drivers/gpio/gpiolib-of.c - codeaurora/cp-linux - Gitiles

 /*
  * OF helpers for the GPIO API
  *
  * Copyright (c) 2007-2008  MontaVista Software, Inc.
  *
  * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  */

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/gpio/consumer.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_gpio.h>
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/slab.h>
 #include <linux/gpio/machine.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>

 #include "gpiolib.h"

 /* Private data structure for of_gpiochip_find_and_xlate */
 struct gg_data {
 	enum of_gpio_flags *flags;
 	struct of_phandle_args gpiospec;

 	struct gpio_desc *out_gpio;
 };

 /* Private function for resolving node pointer to gpio_chip */
 static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
 {
 	struct gg_data *gg_data = data;
 	int ret;

 	if ((gc->of_node != gg_data->gpiospec.np) ||
 	    (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
 	    (!gc->of_xlate))
 		return false;

 	ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
 	if (ret < 0) {
 		/* We've found a gpio chip, but the translation failed.
 		 * Store translation error in out_gpio.
 		 * Return false to keep looking, as more than one gpio chip
 		 * could be registered per of-node.
 		 */
 		gg_data->out_gpio = ERR_PTR(ret);
 		return false;
 	 }

 	gg_data->out_gpio = gpiochip_get_desc(gc, ret);
 	return true;
 }

 /**
  * of_get_named_gpiod_flags() - Get a GPIO descriptor and flags for GPIO API
  * @np:		device node to get GPIO from
  * @propname:	property name containing gpio specifier(s)
  * @index:	index of the GPIO
  * @flags:	a flags pointer to fill in
  *
  * Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
  * value on the error condition. If @flags is not NULL the function also fills
  * in flags for the GPIO.
  */
 struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 		     const char *propname, int index, enum of_gpio_flags *flags)
 {
 	/* Return -EPROBE_DEFER to support probe() functions to be called
 	 * later when the GPIO actually becomes available
 	 */
 	struct gg_data gg_data = {
 		.flags = flags,
 		.out_gpio = ERR_PTR(-EPROBE_DEFER)
 	};
 	int ret;

 	/* .of_xlate might decide to not fill in the flags, so clear it. */
 	if (flags)
 		*flags = 0;

 	ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
 					 &gg_data.gpiospec);
 	if (ret) {
 		pr_debug("%s: can't parse '%s' property of node '%s[%d]'\n",
 			__func__, propname, np->full_name, index);
 		return ERR_PTR(ret);
 	}

 	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);

 	of_node_put(gg_data.gpiospec.np);
 	pr_debug("%s: parsed '%s' property of node '%s[%d]' - status (%d)\n",
 		 __func__, propname, np->full_name, index,
 		 PTR_ERR_OR_ZERO(gg_data.out_gpio));
 	return gg_data.out_gpio;
 }

 int of_get_named_gpio_flags(struct device_node *np, const char *list_name,
 			    int index, enum of_gpio_flags *flags)
 {
 	struct gpio_desc *desc;

 	desc = of_get_named_gpiod_flags(np, list_name, index, flags);

 	if (IS_ERR(desc))
 		return PTR_ERR(desc);
 	else
 		return desc_to_gpio(desc);
 }
 EXPORT_SYMBOL(of_get_named_gpio_flags);

 /**
  * of_parse_own_gpio() - Get a GPIO hog descriptor, names and flags for GPIO API
  * @np:		device node to get GPIO from
  * @name:	GPIO line name
  * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
  *		of_parse_own_gpio()
  * @dflags:	gpiod_flags - optional GPIO initialization flags
  *
  * Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
  * value on the error condition.
  */
 static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
 					   const char **name,
 					   enum gpio_lookup_flags *lflags,
 					   enum gpiod_flags *dflags)
 {
 	struct device_node *chip_np;
 	enum of_gpio_flags xlate_flags;
 	struct gg_data gg_data = {
 		.flags = &xlate_flags,
 	};
 	u32 tmp;
 	int i, ret;

 	chip_np = np->parent;
 	if (!chip_np)
 		return ERR_PTR(-EINVAL);

 	xlate_flags = 0;
 	*lflags = 0;
 	*dflags = 0;

 	ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
 	if (ret)
 		return ERR_PTR(ret);

 	if (tmp > MAX_PHANDLE_ARGS)
 		return ERR_PTR(-EINVAL);

 	gg_data.gpiospec.args_count = tmp;
 	gg_data.gpiospec.np = chip_np;
 	for (i = 0; i < tmp; i++) {
 		ret = of_property_read_u32_index(np, "gpios", i,
 					   &gg_data.gpiospec.args[i]);
 		if (ret)
 			return ERR_PTR(ret);
 	}

 	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
 	if (!gg_data.out_gpio) {
 		if (np->parent == np)
 			return ERR_PTR(-ENXIO);
 		else
 			return ERR_PTR(-EINVAL);
 	}

 	if (xlate_flags & OF_GPIO_ACTIVE_LOW)
 		*lflags |= GPIO_ACTIVE_LOW;

 	if (of_property_read_bool(np, "input"))
 		*dflags |= GPIOD_IN;
 	else if (of_property_read_bool(np, "output-low"))
 		*dflags |= GPIOD_OUT_LOW;
 	else if (of_property_read_bool(np, "output-high"))
 		*dflags |= GPIOD_OUT_HIGH;
 	else {
 		pr_warn("GPIO line %d (%s): no hogging state specified, bailing out\n",
 			desc_to_gpio(gg_data.out_gpio), np->name);
 		return ERR_PTR(-EINVAL);
 	}

 	if (name && of_property_read_string(np, "line-name", name))
 		*name = np->name;

 	return gg_data.out_gpio;
 }

 /**
  * of_gpiochip_scan_gpios - Scan gpio-controller for gpio definitions
  * @chip:	gpio chip to act on
  *
  * This is only used by of_gpiochip_add to request/set GPIO initial
  * configuration.
  */
 static void of_gpiochip_scan_gpios(struct gpio_chip *chip)
 {
 	struct gpio_desc *desc = NULL;
 	struct device_node *np;
 	const char *name;
 	enum gpio_lookup_flags lflags;
 	enum gpiod_flags dflags;

 	for_each_child_of_node(chip->of_node, np) {
 		if (!of_property_read_bool(np, "gpio-hog"))
 			continue;

 		desc = of_parse_own_gpio(np, &name, &lflags, &dflags);
 		if (IS_ERR(desc))
 			continue;

 		if (gpiod_hog(desc, name, lflags, dflags))
 			continue;
 	}
 }

 /**
  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
  * @gc:		pointer to the gpio_chip structure
  * @np:		device node of the GPIO chip
  * @gpio_spec:	gpio specifier as found in the device tree
  * @flags:	a flags pointer to fill in
  *
  * This is simple translation function, suitable for the most 1:1 mapped
  * gpio chips. This function performs only one sanity check: whether gpio
  * is less than ngpios (that is specified in the gpio_chip).
  */
 int of_gpio_simple_xlate(struct gpio_chip *gc,
 			 const struct of_phandle_args *gpiospec, u32 *flags)
 {
 	/*
 	 * We're discouraging gpio_cells < 2, since that way you'll have to
 	 * write your own xlate function (that will have to retrieve the GPIO
 	 * number and the flags from a single gpio cell -- this is possible,
 	 * but not recommended).
 	 */
 	if (gc->of_gpio_n_cells < 2) {
 		WARN_ON(1);
 		return -EINVAL;
 	}

 	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
 		return -EINVAL;

 	if (gpiospec->args[0] >= gc->ngpio)
 		return -EINVAL;

 	if (flags)
 		*flags = gpiospec->args[1];

 	return gpiospec->args[0];
 }
 EXPORT_SYMBOL(of_gpio_simple_xlate);

 /**
  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
  * @np:		device node of the GPIO chip
  * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
  *
  * To use this function you should allocate and fill mm_gc with:
  *
  * 1) In the gpio_chip structure:
  *    - all the callbacks
  *    - of_gpio_n_cells
  *    - of_xlate callback (optional)
  *
  * 3) In the of_mm_gpio_chip structure:
  *    - save_regs callback (optional)
  *
  * If succeeded, this function will map bank's memory and will
  * do all necessary work for you. Then you'll able to use .regs
  * to manage GPIOs from the callbacks.
  */
 int of_mm_gpiochip_add(struct device_node *np,
 		       struct of_mm_gpio_chip *mm_gc)
 {
 	int ret = -ENOMEM;
 	struct gpio_chip *gc = &mm_gc->gc;

 	gc->label = kstrdup(np->full_name, GFP_KERNEL);
 	if (!gc->label)
 		goto err0;

 	mm_gc->regs = of_iomap(np, 0);
 	if (!mm_gc->regs)
 		goto err1;

 	gc->base = -1;

 	if (mm_gc->save_regs)
 		mm_gc->save_regs(mm_gc);

 	mm_gc->gc.of_node = np;

 	ret = gpiochip_add(gc);
 	if (ret)
 		goto err2;

 	return 0;
 err2:
 	iounmap(mm_gc->regs);
 err1:
 	kfree(gc->label);
 err0:
 	pr_err("%s: GPIO chip registration failed with status %d\n",
 	       np->full_name, ret);
 	return ret;
 }
 EXPORT_SYMBOL(of_mm_gpiochip_add);

 /**
  * of_mm_gpiochip_remove - Remove memory mapped GPIO chip (bank)
  * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
  */
 void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
 {
 	struct gpio_chip *gc = &mm_gc->gc;

 	if (!mm_gc)
 		return;

 	gpiochip_remove(gc);
 	iounmap(mm_gc->regs);
 	kfree(gc->label);
 }
 EXPORT_SYMBOL(of_mm_gpiochip_remove);

 #ifdef CONFIG_PINCTRL
 static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
 {
 	struct device_node *np = chip->of_node;
 	struct of_phandle_args pinspec;
 	struct pinctrl_dev *pctldev;
 	int index = 0, ret;
 	const char *name;
 	static const char group_names_propname[] = "gpio-ranges-group-names";
 	struct property *group_names;

 	if (!np)
 		return 0;

 	group_names = of_find_property(np, group_names_propname, NULL);

 	for (;; index++) {
 		ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
 				index, &pinspec);
 		if (ret)
 			break;

 		pctldev = of_pinctrl_get(pinspec.np);
 		if (!pctldev)
 			return -EPROBE_DEFER;

 		if (pinspec.args[2]) {
 			if (group_names) {
 				of_property_read_string_index(np,
 						group_names_propname,
 						index, &name);
 				if (strlen(name)) {
 					pr_err("%s: Group name of numeric GPIO ranges must be the empty string.\n",
 						np->full_name);
 					break;
 				}
 			}
 			/* npins != 0: linear range */
 			ret = gpiochip_add_pin_range(chip,
 					pinctrl_dev_get_devname(pctldev),
 					pinspec.args[0],
 					pinspec.args[1],
 					pinspec.args[2]);
 			if (ret)
 				return ret;
 		} else {
 			/* npins == 0: special range */
 			if (pinspec.args[1]) {
 				pr_err("%s: Illegal gpio-range format.\n",
 					np->full_name);
 				break;
 			}

 			if (!group_names) {
 				pr_err("%s: GPIO group range requested but no %s property.\n",
 					np->full_name, group_names_propname);
 				break;
 			}

 			ret = of_property_read_string_index(np,
 						group_names_propname,
 						index, &name);
 			if (ret)
 				break;

 			if (!strlen(name)) {
 				pr_err("%s: Group name of GPIO group range cannot be the empty string.\n",
 				np->full_name);
 				break;
 			}

 			ret = gpiochip_add_pingroup_range(chip, pctldev,
 						pinspec.args[0], name);
 			if (ret)
 				return ret;
 		}
 	}

 	return 0;
 }

 #else
 static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
 #endif

 int of_gpiochip_add(struct gpio_chip *chip)
 {
 	int status;

 	if ((!chip->of_node) && (chip->dev))
 		chip->of_node = chip->dev->of_node;

 	if (!chip->of_node)
 		return 0;

 	if (!chip->of_xlate) {
 		chip->of_gpio_n_cells = 2;
 		chip->of_xlate = of_gpio_simple_xlate;
 	}

 	status = of_gpiochip_add_pin_range(chip);
 	if (status)
 		return status;

 	of_node_get(chip->of_node);

 	of_gpiochip_scan_gpios(chip);

 	return 0;
 }

 void of_gpiochip_remove(struct gpio_chip *chip)
 {
 	gpiochip_remove_pin_ranges(chip);
 	of_node_put(chip->of_node);
 }

 static struct of_device_id gpio_export_ids[] = {
 	{ .compatible = "gpio-export" },
 	{ /* sentinel */ }
 };

 static int __init of_gpio_export_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct device_node *cnp;
 	u32 val;
 	int nb = 0;

 	for_each_child_of_node(np, cnp) {
 		const char *name = NULL;
 		int gpio;
 		bool dmc;
 		int max_gpio = 1;
 		int i;

 		of_property_read_string(cnp, "gpio-export,name", &name);

 		if (!name)
 			max_gpio = of_gpio_count(cnp);

 		for (i = 0; i < max_gpio; i++) {
 			unsigned flags = 0;
 			enum of_gpio_flags of_flags;

 			gpio = of_get_gpio_flags(cnp, i, &of_flags);

 			if (of_flags == OF_GPIO_ACTIVE_LOW)
 				flags |= GPIOF_ACTIVE_LOW;

 			if (!of_property_read_u32(cnp, "gpio-export,output", &val))
 				flags |= val ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
 			else
 				flags |= GPIOF_IN;

 			if (devm_gpio_request_one(&pdev->dev, gpio, flags, name ? name : of_node_full_name(np)))
 				continue;

 			dmc = of_property_read_bool(cnp, "gpio-export,direction_may_change");
 			gpio_export_with_name(gpio, dmc, name);
 			nb++;
 		}
 	}

 	dev_info(&pdev->dev, "%d gpio(s) exported\n", nb);

 	return 0;
 }

 static struct platform_driver gpio_export_driver = {
 	.driver		= {
 		.name		= "gpio-export",
 		.owner	= THIS_MODULE,
 		.of_match_table	= of_match_ptr(gpio_export_ids),
 	},
 };

 static int __init of_gpio_export_init(void)
 {
 	return platform_driver_probe(&gpio_export_driver, of_gpio_export_probe);
 }
 device_initcall(of_gpio_export_init);
	/*
	* OF helpers for the GPIO API
	*
	* Copyright (c) 2007-2008 MontaVista Software, Inc.
	*
	* Author: Anton Vorontsov <avorontsov@ru.mvista.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*/

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/module.h>
	#include <linux/io.h>
	#include <linux/gpio/consumer.h>
	#include <linux/of.h>
	#include <linux/of_address.h>
	#include <linux/of_gpio.h>
	#include <linux/pinctrl/pinctrl.h>
	#include <linux/slab.h>
	#include <linux/gpio/machine.h>
	#include <linux/init.h>
	#include <linux/platform_device.h>

	#include "gpiolib.h"

	/* Private data structure for of_gpiochip_find_and_xlate */
	struct gg_data {
	enum of_gpio_flags *flags;
	struct of_phandle_args gpiospec;

	struct gpio_desc *out_gpio;
	};

	/* Private function for resolving node pointer to gpio_chip */
	static int of_gpiochip_find_and_xlate(struct gpio_chip gc, void data)
	{
	struct gg_data *gg_data = data;
	int ret;

	if ((gc->of_node != gg_data->gpiospec.np) \|\|
	(gc->of_gpio_n_cells != gg_data->gpiospec.args_count) \|\|
	(!gc->of_xlate))
	return false;

	ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
	if (ret < 0) {
	/* We've found a gpio chip, but the translation failed.
	* Store translation error in out_gpio.
	* Return false to keep looking, as more than one gpio chip
	* could be registered per of-node.
	*/
	gg_data->out_gpio = ERR_PTR(ret);
	return false;
	}

	gg_data->out_gpio = gpiochip_get_desc(gc, ret);
	return true;
	}

	/**
	* of_get_named_gpiod_flags() - Get a GPIO descriptor and flags for GPIO API
	* @np: device node to get GPIO from
	* @propname: property name containing gpio specifier(s)
	* @index: index of the GPIO
	* @flags: a flags pointer to fill in
	*
	* Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
	* value on the error condition. If @flags is not NULL the function also fills
	* in flags for the GPIO.
	*/
	struct gpio_desc of_get_named_gpiod_flags(struct device_node np,
	const char propname, int index, enum of_gpio_flags flags)
	{
	/* Return -EPROBE_DEFER to support probe() functions to be called
	* later when the GPIO actually becomes available
	*/
	struct gg_data gg_data = {
	.flags = flags,
	.out_gpio = ERR_PTR(-EPROBE_DEFER)
	};
	int ret;

	/* .of_xlate might decide to not fill in the flags, so clear it. */
	if (flags)
	*flags = 0;

	ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
	&gg_data.gpiospec);
	if (ret) {
	pr_debug("%s: can't parse '%s' property of node '%s[%d]'\n",
	__func__, propname, np->full_name, index);
	return ERR_PTR(ret);
	}

	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);

	of_node_put(gg_data.gpiospec.np);
	pr_debug("%s: parsed '%s' property of node '%s[%d]' - status (%d)\n",
	__func__, propname, np->full_name, index,
	PTR_ERR_OR_ZERO(gg_data.out_gpio));
	return gg_data.out_gpio;
	}

	int of_get_named_gpio_flags(struct device_node np, const char list_name,
	int index, enum of_gpio_flags *flags)
	{
	struct gpio_desc *desc;

	desc = of_get_named_gpiod_flags(np, list_name, index, flags);

	if (IS_ERR(desc))
	return PTR_ERR(desc);
	else
	return desc_to_gpio(desc);
	}
	EXPORT_SYMBOL(of_get_named_gpio_flags);

	/**
	* of_parse_own_gpio() - Get a GPIO hog descriptor, names and flags for GPIO API
	* @np: device node to get GPIO from
	* @name: GPIO line name
	* @lflags: gpio_lookup_flags - returned from of_find_gpio() or
	* of_parse_own_gpio()
	* @dflags: gpiod_flags - optional GPIO initialization flags
	*
	* Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
	* value on the error condition.
	*/
	static struct gpio_desc of_parse_own_gpio(struct device_node np,
	const char **name,
	enum gpio_lookup_flags *lflags,
	enum gpiod_flags *dflags)
	{
	struct device_node *chip_np;
	enum of_gpio_flags xlate_flags;
	struct gg_data gg_data = {
	.flags = &xlate_flags,
	};
	u32 tmp;
	int i, ret;

	chip_np = np->parent;
	if (!chip_np)
	return ERR_PTR(-EINVAL);

	xlate_flags = 0;
	*lflags = 0;
	*dflags = 0;

	ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
	if (ret)
	return ERR_PTR(ret);

	if (tmp > MAX_PHANDLE_ARGS)
	return ERR_PTR(-EINVAL);

	gg_data.gpiospec.args_count = tmp;
	gg_data.gpiospec.np = chip_np;
	for (i = 0; i < tmp; i++) {
	ret = of_property_read_u32_index(np, "gpios", i,
	&gg_data.gpiospec.args[i]);
	if (ret)
	return ERR_PTR(ret);
	}

	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
	if (!gg_data.out_gpio) {
	if (np->parent == np)
	return ERR_PTR(-ENXIO);
	else
	return ERR_PTR(-EINVAL);
	}

	if (xlate_flags & OF_GPIO_ACTIVE_LOW)
	*lflags \|= GPIO_ACTIVE_LOW;

	if (of_property_read_bool(np, "input"))
	*dflags \|= GPIOD_IN;
	else if (of_property_read_bool(np, "output-low"))
	*dflags \|= GPIOD_OUT_LOW;
	else if (of_property_read_bool(np, "output-high"))
	*dflags \|= GPIOD_OUT_HIGH;
	else {
	pr_warn("GPIO line %d (%s): no hogging state specified, bailing out\n",
	desc_to_gpio(gg_data.out_gpio), np->name);
	return ERR_PTR(-EINVAL);
	}

	if (name && of_property_read_string(np, "line-name", name))
	*name = np->name;

	return gg_data.out_gpio;
	}

	/**
	* of_gpiochip_scan_gpios - Scan gpio-controller for gpio definitions
	* @chip: gpio chip to act on
	*
	* This is only used by of_gpiochip_add to request/set GPIO initial
	* configuration.
	*/
	static void of_gpiochip_scan_gpios(struct gpio_chip *chip)
	{
	struct gpio_desc *desc = NULL;
	struct device_node *np;
	const char *name;
	enum gpio_lookup_flags lflags;
	enum gpiod_flags dflags;

	for_each_child_of_node(chip->of_node, np) {
	if (!of_property_read_bool(np, "gpio-hog"))
	continue;

	desc = of_parse_own_gpio(np, &name, &lflags, &dflags);
	if (IS_ERR(desc))
	continue;

	if (gpiod_hog(desc, name, lflags, dflags))
	continue;
	}
	}

	/**
	* of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
	* @gc: pointer to the gpio_chip structure
	* @np: device node of the GPIO chip
	* @gpio_spec: gpio specifier as found in the device tree
	* @flags: a flags pointer to fill in
	*
	* This is simple translation function, suitable for the most 1:1 mapped
	* gpio chips. This function performs only one sanity check: whether gpio
	* is less than ngpios (that is specified in the gpio_chip).
	*/
	int of_gpio_simple_xlate(struct gpio_chip *gc,
	const struct of_phandle_args gpiospec, u32 flags)
	{
	/*
	* We're discouraging gpio_cells < 2, since that way you'll have to
	* write your own xlate function (that will have to retrieve the GPIO
	* number and the flags from a single gpio cell -- this is possible,
	* but not recommended).
	*/
	if (gc->of_gpio_n_cells < 2) {
	WARN_ON(1);
	return -EINVAL;
	}

	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
	return -EINVAL;

	if (gpiospec->args[0] >= gc->ngpio)
	return -EINVAL;

	if (flags)
	*flags = gpiospec->args[1];

	return gpiospec->args[0];
	}
	EXPORT_SYMBOL(of_gpio_simple_xlate);

	/**
	* of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
	* @np: device node of the GPIO chip
	* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
	*
	* To use this function you should allocate and fill mm_gc with:
	*
	* 1) In the gpio_chip structure:
	* - all the callbacks
	* - of_gpio_n_cells
	* - of_xlate callback (optional)
	*
	* 3) In the of_mm_gpio_chip structure:
	* - save_regs callback (optional)
	*
	* If succeeded, this function will map bank's memory and will
	* do all necessary work for you. Then you'll able to use .regs
	* to manage GPIOs from the callbacks.
	*/
	int of_mm_gpiochip_add(struct device_node *np,
	struct of_mm_gpio_chip *mm_gc)
	{
	int ret = -ENOMEM;
	struct gpio_chip *gc = &mm_gc->gc;

	gc->label = kstrdup(np->full_name, GFP_KERNEL);
	if (!gc->label)
	goto err0;

	mm_gc->regs = of_iomap(np, 0);
	if (!mm_gc->regs)
	goto err1;

	gc->base = -1;

	if (mm_gc->save_regs)
	mm_gc->save_regs(mm_gc);

	mm_gc->gc.of_node = np;

	ret = gpiochip_add(gc);
	if (ret)
	goto err2;

	return 0;
	err2:
	iounmap(mm_gc->regs);
	err1:
	kfree(gc->label);
	err0:
	pr_err("%s: GPIO chip registration failed with status %d\n",
	np->full_name, ret);
	return ret;
	}
	EXPORT_SYMBOL(of_mm_gpiochip_add);

	/**
	* of_mm_gpiochip_remove - Remove memory mapped GPIO chip (bank)
	* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
	*/
	void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
	{
	struct gpio_chip *gc = &mm_gc->gc;

	if (!mm_gc)
	return;

	gpiochip_remove(gc);
	iounmap(mm_gc->regs);
	kfree(gc->label);
	}
	EXPORT_SYMBOL(of_mm_gpiochip_remove);

	#ifdef CONFIG_PINCTRL
	static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
	{
	struct device_node *np = chip->of_node;
	struct of_phandle_args pinspec;
	struct pinctrl_dev *pctldev;
	int index = 0, ret;
	const char *name;
	static const char group_names_propname[] = "gpio-ranges-group-names";
	struct property *group_names;

	if (!np)
	return 0;

	group_names = of_find_property(np, group_names_propname, NULL);

	for (;; index++) {
	ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
	index, &pinspec);
	if (ret)
	break;

	pctldev = of_pinctrl_get(pinspec.np);
	if (!pctldev)
	return -EPROBE_DEFER;

	if (pinspec.args[2]) {
	if (group_names) {
	of_property_read_string_index(np,
	group_names_propname,
	index, &name);
	if (strlen(name)) {
	pr_err("%s: Group name of numeric GPIO ranges must be the empty string.\n",
	np->full_name);
	break;
	}
	}
	/* npins != 0: linear range */
	ret = gpiochip_add_pin_range(chip,
	pinctrl_dev_get_devname(pctldev),
	pinspec.args[0],
	pinspec.args[1],
	pinspec.args[2]);
	if (ret)
	return ret;
	} else {
	/* npins == 0: special range */
	if (pinspec.args[1]) {
	pr_err("%s: Illegal gpio-range format.\n",
	np->full_name);
	break;
	}

	if (!group_names) {
	pr_err("%s: GPIO group range requested but no %s property.\n",
	np->full_name, group_names_propname);
	break;
	}

	ret = of_property_read_string_index(np,
	group_names_propname,
	index, &name);
	if (ret)
	break;

	if (!strlen(name)) {
	pr_err("%s: Group name of GPIO group range cannot be the empty string.\n",
	np->full_name);
	break;
	}

	ret = gpiochip_add_pingroup_range(chip, pctldev,
	pinspec.args[0], name);
	if (ret)
	return ret;
	}
	}

	return 0;
	}

	#else
	static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
	#endif

	int of_gpiochip_add(struct gpio_chip *chip)
	{
	int status;

	if ((!chip->of_node) && (chip->dev))
	chip->of_node = chip->dev->of_node;

	if (!chip->of_node)
	return 0;

	if (!chip->of_xlate) {
	chip->of_gpio_n_cells = 2;
	chip->of_xlate = of_gpio_simple_xlate;
	}

	status = of_gpiochip_add_pin_range(chip);
	if (status)
	return status;

	of_node_get(chip->of_node);

	of_gpiochip_scan_gpios(chip);

	return 0;
	}

	void of_gpiochip_remove(struct gpio_chip *chip)
	{
	gpiochip_remove_pin_ranges(chip);
	of_node_put(chip->of_node);
	}

	static struct of_device_id gpio_export_ids[] = {
	{ .compatible = "gpio-export" },
	{ /* sentinel */ }
	};

	static int __init of_gpio_export_probe(struct platform_device *pdev)
	{
	struct device_node *np = pdev->dev.of_node;
	struct device_node *cnp;
	u32 val;
	int nb = 0;

	for_each_child_of_node(np, cnp) {
	const char *name = NULL;
	int gpio;
	bool dmc;
	int max_gpio = 1;
	int i;

	of_property_read_string(cnp, "gpio-export,name", &name);

	if (!name)
	max_gpio = of_gpio_count(cnp);

	for (i = 0; i < max_gpio; i++) {
	unsigned flags = 0;
	enum of_gpio_flags of_flags;

	gpio = of_get_gpio_flags(cnp, i, &of_flags);

	if (of_flags == OF_GPIO_ACTIVE_LOW)
	flags \|= GPIOF_ACTIVE_LOW;

	if (!of_property_read_u32(cnp, "gpio-export,output", &val))
	flags \|= val ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
	else
	flags \|= GPIOF_IN;

	if (devm_gpio_request_one(&pdev->dev, gpio, flags, name ? name : of_node_full_name(np)))
	continue;

	dmc = of_property_read_bool(cnp, "gpio-export,direction_may_change");
	gpio_export_with_name(gpio, dmc, name);
	nb++;
	}
	}

	dev_info(&pdev->dev, "%d gpio(s) exported\n", nb);

	return 0;
	}

	static struct platform_driver gpio_export_driver = {
	.driver = {
	.name = "gpio-export",
	.owner = THIS_MODULE,
	.of_match_table = of_match_ptr(gpio_export_ids),
	},
	};

	static int __init of_gpio_export_init(void)
	{
	return platform_driver_probe(&gpio_export_driver, of_gpio_export_probe);
	}
	device_initcall(of_gpio_export_init);