linux/drivers/mmc/core/slot-gpio.c
Laurent Pinchart 214fc309d1 mmc: slot-gpio: Add debouncing capability to mmc_gpio_request_cd()
Add a debounce parameter to the mmc_gpio_request_cd() function that
enables GPIO debouncing when set to a non-zero value. This can be used
by MMC host drivers to enable debouncing on the card detect signal.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
2013-08-24 23:45:09 -04:00

258 lines
6.4 KiB
C

/*
* Generic GPIO card-detect helper
*
* Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/mmc/host.h>
#include <linux/mmc/slot-gpio.h>
#include <linux/module.h>
#include <linux/slab.h>
struct mmc_gpio {
int ro_gpio;
int cd_gpio;
char *ro_label;
char cd_label[0];
};
static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
{
/* Schedule a card detection after a debounce timeout */
struct mmc_host *host = dev_id;
if (host->ops->card_event)
host->ops->card_event(host);
mmc_detect_change(host, msecs_to_jiffies(200));
return IRQ_HANDLED;
}
static int mmc_gpio_alloc(struct mmc_host *host)
{
size_t len = strlen(dev_name(host->parent)) + 4;
struct mmc_gpio *ctx;
mutex_lock(&host->slot.lock);
ctx = host->slot.handler_priv;
if (!ctx) {
/*
* devm_kzalloc() can be called after device_initialize(), even
* before device_add(), i.e., between mmc_alloc_host() and
* mmc_add_host()
*/
ctx = devm_kzalloc(&host->class_dev, sizeof(*ctx) + 2 * len,
GFP_KERNEL);
if (ctx) {
ctx->ro_label = ctx->cd_label + len;
snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
ctx->cd_gpio = -EINVAL;
ctx->ro_gpio = -EINVAL;
host->slot.handler_priv = ctx;
}
}
mutex_unlock(&host->slot.lock);
return ctx ? 0 : -ENOMEM;
}
int mmc_gpio_get_ro(struct mmc_host *host)
{
struct mmc_gpio *ctx = host->slot.handler_priv;
if (!ctx || !gpio_is_valid(ctx->ro_gpio))
return -ENOSYS;
return !gpio_get_value_cansleep(ctx->ro_gpio) ^
!!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);
}
EXPORT_SYMBOL(mmc_gpio_get_ro);
int mmc_gpio_get_cd(struct mmc_host *host)
{
struct mmc_gpio *ctx = host->slot.handler_priv;
if (!ctx || !gpio_is_valid(ctx->cd_gpio))
return -ENOSYS;
return !gpio_get_value_cansleep(ctx->cd_gpio) ^
!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
}
EXPORT_SYMBOL(mmc_gpio_get_cd);
/**
* mmc_gpio_request_ro - request a gpio for write-protection
* @host: mmc host
* @gpio: gpio number requested
*
* As devm_* managed functions are used in mmc_gpio_request_ro(), client
* drivers do not need to explicitly call mmc_gpio_free_ro() for freeing up,
* if the requesting and freeing are only needed at probing and unbinding time
* for once. However, if client drivers do something special like runtime
* switching for write-protection, they are responsible for calling
* mmc_gpio_request_ro() and mmc_gpio_free_ro() as a pair on their own.
*
* Returns zero on success, else an error.
*/
int mmc_gpio_request_ro(struct mmc_host *host, unsigned int gpio)
{
struct mmc_gpio *ctx;
int ret;
if (!gpio_is_valid(gpio))
return -EINVAL;
ret = mmc_gpio_alloc(host);
if (ret < 0)
return ret;
ctx = host->slot.handler_priv;
ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
ctx->ro_label);
if (ret < 0)
return ret;
ctx->ro_gpio = gpio;
return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_ro);
/**
* mmc_gpio_request_cd - request a gpio for card-detection
* @host: mmc host
* @gpio: gpio number requested
* @debounce: debounce time in microseconds
*
* As devm_* managed functions are used in mmc_gpio_request_cd(), client
* drivers do not need to explicitly call mmc_gpio_free_cd() for freeing up,
* if the requesting and freeing are only needed at probing and unbinding time
* for once. However, if client drivers do something special like runtime
* switching for card-detection, they are responsible for calling
* mmc_gpio_request_cd() and mmc_gpio_free_cd() as a pair on their own.
*
* If GPIO debouncing is desired, set the debounce parameter to a non-zero
* value. The caller is responsible for ensuring that the GPIO driver associated
* with the GPIO supports debouncing, otherwise an error will be returned.
*
* Returns zero on success, else an error.
*/
int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio,
unsigned int debounce)
{
struct mmc_gpio *ctx;
int irq = gpio_to_irq(gpio);
int ret;
ret = mmc_gpio_alloc(host);
if (ret < 0)
return ret;
ctx = host->slot.handler_priv;
ret = devm_gpio_request_one(&host->class_dev, gpio, GPIOF_DIR_IN,
ctx->cd_label);
if (ret < 0)
/*
* don't bother freeing memory. It might still get used by other
* slot functions, in any case it will be freed, when the device
* is destroyed.
*/
return ret;
if (debounce) {
ret = gpio_set_debounce(gpio, debounce);
if (ret < 0)
return ret;
}
/*
* Even if gpio_to_irq() returns a valid IRQ number, the platform might
* still prefer to poll, e.g., because that IRQ number is already used
* by another unit and cannot be shared.
*/
if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
irq = -EINVAL;
if (irq >= 0) {
ret = devm_request_threaded_irq(&host->class_dev, irq,
NULL, mmc_gpio_cd_irqt,
IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
ctx->cd_label, host);
if (ret < 0)
irq = ret;
}
host->slot.cd_irq = irq;
if (irq < 0)
host->caps |= MMC_CAP_NEEDS_POLL;
ctx->cd_gpio = gpio;
return 0;
}
EXPORT_SYMBOL(mmc_gpio_request_cd);
/**
* mmc_gpio_free_ro - free the write-protection gpio
* @host: mmc host
*
* It's provided only for cases that client drivers need to manually free
* up the write-protection gpio requested by mmc_gpio_request_ro().
*/
void mmc_gpio_free_ro(struct mmc_host *host)
{
struct mmc_gpio *ctx = host->slot.handler_priv;
int gpio;
if (!ctx || !gpio_is_valid(ctx->ro_gpio))
return;
gpio = ctx->ro_gpio;
ctx->ro_gpio = -EINVAL;
devm_gpio_free(&host->class_dev, gpio);
}
EXPORT_SYMBOL(mmc_gpio_free_ro);
/**
* mmc_gpio_free_cd - free the card-detection gpio
* @host: mmc host
*
* It's provided only for cases that client drivers need to manually free
* up the card-detection gpio requested by mmc_gpio_request_cd().
*/
void mmc_gpio_free_cd(struct mmc_host *host)
{
struct mmc_gpio *ctx = host->slot.handler_priv;
int gpio;
if (!ctx || !gpio_is_valid(ctx->cd_gpio))
return;
if (host->slot.cd_irq >= 0) {
devm_free_irq(&host->class_dev, host->slot.cd_irq, host);
host->slot.cd_irq = -EINVAL;
}
gpio = ctx->cd_gpio;
ctx->cd_gpio = -EINVAL;
devm_gpio_free(&host->class_dev, gpio);
}
EXPORT_SYMBOL(mmc_gpio_free_cd);