drivers/gpio/gpiolib-acpi.c

/*
 * ACPI helpers for GPIO API
 *
 * Copyright (C) 2012, Intel Corporation
 * Authors: Mathias Nyman <mathias.nyman@linux.intel.com>
 *          Mika Westerberg <mika.westerberg@linux.intel.com>
 *
 * 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/errno.h>
#include <linux/gpio.h>
#include <linux/export.h>
#include <linux/acpi_gpio.h>
#include <linux/acpi.h>

static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
{
	if (!gc->dev)
		return false;

	return ACPI_HANDLE(gc->dev) == data;
}

/**
 * acpi_get_gpio() - Translate ACPI GPIO pin to GPIO number usable with GPIO API
 * @path:	ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
 * @pin:	ACPI GPIO pin number (0-based, controller-relative)
 *
 * Returns GPIO number to use with Linux generic GPIO API, or errno error value
 */

int acpi_get_gpio(char *path, int pin)
{
	struct gpio_chip *chip;
	acpi_handle handle;
	acpi_status status;

	status = acpi_get_handle(NULL, path, &handle);
	if (ACPI_FAILURE(status))
		return -ENODEV;

	chip = gpiochip_find(handle, acpi_gpiochip_find);
	if (!chip)
		return -ENODEV;

	if (!gpio_is_valid(chip->base + pin))
		return -EINVAL;

	return chip->base + pin;
}
EXPORT_SYMBOL_GPL(acpi_get_gpio);