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