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_gpio_flags - Get a GPIO number and flags to use with GPIO API
25 * @np:		device node to get GPIO from
26 * @index:	index of the GPIO
27 * @flags:	a flags pointer to fill in
28 *
29 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
30 * value on the error condition. If @flags is not NULL the function also fills
31 * in flags for the GPIO.
32 */
33int of_get_gpio_flags(struct device_node *np, int index,
34		      enum of_gpio_flags *flags)
35{
36	int ret;
37	struct device_node *gpio_np;
38	struct gpio_chip *gc;
39	int size;
40	const void *gpio_spec;
41	const __be32 *gpio_cells;
42
43	ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
44					  &gpio_np, &gpio_spec);
45	if (ret) {
46		pr_debug("%s: can't parse gpios property\n", __func__);
47		goto err0;
48	}
49
50	gc = of_node_to_gpiochip(gpio_np);
51	if (!gc) {
52		pr_debug("%s: gpio controller %s isn't registered\n",
53			 np->full_name, gpio_np->full_name);
54		ret = -ENODEV;
55		goto err1;
56	}
57
58	gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
59	if (!gpio_cells || size != sizeof(*gpio_cells) ||
60			be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) {
61		pr_debug("%s: wrong #gpio-cells for %s\n",
62			 np->full_name, gpio_np->full_name);
63		ret = -EINVAL;
64		goto err1;
65	}
66
67	/* .xlate might decide to not fill in the flags, so clear it. */
68	if (flags)
69		*flags = 0;
70
71	ret = gc->of_xlate(gc, np, gpio_spec, flags);
72	if (ret < 0)
73		goto err1;
74
75	ret += gc->base;
76err1:
77	of_node_put(gpio_np);
78err0:
79	pr_debug("%s exited with status %d\n", __func__, ret);
80	return ret;
81}
82EXPORT_SYMBOL(of_get_gpio_flags);
83
84/**
85 * of_gpio_count - Count GPIOs for a device
86 * @np:		device node to count GPIOs for
87 *
88 * The function returns the count of GPIOs specified for a node.
89 *
90 * Note that the empty GPIO specifiers counts too. For example,
91 *
92 * gpios = <0
93 *          &pio1 1 2
94 *          0
95 *          &pio2 3 4>;
96 *
97 * defines four GPIOs (so this function will return 4), two of which
98 * are not specified.
99 */
100unsigned int of_gpio_count(struct device_node *np)
101{
102	unsigned int cnt = 0;
103
104	do {
105		int ret;
106
107		ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
108						  cnt, NULL, NULL);
109		/* A hole in the gpios = <> counts anyway. */
110		if (ret < 0 && ret != -EEXIST)
111			break;
112	} while (++cnt);
113
114	return cnt;
115}
116EXPORT_SYMBOL(of_gpio_count);
117
118/**
119 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
120 * @gc:		pointer to the gpio_chip structure
121 * @np:		device node of the GPIO chip
122 * @gpio_spec:	gpio specifier as found in the device tree
123 * @flags:	a flags pointer to fill in
124 *
125 * This is simple translation function, suitable for the most 1:1 mapped
126 * gpio chips. This function performs only one sanity check: whether gpio
127 * is less than ngpios (that is specified in the gpio_chip).
128 */
129static int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
130				const void *gpio_spec, u32 *flags)
131{
132	const __be32 *gpio = gpio_spec;
133	const u32 n = be32_to_cpup(gpio);
134
135	/*
136	 * We're discouraging gpio_cells < 2, since that way you'll have to
137	 * write your own xlate function (that will have to retrive the GPIO
138	 * number and the flags from a single gpio cell -- this is possible,
139	 * but not recommended).
140	 */
141	if (gc->of_gpio_n_cells < 2) {
142		WARN_ON(1);
143		return -EINVAL;
144	}
145
146	if (n > gc->ngpio)
147		return -EINVAL;
148
149	if (flags)
150		*flags = be32_to_cpu(gpio[1]);
151
152	return n;
153}
154
155/**
156 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
157 * @np:		device node of the GPIO chip
158 * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
159 *
160 * To use this function you should allocate and fill mm_gc with:
161 *
162 * 1) In the gpio_chip structure:
163 *    - all the callbacks
164 *    - of_gpio_n_cells
165 *    - of_xlate callback (optional)
166 *
167 * 3) In the of_mm_gpio_chip structure:
168 *    - save_regs callback (optional)
169 *
170 * If succeeded, this function will map bank's memory and will
171 * do all necessary work for you. Then you'll able to use .regs
172 * to manage GPIOs from the callbacks.
173 */
174int of_mm_gpiochip_add(struct device_node *np,
175		       struct of_mm_gpio_chip *mm_gc)
176{
177	int ret = -ENOMEM;
178	struct gpio_chip *gc = &mm_gc->gc;
179
180	gc->label = kstrdup(np->full_name, GFP_KERNEL);
181	if (!gc->label)
182		goto err0;
183
184	mm_gc->regs = of_iomap(np, 0);
185	if (!mm_gc->regs)
186		goto err1;
187
188	gc->base = -1;
189
190	if (mm_gc->save_regs)
191		mm_gc->save_regs(mm_gc);
192
193	mm_gc->gc.of_node = np;
194
195	ret = gpiochip_add(gc);
196	if (ret)
197		goto err2;
198
199	pr_debug("%s: registered as generic GPIO chip, base is %d\n",
200		 np->full_name, gc->base);
201	return 0;
202err2:
203	iounmap(mm_gc->regs);
204err1:
205	kfree(gc->label);
206err0:
207	pr_err("%s: GPIO chip registration failed with status %d\n",
208	       np->full_name, ret);
209	return ret;
210}
211EXPORT_SYMBOL(of_mm_gpiochip_add);
212
213void of_gpiochip_add(struct gpio_chip *chip)
214{
215	if ((!chip->of_node) && (chip->dev))
216		chip->of_node = chip->dev->of_node;
217
218	if (!chip->of_node)
219		return;
220
221	if (!chip->of_xlate) {
222		chip->of_gpio_n_cells = 2;
223		chip->of_xlate = of_gpio_simple_xlate;
224	}
225
226	of_node_get(chip->of_node);
227}
228
229void of_gpiochip_remove(struct gpio_chip *chip)
230{
231	if (chip->of_node)
232		of_node_put(chip->of_node);
233}
234
235/* Private function for resolving node pointer to gpio_chip */
236static int of_gpiochip_is_match(struct gpio_chip *chip, void *data)
237{
238	return chip->of_node == data;
239}
240
241struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
242{
243	return gpiochip_find(np, of_gpiochip_is_match);
244}
245