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_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
  25  * @np:         device node to get GPIO from
  26  * @propname:   property name containing gpio specifier(s)
  27  * @index:      index of the GPIO
  28  * @flags:      a flags pointer to fill in
  29  *
  30  * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
  31  * value on the error condition. If @flags is not NULL the function also fills
  32  * in flags for the GPIO.
  33  */
  34 int of_get_named_gpio_flags(struct device_node *np, const char *propname,
  35                            int index, enum of_gpio_flags *flags)
  36 {
  37         int ret;
  38         struct device_node *gpio_np;
  39         struct gpio_chip *gc;
  40         int size;
  41         const void *gpio_spec;
  42         const __be32 *gpio_cells;
  43
  44         ret = of_parse_phandles_with_args(np, propname, "#gpio-cells", index,
  45                                           &gpio_np, &gpio_spec);
  46         if (ret) {
  47                 pr_debug("%s: can't parse gpios property\n", __func__);
  48                 goto err0;
  49         }
  50
  51         gc = of_node_to_gpiochip(gpio_np);
  52         if (!gc) {
  53                 pr_debug("%s: gpio controller %s isn't registered\n",
  54                          np->full_name, gpio_np->full_name);
  55                 ret = -ENODEV;
  56                 goto err1;
  57         }
  58
  59         gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
  60         if (!gpio_cells || size != sizeof(*gpio_cells) ||
  61                         be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) {
  62                 pr_debug("%s: wrong #gpio-cells for %s\n",
  63                          np->full_name, gpio_np->full_name);
  64                 ret = -EINVAL;
  65                 goto err1;
  66         }
  67
  68         /* .xlate might decide to not fill in the flags, so clear it. */
  69         if (flags)
  70                 *flags = 0;
  71
  72         ret = gc->of_xlate(gc, np, gpio_spec, flags);
  73         if (ret < 0)
  74                 goto err1;
  75
  76         ret += gc->base;
  77 err1:
  78         of_node_put(gpio_np);
  79 err0:
  80         pr_debug("%s exited with status %d\n", __func__, ret);
  81         return ret;
  82 }
  83 EXPORT_SYMBOL(of_get_named_gpio_flags);
  84
  85 /**
  86  * of_gpio_count - Count GPIOs for a device
  87  * @np:         device node to count GPIOs for
  88  *
  89  * The function returns the count of GPIOs specified for a node.
  90  *
  91  * Note that the empty GPIO specifiers counts too. For example,
  92  *
  93  * gpios = <0
  94  *          &pio1 1 2
  95  *          0
  96  *          &pio2 3 4>;
  97  *
  98  * defines four GPIOs (so this function will return 4), two of which
  99  * are not specified.
 100  */
 101 unsigned int of_gpio_count(struct device_node *np)
 102 {
 103         unsigned int cnt = 0;
 104
 105         do {
 106                 int ret;
 107
 108                 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
 109                                                   cnt, NULL, NULL);
 110                 /* A hole in the gpios = <> counts anyway. */
 111                 if (ret < 0 && ret != -EEXIST)
 112                         break;
 113         } while (++cnt);
 114
 115         return cnt;
 116 }
 117 EXPORT_SYMBOL(of_gpio_count);
 118
 119 /**
 120  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 121  * @gc:         pointer to the gpio_chip structure
 122  * @np:         device node of the GPIO chip
 123  * @gpio_spec:  gpio specifier as found in the device tree
 124  * @flags:      a flags pointer to fill in
 125  *
 126  * This is simple translation function, suitable for the most 1:1 mapped
 127  * gpio chips. This function performs only one sanity check: whether gpio
 128  * is less than ngpios (that is specified in the gpio_chip).
 129  */
 130 static int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
 131                                 const void *gpio_spec, u32 *flags)
 132 {
 133         const __be32 *gpio = gpio_spec;
 134         const u32 n = be32_to_cpup(gpio);
 135
 136         /*
 137          * We're discouraging gpio_cells < 2, since that way you'll have to
 138          * write your own xlate function (that will have to retrive the GPIO
 139          * number and the flags from a single gpio cell -- this is possible,
 140          * but not recommended).
 141          */
 142         if (gc->of_gpio_n_cells < 2) {
 143                 WARN_ON(1);
 144                 return -EINVAL;
 145         }
 146
 147         if (n > gc->ngpio)
 148                 return -EINVAL;
 149
 150         if (flags)
 151                 *flags = be32_to_cpu(gpio[1]);
 152
 153         return n;
 154 }
 155
 156 /**
 157  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 158  * @np:         device node of the GPIO chip
 159  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 160  *
 161  * To use this function you should allocate and fill mm_gc with:
 162  *
 163  * 1) In the gpio_chip structure:
 164  *    - all the callbacks
 165  *    - of_gpio_n_cells
 166  *    - of_xlate callback (optional)
 167  *
 168  * 3) In the of_mm_gpio_chip structure:
 169  *    - save_regs callback (optional)
 170  *
 171  * If succeeded, this function will map bank's memory and will
 172  * do all necessary work for you. Then you'll able to use .regs
 173  * to manage GPIOs from the callbacks.
 174  */
 175 int of_mm_gpiochip_add(struct device_node *np,
 176                        struct of_mm_gpio_chip *mm_gc)
 177 {
 178         int ret = -ENOMEM;
 179         struct gpio_chip *gc = &mm_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 (mm_gc->save_regs)
 192                 mm_gc->save_regs(mm_gc);
 193
 194         mm_gc->gc.of_node = np;
 195
 196         ret = gpiochip_add(gc);
 197         if (ret)
 198                 goto err2;
 199
 200         pr_debug("%s: registered as generic GPIO chip, base is %d\n",
 201                  np->full_name, gc->base);
 202         return 0;
 203 err2:
 204         iounmap(mm_gc->regs);
 205 err1:
 206         kfree(gc->label);
 207 err0:
 208         pr_err("%s: GPIO chip registration failed with status %d\n",
 209                np->full_name, ret);
 210         return ret;
 211 }
 212 EXPORT_SYMBOL(of_mm_gpiochip_add);
 213
 214 void of_gpiochip_add(struct gpio_chip *chip)
 215 {
 216         if ((!chip->of_node) && (chip->dev))
 217                 chip->of_node = chip->dev->of_node;
 218
 219         if (!chip->of_node)
 220                 return;
 221
 222         if (!chip->of_xlate) {
 223                 chip->of_gpio_n_cells = 2;
 224                 chip->of_xlate = of_gpio_simple_xlate;
 225         }
 226
 227         of_node_get(chip->of_node);
 228 }
 229
 230 void of_gpiochip_remove(struct gpio_chip *chip)
 231 {
 232         if (chip->of_node)
 233                 of_node_put(chip->of_node);
 234 }
 235
 236 /* Private function for resolving node pointer to gpio_chip */
 237 static int of_gpiochip_is_match(struct gpio_chip *chip, void *data)
 238 {
 239         return chip->of_node == data;
 240 }
 241
 242 struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
 243 {
 244         return gpiochip_find(np, of_gpiochip_is_match);
 245 }