[ARM] 3531/1: i.MX/MX1 SD/MMC ensure, that clock are stopped before new command and...

[firewire-audio.git] / drivers / mmc / mmc.c

/*
 *  linux/drivers/mmc/mmc.c
 *
 *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
 *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.
 *  SD support Copyright (C) 2005 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/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/pagemap.h>
#include <linux/err.h>
#include <asm/scatterlist.h>
#include <linux/scatterlist.h>

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

#include "mmc.h"

#define CMD_RETRIES     3

/*
 * OCR Bit positions to 10s of Vdd mV.
 */
static const unsigned short mmc_ocr_bit_to_vdd[] = {
        150,    155,    160,    165,    170,    180,    190,    200,
        210,    220,    230,    240,    250,    260,    270,    280,
        290,    300,    310,    320,    330,    340,    350,    360
};

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,
};


/**
 *      mmc_request_done - finish processing an MMC request
 *      @host: MMC host which completed request
 *      @mrq: MMC request which request
 *
 *      MMC drivers should call this function when they have completed
 *      their processing of a request.
 */
void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
{
        struct mmc_command *cmd = mrq->cmd;
        int err = cmd->error;

        pr_debug("%s: req done (CMD%u): %d/%d/%d: %08x %08x %08x %08x\n",
                 mmc_hostname(host), cmd->opcode, err,
                 mrq->data ? mrq->data->error : 0,
                 mrq->stop ? mrq->stop->error : 0,
                 cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3]);

        if (err && cmd->retries) {
                cmd->retries--;
                cmd->error = 0;
                host->ops->request(host, mrq);
        } else if (mrq->done) {
                mrq->done(mrq);
        }
}

EXPORT_SYMBOL(mmc_request_done);

/**
 *      mmc_start_request - start a command on a host
 *      @host: MMC host to start command on
 *      @mrq: MMC request to start
 *
 *      Queue a command on the specified host.  We expect the
 *      caller to be holding the host lock with interrupts disabled.
 */
void
mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
{
        pr_debug("%s: starting CMD%u arg %08x flags %08x\n",
                 mmc_hostname(host), mrq->cmd->opcode,
                 mrq->cmd->arg, mrq->cmd->flags);

        WARN_ON(host->card_busy == NULL);

        mrq->cmd->error = 0;
        mrq->cmd->mrq = mrq;
        if (mrq->data) {
                mrq->cmd->data = mrq->data;
                mrq->data->error = 0;
                mrq->data->mrq = mrq;
                if (mrq->stop) {
                        mrq->data->stop = mrq->stop;
                        mrq->stop->error = 0;
                        mrq->stop->mrq = mrq;
                }
        }
        host->ops->request(host, mrq);
}

EXPORT_SYMBOL(mmc_start_request);

static void mmc_wait_done(struct mmc_request *mrq)
{
        complete(mrq->done_data);
}

int mmc_wait_for_req(struct mmc_host *host, struct mmc_request *mrq)
{
        DECLARE_COMPLETION(complete);

        mrq->done_data = &complete;
        mrq->done = mmc_wait_done;

        mmc_start_request(host, mrq);

        wait_for_completion(&complete);

        return 0;
}

EXPORT_SYMBOL(mmc_wait_for_req);

/**
 *      mmc_wait_for_cmd - start a command and wait for completion
 *      @host: MMC host to start command
 *      @cmd: MMC command to start
 *      @retries: maximum number of retries
 *
 *      Start a new MMC command for a host, and wait for the command
 *      to complete.  Return any error that occurred while the command
 *      was executing.  Do not attempt to parse the response.
 */
int mmc_wait_for_cmd(struct mmc_host *host, struct mmc_command *cmd, int retries)
{
        struct mmc_request mrq;

        BUG_ON(host->card_busy == NULL);

        memset(&mrq, 0, sizeof(struct mmc_request));

        memset(cmd->resp, 0, sizeof(cmd->resp));
        cmd->retries = retries;

        mrq.cmd = cmd;
        cmd->data = NULL;

        mmc_wait_for_req(host, &mrq);

        return cmd->error;
}

EXPORT_SYMBOL(mmc_wait_for_cmd);

/**
 *      mmc_wait_for_app_cmd - start an application command and wait for
                               completion
 *      @host: MMC host to start command
 *      @rca: RCA to send MMC_APP_CMD to
 *      @cmd: MMC command to start
 *      @retries: maximum number of retries
 *
 *      Sends a MMC_APP_CMD, checks the card response, sends the command
 *      in the parameter and waits for it to complete. Return any error
 *      that occurred while the command was executing.  Do not attempt to
 *      parse the response.
 */
int mmc_wait_for_app_cmd(struct mmc_host *host, unsigned int rca,
        struct mmc_command *cmd, int retries)
{
        struct mmc_request mrq;
        struct mmc_command appcmd;

        int i, err;

        BUG_ON(host->card_busy == NULL);
        BUG_ON(retries < 0);

        err = MMC_ERR_INVALID;

        /*
         * We have to resend MMC_APP_CMD for each attempt so
         * we cannot use the retries field in mmc_command.
         */
        for (i = 0;i <= retries;i++) {
                memset(&mrq, 0, sizeof(struct mmc_request));

                appcmd.opcode = MMC_APP_CMD;
                appcmd.arg = rca << 16;
                appcmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
                appcmd.retries = 0;
                memset(appcmd.resp, 0, sizeof(appcmd.resp));
                appcmd.data = NULL;

                mrq.cmd = &appcmd;
                appcmd.data = NULL;

                mmc_wait_for_req(host, &mrq);

                if (appcmd.error) {
                        err = appcmd.error;
                        continue;
                }

                /* Check that card supported application commands */
                if (!(appcmd.resp[0] & R1_APP_CMD))
                        return MMC_ERR_FAILED;

                memset(&mrq, 0, sizeof(struct mmc_request));

                memset(cmd->resp, 0, sizeof(cmd->resp));
                cmd->retries = 0;

                mrq.cmd = cmd;
                cmd->data = NULL;

                mmc_wait_for_req(host, &mrq);

                err = cmd->error;
                if (cmd->error == MMC_ERR_NONE)
                        break;
        }

        return err;
}

EXPORT_SYMBOL(mmc_wait_for_app_cmd);

static int mmc_select_card(struct mmc_host *host, struct mmc_card *card);

/**
 *      __mmc_claim_host - exclusively claim a host
 *      @host: mmc host to claim
 *      @card: mmc card to claim host for
 *
 *      Claim a host for a set of operations.  If a valid card
 *      is passed and this wasn't the last card selected, select
 *      the card before returning.
 *
 *      Note: you should use mmc_card_claim_host or mmc_claim_host.
 */
int __mmc_claim_host(struct mmc_host *host, struct mmc_card *card)
{
        DECLARE_WAITQUEUE(wait, current);
        unsigned long flags;
        int err = 0;

        add_wait_queue(&host->wq, &wait);
        spin_lock_irqsave(&host->lock, flags);
        while (1) {
                set_current_state(TASK_UNINTERRUPTIBLE);
                if (host->card_busy == NULL)
                        break;
                spin_unlock_irqrestore(&host->lock, flags);
                schedule();
                spin_lock_irqsave(&host->lock, flags);
        }
        set_current_state(TASK_RUNNING);
        host->card_busy = card;
        spin_unlock_irqrestore(&host->lock, flags);
        remove_wait_queue(&host->wq, &wait);

        if (card != (void *)-1) {
                err = mmc_select_card(host, card);
                if (err != MMC_ERR_NONE)
                        return err;
        }

        return err;
}

EXPORT_SYMBOL(__mmc_claim_host);

/**
 *      mmc_release_host - release a host
 *      @host: mmc host to release
 *
 *      Release a MMC host, allowing others to claim the host
 *      for their operations.
 */
void mmc_release_host(struct mmc_host *host)
{
        unsigned long flags;

        BUG_ON(host->card_busy == NULL);

        spin_lock_irqsave(&host->lock, flags);
        host->card_busy = NULL;
        spin_unlock_irqrestore(&host->lock, flags);

        wake_up(&host->wq);
}

EXPORT_SYMBOL(mmc_release_host);

static inline void mmc_set_ios(struct mmc_host *host)
{
        struct mmc_ios *ios = &host->ios;

        pr_debug("%s: clock %uHz busmode %u powermode %u cs %u Vdd %u width %u\n",
                 mmc_hostname(host), ios->clock, ios->bus_mode,
                 ios->power_mode, ios->chip_select, ios->vdd,
                 ios->bus_width);
        
        host->ops->set_ios(host, ios);
}

static int mmc_select_card(struct mmc_host *host, struct mmc_card *card)
{
        int err;
        struct mmc_command cmd;

        BUG_ON(host->card_busy == NULL);

        if (host->card_selected == card)
                return MMC_ERR_NONE;

        host->card_selected = card;

        cmd.opcode = MMC_SELECT_CARD;
        cmd.arg = card->rca << 16;
        cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;

        err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
        if (err != MMC_ERR_NONE)
                return err;

        /*
         * Default bus width is 1 bit.
         */
        host->ios.bus_width = MMC_BUS_WIDTH_1;

        /*
         * We can only change the bus width of the selected
         * card so therefore we have to put the handling
         * here.
         */
        if (host->caps & MMC_CAP_4_BIT_DATA) {
                /*
                 * The card is in 1 bit mode by default so
                 * we only need to change if it supports the
                 * wider version.
                 */
                if (mmc_card_sd(card) &&
                        (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
                        struct mmc_command cmd;
                        cmd.opcode = SD_APP_SET_BUS_WIDTH;
                        cmd.arg = SD_BUS_WIDTH_4;
                        cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;

                        err = mmc_wait_for_app_cmd(host, card->rca, &cmd,
                                CMD_RETRIES);
                        if (err != MMC_ERR_NONE)
                                return err;

                        host->ios.bus_width = MMC_BUS_WIDTH_4;
                }
        }

        mmc_set_ios(host);

        return MMC_ERR_NONE;
}

/*
 * Ensure that no card is selected.
 */
static void mmc_deselect_cards(struct mmc_host *host)
{
        struct mmc_command cmd;

        if (host->card_selected) {
                host->card_selected = NULL;

                cmd.opcode = MMC_SELECT_CARD;
                cmd.arg = 0;
                cmd.flags = MMC_RSP_NONE | MMC_CMD_AC;

                mmc_wait_for_cmd(host, &cmd, 0);
        }
}


static inline void mmc_delay(unsigned int ms)
{
        if (ms < HZ / 1000) {
                yield();
                mdelay(ms);
        } else {
                msleep_interruptible (ms);
        }
}

/*
 * Mask off any voltages we don't support and select
 * the lowest voltage
 */
static u32 mmc_select_voltage(struct mmc_host *host, u32 ocr)
{
        int bit;

        ocr &= host->ocr_avail;

        bit = ffs(ocr);
        if (bit) {
                bit -= 1;

                ocr = 3 << bit;

                host->ios.vdd = bit;
                mmc_set_ios(host);
        } else {
                ocr = 0;
        }

        return ocr;
}

#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.
 */
static void mmc_decode_cid(struct mmc_card *card)
{
        u32 *resp = card->raw_cid;

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

        if (mmc_card_sd(card)) {
                /*
                 * 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 */
        } else {
                /*
                 * The selection of the format here is based upon published
                 * specs from sandisk and from what people have reported.
                 */
                switch (card->csd.mmca_vsn) {
                case 0: /* MMC v1.0 - v1.2 */
                case 1: /* MMC v1.4 */
                        card->cid.manfid        = UNSTUFF_BITS(resp, 104, 24);
                        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.prod_name[5]  = UNSTUFF_BITS(resp, 56, 8);
                        card->cid.prod_name[6]  = UNSTUFF_BITS(resp, 48, 8);
                        card->cid.hwrev         = UNSTUFF_BITS(resp, 44, 4);
                        card->cid.fwrev         = UNSTUFF_BITS(resp, 40, 4);
                        card->cid.serial        = UNSTUFF_BITS(resp, 16, 24);
                        card->cid.month         = UNSTUFF_BITS(resp, 12, 4);
                        card->cid.year          = UNSTUFF_BITS(resp, 8, 4) + 1997;
                        break;

                case 2: /* MMC v2.0 - v2.2 */
                case 3: /* MMC v3.1 - v3.3 */
                case 4: /* MMC v4 */
                        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.prod_name[5]  = UNSTUFF_BITS(resp, 56, 8);
                        card->cid.serial        = UNSTUFF_BITS(resp, 16, 32);
                        card->cid.month         = UNSTUFF_BITS(resp, 12, 4);
                        card->cid.year          = UNSTUFF_BITS(resp, 8, 4) + 1997;
                        break;

                default:
                        printk("%s: card has unknown MMCA version %d\n",
                                mmc_hostname(card->host), card->csd.mmca_vsn);
                        mmc_card_set_bad(card);
                        break;
                }
        }
}

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

        if (mmc_card_sd(card)) {
                csd_struct = UNSTUFF_BITS(resp, 126, 2);
                if (csd_struct != 0) {
                        printk("%s: unrecognised CSD structure version %d\n",
                                mmc_hostname(card->host), csd_struct);
                        mmc_card_set_bad(card);
                        return;
                }

                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);
        } else {
                /*
                 * We only understand CSD structure v1.1 and v1.2.
                 * v1.2 has extra information in bits 15, 11 and 10.
                 */
                csd_struct = UNSTUFF_BITS(resp, 126, 2);
                if (csd_struct != 1 && csd_struct != 2) {
                        printk("%s: unrecognised CSD structure version %d\n",
                                mmc_hostname(card->host), csd_struct);
                        mmc_card_set_bad(card);
                        return;
                }

                csd->mmca_vsn    = UNSTUFF_BITS(resp, 122, 4);
                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);
        }
}

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

        BUG_ON(!mmc_card_sd(card));

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

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

        scr->sda_vsn = UNSTUFF_BITS(resp, 56, 4);
        scr->bus_widths = UNSTUFF_BITS(resp, 48, 4);
}

/*
 * Locate a MMC card on this MMC host given a raw CID.
 */
static struct mmc_card *mmc_find_card(struct mmc_host *host, u32 *raw_cid)
{
        struct mmc_card *card;

        list_for_each_entry(card, &host->cards, node) {
                if (memcmp(card->raw_cid, raw_cid, sizeof(card->raw_cid)) == 0)
                        return card;
        }
        return NULL;
}

/*
 * Allocate a new MMC card, and assign a unique RCA.
 */
static struct mmc_card *
mmc_alloc_card(struct mmc_host *host, u32 *raw_cid, unsigned int *frca)
{
        struct mmc_card *card, *c;
        unsigned int rca = *frca;

        card = kmalloc(sizeof(struct mmc_card), GFP_KERNEL);
        if (!card)
                return ERR_PTR(-ENOMEM);

        mmc_init_card(card, host);
        memcpy(card->raw_cid, raw_cid, sizeof(card->raw_cid));

 again:
        list_for_each_entry(c, &host->cards, node)
                if (c->rca == rca) {
                        rca++;
                        goto again;
                }

        card->rca = rca;

        *frca = rca;

        return card;
}

/*
 * Tell attached cards to go to IDLE state
 */
static void mmc_idle_cards(struct mmc_host *host)
{
        struct mmc_command cmd;

        host->ios.chip_select = MMC_CS_HIGH;
        mmc_set_ios(host);

        mmc_delay(1);

        cmd.opcode = MMC_GO_IDLE_STATE;
        cmd.arg = 0;
        cmd.flags = MMC_RSP_NONE | MMC_CMD_BC;

        mmc_wait_for_cmd(host, &cmd, 0);

        mmc_delay(1);

        host->ios.chip_select = MMC_CS_DONTCARE;
        mmc_set_ios(host);

        mmc_delay(1);
}

/*
 * Apply power to the MMC stack.  This is a two-stage process.
 * First, we enable power to the card without the clock running.
 * We then wait a bit for the power to stabilise.  Finally,
 * enable the bus drivers and clock to the card.
 *
 * We must _NOT_ enable the clock prior to power stablising.
 *
 * If a host does all the power sequencing itself, ignore the
 * initial MMC_POWER_UP stage.
 */
static void mmc_power_up(struct mmc_host *host)
{
        int bit = fls(host->ocr_avail) - 1;

        host->ios.vdd = bit;
        host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
        host->ios.chip_select = MMC_CS_DONTCARE;
        host->ios.power_mode = MMC_POWER_UP;
        host->ios.bus_width = MMC_BUS_WIDTH_1;
        mmc_set_ios(host);

        mmc_delay(1);

        host->ios.clock = host->f_min;
        host->ios.power_mode = MMC_POWER_ON;
        mmc_set_ios(host);

        mmc_delay(2);
}

static void mmc_power_off(struct mmc_host *host)
{
        host->ios.clock = 0;
        host->ios.vdd = 0;
        host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
        host->ios.chip_select = MMC_CS_DONTCARE;
        host->ios.power_mode = MMC_POWER_OFF;
        host->ios.bus_width = MMC_BUS_WIDTH_1;
        mmc_set_ios(host);
}

static int mmc_send_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
{
        struct mmc_command cmd;
        int i, err = 0;

        cmd.opcode = MMC_SEND_OP_COND;
        cmd.arg = ocr;
        cmd.flags = MMC_RSP_R3 | MMC_CMD_BCR;

        for (i = 100; i; i--) {
                err = mmc_wait_for_cmd(host, &cmd, 0);
                if (err != MMC_ERR_NONE)
                        break;

                if (cmd.resp[0] & MMC_CARD_BUSY || ocr == 0)
                        break;

                err = MMC_ERR_TIMEOUT;

                mmc_delay(10);
        }

        if (rocr)
                *rocr = cmd.resp[0];

        return err;
}

static int mmc_send_app_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
{
        struct mmc_command cmd;
        int i, err = 0;

        cmd.opcode = SD_APP_OP_COND;
        cmd.arg = ocr;
        cmd.flags = MMC_RSP_R3 | MMC_CMD_BCR;

        for (i = 100; i; i--) {
                err = mmc_wait_for_app_cmd(host, 0, &cmd, CMD_RETRIES);
                if (err != MMC_ERR_NONE)
                        break;

                if (cmd.resp[0] & MMC_CARD_BUSY || ocr == 0)
                        break;

                err = MMC_ERR_TIMEOUT;

                mmc_delay(10);
        }

        if (rocr)
                *rocr = cmd.resp[0];

        return err;
}

/*
 * Discover cards by requesting their CID.  If this command
 * times out, it is not an error; there are no further cards
 * to be discovered.  Add new cards to the list.
 *
 * Create a mmc_card entry for each discovered card, assigning
 * it an RCA, and save the raw CID for decoding later.
 */
static void mmc_discover_cards(struct mmc_host *host)
{
        struct mmc_card *card;
        unsigned int first_rca = 1, err;

        while (1) {
                struct mmc_command cmd;

                cmd.opcode = MMC_ALL_SEND_CID;
                cmd.arg = 0;
                cmd.flags = MMC_RSP_R2 | MMC_CMD_BCR;

                err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
                if (err == MMC_ERR_TIMEOUT) {
                        err = MMC_ERR_NONE;
                        break;
                }
                if (err != MMC_ERR_NONE) {
                        printk(KERN_ERR "%s: error requesting CID: %d\n",
                                mmc_hostname(host), err);
                        break;
                }

                card = mmc_find_card(host, cmd.resp);
                if (!card) {
                        card = mmc_alloc_card(host, cmd.resp, &first_rca);
                        if (IS_ERR(card)) {
                                err = PTR_ERR(card);
                                break;
                        }
                        list_add(&card->node, &host->cards);
                }

                card->state &= ~MMC_STATE_DEAD;

                if (host->mode == MMC_MODE_SD) {
                        mmc_card_set_sd(card);

                        cmd.opcode = SD_SEND_RELATIVE_ADDR;
                        cmd.arg = 0;
                        cmd.flags = MMC_RSP_R6 | MMC_CMD_BCR;

                        err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
                        if (err != MMC_ERR_NONE)
                                mmc_card_set_dead(card);
                        else {
                                card->rca = cmd.resp[0] >> 16;

                                if (!host->ops->get_ro) {
                                        printk(KERN_WARNING "%s: host does not "
                                                "support reading read-only "
                                                "switch. assuming write-enable.\n",
                                                mmc_hostname(host));
                                } else {
                                        if (host->ops->get_ro(host))
                                                mmc_card_set_readonly(card);
                                }
                        }
                } else {
                        cmd.opcode = MMC_SET_RELATIVE_ADDR;
                        cmd.arg = card->rca << 16;
                        cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;

                        err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
                        if (err != MMC_ERR_NONE)
                                mmc_card_set_dead(card);
                }
        }
}

static void mmc_read_csds(struct mmc_host *host)
{
        struct mmc_card *card;

        list_for_each_entry(card, &host->cards, node) {
                struct mmc_command cmd;
                int err;

                if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
                        continue;

                cmd.opcode = MMC_SEND_CSD;
                cmd.arg = card->rca << 16;
                cmd.flags = MMC_RSP_R2 | MMC_CMD_AC;

                err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
                if (err != MMC_ERR_NONE) {
                        mmc_card_set_dead(card);
                        continue;
                }

                memcpy(card->raw_csd, cmd.resp, sizeof(card->raw_csd));

                mmc_decode_csd(card);
                mmc_decode_cid(card);
        }
}

static void mmc_read_scrs(struct mmc_host *host)
{
        int err;
        struct mmc_card *card;

        struct mmc_request mrq;
        struct mmc_command cmd;
        struct mmc_data data;

        struct scatterlist sg;

        list_for_each_entry(card, &host->cards, node) {
                if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
                        continue;
                if (!mmc_card_sd(card))
                        continue;

                err = mmc_select_card(host, card);
                if (err != MMC_ERR_NONE) {
                        mmc_card_set_dead(card);
                        continue;
                }

                memset(&cmd, 0, sizeof(struct mmc_command));

                cmd.opcode = MMC_APP_CMD;
                cmd.arg = card->rca << 16;
                cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;

                err = mmc_wait_for_cmd(host, &cmd, 0);
                if ((err != MMC_ERR_NONE) || !(cmd.resp[0] & R1_APP_CMD)) {
                        mmc_card_set_dead(card);
                        continue;
                }

                memset(&cmd, 0, sizeof(struct mmc_command));

                cmd.opcode = SD_APP_SEND_SCR;
                cmd.arg = 0;
                cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;

                memset(&data, 0, sizeof(struct mmc_data));

                data.timeout_ns = card->csd.tacc_ns * 10;
                data.timeout_clks = card->csd.tacc_clks * 10;
                data.blksz_bits = 3;
                data.blksz = 1 << 3;
                data.blocks = 1;
                data.flags = MMC_DATA_READ;
                data.sg = &sg;
                data.sg_len = 1;

                memset(&mrq, 0, sizeof(struct mmc_request));

                mrq.cmd = &cmd;
                mrq.data = &data;

                sg_init_one(&sg, (u8*)card->raw_scr, 8);

                mmc_wait_for_req(host, &mrq);

                if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
                        mmc_card_set_dead(card);
                        continue;
                }

                card->raw_scr[0] = ntohl(card->raw_scr[0]);
                card->raw_scr[1] = ntohl(card->raw_scr[1]);

                mmc_decode_scr(card);
        }

        mmc_deselect_cards(host);
}

static unsigned int mmc_calculate_clock(struct mmc_host *host)
{
        struct mmc_card *card;
        unsigned int max_dtr = host->f_max;

        list_for_each_entry(card, &host->cards, node)
                if (!mmc_card_dead(card) && max_dtr > card->csd.max_dtr)
                        max_dtr = card->csd.max_dtr;

        pr_debug("%s: selected %d.%03dMHz transfer rate\n",
                 mmc_hostname(host),
                 max_dtr / 1000000, (max_dtr / 1000) % 1000);

        return max_dtr;
}

/*
 * Check whether cards we already know about are still present.
 * We do this by requesting status, and checking whether a card
 * responds.
 *
 * A request for status does not cause a state change in data
 * transfer mode.
 */
static void mmc_check_cards(struct mmc_host *host)
{
        struct list_head *l, *n;

        mmc_deselect_cards(host);

        list_for_each_safe(l, n, &host->cards) {
                struct mmc_card *card = mmc_list_to_card(l);
                struct mmc_command cmd;
                int err;

                cmd.opcode = MMC_SEND_STATUS;
                cmd.arg = card->rca << 16;
                cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;

                err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
                if (err == MMC_ERR_NONE)
                        continue;

                mmc_card_set_dead(card);
        }
}

static void mmc_setup(struct mmc_host *host)
{
        if (host->ios.power_mode != MMC_POWER_ON) {
                int err;
                u32 ocr;

                host->mode = MMC_MODE_SD;

                mmc_power_up(host);
                mmc_idle_cards(host);

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

                /*
                 * If we fail to detect any SD cards then try
                 * searching for MMC cards.
                 */
                if (err != MMC_ERR_NONE) {
                        host->mode = MMC_MODE_MMC;

                        err = mmc_send_op_cond(host, 0, &ocr);
                        if (err != MMC_ERR_NONE)
                                return;
                }

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

                /*
                 * 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.
                 */
                if (host->ocr)
                        mmc_idle_cards(host);
        } else {
                host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
                host->ios.clock = host->f_min;
                mmc_set_ios(host);

                /*
                 * We should remember the OCR mask from the existing
                 * cards, and detect the new cards OCR mask, combine
                 * the two and re-select the VDD.  However, if we do
                 * change VDD, we should do an idle, and then do a
                 * full re-initialisation.  We would need to notify
                 * drivers so that they can re-setup the cards as
                 * well, while keeping their queues at bay.
                 *
                 * For the moment, we take the easy way out - if the
                 * new cards don't like our currently selected VDD,
                 * they drop off the bus.
                 */
        }

        if (host->ocr == 0)
                return;

        /*
         * Send the selected OCR multiple times... until the cards
         * all get the idea that they should be ready for CMD2.
         * (My SanDisk card seems to need this.)
         */
        if (host->mode == MMC_MODE_SD)
                mmc_send_app_op_cond(host, host->ocr, NULL);
        else
                mmc_send_op_cond(host, host->ocr, NULL);

        mmc_discover_cards(host);

        /*
         * Ok, now switch to push-pull mode.
         */
        host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
        mmc_set_ios(host);

        mmc_read_csds(host);

        if (host->mode == MMC_MODE_SD)
                mmc_read_scrs(host);
}


/**
 *      mmc_detect_change - process change of state on a MMC socket
 *      @host: host which changed state.
 *      @delay: optional delay to wait before detection (jiffies)
 *
 *      All we know is that card(s) have been inserted or removed
 *      from the socket(s).  We don't know which socket or cards.
 */
void mmc_detect_change(struct mmc_host *host, unsigned long delay)
{
        if (delay)
                schedule_delayed_work(&host->detect, delay);
        else
                schedule_work(&host->detect);
}

EXPORT_SYMBOL(mmc_detect_change);


static void mmc_rescan(void *data)
{
        struct mmc_host *host = data;
        struct list_head *l, *n;

        mmc_claim_host(host);

        if (host->ios.power_mode == MMC_POWER_ON)
                mmc_check_cards(host);

        mmc_setup(host);

        if (!list_empty(&host->cards)) {
                /*
                 * (Re-)calculate the fastest clock rate which the
                 * attached cards and the host support.
                 */
                host->ios.clock = mmc_calculate_clock(host);
                mmc_set_ios(host);
        }

        mmc_release_host(host);

        list_for_each_safe(l, n, &host->cards) {
                struct mmc_card *card = mmc_list_to_card(l);

                /*
                 * If this is a new and good card, register it.
                 */
                if (!mmc_card_present(card) && !mmc_card_dead(card)) {
                        if (mmc_register_card(card))
                                mmc_card_set_dead(card);
                        else
                                mmc_card_set_present(card);
                }

                /*
                 * If this card is dead, destroy it.
                 */
                if (mmc_card_dead(card)) {
                        list_del(&card->node);
                        mmc_remove_card(card);
                }
        }

        /*
         * If we discover that there are no cards on the
         * bus, turn off the clock and power down.
         */
        if (list_empty(&host->cards))
                mmc_power_off(host);
}


/**
 *      mmc_alloc_host - initialise the per-host structure.
 *      @extra: sizeof private data structure
 *      @dev: pointer to host device model structure
 *
 *      Initialise the per-host structure.
 */
struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
{
        struct mmc_host *host;

        host = mmc_alloc_host_sysfs(extra, dev);
        if (host) {
                spin_lock_init(&host->lock);
                init_waitqueue_head(&host->wq);
                INIT_LIST_HEAD(&host->cards);
                INIT_WORK(&host->detect, mmc_rescan, host);

                /*
                 * By default, hosts do not support SGIO or large requests.
                 * They have to set these according to their abilities.
                 */
                host->max_hw_segs = 1;
                host->max_phys_segs = 1;
                host->max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
                host->max_seg_size = PAGE_CACHE_SIZE;
        }

        return host;
}

EXPORT_SYMBOL(mmc_alloc_host);

/**
 *      mmc_add_host - initialise host hardware
 *      @host: mmc host
 */
int mmc_add_host(struct mmc_host *host)
{
        int ret;

        ret = mmc_add_host_sysfs(host);
        if (ret == 0) {
                mmc_power_off(host);
                mmc_detect_change(host, 0);
        }

        return ret;
}

EXPORT_SYMBOL(mmc_add_host);

/**
 *      mmc_remove_host - remove host hardware
 *      @host: mmc host
 *
 *      Unregister and remove all cards associated with this host,
 *      and power down the MMC bus.
 */
void mmc_remove_host(struct mmc_host *host)
{
        struct list_head *l, *n;

        list_for_each_safe(l, n, &host->cards) {
                struct mmc_card *card = mmc_list_to_card(l);

                mmc_remove_card(card);
        }

        mmc_power_off(host);
        mmc_remove_host_sysfs(host);
}

EXPORT_SYMBOL(mmc_remove_host);

/**
 *      mmc_free_host - free the host structure
 *      @host: mmc host
 *
 *      Free the host once all references to it have been dropped.
 */
void mmc_free_host(struct mmc_host *host)
{
        flush_scheduled_work();
        mmc_free_host_sysfs(host);
}

EXPORT_SYMBOL(mmc_free_host);

#ifdef CONFIG_PM

/**
 *      mmc_suspend_host - suspend a host
 *      @host: mmc host
 *      @state: suspend mode (PM_SUSPEND_xxx)
 */
int mmc_suspend_host(struct mmc_host *host, pm_message_t state)
{
        mmc_claim_host(host);
        mmc_deselect_cards(host);
        mmc_power_off(host);
        mmc_release_host(host);

        return 0;
}

EXPORT_SYMBOL(mmc_suspend_host);

/**
 *      mmc_resume_host - resume a previously suspended host
 *      @host: mmc host
 */
int mmc_resume_host(struct mmc_host *host)
{
        mmc_rescan(host);

        return 0;
}

EXPORT_SYMBOL(mmc_resume_host);

#endif

MODULE_LICENSE("GPL");