summaryrefslogtreecommitdiffstats
path: root/drivers/of/gpio.c
blob: 7cd7301b583992683391215816bd6bd277785691 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
/*
 * OF helpers for the GPIO API
 *
 * Copyright (c) 2007-2008  MontaVista Software, Inc.
 *
 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <asm/prom.h>

/**
 * of_get_gpio - Get a GPIO number from the device tree to use with GPIO API
 * @np:		device node to get GPIO from
 * @index:	index of the GPIO
 *
 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
 * value on the error condition.
 */
int of_get_gpio(struct device_node *np, int index)
{
	int ret;
	struct device_node *gc;
	struct of_gpio_chip *of_gc = NULL;
	int size;
	const void *gpio_spec;
	const u32 *gpio_cells;

	ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
					  &gc, &gpio_spec);
	if (ret) {
		pr_debug("%s: can't parse gpios property\n", __func__);
		goto err0;
	}

	of_gc = gc->data;
	if (!of_gc) {
		pr_debug("%s: gpio controller %s isn't registered\n",
			 np->full_name, gc->full_name);
		ret = -ENODEV;
		goto err1;
	}

	gpio_cells = of_get_property(gc, "#gpio-cells", &size);
	if (!gpio_cells || size != sizeof(*gpio_cells) ||
			*gpio_cells != of_gc->gpio_cells) {
		pr_debug("%s: wrong #gpio-cells for %s\n",
			 np->full_name, gc->full_name);
		ret = -EINVAL;
		goto err1;
	}

	ret = of_gc->xlate(of_gc, np, gpio_spec);
	if (ret < 0)
		goto err1;

	ret += of_gc->gc.base;
err1:
	of_node_put(gc);
err0:
	pr_debug("%s exited with status %d\n", __func__, ret);
	return ret;
}
EXPORT_SYMBOL(of_get_gpio);

/**
 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number
 * @of_gc:	pointer to the of_gpio_chip structure
 * @np:		device node of the GPIO chip
 * @gpio_spec:	gpio specifier as found in the device tree
 *
 * This is simple translation function, suitable for the most 1:1 mapped
 * gpio chips. This function performs only one sanity check: whether gpio
 * is less than ngpios (that is specified in the gpio_chip).
 */
int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
			 const void *gpio_spec)
{
	const u32 *gpio = gpio_spec;

	if (*gpio > of_gc->gc.ngpio)
		return -EINVAL;

	return *gpio;
}
EXPORT_SYMBOL(of_gpio_simple_xlate);

/**
 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 * @np:		device node of the GPIO chip
 * @mm_gc:	pointer to the of_mm_gpio_chip allocated structure
 *
 * To use this function you should allocate and fill mm_gc with:
 *
 * 1) In the gpio_chip structure:
 *    - all the callbacks
 *
 * 2) In the of_gpio_chip structure:
 *    - gpio_cells
 *    - xlate callback (optional)
 *
 * 3) In the of_mm_gpio_chip structure:
 *    - save_regs callback (optional)
 *
 * If succeeded, this function will map bank's memory and will
 * do all necessary work for you. Then you'll able to use .regs
 * to manage GPIOs from the callbacks.
 */
int of_mm_gpiochip_add(struct device_node *np,
		       struct of_mm_gpio_chip *mm_gc)
{
	int ret = -ENOMEM;
	struct of_gpio_chip *of_gc = &mm_gc->of_gc;
	struct gpio_chip *gc = &of_gc->gc;

	gc->label = kstrdup(np->full_name, GFP_KERNEL);
	if (!gc->label)
		goto err0;

	mm_gc->regs = of_iomap(np, 0);
	if (!mm_gc->regs)
		goto err1;

	gc->base = -1;

	if (!of_gc->xlate)
		of_gc->xlate = of_gpio_simple_xlate;

	if (mm_gc->save_regs)
		mm_gc->save_regs(mm_gc);

	np->data = of_gc;

	ret = gpiochip_add(gc);
	if (ret)
		goto err2;

	/* We don't want to lose the node and its ->data */
	of_node_get(np);

	pr_debug("%s: registered as generic GPIO chip, base is %d\n",
		 np->full_name, gc->base);
	return 0;
err2:
	np->data = NULL;
	iounmap(mm_gc->regs);
err1:
	kfree(gc->label);
err0:
	pr_err("%s: GPIO chip registration failed with status %d\n",
	       np->full_name, ret);
	return ret;
}
EXPORT_SYMBOL(of_mm_gpiochip_add);