sd.c

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/*
 *  linux/drivers/mmc/core/sd.c
 *
 *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
 *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.
 *  Copyright (C) 2005-2007 Pierre Ossman, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/err.h>
#include <linux/slab.h>
#include <linux/stat.h>

#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
#include <linux/mmc/mmc.h>
#include <linux/mmc/sd.h>

#include "core.h"
#include "bus.h"
#include "mmc_ops.h"
#include "sd.h"
#include "sd_ops.h"

static const unsigned int tran_exp[] = {
    10000,      100000,     1000000,    10000000,
    0,      0,      0,      0
};

static const unsigned char tran_mant[] = {
    0,  10, 12, 13, 15, 20, 25, 30,
    35, 40, 45, 50, 55, 60, 70, 80,
};

static const unsigned int tacc_exp[] = {
    1,  10, 100,    1000,   10000,  100000, 1000000, 10000000,
};

static const unsigned int tacc_mant[] = {
    0,  10, 12, 13, 15, 20, 25, 30,
    35, 40, 45, 50, 55, 60, 70, 80,
};

#define UNSTUFF_BITS(resp,start,size)                   \
    ({                              \
        const int __size = size;                \
        const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1; \
        const int __off = 3 - ((start) / 32);           \
        const int __shft = (start) & 31;            \
        u32 __res;                      \
                                    \
        __res = resp[__off] >> __shft;              \
        if (__size + __shft > 32)               \
            __res |= resp[__off-1] << ((32 - __shft) % 32); \
        __res & __mask;                     \
    })

/*
 * Given the decoded CSD structure, decode the raw CID to our CID structure.
 */
void mmc_decode_cid(struct mmc_card *card)
{
    u32 *resp = card->raw_cid;

    memset(&card->cid, 0, sizeof(struct mmc_cid));

    /*
     * SD doesn't currently have a version field so we will
     * have to assume we can parse this.
     */
    card->cid.manfid        = UNSTUFF_BITS(resp, 120, 8);
    card->cid.oemid         = UNSTUFF_BITS(resp, 104, 16);
    card->cid.prod_name[0]      = UNSTUFF_BITS(resp, 96, 8);
    card->cid.prod_name[1]      = UNSTUFF_BITS(resp, 88, 8);
    card->cid.prod_name[2]      = UNSTUFF_BITS(resp, 80, 8);
    card->cid.prod_name[3]      = UNSTUFF_BITS(resp, 72, 8);
    card->cid.prod_name[4]      = UNSTUFF_BITS(resp, 64, 8);
    card->cid.hwrev         = UNSTUFF_BITS(resp, 60, 4);
    card->cid.fwrev         = UNSTUFF_BITS(resp, 56, 4);
    card->cid.serial        = UNSTUFF_BITS(resp, 24, 32);
    card->cid.year          = UNSTUFF_BITS(resp, 12, 8);
    card->cid.month         = UNSTUFF_BITS(resp, 8, 4);

    card->cid.year += 2000; /* SD cards year offset */
}

/*
 * Given a 128-bit response, decode to our card CSD structure.
 */
static int mmc_decode_csd(struct mmc_card *card)
{
    struct mmc_csd *csd = &card->csd;
    unsigned int e, m, csd_struct;
    u32 *resp = card->raw_csd;

    csd_struct = UNSTUFF_BITS(resp, 126, 2);

    switch (csd_struct) {
    case 0:
        m = UNSTUFF_BITS(resp, 115, 4);
        e = UNSTUFF_BITS(resp, 112, 3);
        csd->tacc_ns     = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
        csd->tacc_clks   = UNSTUFF_BITS(resp, 104, 8) * 100;

        m = UNSTUFF_BITS(resp, 99, 4);
        e = UNSTUFF_BITS(resp, 96, 3);
        csd->max_dtr      = tran_exp[e] * tran_mant[m];
        csd->cmdclass     = UNSTUFF_BITS(resp, 84, 12);

        e = UNSTUFF_BITS(resp, 47, 3);
        m = UNSTUFF_BITS(resp, 62, 12);
        csd->capacity     = (1 + m) << (e + 2);

        csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
        csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
        csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
        csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
        csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
        csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
        csd->write_partial = UNSTUFF_BITS(resp, 21, 1);

        if (UNSTUFF_BITS(resp, 46, 1)) {
            csd->erase_size = 1;
        } else if (csd->write_blkbits >= 9) {
            csd->erase_size = UNSTUFF_BITS(resp, 39, 7) + 1;
            csd->erase_size <<= csd->write_blkbits - 9;
        }
        break;
    case 1:
        /*
         * This is a block-addressed SDHC or SDXC card. Most
         * interesting fields are unused and have fixed
         * values. To avoid getting tripped by buggy cards,
         * we assume those fixed values ourselves.
         */
        mmc_card_set_blockaddr(card);

        csd->tacc_ns     = 0; /* Unused */
        csd->tacc_clks   = 0; /* Unused */

        m = UNSTUFF_BITS(resp, 99, 4);
        e = UNSTUFF_BITS(resp, 96, 3);
        csd->max_dtr      = tran_exp[e] * tran_mant[m];
        csd->cmdclass     = UNSTUFF_BITS(resp, 84, 12);
        csd->c_size   = UNSTUFF_BITS(resp, 48, 22);

        /* SDXC cards have a minimum C_SIZE of 0x00FFFF */
        if (csd->c_size >= 0xFFFF)
            mmc_card_set_ext_capacity(card);

        m = UNSTUFF_BITS(resp, 48, 22);
        csd->capacity     = (1 + m) << 10;

        csd->read_blkbits = 9;
        csd->read_partial = 0;
        csd->write_misalign = 0;
        csd->read_misalign = 0;
        csd->r2w_factor = 4; /* Unused */
        csd->write_blkbits = 9;
        csd->write_partial = 0;
        csd->erase_size = 1;
        break;
    default:
        pr_err("%s: unrecognised CSD structure version %d\n",
            mmc_hostname(card->host), csd_struct);
        return -EINVAL;
    }

    card->erase_size = csd->erase_size;

    return 0;
}

/*
 * Given a 64-bit response, decode to our card SCR structure.
 */
static int mmc_decode_scr(struct mmc_card *card)
{
    struct sd_scr *scr = &card->scr;
    unsigned int scr_struct;
    u32 resp[4];

    resp[3] = card->raw_scr[1];
    resp[2] = card->raw_scr[0];

    scr_struct = UNSTUFF_BITS(resp, 60, 4);
    if (scr_struct != 0) {
        pr_err("%s: unrecognised SCR structure version %d\n",
            mmc_hostname(card->host), scr_struct);
        return -EINVAL;
    }

    scr->sda_vsn = UNSTUFF_BITS(resp, 56, 4);
    scr->bus_widths = UNSTUFF_BITS(resp, 48, 4);
    if (scr->sda_vsn == SCR_SPEC_VER_2)
        /* Check if Physical Layer Spec v3.0 is supported */
        scr->sda_spec3 = UNSTUFF_BITS(resp, 47, 1);

    if (UNSTUFF_BITS(resp, 55, 1))
        card->erased_byte = 0xFF;
    else
        card->erased_byte = 0x0;

    if (scr->sda_spec3)
        scr->cmds = UNSTUFF_BITS(resp, 32, 2);
    return 0;
}

/*
 * Fetch and process SD Status register.
 */
static int mmc_read_ssr(struct mmc_card *card)
{
    unsigned int au, es, et, eo;
    int err, i;
    u32 *ssr;

    if (!(card->csd.cmdclass & CCC_APP_SPEC)) {
        pr_warning("%s: card lacks mandatory SD Status "
            "function.\n", mmc_hostname(card->host));
        return 0;
    }

    ssr = kmalloc(64, GFP_KERNEL);
    if (!ssr)
        return -ENOMEM;

    err = mmc_app_sd_status(card, ssr);
    if (err) {
        pr_warning("%s: problem reading SD Status "
            "register.\n", mmc_hostname(card->host));
        err = 0;
        goto out;
    }

    for (i = 0; i < 16; i++)
        ssr[i] = be32_to_cpu(ssr[i]);

    /*
     * UNSTUFF_BITS only works with four u32s so we have to offset the
     * bitfield positions accordingly.
     */
    au = UNSTUFF_BITS(ssr, 428 - 384, 4);
    if (au > 0 && au <= 9) {
        card->ssr.au = 1 << (au + 4);
        es = UNSTUFF_BITS(ssr, 408 - 384, 16);
        et = UNSTUFF_BITS(ssr, 402 - 384, 6);
        eo = UNSTUFF_BITS(ssr, 400 - 384, 2);
        if (es && et) {
            card->ssr.erase_timeout = (et * 1000) / es;
            card->ssr.erase_offset = eo * 1000;
        }
    } else {
        pr_warning("%s: SD Status: Invalid Allocation Unit "
            "size.\n", mmc_hostname(card->host));
    }
out:
    kfree(ssr);
    return err;
}

/*
 * Fetches and decodes switch information
 */
static int mmc_read_switch(struct mmc_card *card)
{
    int err;
    u8 *status;

    if (card->scr.sda_vsn < SCR_SPEC_VER_1)
        return 0;

    if (!(card->csd.cmdclass & CCC_SWITCH)) {
        pr_warning("%s: card lacks mandatory switch "
            "function, performance might suffer.\n",
            mmc_hostname(card->host));
        return 0;
    }

    err = -EIO;

    status = kmalloc(64, GFP_KERNEL);
    if (!status) {
        pr_err("%s: could not allocate a buffer for "
            "switch capabilities.\n",
            mmc_hostname(card->host));
        return -ENOMEM;
    }

    /*
     * Find out the card's support bits with a mode 0 operation.
     * The argument does not matter, as the support bits do not
     * change with the arguments.
     */
    err = mmc_sd_switch(card, 0, 0, 0, status);
    if (err) {
        /*
         * If the host or the card can't do the switch,
         * fail more gracefully.
         */
        if (err != -EINVAL && err != -ENOSYS && err != -EFAULT)
            goto out;

        pr_warning("%s: problem reading Bus Speed modes.\n",
            mmc_hostname(card->host));
        err = 0;

        goto out;
    }

    if (status[13] & SD_MODE_HIGH_SPEED)
        card->sw_caps.hs_max_dtr = HIGH_SPEED_MAX_DTR;

    if (card->scr.sda_spec3) {
        card->sw_caps.sd3_bus_mode = status[13];
        /* Driver Strengths supported by the card */
        card->sw_caps.sd3_drv_type = status[9];
    }

out:
    kfree(status);

    return err;
}

/*
 * Test if the card supports high-speed mode and, if so, switch to it.
 */
int mmc_sd_switch_hs(struct mmc_card *card)
{
    int err;
    u8 *status;

    if (card->scr.sda_vsn < SCR_SPEC_VER_1)
        return 0;

    if (!(card->csd.cmdclass & CCC_SWITCH))
        return 0;

    if (!(card->host->caps & MMC_CAP_SD_HIGHSPEED))
        return 0;

    if (card->sw_caps.hs_max_dtr == 0)
        return 0;

    err = -EIO;

    status = kmalloc(64, GFP_KERNEL);
    if (!status) {
        pr_err("%s: could not allocate a buffer for "
            "switch capabilities.\n", mmc_hostname(card->host));
        return -ENOMEM;
    }

    err = mmc_sd_switch(card, 1, 0, 1, status);
    if (err)
        goto out;

    if ((status[16] & 0xF) != 1) {
        pr_warning("%s: Problem switching card "
            "into high-speed mode!\n",
            mmc_hostname(card->host));
        err = 0;
    } else {
        err = 1;
    }

out:
    kfree(status);

    return err;
}

static int sd_select_driver_type(struct mmc_card *card, u8 *status)
{
    int host_drv_type = SD_DRIVER_TYPE_B;
    int card_drv_type = SD_DRIVER_TYPE_B;
    int drive_strength;
    int err;

    /*
     * If the host doesn't support any of the Driver Types A,C or D,
     * or there is no board specific handler then default Driver
     * Type B is used.
     */
    if (!(card->host->caps & (MMC_CAP_DRIVER_TYPE_A | MMC_CAP_DRIVER_TYPE_C
        | MMC_CAP_DRIVER_TYPE_D)))
        return 0;

    if (!card->host->ops->select_drive_strength)
        return 0;

    if (card->host->caps & MMC_CAP_DRIVER_TYPE_A)
        host_drv_type |= SD_DRIVER_TYPE_A;

    if (card->host->caps & MMC_CAP_DRIVER_TYPE_C)
        host_drv_type |= SD_DRIVER_TYPE_C;

    if (card->host->caps & MMC_CAP_DRIVER_TYPE_D)
        host_drv_type |= SD_DRIVER_TYPE_D;

    if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_A)
        card_drv_type |= SD_DRIVER_TYPE_A;

    if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C)
        card_drv_type |= SD_DRIVER_TYPE_C;

    if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_D)
        card_drv_type |= SD_DRIVER_TYPE_D;

    /*
     * The drive strength that the hardware can support
     * depends on the board design.  Pass the appropriate
     * information and let the hardware specific code
     * return what is possible given the options
     */
    mmc_host_clk_hold(card->host);
    drive_strength = card->host->ops->select_drive_strength(
        card->sw_caps.uhs_max_dtr,
        host_drv_type, card_drv_type);
    mmc_host_clk_release(card->host);

    err = mmc_sd_switch(card, 1, 2, drive_strength, status);
    if (err)
        return err;

    if ((status[15] & 0xF) != drive_strength) {
        pr_warning("%s: Problem setting drive strength!\n",
            mmc_hostname(card->host));
        return 0;
    }

    mmc_set_driver_type(card->host, drive_strength);

    return 0;
}

static void sd_update_bus_speed_mode(struct mmc_card *card)
{
    /*
     * If the host doesn't support any of the UHS-I modes, fallback on
     * default speed.
     */
    if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
        MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) {
        card->sd_bus_speed = 0;
        return;
    }

    if ((card->host->caps & MMC_CAP_UHS_SDR104) &&
        (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR104)) {
            card->sd_bus_speed = UHS_SDR104_BUS_SPEED;
    } else if ((card->host->caps & MMC_CAP_UHS_DDR50) &&
           (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_DDR50)) {
            card->sd_bus_speed = UHS_DDR50_BUS_SPEED;
    } else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
            MMC_CAP_UHS_SDR50)) && (card->sw_caps.sd3_bus_mode &
            SD_MODE_UHS_SDR50)) {
            card->sd_bus_speed = UHS_SDR50_BUS_SPEED;
    } else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
            MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25)) &&
           (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR25)) {
            card->sd_bus_speed = UHS_SDR25_BUS_SPEED;
    } else if ((card->host->caps & (MMC_CAP_UHS_SDR104 |
            MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25 |
            MMC_CAP_UHS_SDR12)) && (card->sw_caps.sd3_bus_mode &
            SD_MODE_UHS_SDR12)) {
            card->sd_bus_speed = UHS_SDR12_BUS_SPEED;
    }
}

static int sd_set_bus_speed_mode(struct mmc_card *card, u8 *status)
{
    int err;
    unsigned int timing = 0;

    switch (card->sd_bus_speed) {
    case UHS_SDR104_BUS_SPEED:
        timing = MMC_TIMING_UHS_SDR104;
        card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR;
        break;
    case UHS_DDR50_BUS_SPEED:
        timing = MMC_TIMING_UHS_DDR50;
        card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR;
        break;
    case UHS_SDR50_BUS_SPEED:
        timing = MMC_TIMING_UHS_SDR50;
        card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR;
        break;
    case UHS_SDR25_BUS_SPEED:
        timing = MMC_TIMING_UHS_SDR25;
        card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR;
        break;
    case UHS_SDR12_BUS_SPEED:
        timing = MMC_TIMING_UHS_SDR12;
        card->sw_caps.uhs_max_dtr = UHS_SDR12_MAX_DTR;
        break;
    default:
        return 0;
    }

    err = mmc_sd_switch(card, 1, 0, card->sd_bus_speed, status);
    if (err)
        return err;

    if ((status[16] & 0xF) != card->sd_bus_speed)
        pr_warning("%s: Problem setting bus speed mode!\n",
            mmc_hostname(card->host));
    else {
        mmc_set_timing(card->host, timing);
        mmc_set_clock(card->host, card->sw_caps.uhs_max_dtr);
    }

    return 0;
}

/* Get host's max current setting at its current voltage */
static u32 sd_get_host_max_current(struct mmc_host *host)
{
    u32 voltage, max_current;

    voltage = 1 << host->ios.vdd;
    switch (voltage) {
    case MMC_VDD_165_195:
        max_current = host->max_current_180;
        break;
    case MMC_VDD_29_30:
    case MMC_VDD_30_31:
        max_current = host->max_current_300;
        break;
    case MMC_VDD_32_33:
    case MMC_VDD_33_34:
        max_current = host->max_current_330;
        break;
    default:
        max_current = 0;
    }

    return max_current;
}

static int sd_set_current_limit(struct mmc_card *card, u8 *status)
{
    int current_limit = SD_SET_CURRENT_NO_CHANGE;
    int err;
    u32 max_current;

    /*
     * Current limit switch is only defined for SDR50, SDR104, and DDR50
     * bus speed modes. For other bus speed modes, we do not change the
     * current limit.
     */
    if ((card->sd_bus_speed != UHS_SDR50_BUS_SPEED) &&
        (card->sd_bus_speed != UHS_SDR104_BUS_SPEED) &&
        (card->sd_bus_speed != UHS_DDR50_BUS_SPEED))
        return 0;

    /*
     * Host has different current capabilities when operating at
     * different voltages, so find out its max current first.
     */
    max_current = sd_get_host_max_current(card->host);

    /*
     * We only check host's capability here, if we set a limit that is
     * higher than the card's maximum current, the card will be using its
     * maximum current, e.g. if the card's maximum current is 300ma, and
     * when we set current limit to 200ma, the card will draw 200ma, and
     * when we set current limit to 400/600/800ma, the card will draw its
     * maximum 300ma from the host.
     */
    if (max_current >= 800)
        current_limit = SD_SET_CURRENT_LIMIT_800;
    else if (max_current >= 600)
        current_limit = SD_SET_CURRENT_LIMIT_600;
    else if (max_current >= 400)
        current_limit = SD_SET_CURRENT_LIMIT_400;
    else if (max_current >= 200)
        current_limit = SD_SET_CURRENT_LIMIT_200;

    if (current_limit != SD_SET_CURRENT_NO_CHANGE) {
        err = mmc_sd_switch(card, 1, 3, current_limit, status);
        if (err)
            return err;

        if (((status[15] >> 4) & 0x0F) != current_limit)
            pr_warning("%s: Problem setting current limit!\n",
                mmc_hostname(card->host));

    }

    return 0;
}

/*
 * UHS-I specific initialization procedure
 */
static int mmc_sd_init_uhs_card(struct mmc_card *card)
{
    int err;
    u8 *status;

    if (!card->scr.sda_spec3)
        return 0;

    if (!(card->csd.cmdclass & CCC_SWITCH))
        return 0;

    status = kmalloc(64, GFP_KERNEL);
    if (!status) {
        pr_err("%s: could not allocate a buffer for "
            "switch capabilities.\n", mmc_hostname(card->host));
        return -ENOMEM;
    }

    /* Set 4-bit bus width */
    if ((card->host->caps & MMC_CAP_4_BIT_DATA) &&
        (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
        err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
        if (err)
            goto out;

        mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
    }

    /*
     * Select the bus speed mode depending on host
     * and card capability.
     */
    sd_update_bus_speed_mode(card);

    /* Set the driver strength for the card */
    err = sd_select_driver_type(card, status);
    if (err)
        goto out;

    /* Set current limit for the card */
    err = sd_set_current_limit(card, status);
    if (err)
        goto out;

    /* Set bus speed mode of the card */
    err = sd_set_bus_speed_mode(card, status);
    if (err)
        goto out;

    /* SPI mode doesn't define CMD19 */
    if (!mmc_host_is_spi(card->host) && card->host->ops->execute_tuning) {
        mmc_host_clk_hold(card->host);
        err = card->host->ops->execute_tuning(card->host,
                              MMC_SEND_TUNING_BLOCK);
        mmc_host_clk_release(card->host);
    }

out:
    kfree(status);

    return err;
}

MMC_DEV_ATTR(cid, "%08x%08x%08x%08x\n", card->raw_cid[0], card->raw_cid[1],
    card->raw_cid[2], card->raw_cid[3]);
MMC_DEV_ATTR(csd, "%08x%08x%08x%08x\n", card->raw_csd[0], card->raw_csd[1],
    card->raw_csd[2], card->raw_csd[3]);
MMC_DEV_ATTR(scr, "%08x%08x\n", card->raw_scr[0], card->raw_scr[1]);
MMC_DEV_ATTR(date, "%02d/%04d\n", card->cid.month, card->cid.year);
MMC_DEV_ATTR(erase_size, "%u\n", card->erase_size << 9);
MMC_DEV_ATTR(preferred_erase_size, "%u\n", card->pref_erase << 9);
MMC_DEV_ATTR(fwrev, "0x%x\n", card->cid.fwrev);
MMC_DEV_ATTR(hwrev, "0x%x\n", card->cid.hwrev);
MMC_DEV_ATTR(manfid, "0x%06x\n", card->cid.manfid);
MMC_DEV_ATTR(name, "%s\n", card->cid.prod_name);
MMC_DEV_ATTR(oemid, "0x%04x\n", card->cid.oemid);
MMC_DEV_ATTR(serial, "0x%08x\n", card->cid.serial);


static struct attribute *sd_std_attrs[] = {
    &dev_attr_cid.attr,
    &dev_attr_csd.attr,
    &dev_attr_scr.attr,
    &dev_attr_date.attr,
    &dev_attr_erase_size.attr,
    &dev_attr_preferred_erase_size.attr,
    &dev_attr_fwrev.attr,
    &dev_attr_hwrev.attr,
    &dev_attr_manfid.attr,
    &dev_attr_name.attr,
    &dev_attr_oemid.attr,
    &dev_attr_serial.attr,
    NULL,
};

static struct attribute_group sd_std_attr_group = {
    .attrs = sd_std_attrs,
};

static const struct attribute_group *sd_attr_groups[] = {
    &sd_std_attr_group,
    NULL,
};

struct device_type sd_type = {
    .groups = sd_attr_groups,
};

/*
 * Fetch CID from card.
 */
int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid, u32 *rocr)
{
    int err;
    u32 max_current;

    /*
     * Since we're changing the OCR value, we seem to
     * need to tell some cards to go back to the idle
     * state.  We wait 1ms to give cards time to
     * respond.
     */
    mmc_go_idle(host);

    /*
     * If SD_SEND_IF_COND indicates an SD 2.0
     * compliant card and we should set bit 30
     * of the ocr to indicate that we can handle
     * block-addressed SDHC cards.
     */
    err = mmc_send_if_cond(host, ocr);
    if (!err)
        ocr |= SD_OCR_CCS;

    /*
     * If the host supports one of UHS-I modes, request the card
     * to switch to 1.8V signaling level.
     */
    if (host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
        MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))
        ocr |= SD_OCR_S18R;

    /*
     * If the host can supply more than 150mA at current voltage,
     * XPC should be set to 1.
     */
    max_current = sd_get_host_max_current(host);
    if (max_current > 150)
        ocr |= SD_OCR_XPC;

try_again:
    err = mmc_send_app_op_cond(host, ocr, rocr);
    if (err)
        return err;

    /*
     * In case CCS and S18A in the response is set, start Signal Voltage
     * Switch procedure. SPI mode doesn't support CMD11.
     */
    if (!mmc_host_is_spi(host) && rocr &&
       ((*rocr & 0x41000000) == 0x41000000)) {
        err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180, true);
        if (err) {
            ocr &= ~SD_OCR_S18R;
            goto try_again;
        }
    }

    if (mmc_host_is_spi(host))
        err = mmc_send_cid(host, cid);
    else
        err = mmc_all_send_cid(host, cid);

    return err;
}

int mmc_sd_get_csd(struct mmc_host *host, struct mmc_card *card)
{
    int err;

    /*
     * Fetch CSD from card.
     */
    err = mmc_send_csd(card, card->raw_csd);
    if (err)
        return err;

    err = mmc_decode_csd(card);
    if (err)
        return err;

    return 0;
}

int mmc_sd_setup_card(struct mmc_host *host, struct mmc_card *card,
    bool reinit)
{
    int err;

    if (!reinit) {
        /*
         * Fetch SCR from card.
         */
        err = mmc_app_send_scr(card, card->raw_scr);
        if (err)
            return err;

        err = mmc_decode_scr(card);
        if (err)
            return err;

        /*
         * Fetch and process SD Status register.
         */
        err = mmc_read_ssr(card);
        if (err)
            return err;

        /* Erase init depends on CSD and SSR */
        mmc_init_erase(card);

        /*
         * Fetch switch information from card.
         */
        err = mmc_read_switch(card);
        if (err)
            return err;
    }

    /*
     * For SPI, enable CRC as appropriate.
     * This CRC enable is located AFTER the reading of the
     * card registers because some SDHC cards are not able
     * to provide valid CRCs for non-512-byte blocks.
     */
    if (mmc_host_is_spi(host)) {
        err = mmc_spi_set_crc(host, use_spi_crc);
        if (err)
            return err;
    }

    /*
     * Check if read-only switch is active.
     */
    if (!reinit) {
        int ro = -1;

        if (host->ops->get_ro) {
            mmc_host_clk_hold(card->host);
            ro = host->ops->get_ro(host);
            mmc_host_clk_release(card->host);
        }

        if (ro < 0) {
            pr_warning("%s: host does not "
                "support reading read-only "
                "switch. assuming write-enable.\n",
                mmc_hostname(host));
        } else if (ro > 0) {
            mmc_card_set_readonly(card);
        }
    }

    return 0;
}

unsigned mmc_sd_get_max_clock(struct mmc_card *card)
{
    unsigned max_dtr = (unsigned int)-1;

    if (mmc_card_highspeed(card)) {
        if (max_dtr > card->sw_caps.hs_max_dtr)
            max_dtr = card->sw_caps.hs_max_dtr;
    } else if (max_dtr > card->csd.max_dtr) {
        max_dtr = card->csd.max_dtr;
    }

    return max_dtr;
}

void mmc_sd_go_highspeed(struct mmc_card *card)
{
    mmc_card_set_highspeed(card);
    mmc_set_timing(card->host, MMC_TIMING_SD_HS);
}

/*
 * Handle the detection and initialisation of a card.
 *
 * In the case of a resume, "oldcard" will contain the card
 * we're trying to reinitialise.
 */
static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
    struct mmc_card *oldcard)
{
    struct mmc_card *card;
    int err;
    u32 cid[4];
    u32 rocr = 0;

    BUG_ON(!host);
    WARN_ON(!host->claimed);

    err = mmc_sd_get_cid(host, ocr, cid, &rocr);
    if (err)
        return err;

    if (oldcard) {
        if (memcmp(cid, oldcard->raw_cid, sizeof(cid)) != 0)
            return -ENOENT;

        card = oldcard;
    } else {
        /*
         * Allocate card structure.
         */
        card = mmc_alloc_card(host, &sd_type);
        if (IS_ERR(card))
            return PTR_ERR(card);

        card->type = MMC_TYPE_SD;
        memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
    }

    /*
     * For native busses:  get card RCA and quit open drain mode.
     */
    if (!mmc_host_is_spi(host)) {
        err = mmc_send_relative_addr(host, &card->rca);
        if (err)
            return err;
    }

    if (!oldcard) {
        err = mmc_sd_get_csd(host, card);
        if (err)
            return err;

        mmc_decode_cid(card);
    }

    /*
     * Select card, as all following commands rely on that.
     */
    if (!mmc_host_is_spi(host)) {
        err = mmc_select_card(card);
        if (err)
            return err;
    }

    err = mmc_sd_setup_card(host, card, oldcard != NULL);
    if (err)
        goto free_card;

    /* Initialization sequence for UHS-I cards */
    if (rocr & SD_ROCR_S18A) {
        err = mmc_sd_init_uhs_card(card);
        if (err)
            goto free_card;

        /* Card is an ultra-high-speed card */
        mmc_card_set_uhs(card);

        /*
         * Since initialization is now complete, enable preset
         * value registers for UHS-I cards.
         */
        if (host->ops->enable_preset_value) {
            mmc_host_clk_hold(card->host);
            host->ops->enable_preset_value(host, true);
            mmc_host_clk_release(card->host);
        }
    } else {
        /*
         * Attempt to change to high-speed (if supported)
         */
        err = mmc_sd_switch_hs(card);
        if (err > 0)
            mmc_sd_go_highspeed(card);
        else if (err)
            goto free_card;

        /*
         * Set bus speed.
         */
        mmc_set_clock(host, mmc_sd_get_max_clock(card));

        /*
         * Switch to wider bus (if supported).
         */
        if ((host->caps & MMC_CAP_4_BIT_DATA) &&
            (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
            err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
            if (err)
                goto free_card;

            mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
        }
    }

    host->card = card;
    return 0;

free_card:
    if (!oldcard)
        mmc_remove_card(card);

    return err;
}

/*
 * Host is being removed. Free up the current card.
 */
static void mmc_sd_remove(struct mmc_host *host)
{
    BUG_ON(!host);
    BUG_ON(!host->card);

    mmc_remove_card(host->card);
    host->card = NULL;
}

/*
 * Card detection - card is alive.
 */
static int mmc_sd_alive(struct mmc_host *host)
{
    return mmc_send_status(host->card, NULL);
}

/*
 * Card detection callback from host.
 */
static void mmc_sd_detect(struct mmc_host *host)
{
    int err;

    BUG_ON(!host);
    BUG_ON(!host->card);

    mmc_claim_host(host);

    /*
     * Just check if our card has been removed.
     */
    err = _mmc_detect_card_removed(host);

    mmc_release_host(host);

    if (err) {
        mmc_sd_remove(host);

        mmc_claim_host(host);
        mmc_detach_bus(host);
        mmc_power_off(host);
        mmc_release_host(host);
    }
}

/*
 * Suspend callback from host.
 */
static int mmc_sd_suspend(struct mmc_host *host)
{
    int err = 0;

    BUG_ON(!host);
    BUG_ON(!host->card);

    mmc_claim_host(host);
    if (!mmc_host_is_spi(host))
        err = mmc_deselect_cards(host);
    host->card->state &= ~MMC_STATE_HIGHSPEED;
    mmc_release_host(host);

    return err;
}

/*
 * Resume callback from host.
 *
 * This function tries to determine if the same card is still present
 * and, if so, restore all state to it.
 */
static int mmc_sd_resume(struct mmc_host *host)
{
    int err;

    BUG_ON(!host);
    BUG_ON(!host->card);

    mmc_claim_host(host);
    err = mmc_sd_init_card(host, host->ocr, host->card);
    mmc_release_host(host);

    return err;
}

static int mmc_sd_power_restore(struct mmc_host *host)
{
    int ret;

    host->card->state &= ~MMC_STATE_HIGHSPEED;
    mmc_claim_host(host);
    ret = mmc_sd_init_card(host, host->ocr, host->card);
    mmc_release_host(host);

    return ret;
}

static const struct mmc_bus_ops mmc_sd_ops = {
    .remove = mmc_sd_remove,
    .detect = mmc_sd_detect,
    .suspend = NULL,
    .resume = NULL,
    .power_restore = mmc_sd_power_restore,
    .alive = mmc_sd_alive,
};

static const struct mmc_bus_ops mmc_sd_ops_unsafe = {
    .remove = mmc_sd_remove,
    .detect = mmc_sd_detect,
    .suspend = mmc_sd_suspend,
    .resume = mmc_sd_resume,
    .power_restore = mmc_sd_power_restore,
    .alive = mmc_sd_alive,
};

static void mmc_sd_attach_bus_ops(struct mmc_host *host)
{
    const struct mmc_bus_ops *bus_ops;

    if (!mmc_card_is_removable(host))
        bus_ops = &mmc_sd_ops_unsafe;
    else
        bus_ops = &mmc_sd_ops;
    mmc_attach_bus(host, bus_ops);
}

/*
 * Starting point for SD card init.
 */
int mmc_attach_sd(struct mmc_host *host)
{
    int err;
    u32 ocr;

    BUG_ON(!host);
    WARN_ON(!host->claimed);

    /* Disable preset value enable if already set since last time */
    if (host->ops->enable_preset_value) {
        mmc_host_clk_hold(host);
        host->ops->enable_preset_value(host, false);
        mmc_host_clk_release(host);
    }

    err = mmc_send_app_op_cond(host, 0, &ocr);
    if (err)
        return err;

    mmc_sd_attach_bus_ops(host);
    if (host->ocr_avail_sd)
        host->ocr_avail = host->ocr_avail_sd;

    /*
     * We need to get OCR a different way for SPI.
     */
    if (mmc_host_is_spi(host)) {
        mmc_go_idle(host);

        err = mmc_spi_read_ocr(host, 0, &ocr);
        if (err)
            goto err;
    }

    /*
     * Sanity check the voltages that the card claims to
     * support.
     */
    if (ocr & 0x7F) {
        pr_warning("%s: card claims to support voltages "
               "below the defined range. These will be ignored.\n",
               mmc_hostname(host));
        ocr &= ~0x7F;
    }

    if ((ocr & MMC_VDD_165_195) &&
        !(host->ocr_avail_sd & MMC_VDD_165_195)) {
        pr_warning("%s: SD card claims to support the "
               "incompletely defined 'low voltage range'. This "
               "will be ignored.\n", mmc_hostname(host));
        ocr &= ~MMC_VDD_165_195;
    }

    host->ocr = mmc_select_voltage(host, ocr);

    /*
     * Can we support the voltage(s) of the card(s)?
     */
    if (!host->ocr) {
        err = -EINVAL;
        goto err;
    }

    /*
     * Detect and init the card.
     */
    err = mmc_sd_init_card(host, host->ocr, NULL);
    if (err)
        goto err;

    mmc_release_host(host);
    err = mmc_add_card(host->card);
    mmc_claim_host(host);
    if (err)
        goto remove_card;

    return 0;

remove_card:
    mmc_release_host(host);
    mmc_remove_card(host->card);
    host->card = NULL;
    mmc_claim_host(host);
err:
    mmc_detach_bus(host);

    pr_err("%s: error %d whilst initialising SD card\n",
        mmc_hostname(host), err);

    return err;
}