drivers/gpio/gpiolib-of.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/gpio.h>
  19 #include <linux/of.h>
  20 #include <linux/of_address.h>
  21 #include <linux/of_gpio.h>
  22 #include <linux/slab.h>
  23
  24 /* Private data structure for of_gpiochip_is_match */
  25 struct gg_data {
  26         enum of_gpio_flags *flags;
  27         struct of_phandle_args gpiospec;
  28
  29         int out_gpio;
  30 };
  31
  32 /* Private function for resolving node pointer to gpio_chip */
  33 static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
  34 {
  35         struct gg_data *gg_data = data;
  36         int ret;
  37
  38         if ((gc->of_node != gg_data->gpiospec.np) ||
  39             (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
  40             (!gc->of_xlate))
  41                 return false;
  42
  43         ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
  44         if (ret < 0)
  45                 return false;
  46
  47         gg_data->out_gpio = ret + gc->base;
  48         return true;
  49 }
  50
  51 /**
  52  * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
  53  * @np:         device node to get GPIO from
  54  * @propname:   property name containing gpio specifier(s)
  55  * @index:      index of the GPIO
  56  * @flags:      a flags pointer to fill in
  57  *
  58  * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
  59  * value on the error condition. If @flags is not NULL the function also fills
  60  * in flags for the GPIO.
  61  */
  62 int of_get_named_gpio_flags(struct device_node *np, const char *propname,
  63                            int index, enum of_gpio_flags *flags)
  64 {
  65         struct gg_data gg_data = { .flags = flags, .out_gpio = -ENODEV };
  66         int ret;
  67
  68         /* .of_xlate might decide to not fill in the flags, so clear it. */
  69         if (flags)
  70                 *flags = 0;
  71
  72         ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
  73                                          &gg_data.gpiospec);
  74         if (ret) {
  75                 pr_debug("%s: can't parse gpios property\n", __func__);
  76                 return -EINVAL;
  77         }
  78
  79         gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
  80
  81         of_node_put(gg_data.gpiospec.np);
  82         pr_debug("%s exited with status %d\n", __func__, ret);
  83         return gg_data.out_gpio;
  84 }
  85 EXPORT_SYMBOL(of_get_named_gpio_flags);
  86
  87 /**
  88  * of_gpio_named_count - Count GPIOs for a device
  89  * @np:         device node to count GPIOs for
  90  * @propname:   property name containing gpio specifier(s)
  91  *
  92  * The function returns the count of GPIOs specified for a node.
  93  *
  94  * Note that the empty GPIO specifiers counts too. For example,
  95  *
  96  * gpios = <0
  97  *          &pio1 1 2
  98  *          0
  99  *          &pio2 3 4>;
 100  *
 101  * defines four GPIOs (so this function will return 4), two of which
 102  * are not specified.
 103  */
 104 unsigned int of_gpio_named_count(struct device_node *np, const char* propname)
 105 {
 106         unsigned int cnt = 0;
 107
 108         do {
 109                 int ret;
 110
 111                 ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
 112                                                  cnt, NULL);
 113                 /* A hole in the gpios = <> counts anyway. */
 114                 if (ret < 0 && ret != -EEXIST)
 115                         break;
 116         } while (++cnt);
 117
 118         return cnt;
 119 }
 120 EXPORT_SYMBOL(of_gpio_named_count);
 121
 122 /**
 123  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 124  * @gc:         pointer to the gpio_chip structure
 125  * @np:         device node of the GPIO chip
 126  * @gpio_spec:  gpio specifier as found in the device tree
 127  * @flags:      a flags pointer to fill in
 128  *
 129  * This is simple translation function, suitable for the most 1:1 mapped
 130  * gpio chips. This function performs only one sanity check: whether gpio
 131  * is less than ngpios (that is specified in the gpio_chip).
 132  */
 133 int of_gpio_simple_xlate(struct gpio_chip *gc,
 134                          const struct of_phandle_args *gpiospec, u32 *flags)
 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 (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
 148                 return -EINVAL;
 149
 150         if (gpiospec->args[0] >= gc->ngpio)
 151                 return -EINVAL;
 152
 153         if (flags)
 154                 *flags = gpiospec->args[1];
 155
 156         return gpiospec->args[0];
 157 }
 158 EXPORT_SYMBOL(of_gpio_simple_xlate);
 159
 160 /**
 161  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 162  * @np:         device node of the GPIO chip
 163  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 164  *
 165  * To use this function you should allocate and fill mm_gc with:
 166  *
 167  * 1) In the gpio_chip structure:
 168  *    - all the callbacks
 169  *    - of_gpio_n_cells
 170  *    - of_xlate callback (optional)
 171  *
 172  * 3) In the of_mm_gpio_chip structure:
 173  *    - save_regs callback (optional)
 174  *
 175  * If succeeded, this function will map bank's memory and will
 176  * do all necessary work for you. Then you'll able to use .regs
 177  * to manage GPIOs from the callbacks.
 178  */
 179 int of_mm_gpiochip_add(struct device_node *np,
 180                        struct of_mm_gpio_chip *mm_gc)
 181 {
 182         int ret = -ENOMEM;
 183         struct gpio_chip *gc = &mm_gc->gc;
 184
 185         gc->label = kstrdup(np->full_name, GFP_KERNEL);
 186         if (!gc->label)
 187                 goto err0;
 188
 189         mm_gc->regs = of_iomap(np, 0);
 190         if (!mm_gc->regs)
 191                 goto err1;
 192
 193         gc->base = -1;
 194
 195         if (mm_gc->save_regs)
 196                 mm_gc->save_regs(mm_gc);
 197
 198         mm_gc->gc.of_node = np;
 199
 200         ret = gpiochip_add(gc);
 201         if (ret)
 202                 goto err2;
 203
 204         return 0;
 205 err2:
 206         iounmap(mm_gc->regs);
 207 err1:
 208         kfree(gc->label);
 209 err0:
 210         pr_err("%s: GPIO chip registration failed with status %d\n",
 211                np->full_name, ret);
 212         return ret;
 213 }
 214 EXPORT_SYMBOL(of_mm_gpiochip_add);
 215
 216 void of_gpiochip_add(struct gpio_chip *chip)
 217 {
 218         if ((!chip->of_node) && (chip->dev))
 219                 chip->of_node = chip->dev->of_node;
 220
 221         if (!chip->of_node)
 222                 return;
 223
 224         if (!chip->of_xlate) {
 225                 chip->of_gpio_n_cells = 2;
 226                 chip->of_xlate = of_gpio_simple_xlate;
 227         }
 228
 229         of_node_get(chip->of_node);
 230 }
 231
 232 void of_gpiochip_remove(struct gpio_chip *chip)
 233 {
 234         if (chip->of_node)
 235                 of_node_put(chip->of_node);
 236 }