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mmc: add a generic GPIO card-detect helper

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This patch adds a primitive helper to support card hotplug detection on
platforms, where a GPIO, capable of producing interrupts, is used for
detection of card-insertion and -removal events.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Guennadi Liakhovetski 2011-12-25 21:36:02 +01:00 committed by Chris Ball
parent b67e198073
commit 349ab52446
3 changed files with 94 additions and 1 deletions
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2
drivers/mmc/core/Makefile
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@ -7,6 +7,6 @@ mmc_core-y := core.o bus.o host.o \
mmc.o mmc_ops.o sd.o sd_ops.o \
sdio.o sdio_ops.o sdio_bus.o \
sdio_cis.o sdio_io.o sdio_irq.o \
quirks.o
quirks.o cd-gpio.o
mmc_core-$(CONFIG_DEBUG_FS) += debugfs.o

74
drivers/mmc/core/cd-gpio.c Normal file
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@ -0,0 +1,74 @@
/*
* 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/module.h>
#include <linux/slab.h>
struct mmc_cd_gpio {
unsigned int gpio;
char label[0];
};
static irqreturn_t mmc_cd_gpio_irqt(int irq, void *dev_id)
{
/* Schedule a card detection after a debounce timeout */
mmc_detect_change(dev_id, msecs_to_jiffies(100));
return IRQ_HANDLED;
}
int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
unsigned int irq, unsigned long flags)
{
size_t len = strlen(dev_name(host->parent)) + 4;
struct mmc_cd_gpio *cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
int ret;
if (!cd)
return -ENOMEM;
snprintf(cd->label, len, "%s cd", dev_name(host->parent));
ret = gpio_request_one(gpio, GPIOF_DIR_IN, cd->label);
if (ret < 0)
goto egpioreq;
ret = request_threaded_irq(irq, NULL, mmc_cd_gpio_irqt,
flags, cd->label, host);
if (ret < 0)
goto eirqreq;
cd->gpio = gpio;
host->hotplug.irq = irq;
host->hotplug.handler_priv = cd;
return 0;
eirqreq:
gpio_free(gpio);
egpioreq:
kfree(cd);
return ret;
}
EXPORT_SYMBOL(mmc_cd_gpio_request);
void mmc_cd_gpio_free(struct mmc_host *host)
{
struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
free_irq(host->hotplug.irq, host);
gpio_free(cd->gpio);
kfree(cd);
}
EXPORT_SYMBOL(mmc_cd_gpio_free);

19
include/linux/mmc/cd-gpio.h Normal file
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@ -0,0 +1,19 @@
/*
* Generic GPIO card-detect helper header
*
* 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.
*/
#ifndef MMC_CD_GPIO_H
#define MMC_CD_GPIO_H
struct mmc_host;
int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
unsigned int irq, unsigned long flags);
void mmc_cd_gpio_free(struct mmc_host *host);
#endif