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;
32 struct device_node *gc;
33 struct of_gpio_chip *of_gc = NULL;
34 int size;
35 const void *gpio_spec;
36 const u32 *gpio_cells;
37
38 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
39 &gc, &gpio_spec);
40 if (ret) {
41 pr_debug("%s: can't parse gpios property\n", __func__);
42 goto err0;
43 }
44
45 of_gc = gc->data;
46 if (!of_gc) {
47 pr_debug("%s: gpio controller %s isn't registered\n",
48 np->full_name, gc->full_name);
49 ret = -ENODEV;
50 goto err1;
51 }
52
53 gpio_cells = of_get_property(gc, "#gpio-cells", &size);
54 if (!gpio_cells || size != sizeof(*gpio_cells) ||
55 *gpio_cells != of_gc->gpio_cells) {
56 pr_debug("%s: wrong #gpio-cells for %s\n",
57 np->full_name, gc->full_name);
58 ret = -EINVAL;
59 goto err1;
60 }
61
62 ret = of_gc->xlate(of_gc, np, gpio_spec);
63 if (ret < 0)
64 goto err1;
65
66 ret += of_gc->gc.base;
67err1:
68 of_node_put(gc);
69err0:
70 pr_debug("%s exited with status %d\n", __func__, ret);
71 return ret;
72}
73EXPORT_SYMBOL(of_get_gpio);
74
75/**
76 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number
77 * @of_gc: pointer to the of_gpio_chip structure
78 * @np: device node of the GPIO chip
79 * @gpio_spec: gpio specifier as found in the device tree
80 *
81 * This is simple translation function, suitable for the most 1:1 mapped
82 * gpio chips. This function performs only one sanity check: whether gpio
83 * is less than ngpios (that is specified in the gpio_chip).
84 */
85int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
86 const void *gpio_spec)
87{
88 const u32 *gpio = gpio_spec;
89
90 if (*gpio > of_gc->gc.ngpio)
91 return -EINVAL;
92
93 return *gpio;
94}
95EXPORT_SYMBOL(of_gpio_simple_xlate);
96
97/**
98 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
99 * @np: device node of the GPIO chip
100 * @mm_gc: pointer to the of_mm_gpio_chip allocated structure
101 *
102 * To use this function you should allocate and fill mm_gc with:
103 *
104 * 1) In the gpio_chip structure:
105 * - all the callbacks
106 *
107 * 2) In the of_gpio_chip structure:
108 * - gpio_cells
109 * - xlate callback (optional)
110 *
111 * 3) In the of_mm_gpio_chip structure:
112 * - save_regs callback (optional)
113 *
114 * If succeeded, this function will map bank's memory and will
115 * do all necessary work for you. Then you'll able to use .regs
116 * to manage GPIOs from the callbacks.
117 */
118int of_mm_gpiochip_add(struct device_node *np,
119 struct of_mm_gpio_chip *mm_gc)
120{
121 int ret = -ENOMEM;
122 struct of_gpio_chip *of_gc = &mm_gc->of_gc;
123 struct gpio_chip *gc = &of_gc->gc;
124
125 gc->label = kstrdup(np->full_name, GFP_KERNEL);
126 if (!gc->label)
127 goto err0;
128
129 mm_gc->regs = of_iomap(np, 0);
130 if (!mm_gc->regs)
131 goto err1;
132
133 gc->base = -1;
134
135 if (!of_gc->xlate)
136 of_gc->xlate = of_gpio_simple_xlate;
137
138 if (mm_gc->save_regs)
139 mm_gc->save_regs(mm_gc);
140
141 np->data = of_gc;
142
143 ret = gpiochip_add(gc);
144 if (ret)
145 goto err2;
146
147 /* We don't want to lose the node and its ->data */
148 of_node_get(np);
149
150 pr_debug("%s: registered as generic GPIO chip, base is %d\n",
151 np->full_name, gc->base);
152 return 0;
153err2:
154 np->data = NULL;
155 iounmap(mm_gc->regs);
156err1:
157 kfree(gc->label);
158err0:
159 pr_err("%s: GPIO chip registration failed with status %d\n",
160 np->full_name, ret);
161 return ret;
162}
163EXPORT_SYMBOL(of_mm_gpiochip_add);