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/of.h>
 19#include <linux/of_address.h>
 20#include <linux/of_gpio.h>
 21#include <linux/slab.h>
 22
 23/**
 24 * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
 25 * @np:		device node to get GPIO from
 26 * @propname:	property name containing gpio specifier(s)
 27 * @index:	index of the GPIO
 28 * @flags:	a flags pointer to fill in
 29 *
 30 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
 31 * value on the error condition. If @flags is not NULL the function also fills
 32 * in flags for the GPIO.
 33 */
 34int of_get_named_gpio_flags(struct device_node *np, const char *propname,
 35                           int index, enum of_gpio_flags *flags)
 36{
 37	int ret;
 38	struct device_node *gpio_np;
 39	struct gpio_chip *gc;
 40	int size;
 41	const void *gpio_spec;
 42	const __be32 *gpio_cells;
 43
 44	ret = of_parse_phandles_with_args(np, propname, "#gpio-cells", index,
 45					  &gpio_np, &gpio_spec);
 46	if (ret) {
 47		pr_debug("%s: can't parse gpios property\n", __func__);
 48		goto err0;
 49	}
 50
 51	gc = of_node_to_gpiochip(gpio_np);
 52	if (!gc) {
 53		pr_debug("%s: gpio controller %s isn't registered\n",
 54			 np->full_name, gpio_np->full_name);
 55		ret = -ENODEV;
 56		goto err1;
 57	}
 58
 59	gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
 60	if (!gpio_cells || size != sizeof(*gpio_cells) ||
 61			be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) {
 62		pr_debug("%s: wrong #gpio-cells for %s\n",
 63			 np->full_name, gpio_np->full_name);
 64		ret = -EINVAL;
 65		goto err1;
 66	}
 67
 68	/* .xlate might decide to not fill in the flags, so clear it. */
 69	if (flags)
 70		*flags = 0;
 71
 72	ret = gc->of_xlate(gc, np, gpio_spec, flags);
 73	if (ret < 0)
 74		goto err1;
 75
 76	ret += gc->base;
 77err1:
 78	of_node_put(gpio_np);
 79err0:
 80	pr_debug("%s exited with status %d\n", __func__, ret);
 81	return ret;
 82}
 83EXPORT_SYMBOL(of_get_named_gpio_flags);
 84
 85/**
 86 * of_gpio_count - Count GPIOs for a device
 87 * @np:		device node to count GPIOs for
 88 *
 89 * The function returns the count of GPIOs specified for a node.
 90 *
 91 * Note that the empty GPIO specifiers counts too. For example,
 92 *
 93 * gpios = <0
 94 *          &pio1 1 2
 95 *          0
 96 *          &pio2 3 4>;
 97 *
 98 * defines four GPIOs (so this function will return 4), two of which
 99 * are not specified.
100 */
101unsigned int of_gpio_count(struct device_node *np)
102{
103	unsigned int cnt = 0;
104
105	do {
106		int ret;
107
108		ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
109						  cnt, NULL, NULL);
110		/* A hole in the gpios = <> counts anyway. */
111		if (ret < 0 && ret != -EEXIST)
112			break;
113	} while (++cnt);
114
115	return cnt;
116}
117EXPORT_SYMBOL(of_gpio_count);
118
119/**
120 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
121 * @gc:		pointer to the gpio_chip structure
122 * @np:		device node of the GPIO chip
123 * @gpio_spec:	gpio specifier as found in the device tree
124 * @flags:	a flags pointer to fill in
125 *
126 * This is simple translation function, suitable for the most 1:1 mapped
127 * gpio chips. This function performs only one sanity check: whether gpio
128 * is less than ngpios (that is specified in the gpio_chip).
129 */
130int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
131			 const void *gpio_spec, u32 *flags)
132{
133	const __be32 *gpio = gpio_spec;
134	const u32 n = be32_to_cpup(gpio);
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 (n > gc->ngpio)
148		return -EINVAL;
149
150	if (flags)
151		*flags = be32_to_cpu(gpio[1]);
152
153	return n;
154}
155EXPORT_SYMBOL(of_gpio_simple_xlate);
156
157/**
158 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
159 * @np:		device node of the GPIO chip
160 * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
161 *
162 * To use this function you should allocate and fill mm_gc with:
163 *
164 * 1) In the gpio_chip structure:
165 *    - all the callbacks
166 *    - of_gpio_n_cells
167 *    - of_xlate callback (optional)
168 *
169 * 3) In the of_mm_gpio_chip structure:
170 *    - save_regs callback (optional)
171 *
172 * If succeeded, this function will map bank's memory and will
173 * do all necessary work for you. Then you'll able to use .regs
174 * to manage GPIOs from the callbacks.
175 */
176int of_mm_gpiochip_add(struct device_node *np,
177		       struct of_mm_gpio_chip *mm_gc)
178{
179	int ret = -ENOMEM;
180	struct gpio_chip *gc = &mm_gc->gc;
181
182	gc->label = kstrdup(np->full_name, GFP_KERNEL);
183	if (!gc->label)
184		goto err0;
185
186	mm_gc->regs = of_iomap(np, 0);
187	if (!mm_gc->regs)
188		goto err1;
189
190	gc->base = -1;
191
192	if (mm_gc->save_regs)
193		mm_gc->save_regs(mm_gc);
194
195	mm_gc->gc.of_node = np;
196
197	ret = gpiochip_add(gc);
198	if (ret)
199		goto err2;
200
201	pr_debug("%s: registered as generic GPIO chip, base is %d\n",
202		 np->full_name, gc->base);
203	return 0;
204err2:
205	iounmap(mm_gc->regs);
206err1:
207	kfree(gc->label);
208err0:
209	pr_err("%s: GPIO chip registration failed with status %d\n",
210	       np->full_name, ret);
211	return ret;
212}
213EXPORT_SYMBOL(of_mm_gpiochip_add);
214
215void of_gpiochip_add(struct gpio_chip *chip)
216{
217	if ((!chip->of_node) && (chip->dev))
218		chip->of_node = chip->dev->of_node;
219
220	if (!chip->of_node)
221		return;
222
223	if (!chip->of_xlate) {
224		chip->of_gpio_n_cells = 2;
225		chip->of_xlate = of_gpio_simple_xlate;
226	}
227
228	of_node_get(chip->of_node);
229}
230
231void of_gpiochip_remove(struct gpio_chip *chip)
232{
233	if (chip->of_node)
234		of_node_put(chip->of_node);
235}
236
237/* Private function for resolving node pointer to gpio_chip */
238static int of_gpiochip_is_match(struct gpio_chip *chip, void *data)
239{
240	return chip->of_node == data;
241}
242
243struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
244{
245	return gpiochip_find(np, of_gpiochip_is_match);
246}