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