linux/drivers/gpio/gpiolib-acpi.c
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   1/*
   2 * ACPI helpers for GPIO API
   3 *
   4 * Copyright (C) 2012, Intel Corporation
   5 * Authors: Mathias Nyman <mathias.nyman@linux.intel.com>
   6 *          Mika Westerberg <mika.westerberg@linux.intel.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12
  13#include <linux/errno.h>
  14#include <linux/gpio.h>
  15#include <linux/export.h>
  16#include <linux/acpi_gpio.h>
  17#include <linux/acpi.h>
  18
  19static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
  20{
  21        if (!gc->dev)
  22                return false;
  23
  24        return ACPI_HANDLE(gc->dev) == data;
  25}
  26
  27/**
  28 * acpi_get_gpio() - Translate ACPI GPIO pin to GPIO number usable with GPIO API
  29 * @path:       ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
  30 * @pin:        ACPI GPIO pin number (0-based, controller-relative)
  31 *
  32 * Returns GPIO number to use with Linux generic GPIO API, or errno error value
  33 */
  34
  35int acpi_get_gpio(char *path, int pin)
  36{
  37        struct gpio_chip *chip;
  38        acpi_handle handle;
  39        acpi_status status;
  40
  41        status = acpi_get_handle(NULL, path, &handle);
  42        if (ACPI_FAILURE(status))
  43                return -ENODEV;
  44
  45        chip = gpiochip_find(handle, acpi_gpiochip_find);
  46        if (!chip)
  47                return -ENODEV;
  48
  49        if (!gpio_is_valid(chip->base + pin))
  50                return -EINVAL;
  51
  52        return chip->base + pin;
  53}
  54EXPORT_SYMBOL_GPL(acpi_get_gpio);
  55
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