1/*
  2 * OF helpers for the GPIO API
  3 *
  4 * Copyright (c) 2007-2008  MontaVista Software, Inc.
  5 *
  6 * Author: Anton Vorontsov <avorontsov@ru.mvista.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 as published by
 10 * the Free Software Foundation; either version 2 of the License, or
 11 * (at your option) any later version.
 12 */
 13
 14#include <linux/device.h>
 15#include <linux/errno.h>
 16#include <linux/module.h>
 17#include <linux/io.h>
 18#include <linux/gpio.h>
 19#include <linux/of.h>
 20#include <linux/of_address.h>
 21#include <linux/of_gpio.h>
 22#include <linux/slab.h>
 23
 24/* Private data structure for of_gpiochip_is_match */
 25struct gg_data {
 26	enum of_gpio_flags *flags;
 27	struct of_phandle_args gpiospec;
 28
 29	int out_gpio;
 30};
 31
 32/* Private function for resolving node pointer to gpio_chip */
 33static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
 34{
 35	struct gg_data *gg_data = data;
 36	int ret;
 37
 38	if ((gc->of_node != gg_data->gpiospec.np) ||
 39	    (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
 40	    (!gc->of_xlate))
 41		return false;
 42
 43	ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
 44	if (ret < 0)
 45		return false;
 46
 47	gg_data->out_gpio = ret + gc->base;
 48	return true;
 49}
 50
 51/**
 52 * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
 53 * @np:		device node to get GPIO from
 54 * @propname:	property name containing gpio specifier(s)
 55 * @index:	index of the GPIO
 56 * @flags:	a flags pointer to fill in
 57 *
 58 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
 59 * value on the error condition. If @flags is not NULL the function also fills
 60 * in flags for the GPIO.
 61 */
 62int of_get_named_gpio_flags(struct device_node *np, const char *propname,
 63                           int index, enum of_gpio_flags *flags)
 64{
 65	struct gg_data gg_data = { .flags = flags, .out_gpio = -ENODEV };
 66	int ret;
 67
 68	/* .of_xlate might decide to not fill in the flags, so clear it. */
 69	if (flags)
 70		*flags = 0;
 71
 72	ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
 73					 &gg_data.gpiospec);
 74	if (ret) {
 75		pr_debug("%s: can't parse gpios property\n", __func__);
 76		return -EINVAL;
 77	}
 78
 79	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
 80
 81	of_node_put(gg_data.gpiospec.np);
 82	pr_debug("%s exited with status %d\n", __func__, ret);
 83	return gg_data.out_gpio;
 84}
 85EXPORT_SYMBOL(of_get_named_gpio_flags);
 86
 87/**
 88 * of_gpio_named_count - Count GPIOs for a device
 89 * @np:		device node to count GPIOs for
 90 * @propname:	property name containing gpio specifier(s)
 91 *
 92 * The function returns the count of GPIOs specified for a node.
 93 *
 94 * Note that the empty GPIO specifiers counts too. For example,
 95 *
 96 * gpios = <0
 97 *          &pio1 1 2
 98 *          0
 99 *          &pio2 3 4>;
100 *
101 * defines four GPIOs (so this function will return 4), two of which
102 * are not specified.
103 */
104unsigned int of_gpio_named_count(struct device_node *np, const char* propname)
105{
106	unsigned int cnt = 0;
107
108	do {
109		int ret;
110
111		ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
112						 cnt, NULL);
113		/* A hole in the gpios = <> counts anyway. */
114		if (ret < 0 && ret != -EEXIST)
115			break;
116	} while (++cnt);
117
118	return cnt;
119}
120EXPORT_SYMBOL(of_gpio_named_count);
121
122/**
123 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
124 * @gc:		pointer to the gpio_chip structure
125 * @np:		device node of the GPIO chip
126 * @gpio_spec:	gpio specifier as found in the device tree
127 * @flags:	a flags pointer to fill in
128 *
129 * This is simple translation function, suitable for the most 1:1 mapped
130 * gpio chips. This function performs only one sanity check: whether gpio
131 * is less than ngpios (that is specified in the gpio_chip).
132 */
133int of_gpio_simple_xlate(struct gpio_chip *gc,
134			 const struct of_phandle_args *gpiospec, u32 *flags)
135{
136	/*
137	 * We're discouraging gpio_cells < 2, since that way you'll have to
138	 * write your own xlate function (that will have to retrive the GPIO
139	 * number and the flags from a single gpio cell -- this is possible,
140	 * but not recommended).
141	 */
142	if (gc->of_gpio_n_cells < 2) {
143		WARN_ON(1);
144		return -EINVAL;
145	}
146
147	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
148		return -EINVAL;
149
150	if (gpiospec->args[0] >= gc->ngpio)
151		return -EINVAL;
152
153	if (flags)
154		*flags = gpiospec->args[1];
155
156	return gpiospec->args[0];
157}
158EXPORT_SYMBOL(of_gpio_simple_xlate);
159
160/**
161 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
162 * @np:		device node of the GPIO chip
163 * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
164 *
165 * To use this function you should allocate and fill mm_gc with:
166 *
167 * 1) In the gpio_chip structure:
168 *    - all the callbacks
169 *    - of_gpio_n_cells
170 *    - of_xlate callback (optional)
171 *
172 * 3) In the of_mm_gpio_chip structure:
173 *    - save_regs callback (optional)
174 *
175 * If succeeded, this function will map bank's memory and will
176 * do all necessary work for you. Then you'll able to use .regs
177 * to manage GPIOs from the callbacks.
178 */
179int of_mm_gpiochip_add(struct device_node *np,
180		       struct of_mm_gpio_chip *mm_gc)
181{
182	int ret = -ENOMEM;
183	struct gpio_chip *gc = &mm_gc->gc;
184
185	gc->label = kstrdup(np->full_name, GFP_KERNEL);
186	if (!gc->label)
187		goto err0;
188
189	mm_gc->regs = of_iomap(np, 0);
190	if (!mm_gc->regs)
191		goto err1;
192
193	gc->base = -1;
194
195	if (mm_gc->save_regs)
196		mm_gc->save_regs(mm_gc);
197
198	mm_gc->gc.of_node = np;
199
200	ret = gpiochip_add(gc);
201	if (ret)
202		goto err2;
203
204	return 0;
205err2:
206	iounmap(mm_gc->regs);
207err1:
208	kfree(gc->label);
209err0:
210	pr_err("%s: GPIO chip registration failed with status %d\n",
211	       np->full_name, ret);
212	return ret;
213}
214EXPORT_SYMBOL(of_mm_gpiochip_add);
215
216void of_gpiochip_add(struct gpio_chip *chip)
217{
218	if ((!chip->of_node) && (chip->dev))
219		chip->of_node = chip->dev->of_node;
220
221	if (!chip->of_node)
222		return;
223
224	if (!chip->of_xlate) {
225		chip->of_gpio_n_cells = 2;
226		chip->of_xlate = of_gpio_simple_xlate;
227	}
228
229	of_node_get(chip->of_node);
230}
231
232void of_gpiochip_remove(struct gpio_chip *chip)
233{
234	if (chip->of_node)
235		of_node_put(chip->of_node);
236}