adtc, sd_none, sd_none, sd_none, sd_none,

    sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none, sd_none,

};

static const int sd_cmd_class[64] = {

    0,  0,  0,  0,  0,  9, 10,  0,  0,  0,  0,  1,  0,  0,  0,  0,

    2,  2,  2,  2,  3,  3,  3,  3,  4,  4,  4,  4,  6,  6,  6,  6,

    5,  5, 10, 10, 10, 10,  5,  9,  9,  9,  7,  7,  7,  7,  7,  7,

    7,  7, 10,  7,  9,  9,  9,  8,  8, 10,  8,  8,  8,  8,  8,  8,

};

static uint8_t sd_crc7(void *message, size_t width)

{

    int i, bit;

    uint8_t shift_reg = 0x00;

    uint8_t *msg = (uint8_t *) message;

    for (i = 0; i < width; i ++, msg ++)

        for (bit = 7; bit >= 0; bit --) {

            shift_reg <<= 1;

            if ((shift_reg >> 7) ^ ((*msg >> bit) & 1))

                shift_reg ^= 0x89;

        }

    return shift_reg;

}

static uint16_t sd_crc16(void *message, size_t width)

{

    int i, bit;

    uint16_t shift_reg = 0x0000;

    uint16_t *msg = (uint16_t *) message;

    width <<= 1;

    for (i = 0; i < width; i ++, msg ++)

        for (bit = 15; bit >= 0; bit --) {

            shift_reg <<= 1;

            if ((shift_reg >> 15) ^ ((*msg >> bit) & 1))

                shift_reg ^= 0x1011;

        }

    return shift_reg;

}

static void sd_set_ocr(SDState *sd)

{

    /* All voltages OK, card power-up OK, Standard Capacity SD Memory Card */

    sd->ocr = 0x80ffff00;

}

static void sd_set_scr(SDState *sd)

{

    sd->scr[0] = 0x00;                /* SCR Structure */

    sd->scr[1] = 0x2f;                /* SD Security Support */

    sd->scr[2] = 0x00;

    sd->scr[3] = 0x00;

    sd->scr[4] = 0x00;

    sd->scr[5] = 0x00;

    sd->scr[6] = 0x00;

    sd->scr[7] = 0x00;

}

#define MID        0xaa

#define OID        "XY"

#define PNM        "QEMU!"

#define PRV        0x01

#define MDT_YR        2006

#define MDT_MON        2

static void sd_set_cid(SDState *sd)

{

    sd->cid[0] = MID;                /* Fake card manufacturer ID (MID) */

    sd->cid[1] = OID[0];        /* OEM/Application ID (OID) */

    sd->cid[2] = OID[1];

    sd->cid[3] = PNM[0];        /* Fake product name (PNM) */

    sd->cid[4] = PNM[1];

    sd->cid[5] = PNM[2];

    sd->cid[6] = PNM[3];

    sd->cid[7] = PNM[4];

    sd->cid[8] = PRV;                /* Fake product revision (PRV) */

    sd->cid[9] = 0xde;                /* Fake serial number (PSN) */

    sd->cid[10] = 0xad;

    sd->cid[11] = 0xbe;

    sd->cid[12] = 0xef;

    sd->cid[13] = 0x00 |        /* Manufacture date (MDT) */

        ((MDT_YR - 2000) / 10);

    sd->cid[14] = ((MDT_YR % 10) << 4) | MDT_MON;

    sd->cid[15] = (sd_crc7(sd->cid, 15) << 1) | 1;

}

#define HWBLOCK_SHIFT        9                        /* 512 bytes */

#define SECTOR_SHIFT        5                        /* 16 kilobytes */

#define WPGROUP_SHIFT        7                        /* 2 megs */

#define CMULT_SHIFT        9                        /* 512 times HWBLOCK_SIZE */

#define WPGROUP_SIZE        (1 << (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT))

static const uint8_t sd_csd_rw_mask[16] = {

    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfc, 0xfe,

};

static void sd_set_csd(SDState *sd, uint64_t size)

{

    uint32_t csize = (size >> (CMULT_SHIFT + HWBLOCK_SHIFT)) - 1;

    uint32_t sectsize = (1 << (SECTOR_SHIFT + 1)) - 1;

    uint32_t wpsize = (1 << (WPGROUP_SHIFT + 1)) - 1;

    if (size <= 0x40000000) {        /* Standard Capacity SD */

        sd->csd[0] = 0x00;        /* CSD structure */

        sd->csd[1] = 0x26;        /* Data read access-time-1 */

        sd->csd[2] = 0x00;        /* Data read access-time-2 */

        sd->csd[3] = 0x5a;        /* Max. data transfer rate */

        sd->csd[4] = 0x5f;        /* Card Command Classes */

        sd->csd[5] = 0x50 |        /* Max. read data block length */

            HWBLOCK_SHIFT;

        sd->csd[6] = 0xe0 |        /* Partial block for read allowed */

            ((csize >> 10) & 0x03);

        sd->csd[7] = 0x00 |        /* Device size */

            ((csize >> 2) & 0xff);

        sd->csd[8] = 0x3f |        /* Max. read current */

            ((csize << 6) & 0xc0);

        sd->csd[9] = 0xfc |        /* Max. write current */

            ((CMULT_SHIFT - 2) >> 1);

        sd->csd[10] = 0x40 |        /* Erase sector size */

            (((CMULT_SHIFT - 2) << 7) & 0x80) | (sectsize >> 1);

        sd->csd[11] = 0x00 |        /* Write protect group size */

            ((sectsize << 7) & 0x80) | wpsize;

        sd->csd[12] = 0x90 |        /* Write speed factor */

            (HWBLOCK_SHIFT >> 2);

        sd->csd[13] = 0x20 |        /* Max. write data block length */

            ((HWBLOCK_SHIFT << 6) & 0xc0);

        sd->csd[14] = 0x00;        /* File format group */

        sd->csd[15] = (sd_crc7(sd->csd, 15) << 1) | 1;

    } else {                        /* SDHC */

        size /= 512 * 1024;

        size -= 1;

        sd->csd[0] = 0x40;

        sd->csd[1] = 0x0e;

        sd->csd[2] = 0x00;

        sd->csd[3] = 0x32;

        sd->csd[4] = 0x5b;

        sd->csd[5] = 0x59;

        sd->csd[6] = 0x00;

        sd->csd[7] = (size >> 16) & 0xff;

        sd->csd[8] = (size >> 8) & 0xff;

        sd->csd[9] = (size & 0xff);

        sd->csd[10] = 0x7f;

        sd->csd[11] = 0x80;

        sd->csd[12] = 0x0a;

        sd->csd[13] = 0x40;

        sd->csd[14] = 0x00;

        sd->csd[15] = 0x00;

        sd->ocr |= 1 << 30;        /* High Capacity SD Memort Card */

    }

}

static void sd_set_rca(SDState *sd)

{

    sd->rca += 0x4567;

}

#define CARD_STATUS_A        0x02004100

#define CARD_STATUS_B        0x00c01e00

#define CARD_STATUS_C        0xfd39a028

static void sd_set_cardstatus(SDState *sd)

{

    sd->card_status = 0x00000100;

}

static void sd_set_sdstatus(SDState *sd)

{

    memset(sd->sd_status, 0, 64);

}

static int sd_req_crc_validate(SDRequest *req)

{

    uint8_t buffer[5];

    buffer[0] = 0x40 | req->cmd;

    buffer[1] = (req->arg >> 24) & 0xff;

    buffer[2] = (req->arg >> 16) & 0xff;

    buffer[3] = (req->arg >> 8) & 0xff;

    buffer[4] = (req->arg >> 0) & 0xff;

    return 0;

    return sd_crc7(buffer, 5) != req->crc;        /* TODO */

}

static void sd_response_r1_make(SDState *sd,

                                uint8_t *response, uint32_t last_status)

{

    uint32_t mask = CARD_STATUS_B ^ ILLEGAL_COMMAND;

    uint32_t status;

    status = (sd->card_status & ~mask) | (last_status & mask);

    sd->card_status &= ~CARD_STATUS_C | APP_CMD;

    response[0] = (status >> 24) & 0xff;

    response[1] = (status >> 16) & 0xff;

    response[2] = (status >> 8) & 0xff;

    response[3] = (status >> 0) & 0xff;

}

static void sd_response_r3_make(SDState *sd, uint8_t *response)

{

    response[0] = (sd->ocr >> 24) & 0xff;

    response[1] = (sd->ocr >> 16) & 0xff;

    response[2] = (sd->ocr >> 8) & 0xff;

    response[3] = (sd->ocr >> 0) & 0xff;

}

static void sd_response_r6_make(SDState *sd, uint8_t *response)

{

    uint16_t arg;

    uint16_t status;

    arg = sd->rca;

    status = ((sd->card_status >> 8) & 0xc000) |

             ((sd->card_status >> 6) & 0x2000) |

              (sd->card_status & 0x1fff);

    response[0] = (arg >> 8) & 0xff;

    response[1] = arg & 0xff;

    response[2] = (status >> 8) & 0xff;

    response[3] = status & 0xff;

}

static void sd_response_r7_make(SDState *sd, uint8_t *response)

{

    response[0] = (sd->vhs >> 24) & 0xff;

    response[1] = (sd->vhs >> 16) & 0xff;

    response[2] = (sd->vhs >>  8) & 0xff;

    response[3] = (sd->vhs >>  0) & 0xff;

}

static void sd_reset(SDState *sd, BlockDriverState *bdrv)

{

    uint64_t size;

    uint64_t sect;

    if (bdrv) {

        bdrv_get_geometry(bdrv, &sect);

    } else {

        sect = 0;

    }

    sect <<= 9;

    size = sect + 1;

    sect = (size >> (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT)) + 1;

    sd->state = sd_idle_state;

    sd->rca = 0x0000;

    sd_set_ocr(sd);

    sd_set_scr(sd);

    sd_set_cid(sd);

    sd_set_csd(sd, size);

    sd_set_cardstatus(sd);

    sd_set_sdstatus(sd);

    sd->bdrv = bdrv;

    if (sd->wp_groups)

        qemu_free(sd->wp_groups);

    sd->wp_switch = bdrv ? bdrv_is_read_only(bdrv) : 0;

    sd->wp_groups = (int *) qemu_mallocz(sizeof(int) * sect);

    memset(sd->function_group, 0, sizeof(int) * 6);

    sd->erase_start = 0;

    sd->erase_end = 0;

    sd->size = size;

    sd->blk_len = 0x200;

    sd->pwd_len = 0;

}

static void sd_cardchange(void *opaque)

{

    SDState *sd = opaque;

    qemu_set_irq(sd->inserted_cb, bdrv_is_inserted(sd->bdrv));

    if (bdrv_is_inserted(sd->bdrv)) {

        sd_reset(sd, sd->bdrv);

        qemu_set_irq(sd->readonly_cb, sd->wp_switch);

    }

}

/* We do not model the chip select pin, so allow the board to select

   whether card should be in SSI or MMC/SD mode.  It is also up to the

   board to ensure that ssi transfers only occur when the chip select

   is asserted.  */

SDState *sd_init(BlockDriverState *bs, int is_spi)

{

    SDState *sd;

    sd = (SDState *) qemu_mallocz(sizeof(SDState));

    sd->buf = qemu_blockalign(bs, 512);

    sd->spi = is_spi;

    sd->enable = 1;

    sd_reset(sd, bs);

    if (sd->bdrv) {

        bdrv_set_change_cb(sd->bdrv, sd_cardchange, sd);

    }

    return sd;

}

void sd_set_cb(SDState *sd, qemu_irq readonly, qemu_irq insert)

{

    sd->readonly_cb = readonly;

    sd->inserted_cb = insert;

    qemu_set_irq(readonly, bdrv_is_read_only(sd->bdrv));

    qemu_set_irq(insert, bdrv_is_inserted(sd->bdrv));

}

static void sd_erase(SDState *sd)

{

    int i, start, end;

    if (!sd->erase_start || !sd->erase_end) {

        sd->card_status |= ERASE_SEQ_ERROR;

        return;

    }

    start = sd->erase_start >>

            (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT);

    end = sd->erase_end >>

            (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT);

    sd->erase_start = 0;

    sd->erase_end = 0;

    sd->csd[14] |= 0x40;

    for (i = start; i <= end; i ++)

        if (sd->wp_groups[i])

            sd->card_status |= WP_ERASE_SKIP;

}

static uint32_t sd_wpbits(SDState *sd, uint64_t addr)

{

    uint32_t i, wpnum;

    uint32_t ret = 0;

    wpnum = addr >> (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT);

    for (i = 0; i < 32; i ++, wpnum ++, addr += WPGROUP_SIZE)

        if (addr < sd->size && sd->wp_groups[wpnum])

            ret |= (1 << i);

    return ret;

}

static void sd_function_switch(SDState *sd, uint32_t arg)

{

    int i, mode, new_func, crc;

    mode = !!(arg & 0x80000000);

    sd->data[0] = 0x00;                /* Maximum current consumption */

    sd->data[1] = 0x01;

    sd->data[2] = 0x80;                /* Supported group 6 functions */

    sd->data[3] = 0x01;

    sd->data[4] = 0x80;                /* Supported group 5 functions */

    sd->data[5] = 0x01;

    sd->data[6] = 0x80;                /* Supported group 4 functions */

    sd->data[7] = 0x01;

    sd->data[8] = 0x80;                /* Supported group 3 functions */

    sd->data[9] = 0x01;

    sd->data[10] = 0x80;        /* Supported group 2 functions */

    sd->data[11] = 0x43;

    sd->data[12] = 0x80;        /* Supported group 1 functions */

    sd->data[13] = 0x03;

    for (i = 0; i < 6; i ++) {

        new_func = (arg >> (i * 4)) & 0x0f;

        if (mode && new_func != 0x0f)

            sd->function_group[i] = new_func;

        sd->data[14 + (i >> 1)] = new_func << ((i * 4) & 4);

    }

    memset(&sd->data[17], 0, 47);

    crc = sd_crc16(sd->data, 64);

    sd->data[65] = crc >> 8;

    sd->data[66] = crc & 0xff;

}

static inline int sd_wp_addr(SDState *sd, uint32_t addr)

{

    return sd->wp_groups[addr >>

            (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT)];

}

static void sd_lock_command(SDState *sd)

{

    int erase, lock, clr_pwd, set_pwd, pwd_len;

    erase = !!(sd->data[0] & 0x08);

    lock = sd->data[0] & 0x04;

    clr_pwd = sd->data[0] & 0x02;

    set_pwd = sd->data[0] & 0x01;

    if (sd->blk_len > 1)

        pwd_len = sd->data[1];

    else

        pwd_len = 0;

    if (erase) {

        if (!(sd->card_status & CARD_IS_LOCKED) || sd->blk_len > 1 ||

                        set_pwd || clr_pwd || lock || sd->wp_switch ||

                        (sd->csd[14] & 0x20)) {

            sd->card_status |= LOCK_UNLOCK_FAILED;

            return;

        }

        memset(sd->wp_groups, 0, sizeof(int) * (sd->size >>

                        (HWBLOCK_SHIFT + SECTOR_SHIFT + WPGROUP_SHIFT)));

        sd->csd[14] &= ~0x10;

        sd->card_status &= ~CARD_IS_LOCKED;

        sd->pwd_len = 0;

        /* Erasing the entire card here! */

        fprintf(stderr, "SD: Card force-erased by CMD42\n");

        return;

    }

    if (sd->blk_len < 2 + pwd_len ||

                    pwd_len <= sd->pwd_len ||

                    pwd_len > sd->pwd_len + 16) {

        sd->card_status |= LOCK_UNLOCK_FAILED;

        return;

    }

    if (sd->pwd_len && memcmp(sd->pwd, sd->data + 2, sd->pwd_len)) {

        sd->card_status |= LOCK_UNLOCK_FAILED;

        return;

    }

    pwd_len -= sd->pwd_len;

    if ((pwd_len && !set_pwd) ||

                    (clr_pwd && (set_pwd || lock)) ||

                    (lock && !sd->pwd_len && !set_pwd) ||

                    (!set_pwd && !clr_pwd &&

                     (((sd->card_status & CARD_IS_LOCKED) && lock) ||

                      (!(sd->card_status & CARD_IS_LOCKED) && !lock)))) {

        sd->card_status |= LOCK_UNLOCK_FAILED;

        return;

    }

    if (set_pwd) {

        memcpy(sd->pwd, sd->data + 2 + sd->pwd_len, pwd_len);

        sd->pwd_len = pwd_len;

    }

    if (clr_pwd) {

        sd->pwd_len = 0;

    }

    if (lock)

        sd->card_status |= CARD_IS_LOCKED;

    else

        sd->card_status &= ~CARD_IS_LOCKED;

}

static sd_rsp_type_t sd_normal_command(SDState *sd,

                                       SDRequest req)

{

    uint32_t rca = 0x0000;

    uint64_t addr = (sd->ocr & (1 << 30)) ? (uint64_t) req.arg << 9 : req.arg;

    if (sd_cmd_type[req.cmd] == sd_ac || sd_cmd_type[req.cmd] == sd_adtc)

        rca = req.arg >> 16;

    DPRINTF("CMD%d 0x%08x state %d\n", req.cmd, req.arg, sd->state);

    switch (req.cmd) {

    /* Basic commands (Class 0 and Class 1) */

    case 0:        /* CMD0:   GO_IDLE_STATE */

        switch (sd->state) {

        case sd_inactive_state:

            return sd->spi ? sd_r1 : sd_r0;

        default:

            sd->state = sd_idle_state;

            sd_reset(sd, sd->bdrv);

            return sd->spi ? sd_r1 : sd_r0;

        }

        break;

    case 1:        /* CMD1:   SEND_OP_CMD */

        if (!sd->spi)

            goto bad_cmd;

        sd->state = sd_transfer_state;

        return sd_r1;

    case 2:        /* CMD2:   ALL_SEND_CID */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->state) {

        case sd_ready_state:

            sd->state = sd_identification_state;

            return sd_r2_i;

        default:

            break;

        }

        break;

    case 3:        /* CMD3:   SEND_RELATIVE_ADDR */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->state) {

        case sd_identification_state:

        case sd_standby_state:

            sd->state = sd_standby_state;

            sd_set_rca(sd);

            return sd_r6;

        default:

            break;

        }

        break;

    case 4:        /* CMD4:   SEND_DSR */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->state) {

        case sd_standby_state:

            break;

        default:

            break;

        }

        break;

    case 5: /* CMD5: reserved for SDIO cards */

        sd->card_status |= ILLEGAL_COMMAND;

        return sd_r0;

    case 6:        /* CMD6:   SWITCH_FUNCTION */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->mode) {

        case sd_data_transfer_mode:

            sd_function_switch(sd, req.arg);

            sd->state = sd_sendingdata_state;

            sd->data_start = 0;

            sd->data_offset = 0;

            return sd_r1;

        default:

            break;

        }

        break;

    case 7:        /* CMD7:   SELECT/DESELECT_CARD */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->state) {

        case sd_standby_state:

            if (sd->rca != rca)

                return sd_r0;

            sd->state = sd_transfer_state;

            return sd_r1b;

        case sd_transfer_state:

        case sd_sendingdata_state:

            if (sd->rca == rca)

                break;

            sd->state = sd_standby_state;

            return sd_r1b;

        case sd_disconnect_state:

            if (sd->rca != rca)

                return sd_r0;

            sd->state = sd_programming_state;

            return sd_r1b;

        case sd_programming_state:

            if (sd->rca == rca)

                break;

            sd->state = sd_disconnect_state;

            return sd_r1b;

        default:

            break;

        }

        break;

    case 8:        /* CMD8:   SEND_IF_COND */

        /* Physical Layer Specification Version 2.00 command */

        switch (sd->state) {

        case sd_idle_state:

            sd->vhs = 0;

            /* No response if not exactly one VHS bit is set.  */

            if (!(req.arg >> 8) || (req.arg >> ffs(req.arg & ~0xff)))

                return sd->spi ? sd_r7 : sd_r0;

            /* Accept.  */

            sd->vhs = req.arg;

            return sd_r7;

        default:

            break;

        }

        break;

    case 9:        /* CMD9:   SEND_CSD */

        switch (sd->state) {

        case sd_standby_state:

            if (sd->rca != rca)

                return sd_r0;

            return sd_r2_s;

        case sd_transfer_state:

            if (!sd->spi)

                break;

            sd->state = sd_sendingdata_state;

            memcpy(sd->data, sd->csd, 16);

            sd->data_start = addr;

            sd->data_offset = 0;

            return sd_r1;

        default:

            break;

        }

        break;

    case 10:        /* CMD10:  SEND_CID */

        switch (sd->state) {

        case sd_standby_state:

            if (sd->rca != rca)

                return sd_r0;

            return sd_r2_i;

        case sd_transfer_state:

            if (!sd->spi)

                break;

            sd->state = sd_sendingdata_state;

            memcpy(sd->data, sd->cid, 16);

            sd->data_start = addr;

            sd->data_offset = 0;

            return sd_r1;

        default:

            break;

        }

        break;

    case 11:        /* CMD11:  READ_DAT_UNTIL_STOP */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->state) {

        case sd_transfer_state:

            sd->state = sd_sendingdata_state;

            sd->data_start = req.arg;

            sd->data_offset = 0;

            if (sd->data_start + sd->blk_len > sd->size)

                sd->card_status |= ADDRESS_ERROR;

            return sd_r0;

        default:

            break;

        }

        break;

    case 12:        /* CMD12:  STOP_TRANSMISSION */

        switch (sd->state) {

        case sd_sendingdata_state:

            sd->state = sd_transfer_state;

            return sd_r1b;

        case sd_receivingdata_state:

            sd->state = sd_programming_state;

            /* Bzzzzzzztt .... Operation complete.  */

            sd->state = sd_transfer_state;

            return sd_r1b;

        default:

            break;

        }

        break;

    case 13:        /* CMD13:  SEND_STATUS */

        switch (sd->mode) {

        case sd_data_transfer_mode:

            if (sd->rca != rca)

                return sd_r0;

            return sd_r1;

        default:

            break;

        }

        break;

    case 15:        /* CMD15:  GO_INACTIVE_STATE */

        if (sd->spi)

            goto bad_cmd;

        switch (sd->mode) {

        case sd_data_transfer_mode:

            if (sd->rca != rca)

                return sd_r0;

            sd->state = sd_inactive_state;

            return sd_r0;

        default:

            break;

        }

        break;

    /* Block read commands (Classs 2) */

    case 16:        /* CMD16:  SET_BLOCKLEN */

        switch (sd->state) {

        case sd_transfer_state:

            if (req.arg > (1 << HWBLOCK_SHIFT))

                sd->card_status |= BLOCK_LEN_ERROR;

            else

                sd->blk_len = req.arg;

            return sd_r1;

        default:

            break;

        }

        break;

    case 17:        /* CMD17:  READ_SINGLE_BLOCK */