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GPIO: add bindings for managed devices 

This patch adds 2 functions that allow managed devices to request GPIOs.
These GPIOs will then be managed by drivers/base/devres.c.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
John Crispin 2011-12-20 21:40:21 +01:00 committed by Grant Likely
parent e198a8de14
commit 1a0703ede4
3 changed files with 95 additions and 1 deletions
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2
drivers/gpio/Makefile
View File

@ -2,7 +2,7 @@
ccflags-$(CONFIG_DEBUG_GPIO) += -DDEBUG
obj-$(CONFIG_GPIOLIB) += gpiolib.o
obj-$(CONFIG_GPIOLIB) += gpiolib.o devres.o
# Device drivers. Generally keep list sorted alphabetically
obj-$(CONFIG_GPIO_GENERIC) += gpio-generic.o

90
drivers/gpio/devres.c Normal file
View File

@ -0,0 +1,90 @@
/*
* drivers/gpio/devres.c - managed gpio resources
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* This file is based on kernel/irq/devres.c
*
* Copyright (c) 2011 John Crispin <blogic@openwrt.org>
*/
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/device.h>
#include <linux/gfp.h>
static void devm_gpio_release(struct device *dev, void *res)
{
unsigned *gpio = res;
gpio_free(*gpio);
}
static int devm_gpio_match(struct device *dev, void *res, void *data)
{
unsigned *this = res, *gpio = data;
return *this == *gpio;
}
/**
* devm_gpio_request - request a gpio for a managed device
* @dev: device to request the gpio for
* @gpio: gpio to allocate
* @label: the name of the requested gpio
*
* Except for the extra @dev argument, this function takes the
* same arguments and performs the same function as
* gpio_request(). GPIOs requested with this function will be
* automatically freed on driver detach.
*
* If an GPIO allocated with this function needs to be freed
* separately, devm_gpio_free() must be used.
*/
int devm_gpio_request(struct device *dev, unsigned gpio, const char *label)
{
unsigned *dr;
int rc;
dr = devres_alloc(devm_gpio_release, sizeof(unsigned), GFP_KERNEL);
if (!dr)
return -ENOMEM;
rc = gpio_request(gpio, label);
if (rc) {
devres_free(dr);
return rc;
}
*dr = gpio;
devres_add(dev, dr);
return 0;
}
EXPORT_SYMBOL(devm_gpio_request);
/**
* devm_gpio_free - free an interrupt
* @dev: device to free gpio for
* @gpio: gpio to free
*
* Except for the extra @dev argument, this function takes the
* same arguments and performs the same function as gpio_free().
* This function instead of gpio_free() should be used to manually
* free GPIOs allocated with devm_gpio_request().
*/
void devm_gpio_free(struct device *dev, unsigned int gpio)
{
WARN_ON(devres_destroy(dev, devm_gpio_release, devm_gpio_match,
&gpio));
gpio_free(gpio);
}
EXPORT_SYMBOL(devm_gpio_free);

4
include/asm-generic/gpio.h
View File

@ -177,6 +177,10 @@ extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *labe
extern int gpio_request_array(const struct gpio *array, size_t num);
extern void gpio_free_array(const struct gpio *array, size_t num);
/* bindings for managed devices that want to request gpios */
int devm_gpio_request(struct device *dev, unsigned gpio, const char *label);
void devm_gpio_free(struct device *dev, unsigned int gpio);
#ifdef CONFIG_GPIO_SYSFS
/*