drivers/gpio/devres.c

   1 /*
   2  * drivers/gpio/devres.c - managed gpio resources
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2
   6  * as published by the Free Software Foundation.
   7  *
   8  * You should have received a copy of the GNU General Public License
   9  * along with this program; if not, write to the Free Software
  10  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  11  *
  12  * This file is based on kernel/irq/devres.c
  13  *
  14  * Copyright (c) 2011 John Crispin <blogic@openwrt.org>
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/gpio.h>
  19 #include <linux/device.h>
  20 #include <linux/gfp.h>
  21
  22 static void devm_gpio_release(struct device *dev, void *res)
  23 {
  24         unsigned *gpio = res;
  25
  26         gpio_free(*gpio);
  27 }
  28
  29 static int devm_gpio_match(struct device *dev, void *res, void *data)
  30 {
  31         unsigned *this = res, *gpio = data;
  32
  33         return *this == *gpio;
  34 }
  35
  36 /**
  37  *      devm_gpio_request - request a gpio for a managed device
  38  *      @dev: device to request the gpio for
  39  *      @gpio: gpio to allocate
  40  *      @label: the name of the requested gpio
  41  *
  42  *      Except for the extra @dev argument, this function takes the
  43  *      same arguments and performs the same function as
  44  *      gpio_request().  GPIOs requested with this function will be
  45  *      automatically freed on driver detach.
  46  *
  47  *      If an GPIO allocated with this function needs to be freed
  48  *      separately, devm_gpio_free() must be used.
  49  */
  50
  51 int devm_gpio_request(struct device *dev, unsigned gpio, const char *label)
  52 {
  53         unsigned *dr;
  54         int rc;
  55
  56         dr = devres_alloc(devm_gpio_release, sizeof(unsigned), GFP_KERNEL);
  57         if (!dr)
  58                 return -ENOMEM;
  59
  60         rc = gpio_request(gpio, label);
  61         if (rc) {
  62                 devres_free(dr);
  63                 return rc;
  64         }
  65
  66         *dr = gpio;
  67         devres_add(dev, dr);
  68
  69         return 0;
  70 }
  71 EXPORT_SYMBOL(devm_gpio_request);
  72
  73 /**
  74  *      devm_gpio_free - free an interrupt
  75  *      @dev: device to free gpio for
  76  *      @gpio: gpio to free
  77  *
  78  *      Except for the extra @dev argument, this function takes the
  79  *      same arguments and performs the same function as gpio_free().
  80  *      This function instead of gpio_free() should be used to manually
  81  *      free GPIOs allocated with devm_gpio_request().
  82  */
  83 void devm_gpio_free(struct device *dev, unsigned int gpio)
  84 {
  85
  86         WARN_ON(devres_destroy(dev, devm_gpio_release, devm_gpio_match,
  87                 &gpio));
  88         gpio_free(gpio);
  89 }
  90 EXPORT_SYMBOL(devm_gpio_free);