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 gpio_chip *gc;
  39         struct of_phandle_args gpiospec;
  40
  41         ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
  42                                          &gpiospec);
  43         if (ret) {
  44                 pr_debug("%s: can't parse gpios property\n", __func__);
  45                 goto err0;
  46         }
  47
  48         gc = of_node_to_gpiochip(gpiospec.np);
  49         if (!gc) {
  50                 pr_debug("%s: gpio controller %s isn't registered\n",
  51                          np->full_name, gpiospec.np->full_name);
  52                 ret = -ENODEV;
  53                 goto err1;
  54         }
  55
  56         if (gpiospec.args_count != gc->of_gpio_n_cells) {
  57                 pr_debug("%s: wrong #gpio-cells for %s\n",
  58                          np->full_name, gpiospec.np->full_name);
  59                 ret = -EINVAL;
  60                 goto err1;
  61         }
  62
  63         /* .xlate might decide to not fill in the flags, so clear it. */
  64         if (flags)
  65                 *flags = 0;
  66
  67         ret = gc->of_xlate(gc, &gpiospec, flags);
  68         if (ret < 0)
  69                 goto err1;
  70
  71         ret += gc->base;
  72 err1:
  73         of_node_put(gpiospec.np);
  74 err0:
  75         pr_debug("%s exited with status %d\n", __func__, ret);
  76         return ret;
  77 }
  78 EXPORT_SYMBOL(of_get_named_gpio_flags);
  79
  80 /**
  81  * of_gpio_count - Count GPIOs for a device
  82  * @np:         device node to count GPIOs for
  83  *
  84  * The function returns the count of GPIOs specified for a node.
  85  *
  86  * Note that the empty GPIO specifiers counts too. For example,
  87  *
  88  * gpios = <0
  89  *          &pio1 1 2
  90  *          0
  91  *          &pio2 3 4>;
  92  *
  93  * defines four GPIOs (so this function will return 4), two of which
  94  * are not specified.
  95  */
  96 unsigned int of_gpio_count(struct device_node *np)
  97 {
  98         unsigned int cnt = 0;
  99
 100         do {
 101                 int ret;
 102
 103                 ret = of_parse_phandle_with_args(np, "gpios", "#gpio-cells",
 104                                                  cnt, NULL);
 105                 /* A hole in the gpios = <> counts anyway. */
 106                 if (ret < 0 && ret != -EEXIST)
 107                         break;
 108         } while (++cnt);
 109
 110         return cnt;
 111 }
 112 EXPORT_SYMBOL(of_gpio_count);
 113
 114 /**
 115  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 116  * @gc:         pointer to the gpio_chip structure
 117  * @np:         device node of the GPIO chip
 118  * @gpio_spec:  gpio specifier as found in the device tree
 119  * @flags:      a flags pointer to fill in
 120  *
 121  * This is simple translation function, suitable for the most 1:1 mapped
 122  * gpio chips. This function performs only one sanity check: whether gpio
 123  * is less than ngpios (that is specified in the gpio_chip).
 124  */
 125 int of_gpio_simple_xlate(struct gpio_chip *gc,
 126                          const struct of_phandle_args *gpiospec, u32 *flags)
 127 {
 128         /*
 129          * We're discouraging gpio_cells < 2, since that way you'll have to
 130          * write your own xlate function (that will have to retrive the GPIO
 131          * number and the flags from a single gpio cell -- this is possible,
 132          * but not recommended).
 133          */
 134         if (gc->of_gpio_n_cells < 2) {
 135                 WARN_ON(1);
 136                 return -EINVAL;
 137         }
 138
 139         if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
 140                 return -EINVAL;
 141
 142         if (gpiospec->args[0] > gc->ngpio)
 143                 return -EINVAL;
 144
 145         if (flags)
 146                 *flags = gpiospec->args[1];
 147
 148         return gpiospec->args[0];
 149 }
 150 EXPORT_SYMBOL(of_gpio_simple_xlate);
 151
 152 /**
 153  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 154  * @np:         device node of the GPIO chip
 155  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 156  *
 157  * To use this function you should allocate and fill mm_gc with:
 158  *
 159  * 1) In the gpio_chip structure:
 160  *    - all the callbacks
 161  *    - of_gpio_n_cells
 162  *    - of_xlate callback (optional)
 163  *
 164  * 3) In the of_mm_gpio_chip structure:
 165  *    - save_regs callback (optional)
 166  *
 167  * If succeeded, this function will map bank's memory and will
 168  * do all necessary work for you. Then you'll able to use .regs
 169  * to manage GPIOs from the callbacks.
 170  */
 171 int of_mm_gpiochip_add(struct device_node *np,
 172                        struct of_mm_gpio_chip *mm_gc)
 173 {
 174         int ret = -ENOMEM;
 175         struct gpio_chip *gc = &mm_gc->gc;
 176
 177         gc->label = kstrdup(np->full_name, GFP_KERNEL);
 178         if (!gc->label)
 179                 goto err0;
 180
 181         mm_gc->regs = of_iomap(np, 0);
 182         if (!mm_gc->regs)
 183                 goto err1;
 184
 185         gc->base = -1;
 186
 187         if (mm_gc->save_regs)
 188                 mm_gc->save_regs(mm_gc);
 189
 190         mm_gc->gc.of_node = np;
 191
 192         ret = gpiochip_add(gc);
 193         if (ret)
 194                 goto err2;
 195
 196         return 0;
 197 err2:
 198         iounmap(mm_gc->regs);
 199 err1:
 200         kfree(gc->label);
 201 err0:
 202         pr_err("%s: GPIO chip registration failed with status %d\n",
 203                np->full_name, ret);
 204         return ret;
 205 }
 206 EXPORT_SYMBOL(of_mm_gpiochip_add);
 207
 208 void of_gpiochip_add(struct gpio_chip *chip)
 209 {
 210         if ((!chip->of_node) && (chip->dev))
 211                 chip->of_node = chip->dev->of_node;
 212
 213         if (!chip->of_node)
 214                 return;
 215
 216         if (!chip->of_xlate) {
 217                 chip->of_gpio_n_cells = 2;
 218                 chip->of_xlate = of_gpio_simple_xlate;
 219         }
 220
 221         of_node_get(chip->of_node);
 222 }
 223
 224 void of_gpiochip_remove(struct gpio_chip *chip)
 225 {
 226         if (chip->of_node)
 227                 of_node_put(chip->of_node);
 228 }
 229
 230 /* Private function for resolving node pointer to gpio_chip */
 231 static int of_gpiochip_is_match(struct gpio_chip *chip, void *data)
 232 {
 233         return chip->of_node == data;
 234 }
 235
 236 struct gpio_chip *of_node_to_gpiochip(struct device_node *np)
 237 {
 238         return gpiochip_find(np, of_gpiochip_is_match);
 239 }