drivers/of/gpio.c

   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/device.h>
  15 #include <linux/errno.h>
  16 #include <linux/module.h>
  17 #include <linux/io.h>
  18 #include <linux/of.h>
  19 #include <linux/of_address.h>
  20 #include <linux/of_gpio.h>
  21 #include <linux/slab.h>
  22
  23 /**
  24  * of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API
  25  * @np:         device node to get GPIO from
  26  * @index:      index of the GPIO
  27  * @flags:      a flags pointer to fill in
  28  *
  29  * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
  30  * value on the error condition. If @flags is not NULL the function also fills
  31  * in flags for the GPIO.
  32  */
  33 int of_get_gpio_flags(struct device_node *np, int index,
  34                       enum of_gpio_flags *flags)
  35 {
  36         int ret;
  37         struct device_node *gpio_np;
  38         struct gpio_chip *gc;
  39         int size;
  40         const void *gpio_spec;
  41         const __be32 *gpio_cells;
  42
  43         ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
  44                                           &gpio_np, &gpio_spec);
  45         if (ret) {
  46                 pr_debug("%s: can't parse gpios property\n", __func__);
  47                 goto err0;
  48         }
  49
  50         gc = of_node_to_gpiochip(gpio_np);
  51         if (!gc) {
  52                 pr_debug("%s: gpio controller %s isn't registered\n",
  53                          np->full_name, gpio_np->full_name);
  54                 ret = -ENODEV;
  55                 goto err1;
  56         }
  57
  58         gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
  59         if (!gpio_cells || size != sizeof(*gpio_cells) ||
  60                         be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) {
  61                 pr_debug("%s: wrong #gpio-cells for %s\n",
  62                          np->full_name, gpio_np->full_name);
  63                 ret = -EINVAL;
  64                 goto err1;
  65         }
  66
  67         /* .xlate might decide to not fill in the flags, so clear it. */
  68         if (flags)
  69                 *flags = 0;
  70
  71         ret = gc->of_xlate(gc, np, gpio_spec, flags);
  72         if (ret < 0)
  73                 goto err1;
  74
  75         ret += gc->base;
  76 err1:
  77         of_node_put(gpio_np);
  78 err0:
  79         pr_debug("%s exited with status %d\n", __func__, ret);
  80         return ret;
  81 }
  82 EXPORT_SYMBOL(of_get_gpio_flags);
  83
  84 /**
  85  * of_gpio_count - Count GPIOs for a device
  86  * @np:         device node to count GPIOs for
  87  *
  88  * The function returns the count of GPIOs specified for a node.
  89  *
  90  * Note that the empty GPIO specifiers counts too. For example,
  91  *
  92  * gpios = <0
  93  *          &pio1 1 2
  94  *          0
  95  *          &pio2 3 4>;
  96  *
  97  * defines four GPIOs (so this function will return 4), two of which
  98  * are not specified.
  99  */
 100 unsigned int of_gpio_count(struct device_node *np)
 101 {
 102         unsigned int cnt = 0;
 103
 104         do {
 105                 int ret;
 106
 107                 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
 108                                                   cnt, NULL, NULL);
 109                 /* A hole in the gpios = <> counts anyway. */
 110                 if (ret < 0 && ret != -EEXIST)
 111                         break;
 112         } while (++cnt);
 113
 114         return cnt;
 115 }
 116 EXPORT_SYMBOL(of_gpio_count);
 117
 118 /**
 119  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 120  * @gc:         pointer to the gpio_chip structure
 121  * @np:         device node of the GPIO chip
 122  * @gpio_spec:  gpio specifier as found in the device tree
 123  * @flags:      a flags pointer to fill in
 124  *
 125  * This is simple translation function, suitable for the most 1:1 mapped
 126  * gpio chips. This function performs only one sanity check: whether gpio
 127  * is less than ngpios (that is specified in the gpio_chip).
 128  */
 129 static int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
 130                                 const void *gpio_spec, u32 *flags)
 131 {
 132         const __be32 *gpio = gpio_spec;
 133         const u32 n = be32_to_cpup(gpio);
 134
 135         /*
 136          * We're discouraging gpio_cells < 2, since that way you'll have to
 137          * write your own xlate function (that will have to retrive the GPIO
 138          * number and the flags from a single gpio cell -- this is possible,
 139          * but not recommended).
 140          */
 141         if (gc->of_gpio_n_cells < 2) {
 142                 WARN_ON(1);
 143                 return -EINVAL;
 144         }
 145
 146         if (n > gc->ngpio)
 147                 return -EINVAL;
 148
 149         if (flags)
 150                 *flags = be32_to_cpu(gpio[1]);
 151
 152         return n;
 153 }
 154
 155 /**
 156  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 157  * @np:         device node of the GPIO chip
 158  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 159  *
 160  * To use this function you should allocate and fill mm_gc with:
 161  *
 162  * 1) In the gpio_chip structure:
 163  *    - all the callbacks
 164  *    - of_gpio_n_cells
 165  *    - of_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  */
 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 gpio_chip *gc = &mm_gc->gc;
 179
 180         gc->label = kstrdup(np->full_name, GFP_KERNEL);
 181         if (!gc->label)
 182                 goto err0;
 183
 184         mm_gc->regs = of_iomap(np, 0);
 185         if (!mm_gc->regs)
 186                 goto err1;
 187
 188         gc->base = -1;
 189
 190         if (mm_gc->save_regs)
 191                 mm_gc->save_regs(mm_gc);
 192
 193         mm_gc->gc.of_node = np;
 194
 195         ret = gpiochip_add(gc);
 196         if (ret)
 197                 goto err2;
 198
 199         pr_debug("%s: registered as generic GPIO chip, base is %d\n",
 200                  np->full_name, gc->base);
 201         return 0;
 202 err2:
 203         iounmap(mm_gc->regs);
 204 err1:
 205         kfree(gc->label);
 206 err0:
 207         pr_err("%s: GPIO chip registration failed with status %d\n",
 208                np->full_name, ret);
 209         return ret;
 210 }
 211 EXPORT_SYMBOL(of_mm_gpiochip_add);
 212
 213 void of_gpiochip_add(struct gpio_chip *chip)
 214 {
 215         if ((!chip->of_node) && (chip->dev))
 216                 chip->of_node = chip->dev->of_node;
 217
 218         if (!chip->of_node)
 219                 return;
 220
 221         if (!chip->of_xlate) {
 222                 chip->of_gpio_n_cells = 2;
 223                 chip->of_xlate = of_gpio_simple_xlate;
 224         }
 225
 226         of_node_get(chip->of_node);
 227 }
 228
 229 void of_gpiochip_remove(struct gpio_chip *chip)
 230 {
 231         if (chip->of_node)
 232                 of_node_put(chip->of_node);
 233 }
 234
 235 /* Private function for resolving node pointer to gpio_chip */
 236 static int of_gpiochip_is_match(struct gpio_chip *chip, void *data)
 237 {
 238         return chip->of_node == data;
 239 }
 240
 241 struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
 242 {
 243         return gpiochip_find(np, of_gpiochip_is_match);
 244 }