tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/kernel.h>
15#include <linux/errno.h>
16#include <linux/io.h>
17#include <linux/of.h>
18#include <linux/of_gpio.h>
19#include <asm/prom.h>
20
21/**
22 * of_get_gpio - Get a GPIO number from the device tree to use with GPIO API
23 * @np: device node to get GPIO from
24 * @index: index of the GPIO
25 *
26 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
27 * value on the error condition.
28 */
29int of_get_gpio(struct device_node *np, int index)
30{
31 int ret = -EINVAL;
32 struct device_node *gc;
33 struct of_gpio_chip *of_gc = NULL;
34 int size;
35 const u32 *gpios;
36 u32 nr_cells;
37 int i;
38 const void *gpio_spec;
39 const u32 *gpio_cells;
40 int gpio_index = 0;
41
42 gpios = of_get_property(np, "gpios", &size);
43 if (!gpios) {
44 ret = -ENOENT;
45 goto err0;
46 }
47 nr_cells = size / sizeof(u32);
48
49 for (i = 0; i < nr_cells; gpio_index++) {
50 const phandle *gpio_phandle;
51
52 gpio_phandle = gpios + i;
53 gpio_spec = gpio_phandle + 1;
54
55 /* one cell hole in the gpios = <>; */
56 if (!*gpio_phandle) {
57 if (gpio_index == index)
58 return -ENOENT;
59 i++;
60 continue;
61 }
62
63 gc = of_find_node_by_phandle(*gpio_phandle);
64 if (!gc) {
65 pr_debug("%s: could not find phandle for gpios\n",
66 np->full_name);
67 goto err0;
68 }
69
70 of_gc = gc->data;
71 if (!of_gc) {
72 pr_debug("%s: gpio controller %s isn't registered\n",
73 np->full_name, gc->full_name);
74 goto err1;
75 }
76
77 gpio_cells = of_get_property(gc, "#gpio-cells", &size);
78 if (!gpio_cells || size != sizeof(*gpio_cells) ||
79 *gpio_cells != of_gc->gpio_cells) {
80 pr_debug("%s: wrong #gpio-cells for %s\n",
81 np->full_name, gc->full_name);
82 goto err1;
83 }
84
85 /* Next phandle is at phandle cells + #gpio-cells */
86 i += sizeof(*gpio_phandle) / sizeof(u32) + *gpio_cells;
87 if (i >= nr_cells + 1) {
88 pr_debug("%s: insufficient gpio-spec length\n",
89 np->full_name);
90 goto err1;
91 }
92
93 if (gpio_index == index)
94 break;
95
96 of_gc = NULL;
97 of_node_put(gc);
98 }
99
100 if (!of_gc) {
101 ret = -ENOENT;
102 goto err0;
103 }
104
105 ret = of_gc->xlate(of_gc, np, gpio_spec);
106 if (ret < 0)
107 goto err1;
108
109 ret += of_gc->gc.base;
110err1:
111 of_node_put(gc);
112err0:
113 pr_debug("%s exited with status %d\n", __func__, ret);
114 return ret;
115}
116EXPORT_SYMBOL(of_get_gpio);
117
118/**
119 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number
120 * @of_gc: pointer to the of_gpio_chip structure
121 * @np: device node of the GPIO chip
122 * @gpio_spec: gpio specifier as found in the device tree
123 *
124 * This is simple translation function, suitable for the most 1:1 mapped
125 * gpio chips. This function performs only one sanity check: whether gpio
126 * is less than ngpios (that is specified in the gpio_chip).
127 */
128int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
129 const void *gpio_spec)
130{
131 const u32 *gpio = gpio_spec;
132
133 if (*gpio > of_gc->gc.ngpio)
134 return -EINVAL;
135
136 return *gpio;
137}
138EXPORT_SYMBOL(of_gpio_simple_xlate);
139
140/**
141 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
142 * @np: device node of the GPIO chip
143 * @mm_gc: pointer to the of_mm_gpio_chip allocated structure
144 *
145 * To use this function you should allocate and fill mm_gc with:
146 *
147 * 1) In the gpio_chip structure:
148 * - all the callbacks
149 *
150 * 2) In the of_gpio_chip structure:
151 * - gpio_cells
152 * - xlate callback (optional)
153 *
154 * 3) In the of_mm_gpio_chip structure:
155 * - save_regs callback (optional)
156 *
157 * If succeeded, this function will map bank's memory and will
158 * do all necessary work for you. Then you'll able to use .regs
159 * to manage GPIOs from the callbacks.
160 */
161int of_mm_gpiochip_add(struct device_node *np,
162 struct of_mm_gpio_chip *mm_gc)
163{
164 int ret = -ENOMEM;
165 struct of_gpio_chip *of_gc = &mm_gc->of_gc;
166 struct gpio_chip *gc = &of_gc->gc;
167
168 gc->label = kstrdup(np->full_name, GFP_KERNEL);
169 if (!gc->label)
170 goto err0;
171
172 mm_gc->regs = of_iomap(np, 0);
173 if (!mm_gc->regs)
174 goto err1;
175
176 gc->base = -1;
177
178 if (!of_gc->xlate)
179 of_gc->xlate = of_gpio_simple_xlate;
180
181 if (mm_gc->save_regs)
182 mm_gc->save_regs(mm_gc);
183
184 np->data = of_gc;
185
186 ret = gpiochip_add(gc);
187 if (ret)
188 goto err2;
189
190 /* We don't want to lose the node and its ->data */
191 of_node_get(np);
192
193 pr_debug("%s: registered as generic GPIO chip, base is %d\n",
194 np->full_name, gc->base);
195 return 0;
196err2:
197 np->data = NULL;
198 iounmap(mm_gc->regs);
199err1:
200 kfree(gc->label);
201err0:
202 pr_err("%s: GPIO chip registration failed with status %d\n",
203 np->full_name, ret);
204 return ret;
205}
206EXPORT_SYMBOL(of_mm_gpiochip_add);