mmc: add 'enable' and 'disable' methods to mmc host

[safe/jmp/linux-2.6] / drivers / mmc / core / core.c

/*
 *  linux/drivers/mmc/core/core.c
 *
 *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
 *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.
 *  Copyright (C) 2005-2008 Pierre Ossman, All Rights Reserved.
 *  MMCv4 support Copyright (C) 2006 Philip Langdale, 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/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 <linux/leds.h>
#include <linux/scatterlist.h>
#include <linux/log2.h>
#include <linux/regulator/consumer.h>

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

#include "core.h"
#include "bus.h"
#include "host.h"
#include "sdio_bus.h"

#include "mmc_ops.h"
#include "sd_ops.h"
#include "sdio_ops.h"

static struct workqueue_struct *workqueue;

/*
 * Enabling software CRCs on the data blocks can be a significant (30%)
 * performance cost, and for other reasons may not always be desired.
 * So we allow it it to be disabled.
 */
int use_spi_crc = 1;
module_param(use_spi_crc, bool, 0);

/*
 * Internal function. Schedule delayed work in the MMC work queue.
 */
static int mmc_schedule_delayed_work(struct delayed_work *work,
                                     unsigned long delay)
{
        return queue_delayed_work(workqueue, work, delay);
}

/*
 * Internal function. Flush all scheduled work from the MMC work queue.
 */
static void mmc_flush_scheduled_work(void)
{
        flush_workqueue(workqueue);
}

/**
 *      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;

        if (err && cmd->retries && mmc_host_is_spi(host)) {
                if (cmd->resp[0] & R1_SPI_ILLEGAL_COMMAND)
                        cmd->retries = 0;
        }

        if (err && cmd->retries) {
                pr_debug("%s: req failed (CMD%u): %d, retrying...\n",
                        mmc_hostname(host), cmd->opcode, err);

                cmd->retries--;
                cmd->error = 0;
                host->ops->request(host, mrq);
        } else {
                led_trigger_event(host->led, LED_OFF);

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

                if (mrq->data) {
                        pr_debug("%s:     %d bytes transferred: %d\n",
                                mmc_hostname(host),
                                mrq->data->bytes_xfered, mrq->data->error);
                }

                if (mrq->stop) {
                        pr_debug("%s:     (CMD%u): %d: %08x %08x %08x %08x\n",
                                mmc_hostname(host), mrq->stop->opcode,
                                mrq->stop->error,
                                mrq->stop->resp[0], mrq->stop->resp[1],
                                mrq->stop->resp[2], mrq->stop->resp[3]);
                }

                if (mrq->done)
                        mrq->done(mrq);
        }
}

EXPORT_SYMBOL(mmc_request_done);

static void
mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
{
#ifdef CONFIG_MMC_DEBUG
        unsigned int i, sz;
        struct scatterlist *sg;
#endif

        pr_debug("%s: starting CMD%u arg %08x flags %08x\n",
                 mmc_hostname(host), mrq->cmd->opcode,
                 mrq->cmd->arg, mrq->cmd->flags);

        if (mrq->data) {
                pr_debug("%s:     blksz %d blocks %d flags %08x "
                        "tsac %d ms nsac %d\n",
                        mmc_hostname(host), mrq->data->blksz,
                        mrq->data->blocks, mrq->data->flags,
                        mrq->data->timeout_ns / 1000000,
                        mrq->data->timeout_clks);
        }

        if (mrq->stop) {
                pr_debug("%s:     CMD%u arg %08x flags %08x\n",
                         mmc_hostname(host), mrq->stop->opcode,
                         mrq->stop->arg, mrq->stop->flags);
        }

        WARN_ON(!host->claimed);

        led_trigger_event(host->led, LED_FULL);

        mrq->cmd->error = 0;
        mrq->cmd->mrq = mrq;
        if (mrq->data) {
                BUG_ON(mrq->data->blksz > host->max_blk_size);
                BUG_ON(mrq->data->blocks > host->max_blk_count);
                BUG_ON(mrq->data->blocks * mrq->data->blksz >
                        host->max_req_size);

#ifdef CONFIG_MMC_DEBUG
                sz = 0;
                for_each_sg(mrq->data->sg, sg, mrq->data->sg_len, i)
                        sz += sg->length;
                BUG_ON(sz != mrq->data->blocks * mrq->data->blksz);
#endif

                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);
}

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

/**
 *      mmc_wait_for_req - start a request and wait for completion
 *      @host: MMC host to start command
 *      @mrq: MMC request to start
 *
 *      Start a new MMC custom command request for a host, and wait
 *      for the command to complete. Does not attempt to parse the
 *      response.
 */
void mmc_wait_for_req(struct mmc_host *host, struct mmc_request *mrq)
{
        DECLARE_COMPLETION_ONSTACK(complete);

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

        mmc_start_request(host, mrq);

        wait_for_completion(&complete);
}

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;

        WARN_ON(!host->claimed);

        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_set_data_timeout - set the timeout for a data command
 *      @data: data phase for command
 *      @card: the MMC card associated with the data transfer
 *
 *      Computes the data timeout parameters according to the
 *      correct algorithm given the card type.
 */
void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
{
        unsigned int mult;

        /*
         * SDIO cards only define an upper 1 s limit on access.
         */
        if (mmc_card_sdio(card)) {
                data->timeout_ns = 1000000000;
                data->timeout_clks = 0;
                return;
        }

        /*
         * SD cards use a 100 multiplier rather than 10
         */
        mult = mmc_card_sd(card) ? 100 : 10;

        /*
         * Scale up the multiplier (and therefore the timeout) by
         * the r2w factor for writes.
         */
        if (data->flags & MMC_DATA_WRITE)
                mult <<= card->csd.r2w_factor;

        data->timeout_ns = card->csd.tacc_ns * mult;
        data->timeout_clks = card->csd.tacc_clks * mult;

        /*
         * SD cards also have an upper limit on the timeout.
         */
        if (mmc_card_sd(card)) {
                unsigned int timeout_us, limit_us;

                timeout_us = data->timeout_ns / 1000;
                timeout_us += data->timeout_clks * 1000 /
                        (card->host->ios.clock / 1000);

                if (data->flags & MMC_DATA_WRITE)
                        /*
                         * The limit is really 250 ms, but that is
                         * insufficient for some crappy cards.
                         */
                        limit_us = 300000;
                else
                        limit_us = 100000;

                /*
                 * SDHC cards always use these fixed values.
                 */
                if (timeout_us > limit_us || mmc_card_blockaddr(card)) {
                        data->timeout_ns = limit_us * 1000;
                        data->timeout_clks = 0;
                }
        }
        /*
         * Some cards need very high timeouts if driven in SPI mode.
         * The worst observed timeout was 900ms after writing a
         * continuous stream of data until the internal logic
         * overflowed.
         */
        if (mmc_host_is_spi(card->host)) {
                if (data->flags & MMC_DATA_WRITE) {
                        if (data->timeout_ns < 1000000000)
                                data->timeout_ns = 1000000000;  /* 1s */
                } else {
                        if (data->timeout_ns < 100000000)
                                data->timeout_ns =  100000000;  /* 100ms */
                }
        }
}
EXPORT_SYMBOL(mmc_set_data_timeout);

/**
 *      mmc_align_data_size - pads a transfer size to a more optimal value
 *      @card: the MMC card associated with the data transfer
 *      @sz: original transfer size
 *
 *      Pads the original data size with a number of extra bytes in
 *      order to avoid controller bugs and/or performance hits
 *      (e.g. some controllers revert to PIO for certain sizes).
 *
 *      Returns the improved size, which might be unmodified.
 *
 *      Note that this function is only relevant when issuing a
 *      single scatter gather entry.
 */
unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz)
{
        /*
         * FIXME: We don't have a system for the controller to tell
         * the core about its problems yet, so for now we just 32-bit
         * align the size.
         */
        sz = ((sz + 3) / 4) * 4;

        return sz;
}
EXPORT_SYMBOL(mmc_align_data_size);

/**
 *      mmc_host_enable - enable a host.
 *      @host: mmc host to enable
 *
 *      Hosts that support power saving can use the 'enable' and 'disable'
 *      methods to exit and enter power saving states. For more information
 *      see comments for struct mmc_host_ops.
 */
int mmc_host_enable(struct mmc_host *host)
{
        if (!(host->caps & MMC_CAP_DISABLE))
                return 0;

        if (host->en_dis_recurs)
                return 0;

        if (host->nesting_cnt++)
                return 0;

        cancel_delayed_work_sync(&host->disable);

        if (host->enabled)
                return 0;

        if (host->ops->enable) {
                int err;

                host->en_dis_recurs = 1;
                err = host->ops->enable(host);
                host->en_dis_recurs = 0;

                if (err) {
                        pr_debug("%s: enable error %d\n",
                                 mmc_hostname(host), err);
                        return err;
                }
        }
        host->enabled = 1;
        return 0;
}
EXPORT_SYMBOL(mmc_host_enable);

static int mmc_host_do_disable(struct mmc_host *host, int lazy)
{
        if (host->ops->disable) {
                int err;

                host->en_dis_recurs = 1;
                err = host->ops->disable(host, lazy);
                host->en_dis_recurs = 0;

                if (err < 0) {
                        pr_debug("%s: disable error %d\n",
                                 mmc_hostname(host), err);
                        return err;
                }
                if (err > 0) {
                        unsigned long delay = msecs_to_jiffies(err);

                        mmc_schedule_delayed_work(&host->disable, delay);
                }
        }
        host->enabled = 0;
        return 0;
}

/**
 *      mmc_host_disable - disable a host.
 *      @host: mmc host to disable
 *
 *      Hosts that support power saving can use the 'enable' and 'disable'
 *      methods to exit and enter power saving states. For more information
 *      see comments for struct mmc_host_ops.
 */
int mmc_host_disable(struct mmc_host *host)
{
        int err;

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

        if (host->en_dis_recurs)
                return 0;

        if (--host->nesting_cnt)
                return 0;

        if (!host->enabled)
                return 0;

        err = mmc_host_do_disable(host, 0);
        return err;
}
EXPORT_SYMBOL(mmc_host_disable);

/**
 *      __mmc_claim_host - exclusively claim a host
 *      @host: mmc host to claim
 *      @abort: whether or not the operation should be aborted
 *
 *      Claim a host for a set of operations.  If @abort is non null and
 *      dereference a non-zero value then this will return prematurely with
 *      that non-zero value without acquiring the lock.  Returns zero
 *      with the lock held otherwise.
 */
int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
{
        DECLARE_WAITQUEUE(wait, current);
        unsigned long flags;
        int stop;

        might_sleep();

        add_wait_queue(&host->wq, &wait);
        spin_lock_irqsave(&host->lock, flags);
        while (1) {
                set_current_state(TASK_UNINTERRUPTIBLE);
                stop = abort ? atomic_read(abort) : 0;
                if (stop || !host->claimed)
                        break;
                spin_unlock_irqrestore(&host->lock, flags);
                schedule();
                spin_lock_irqsave(&host->lock, flags);
        }
        set_current_state(TASK_RUNNING);
        if (!stop)
                host->claimed = 1;
        else
                wake_up(&host->wq);
        spin_unlock_irqrestore(&host->lock, flags);
        remove_wait_queue(&host->wq, &wait);
        if (!stop)
                mmc_host_enable(host);
        return stop;
}

EXPORT_SYMBOL(__mmc_claim_host);

static int mmc_try_claim_host(struct mmc_host *host)
{
        int claimed_host = 0;
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);
        if (!host->claimed) {
                host->claimed = 1;
                claimed_host = 1;
        }
        spin_unlock_irqrestore(&host->lock, flags);
        return claimed_host;
}

static void mmc_do_release_host(struct mmc_host *host)
{
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);
        host->claimed = 0;
        spin_unlock_irqrestore(&host->lock, flags);

        wake_up(&host->wq);
}

void mmc_host_deeper_disable(struct work_struct *work)
{
        struct mmc_host *host =
                container_of(work, struct mmc_host, disable.work);

        /* If the host is claimed then we do not want to disable it anymore */
        if (!mmc_try_claim_host(host))
                return;
        mmc_host_do_disable(host, 1);
        mmc_do_release_host(host);
}

/**
 *      mmc_host_lazy_disable - lazily disable a host.
 *      @host: mmc host to disable
 *
 *      Hosts that support power saving can use the 'enable' and 'disable'
 *      methods to exit and enter power saving states. For more information
 *      see comments for struct mmc_host_ops.
 */
int mmc_host_lazy_disable(struct mmc_host *host)
{
        if (!(host->caps & MMC_CAP_DISABLE))
                return 0;

        if (host->en_dis_recurs)
                return 0;

        if (--host->nesting_cnt)
                return 0;

        if (!host->enabled)
                return 0;

        if (host->disable_delay) {
                mmc_schedule_delayed_work(&host->disable,
                                msecs_to_jiffies(host->disable_delay));
                return 0;
        } else
                return mmc_host_do_disable(host, 1);
}
EXPORT_SYMBOL(mmc_host_lazy_disable);

/**
 *      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)
{
        WARN_ON(!host->claimed);

        mmc_host_lazy_disable(host);

        mmc_do_release_host(host);
}

EXPORT_SYMBOL(mmc_release_host);

/*
 * Internal function that does the actual ios call to the host driver,
 * optionally printing some debug output.
 */
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 timing %u\n",
                 mmc_hostname(host), ios->clock, ios->bus_mode,
                 ios->power_mode, ios->chip_select, ios->vdd,
                 ios->bus_width, ios->timing);

        host->ops->set_ios(host, ios);
}

/*
 * Control chip select pin on a host.
 */
void mmc_set_chip_select(struct mmc_host *host, int mode)
{
        host->ios.chip_select = mode;
        mmc_set_ios(host);
}

/*
 * Sets the host clock to the highest possible frequency that
 * is below "hz".
 */
void mmc_set_clock(struct mmc_host *host, unsigned int hz)
{
        WARN_ON(hz < host->f_min);

        if (hz > host->f_max)
                hz = host->f_max;

        host->ios.clock = hz;
        mmc_set_ios(host);
}

/*
 * Change the bus mode (open drain/push-pull) of a host.
 */
void mmc_set_bus_mode(struct mmc_host *host, unsigned int mode)
{
        host->ios.bus_mode = mode;
        mmc_set_ios(host);
}

/*
 * Change data bus width of a host.
 */
void mmc_set_bus_width(struct mmc_host *host, unsigned int width)
{
        host->ios.bus_width = width;
        mmc_set_ios(host);
}

/**
 * mmc_vdd_to_ocrbitnum - Convert a voltage to the OCR bit number
 * @vdd:        voltage (mV)
 * @low_bits:   prefer low bits in boundary cases
 *
 * This function returns the OCR bit number according to the provided @vdd
 * value. If conversion is not possible a negative errno value returned.
 *
 * Depending on the @low_bits flag the function prefers low or high OCR bits
 * on boundary voltages. For example,
 * with @low_bits = true, 3300 mV translates to ilog2(MMC_VDD_32_33);
 * with @low_bits = false, 3300 mV translates to ilog2(MMC_VDD_33_34);
 *
 * Any value in the [1951:1999] range translates to the ilog2(MMC_VDD_20_21).
 */
static int mmc_vdd_to_ocrbitnum(int vdd, bool low_bits)
{
        const int max_bit = ilog2(MMC_VDD_35_36);
        int bit;

        if (vdd < 1650 || vdd > 3600)
                return -EINVAL;

        if (vdd >= 1650 && vdd <= 1950)
                return ilog2(MMC_VDD_165_195);

        if (low_bits)
                vdd -= 1;

        /* Base 2000 mV, step 100 mV, bit's base 8. */
        bit = (vdd - 2000) / 100 + 8;
        if (bit > max_bit)
                return max_bit;
        return bit;
}

/**
 * mmc_vddrange_to_ocrmask - Convert a voltage range to the OCR mask
 * @vdd_min:    minimum voltage value (mV)
 * @vdd_max:    maximum voltage value (mV)
 *
 * This function returns the OCR mask bits according to the provided @vdd_min
 * and @vdd_max values. If conversion is not possible the function returns 0.
 *
 * Notes wrt boundary cases:
 * This function sets the OCR bits for all boundary voltages, for example
 * [3300:3400] range is translated to MMC_VDD_32_33 | MMC_VDD_33_34 |
 * MMC_VDD_34_35 mask.
 */
u32 mmc_vddrange_to_ocrmask(int vdd_min, int vdd_max)
{
        u32 mask = 0;

        if (vdd_max < vdd_min)
                return 0;

        /* Prefer high bits for the boundary vdd_max values. */
        vdd_max = mmc_vdd_to_ocrbitnum(vdd_max, false);
        if (vdd_max < 0)
                return 0;

        /* Prefer low bits for the boundary vdd_min values. */
        vdd_min = mmc_vdd_to_ocrbitnum(vdd_min, true);
        if (vdd_min < 0)
                return 0;

        /* Fill the mask, from max bit to min bit. */
        while (vdd_max >= vdd_min)
                mask |= 1 << vdd_max--;

        return mask;
}
EXPORT_SYMBOL(mmc_vddrange_to_ocrmask);

#ifdef CONFIG_REGULATOR

/**
 * mmc_regulator_get_ocrmask - return mask of supported voltages
 * @supply: regulator to use
 *
 * This returns either a negative errno, or a mask of voltages that
 * can be provided to MMC/SD/SDIO devices using the specified voltage
 * regulator.  This would normally be called before registering the
 * MMC host adapter.
 */
int mmc_regulator_get_ocrmask(struct regulator *supply)
{
        int                     result = 0;
        int                     count;
        int                     i;

        count = regulator_count_voltages(supply);
        if (count < 0)
                return count;

        for (i = 0; i < count; i++) {
                int             vdd_uV;
                int             vdd_mV;

                vdd_uV = regulator_list_voltage(supply, i);
                if (vdd_uV <= 0)
                        continue;

                vdd_mV = vdd_uV / 1000;
                result |= mmc_vddrange_to_ocrmask(vdd_mV, vdd_mV);
        }

        return result;
}
EXPORT_SYMBOL(mmc_regulator_get_ocrmask);

/**
 * mmc_regulator_set_ocr - set regulator to match host->ios voltage
 * @vdd_bit: zero for power off, else a bit number (host->ios.vdd)
 * @supply: regulator to use
 *
 * Returns zero on success, else negative errno.
 *
 * MMC host drivers may use this to enable or disable a regulator using
 * a particular supply voltage.  This would normally be called from the
 * set_ios() method.
 */
int mmc_regulator_set_ocr(struct regulator *supply, unsigned short vdd_bit)
{
        int                     result = 0;
        int                     min_uV, max_uV;
        int                     enabled;

        enabled = regulator_is_enabled(supply);
        if (enabled < 0)
                return enabled;

        if (vdd_bit) {
                int             tmp;
                int             voltage;

                /* REVISIT mmc_vddrange_to_ocrmask() may have set some
                 * bits this regulator doesn't quite support ... don't
                 * be too picky, most cards and regulators are OK with
                 * a 0.1V range goof (it's a small error percentage).
                 */
                tmp = vdd_bit - ilog2(MMC_VDD_165_195);
                if (tmp == 0) {
                        min_uV = 1650 * 1000;
                        max_uV = 1950 * 1000;
                } else {
                        min_uV = 1900 * 1000 + tmp * 100 * 1000;
                        max_uV = min_uV + 100 * 1000;
                }

                /* avoid needless changes to this voltage; the regulator
                 * might not allow this operation
                 */
                voltage = regulator_get_voltage(supply);
                if (voltage < 0)
                        result = voltage;
                else if (voltage < min_uV || voltage > max_uV)
                        result = regulator_set_voltage(supply, min_uV, max_uV);
                else
                        result = 0;

                if (result == 0 && !enabled)
                        result = regulator_enable(supply);
        } else if (enabled) {
                result = regulator_disable(supply);
        }

        return result;
}
EXPORT_SYMBOL(mmc_regulator_set_ocr);

#endif

/*
 * Mask off any voltages we don't support and select
 * the lowest voltage
 */
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 {
                pr_warning("%s: host doesn't support card's voltages\n",
                                mmc_hostname(host));
                ocr = 0;
        }

        return ocr;
}

/*
 * Select timing parameters for host.
 */
void mmc_set_timing(struct mmc_host *host, unsigned int timing)
{
        host->ios.timing = timing;
        mmc_set_ios(host);
}

/*
 * 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;

        /* If ocr is set, we use it */
        if (host->ocr)
                bit = ffs(host->ocr) - 1;
        else
                bit = fls(host->ocr_avail) - 1;

        host->ios.vdd = bit;
        if (mmc_host_is_spi(host)) {
                host->ios.chip_select = MMC_CS_HIGH;
                host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
        } else {
                host->ios.chip_select = MMC_CS_DONTCARE;
                host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
        }
        host->ios.power_mode = MMC_POWER_UP;
        host->ios.bus_width = MMC_BUS_WIDTH_1;
        host->ios.timing = MMC_TIMING_LEGACY;
        mmc_set_ios(host);

        /*
         * This delay should be sufficient to allow the power supply
         * to reach the minimum voltage.
         */
        mmc_delay(10);

        if (host->f_min > 400000) {
                pr_warning("%s: Minimum clock frequency too high for "
                                "identification mode\n", mmc_hostname(host));
                host->ios.clock = host->f_min;
        } else
                host->ios.clock = 400000;

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

        /*
         * This delay must be at least 74 clock sizes, or 1 ms, or the
         * time required to reach a stable voltage.
         */
        mmc_delay(10);
}

static void mmc_power_off(struct mmc_host *host)
{
        host->ios.clock = 0;
        host->ios.vdd = 0;
        if (!mmc_host_is_spi(host)) {
                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;
        host->ios.timing = MMC_TIMING_LEGACY;
        mmc_set_ios(host);
}

/*
 * Cleanup when the last reference to the bus operator is dropped.
 */
static void __mmc_release_bus(struct mmc_host *host)
{
        BUG_ON(!host);
        BUG_ON(host->bus_refs);
        BUG_ON(!host->bus_dead);

        host->bus_ops = NULL;
}

/*
 * Increase reference count of bus operator
 */
static inline void mmc_bus_get(struct mmc_host *host)
{
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);
        host->bus_refs++;
        spin_unlock_irqrestore(&host->lock, flags);
}

/*
 * Decrease reference count of bus operator and free it if
 * it is the last reference.
 */
static inline void mmc_bus_put(struct mmc_host *host)
{
        unsigned long flags;

        spin_lock_irqsave(&host->lock, flags);
        host->bus_refs--;
        if ((host->bus_refs == 0) && host->bus_ops)
                __mmc_release_bus(host);
        spin_unlock_irqrestore(&host->lock, flags);
}

/*
 * Assign a mmc bus handler to a host. Only one bus handler may control a
 * host at any given time.
 */
void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops)
{
        unsigned long flags;

        BUG_ON(!host);
        BUG_ON(!ops);

        WARN_ON(!host->claimed);

        spin_lock_irqsave(&host->lock, flags);

        BUG_ON(host->bus_ops);
        BUG_ON(host->bus_refs);

        host->bus_ops = ops;
        host->bus_refs = 1;
        host->bus_dead = 0;

        spin_unlock_irqrestore(&host->lock, flags);
}

/*
 * Remove the current bus handler from a host. Assumes that there are
 * no interesting cards left, so the bus is powered down.
 */
void mmc_detach_bus(struct mmc_host *host)
{
        unsigned long flags;

        BUG_ON(!host);

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

        spin_lock_irqsave(&host->lock, flags);

        host->bus_dead = 1;

        spin_unlock_irqrestore(&host->lock, flags);

        mmc_power_off(host);

        mmc_bus_put(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)
 *
 *      MMC drivers should call this when they detect a card has been
 *      inserted or removed. The MMC layer will confirm that any
 *      present card is still functional, and initialize any newly
 *      inserted.
 */
void mmc_detect_change(struct mmc_host *host, unsigned long delay)
{
#ifdef CONFIG_MMC_DEBUG
        unsigned long flags;
        spin_lock_irqsave(&host->lock, flags);
        WARN_ON(host->removed);
        spin_unlock_irqrestore(&host->lock, flags);
#endif

        mmc_schedule_delayed_work(&host->detect, delay);
}

EXPORT_SYMBOL(mmc_detect_change);


void mmc_rescan(struct work_struct *work)
{
        struct mmc_host *host =
                container_of(work, struct mmc_host, detect.work);
        u32 ocr;
        int err;

        mmc_bus_get(host);

        /* if there is a card registered, check whether it is still present */
        if ((host->bus_ops != NULL) && host->bus_ops->detect && !host->bus_dead)
                host->bus_ops->detect(host);

        mmc_bus_put(host);


        mmc_bus_get(host);

        /* if there still is a card present, stop here */
        if (host->bus_ops != NULL) {
                mmc_bus_put(host);
                goto out;
        }

        /* detect a newly inserted card */

        /*
         * Only we can add a new handler, so it's safe to
         * release the lock here.
         */
        mmc_bus_put(host);

        if (host->ops->get_cd && host->ops->get_cd(host) == 0)
                goto out;

        mmc_claim_host(host);

        mmc_power_up(host);
        mmc_go_idle(host);

        mmc_send_if_cond(host, host->ocr_avail);

        /*
         * First we search for SDIO...
         */
        err = mmc_send_io_op_cond(host, 0, &ocr);
        if (!err) {
                if (mmc_attach_sdio(host, ocr))
                        mmc_power_off(host);
                goto out;
        }

        /*
         * ...then normal SD...
         */
        err = mmc_send_app_op_cond(host, 0, &ocr);
        if (!err) {
                if (mmc_attach_sd(host, ocr))
                        mmc_power_off(host);
                goto out;
        }

        /*
         * ...and finally MMC.
         */
        err = mmc_send_op_cond(host, 0, &ocr);
        if (!err) {
                if (mmc_attach_mmc(host, ocr))
                        mmc_power_off(host);
                goto out;
        }

        mmc_release_host(host);
        mmc_power_off(host);

out:
        if (host->caps & MMC_CAP_NEEDS_POLL)
                mmc_schedule_delayed_work(&host->detect, HZ);
}

void mmc_start_host(struct mmc_host *host)
{
        mmc_power_off(host);
        mmc_detect_change(host, 0);
}

void mmc_stop_host(struct mmc_host *host)
{
#ifdef CONFIG_MMC_DEBUG
        unsigned long flags;
        spin_lock_irqsave(&host->lock, flags);
        host->removed = 1;
        spin_unlock_irqrestore(&host->lock, flags);
#endif

        if (host->caps & MMC_CAP_DISABLE)
                cancel_delayed_work(&host->disable);
        cancel_delayed_work(&host->detect);
        mmc_flush_scheduled_work();

        mmc_bus_get(host);
        if (host->bus_ops && !host->bus_dead) {
                if (host->bus_ops->remove)
                        host->bus_ops->remove(host);

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

        BUG_ON(host->card);

        mmc_power_off(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)
{
        if (host->caps & MMC_CAP_DISABLE)
                cancel_delayed_work(&host->disable);
        cancel_delayed_work(&host->detect);
        mmc_flush_scheduled_work();

        mmc_bus_get(host);
        if (host->bus_ops && !host->bus_dead) {
                if (host->bus_ops->suspend)
                        host->bus_ops->suspend(host);
                if (!host->bus_ops->resume) {
                        if (host->bus_ops->remove)
                                host->bus_ops->remove(host);

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

        mmc_power_off(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_bus_get(host);
        if (host->bus_ops && !host->bus_dead) {
                mmc_power_up(host);
                mmc_select_voltage(host, host->ocr);
                BUG_ON(!host->bus_ops->resume);
                host->bus_ops->resume(host);
        }
        mmc_bus_put(host);

        /*
         * We add a slight delay here so that resume can progress
         * in parallel.
         */
        mmc_detect_change(host, 1);

        return 0;
}

EXPORT_SYMBOL(mmc_resume_host);

#endif

static int __init mmc_init(void)
{
        int ret;

        workqueue = create_singlethread_workqueue("kmmcd");
        if (!workqueue)
                return -ENOMEM;

        ret = mmc_register_bus();
        if (ret)
                goto destroy_workqueue;

        ret = mmc_register_host_class();
        if (ret)
                goto unregister_bus;

        ret = sdio_register_bus();
        if (ret)
                goto unregister_host_class;

        return 0;

unregister_host_class:
        mmc_unregister_host_class();
unregister_bus:
        mmc_unregister_bus();
destroy_workqueue:
        destroy_workqueue(workqueue);

        return ret;
}

static void __exit mmc_exit(void)
{
        sdio_unregister_bus();
        mmc_unregister_host_class();
        mmc_unregister_bus();
        destroy_workqueue(workqueue);
}

subsys_initcall(mmc_init);
module_exit(mmc_exit);

MODULE_LICENSE("GPL");