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29a1f2333e
Introduce gpiod_get_optional() and gpiod_get_index_optional() helpers
that make it easier for drivers to handle optional GPIOs.
Currently in order to handle optional GPIOs, a driver needs to special
case error handling for -ENOENT, such as this:
gpio = gpiod_get(dev, "foo");
if (IS_ERR(gpio)) {
if (PTR_ERR(gpio) != -ENOENT)
return PTR_ERR(gpio);
gpio = NULL;
}
if (gpio) {
/* set up GPIO */
}
With these new helpers the above is reduced to:
gpio = gpiod_get_optional(dev, "foo");
if (IS_ERR(gpio))
return PTR_ERR(gpio);
if (gpio) {
/* set up GPIO */
}
While at it, device-managed variants of these functions are also
provided.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
248 lines
6.5 KiB
C
248 lines
6.5 KiB
C
/*
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* drivers/gpio/devres.c - managed gpio resources
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* This file is based on kernel/irq/devres.c
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*
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* Copyright (c) 2011 John Crispin <blogic@openwrt.org>
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*/
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#include <linux/module.h>
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#include <linux/err.h>
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#include <linux/gpio.h>
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#include <linux/gpio/consumer.h>
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#include <linux/device.h>
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#include <linux/gfp.h>
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static void devm_gpiod_release(struct device *dev, void *res)
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{
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struct gpio_desc **desc = res;
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gpiod_put(*desc);
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}
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static int devm_gpiod_match(struct device *dev, void *res, void *data)
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{
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struct gpio_desc **this = res, **gpio = data;
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return *this == *gpio;
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}
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/**
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* devm_gpiod_get - Resource-managed gpiod_get()
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* @dev: GPIO consumer
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* @con_id: function within the GPIO consumer
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*
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* Managed gpiod_get(). GPIO descriptors returned from this function are
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* automatically disposed on driver detach. See gpiod_get() for detailed
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* information about behavior and return values.
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*/
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struct gpio_desc *__must_check devm_gpiod_get(struct device *dev,
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const char *con_id)
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{
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return devm_gpiod_get_index(dev, con_id, 0);
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}
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EXPORT_SYMBOL(devm_gpiod_get);
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/**
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* devm_gpiod_get_optional - Resource-managed gpiod_get_optional()
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* @dev: GPIO consumer
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* @con_id: function within the GPIO consumer
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*
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* Managed gpiod_get_optional(). GPIO descriptors returned from this function
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* are automatically disposed on driver detach. See gpiod_get_optional() for
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* detailed information about behavior and return values.
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*/
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struct gpio_desc *__must_check devm_gpiod_get_optional(struct device *dev,
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const char *con_id)
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{
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return devm_gpiod_get_index_optional(dev, con_id, 0);
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}
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EXPORT_SYMBOL(devm_gpiod_get_optional);
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/**
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* devm_gpiod_get_index - Resource-managed gpiod_get_index()
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* @dev: GPIO consumer
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* @con_id: function within the GPIO consumer
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* @idx: index of the GPIO to obtain in the consumer
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*
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* Managed gpiod_get_index(). GPIO descriptors returned from this function are
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* automatically disposed on driver detach. See gpiod_get_index() for detailed
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* information about behavior and return values.
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*/
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struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev,
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const char *con_id,
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unsigned int idx)
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{
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struct gpio_desc **dr;
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struct gpio_desc *desc;
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dr = devres_alloc(devm_gpiod_release, sizeof(struct gpiod_desc *),
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GFP_KERNEL);
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if (!dr)
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return ERR_PTR(-ENOMEM);
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desc = gpiod_get_index(dev, con_id, idx);
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if (IS_ERR(desc)) {
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devres_free(dr);
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return desc;
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}
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*dr = desc;
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devres_add(dev, dr);
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return desc;
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}
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EXPORT_SYMBOL(devm_gpiod_get_index);
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/**
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* devm_gpiod_get_index_optional - Resource-managed gpiod_get_index_optional()
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* @dev: GPIO consumer
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* @con_id: function within the GPIO consumer
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* @index: index of the GPIO to obtain in the consumer
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*
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* Managed gpiod_get_index_optional(). GPIO descriptors returned from this
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* function are automatically disposed on driver detach. See
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* gpiod_get_index_optional() for detailed information about behavior and
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* return values.
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*/
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struct gpio_desc *__must_check devm_gpiod_get_index_optional(struct device *dev,
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const char *con_id,
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unsigned int index)
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{
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struct gpio_desc *desc;
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desc = devm_gpiod_get_index(dev, con_id, index);
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if (IS_ERR(desc)) {
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if (PTR_ERR(desc) == -ENOENT)
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return NULL;
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}
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return desc;
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}
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EXPORT_SYMBOL(devm_gpiod_get_index_optional);
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/**
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* devm_gpiod_put - Resource-managed gpiod_put()
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* @desc: GPIO descriptor to dispose of
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*
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* Dispose of a GPIO descriptor obtained with devm_gpiod_get() or
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* devm_gpiod_get_index(). Normally this function will not be called as the GPIO
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* will be disposed of by the resource management code.
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*/
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void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)
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{
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WARN_ON(devres_release(dev, devm_gpiod_release, devm_gpiod_match,
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&desc));
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}
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EXPORT_SYMBOL(devm_gpiod_put);
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static void devm_gpio_release(struct device *dev, void *res)
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{
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unsigned *gpio = res;
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gpio_free(*gpio);
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}
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static int devm_gpio_match(struct device *dev, void *res, void *data)
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{
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unsigned *this = res, *gpio = data;
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return *this == *gpio;
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}
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/**
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* devm_gpio_request - request a GPIO for a managed device
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* @dev: device to request the GPIO for
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* @gpio: GPIO to allocate
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* @label: the name of the requested GPIO
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*
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* Except for the extra @dev argument, this function takes the
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* same arguments and performs the same function as
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* gpio_request(). GPIOs requested with this function will be
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* automatically freed on driver detach.
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*
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* If an GPIO allocated with this function needs to be freed
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* separately, devm_gpio_free() must be used.
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*/
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int devm_gpio_request(struct device *dev, unsigned gpio, const char *label)
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{
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unsigned *dr;
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int rc;
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dr = devres_alloc(devm_gpio_release, sizeof(unsigned), GFP_KERNEL);
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if (!dr)
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return -ENOMEM;
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rc = gpio_request(gpio, label);
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if (rc) {
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devres_free(dr);
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return rc;
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}
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*dr = gpio;
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devres_add(dev, dr);
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return 0;
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}
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EXPORT_SYMBOL(devm_gpio_request);
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/**
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* devm_gpio_request_one - request a single GPIO with initial setup
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* @dev: device to request for
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* @gpio: the GPIO number
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* @flags: GPIO configuration as specified by GPIOF_*
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* @label: a literal description string of this GPIO
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*/
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int devm_gpio_request_one(struct device *dev, unsigned gpio,
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unsigned long flags, const char *label)
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{
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unsigned *dr;
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int rc;
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dr = devres_alloc(devm_gpio_release, sizeof(unsigned), GFP_KERNEL);
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if (!dr)
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return -ENOMEM;
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rc = gpio_request_one(gpio, flags, label);
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if (rc) {
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devres_free(dr);
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return rc;
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}
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*dr = gpio;
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devres_add(dev, dr);
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return 0;
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}
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EXPORT_SYMBOL(devm_gpio_request_one);
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/**
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* devm_gpio_free - free a GPIO
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* @dev: device to free GPIO for
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* @gpio: GPIO to free
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*
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* Except for the extra @dev argument, this function takes the
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* same arguments and performs the same function as gpio_free().
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* This function instead of gpio_free() should be used to manually
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* free GPIOs allocated with devm_gpio_request().
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*/
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void devm_gpio_free(struct device *dev, unsigned int gpio)
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{
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WARN_ON(devres_release(dev, devm_gpio_release, devm_gpio_match,
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&gpio));
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}
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EXPORT_SYMBOL(devm_gpio_free);
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