2 * OF helpers for the GPIO API
4 * Copyright (c) 2007-2008 MontaVista Software, Inc.
6 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
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.
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
18 #include <linux/slab.h>
19 #include <linux/of_gpio.h>
23 * of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API
24 * @np: device node to get GPIO from
25 * @index: index of the GPIO
26 * @flags: a flags pointer to fill in
28 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
29 * value on the error condition. If @flags is not NULL the function also fills
30 * in flags for the GPIO.
32 int of_get_gpio_flags(struct device_node *np, int index,
33 enum of_gpio_flags *flags)
36 struct device_node *gpio_np;
39 const void *gpio_spec;
40 const __be32 *gpio_cells;
42 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
43 &gpio_np, &gpio_spec);
45 pr_debug("%s: can't parse gpios property\n", __func__);
49 gc = of_node_to_gpiochip(gpio_np);
51 pr_debug("%s: gpio controller %s isn't registered\n",
52 np->full_name, gpio_np->full_name);
57 gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
58 if (!gpio_cells || size != sizeof(*gpio_cells) ||
59 be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) {
60 pr_debug("%s: wrong #gpio-cells for %s\n",
61 np->full_name, gpio_np->full_name);
66 /* .xlate might decide to not fill in the flags, so clear it. */
70 ret = gc->of_xlate(gc, np, gpio_spec, flags);
78 pr_debug("%s exited with status %d\n", __func__, ret);
81 EXPORT_SYMBOL(of_get_gpio_flags);
84 * of_gpio_count - Count GPIOs for a device
85 * @np: device node to count GPIOs for
87 * The function returns the count of GPIOs specified for a node.
89 * Note that the empty GPIO specifiers counts too. For example,
96 * defines four GPIOs (so this function will return 4), two of which
99 unsigned int of_gpio_count(struct device_node *np)
101 unsigned int cnt = 0;
106 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
108 /* A hole in the gpios = <> counts anyway. */
109 if (ret < 0 && ret != -EEXIST)
115 EXPORT_SYMBOL(of_gpio_count);
118 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
119 * @gc: pointer to the gpio_chip structure
120 * @np: device node of the GPIO chip
121 * @gpio_spec: gpio specifier as found in the device tree
122 * @flags: a flags pointer to fill in
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).
128 static int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
129 const void *gpio_spec, u32 *flags)
131 const __be32 *gpio = gpio_spec;
132 const u32 n = be32_to_cpup(gpio);
135 * We're discouraging gpio_cells < 2, since that way you'll have to
136 * write your own xlate function (that will have to retrive the GPIO
137 * number and the flags from a single gpio cell -- this is possible,
138 * but not recommended).
140 if (gc->of_gpio_n_cells < 2) {
149 *flags = be32_to_cpu(gpio[1]);
155 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
156 * @np: device node of the GPIO chip
157 * @mm_gc: pointer to the of_mm_gpio_chip allocated structure
159 * To use this function you should allocate and fill mm_gc with:
161 * 1) In the gpio_chip structure:
162 * - all the callbacks
164 * - of_xlate callback (optional)
166 * 3) In the of_mm_gpio_chip structure:
167 * - save_regs callback (optional)
169 * If succeeded, this function will map bank's memory and will
170 * do all necessary work for you. Then you'll able to use .regs
171 * to manage GPIOs from the callbacks.
173 int of_mm_gpiochip_add(struct device_node *np,
174 struct of_mm_gpio_chip *mm_gc)
177 struct gpio_chip *gc = &mm_gc->gc;
179 gc->label = kstrdup(np->full_name, GFP_KERNEL);
183 mm_gc->regs = of_iomap(np, 0);
189 if (mm_gc->save_regs)
190 mm_gc->save_regs(mm_gc);
192 mm_gc->gc.of_node = np;
194 ret = gpiochip_add(gc);
198 pr_debug("%s: registered as generic GPIO chip, base is %d\n",
199 np->full_name, gc->base);
202 iounmap(mm_gc->regs);
206 pr_err("%s: GPIO chip registration failed with status %d\n",
210 EXPORT_SYMBOL(of_mm_gpiochip_add);
212 void of_gpiochip_add(struct gpio_chip *chip)
214 if ((!chip->of_node) && (chip->dev))
215 chip->of_node = chip->dev->of_node;
220 if (!chip->of_xlate) {
221 chip->of_gpio_n_cells = 2;
222 chip->of_xlate = of_gpio_simple_xlate;
225 of_node_get(chip->of_node);
228 void of_gpiochip_remove(struct gpio_chip *chip)
231 of_node_put(chip->of_node);
234 /* Private function for resolving node pointer to gpio_chip */
235 static int of_gpiochip_is_match(struct gpio_chip *chip, void *data)
237 return chip->of_node == data;
240 struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
242 return gpiochip_find(np, of_gpiochip_is_match);