linux/drivers/mmc/core/core.c
David Brownell f6e10b865c mmc: warn about voltage mismatches
Get rid of a silent failure mode when the MMC/SD host doesn't
support the voltages needed to operate a given card, by
adding a warning.  A 3.3V host and a 3.0V card, for example,
no longer need to mysteriously just not work at all.

This isn't the best diagnostic; ideally it would also tell
what voltage the card and host support (and not just by
dumping the bitmasks).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
2008-12-31 19:27:18 +01:00

940 lines
21 KiB
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/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;
}
}
}
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_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);
return stop;
}
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;
WARN_ON(!host->claimed);
spin_lock_irqsave(&host->lock, flags);
host->claimed = 0;
spin_unlock_irqrestore(&host->lock, flags);
wake_up(&host->wq);
}
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);
/*
* 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 = 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(2);
host->ios.clock = host->f_min;
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(2);
}
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 (host->bus_ops == NULL) {
/*
* 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);
} else {
if (host->bus_ops->detect && !host->bus_dead)
host->bus_ops->detect(host);
mmc_bus_put(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
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)
{
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);
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");