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_find_and_xlate */
  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         /* Return -EPROBE_DEFER to support probe() functions to be called
  66          * later when the GPIO actually becomes available
  67          */
  68         struct gg_data gg_data = { .flags = flags, .out_gpio = -EPROBE_DEFER };
  69         int ret;
  70
  71         /* .of_xlate might decide to not fill in the flags, so clear it. */
  72         if (flags)
  73                 *flags = 0;
  74
  75         ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
  76                                          &gg_data.gpiospec);
  77         if (ret) {
  78                 pr_debug("%s: can't parse gpios property\n", __func__);
  79                 return ret;
  80         }
  81
  82         gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
  83
  84         of_node_put(gg_data.gpiospec.np);
  85         pr_debug("%s exited with status %d\n", __func__, gg_data.out_gpio);
  86         return gg_data.out_gpio;
  87 }
  88 EXPORT_SYMBOL(of_get_named_gpio_flags);
  89
  90 /**
  91  * of_gpio_named_count - Count GPIOs for a device
  92  * @np:         device node to count GPIOs for
  93  * @propname:   property name containing gpio specifier(s)
  94  *
  95  * The function returns the count of GPIOs specified for a node.
  96  *
  97  * Note that the empty GPIO specifiers counts too. For example,
  98  *
  99  * gpios = <0
 100  *          &pio1 1 2
 101  *          0
 102  *          &pio2 3 4>;
 103  *
 104  * defines four GPIOs (so this function will return 4), two of which
 105  * are not specified.
 106  */
 107 unsigned int of_gpio_named_count(struct device_node *np, const char* propname)
 108 {
 109         unsigned int cnt = 0;
 110
 111         do {
 112                 int ret;
 113
 114                 ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
 115                                                  cnt, NULL);
 116                 /* A hole in the gpios = <> counts anyway. */
 117                 if (ret < 0 && ret != -EEXIST)
 118                         break;
 119         } while (++cnt);
 120
 121         return cnt;
 122 }
 123 EXPORT_SYMBOL(of_gpio_named_count);
 124
 125 /**
 126  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 127  * @gc:         pointer to the gpio_chip structure
 128  * @np:         device node of the GPIO chip
 129  * @gpio_spec:  gpio specifier as found in the device tree
 130  * @flags:      a flags pointer to fill in
 131  *
 132  * This is simple translation function, suitable for the most 1:1 mapped
 133  * gpio chips. This function performs only one sanity check: whether gpio
 134  * is less than ngpios (that is specified in the gpio_chip).
 135  */
 136 int of_gpio_simple_xlate(struct gpio_chip *gc,
 137                          const struct of_phandle_args *gpiospec, u32 *flags)
 138 {
 139         /*
 140          * We're discouraging gpio_cells < 2, since that way you'll have to
 141          * write your own xlate function (that will have to retrive the GPIO
 142          * number and the flags from a single gpio cell -- this is possible,
 143          * but not recommended).
 144          */
 145         if (gc->of_gpio_n_cells < 2) {
 146                 WARN_ON(1);
 147                 return -EINVAL;
 148         }
 149
 150         if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
 151                 return -EINVAL;
 152
 153         if (gpiospec->args[0] >= gc->ngpio)
 154                 return -EINVAL;
 155
 156         if (flags)
 157                 *flags = gpiospec->args[1];
 158
 159         return gpiospec->args[0];
 160 }
 161 EXPORT_SYMBOL(of_gpio_simple_xlate);
 162
 163 /**
 164  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 165  * @np:         device node of the GPIO chip
 166  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 167  *
 168  * To use this function you should allocate and fill mm_gc with:
 169  *
 170  * 1) In the gpio_chip structure:
 171  *    - all the callbacks
 172  *    - of_gpio_n_cells
 173  *    - of_xlate callback (optional)
 174  *
 175  * 3) In the of_mm_gpio_chip structure:
 176  *    - save_regs callback (optional)
 177  *
 178  * If succeeded, this function will map bank's memory and will
 179  * do all necessary work for you. Then you'll able to use .regs
 180  * to manage GPIOs from the callbacks.
 181  */
 182 int of_mm_gpiochip_add(struct device_node *np,
 183                        struct of_mm_gpio_chip *mm_gc)
 184 {
 185         int ret = -ENOMEM;
 186         struct gpio_chip *gc = &mm_gc->gc;
 187
 188         gc->label = kstrdup(np->full_name, GFP_KERNEL);
 189         if (!gc->label)
 190                 goto err0;
 191
 192         mm_gc->regs = of_iomap(np, 0);
 193         if (!mm_gc->regs)
 194                 goto err1;
 195
 196         gc->base = -1;
 197
 198         if (mm_gc->save_regs)
 199                 mm_gc->save_regs(mm_gc);
 200
 201         mm_gc->gc.of_node = np;
 202
 203         ret = gpiochip_add(gc);
 204         if (ret)
 205                 goto err2;
 206
 207         return 0;
 208 err2:
 209         iounmap(mm_gc->regs);
 210 err1:
 211         kfree(gc->label);
 212 err0:
 213         pr_err("%s: GPIO chip registration failed with status %d\n",
 214                np->full_name, ret);
 215         return ret;
 216 }
 217 EXPORT_SYMBOL(of_mm_gpiochip_add);
 218
 219 void of_gpiochip_add(struct gpio_chip *chip)
 220 {
 221         if ((!chip->of_node) && (chip->dev))
 222                 chip->of_node = chip->dev->of_node;
 223
 224         if (!chip->of_node)
 225                 return;
 226
 227         if (!chip->of_xlate) {
 228                 chip->of_gpio_n_cells = 2;
 229                 chip->of_xlate = of_gpio_simple_xlate;
 230         }
 231
 232         of_node_get(chip->of_node);
 233 }
 234
 235 void of_gpiochip_remove(struct gpio_chip *chip)
 236 {
 237         if (chip->of_node)
 238                 of_node_put(chip->of_node);
 239 }