text: /*
   * 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/errno.h>
  #include <linux/module.h>
  #include <linux/io.h>
  #include <linux/gpio.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/of_gpio.h>
  #include <linux/slab.h>
  
  /* Private data structure for of_gpiochip_is_match */
  struct gg_data {
  	enum of_gpio_flags *flags;
  	struct of_phandle_args gpiospec;
  
  	int 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)
  		return false;
  
  	gg_data->out_gpio = ret + gc->base;
  	return true;
  }
  
  /**
   * of_get_named_gpio_flags() - Get a GPIO number and flags to use with 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 number to use with Linux generic 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.
   */
  int of_get_named_gpio_flags(struct device_node *np, const char *propname,
                             int index, enum of_gpio_flags *flags)
  {
  	struct gg_data gg_data = { .flags = flags, .out_gpio = -ENODEV };
  	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 gpios property\n", __func__);
  		return -EINVAL;
  	}
  
  	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
  
  	of_node_put(gg_data.gpiospec.np);
  	pr_debug("%s exited with status %d\n", __func__, ret);
  	return gg_data.out_gpio;
  }
  EXPORT_SYMBOL(of_get_named_gpio_flags);
  
  /**
   * of_gpio_named_count - Count GPIOs for a device
   * @np:		device node to count GPIOs for
   * @propname:	property name containing gpio specifier(s)
   *
   * The function returns the count of GPIOs specified for a node.
   *
   * Note that the empty GPIO specifiers counts too. For example,
   *
   * gpios = <0
   *          &pio1 1 2
   *          0
   *          &pio2 3 4>;
   *
   * defines four GPIOs (so this function will return 4), two of which
   * are not specified.
   */
  unsigned int of_gpio_named_count(struct device_node *np, const char* propname)
  {
  	unsigned int cnt = 0;
  
  	do {
  		int ret;
  
  		ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
  						 cnt, NULL);
  		/* A hole in the gpios = <> counts anyway. */
  		if (ret < 0 && ret != -EEXIST)
  			break;
  	} while (++cnt);
  
  	return cnt;
  }
  EXPORT_SYMBOL(of_gpio_named_count);
  
  /**
   * 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 retrive 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);
  
  void of_gpiochip_add(struct gpio_chip *chip)
  {
  	if ((!chip->of_node) && (chip->dev))
  		chip->of_node = chip->dev->of_node;
  
  	if (!chip->of_node)
  		return;
  
  	if (!chip->of_xlate) {
  		chip->of_gpio_n_cells = 2;
  		chip->of_xlate = of_gpio_simple_xlate;
  	}
  
  	of_node_get(chip->of_node);
  }
  
  void of_gpiochip_remove(struct gpio_chip *chip)
  {
  	if (chip->of_node)
  		of_node_put(chip->of_node);
  }
  