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/slab.h>
  19 #include <linux/of_gpio.h>
  20 #include <asm/prom.h>
  21
  22 /**
  23  * of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API
  24  * @np:         device node to get GPIO from
  25  * @index:      index of the GPIO
  26  * @flags:      a flags pointer to fill in
  27  *
  28  * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
  29  * value on the error condition. If @flags is not NULL the function also fills
  30  * in flags for the GPIO.
  31  */
  32 int of_get_gpio_flags(struct device_node *np, int index,
  33                       enum of_gpio_flags *flags)
  34 {
  35         int ret;
  36         struct device_node *gc;
  37         struct of_gpio_chip *of_gc = NULL;
  38         int size;
  39         const void *gpio_spec;
  40         const __be32 *gpio_cells;
  41
  42         ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
  43                                           &gc, &gpio_spec);
  44         if (ret) {
  45                 pr_debug("%s: can't parse gpios property\n", __func__);
  46                 goto err0;
  47         }
  48
  49         of_gc = gc->data;
  50         if (!of_gc) {
  51                 pr_debug("%s: gpio controller %s isn't registered\n",
  52                          np->full_name, gc->full_name);
  53                 ret = -ENODEV;
  54                 goto err1;
  55         }
  56
  57         gpio_cells = of_get_property(gc, "#gpio-cells", &size);
  58         if (!gpio_cells || size != sizeof(*gpio_cells) ||
  59                         be32_to_cpup(gpio_cells) != of_gc->gpio_cells) {
  60                 pr_debug("%s: wrong #gpio-cells for %s\n",
  61                          np->full_name, gc->full_name);
  62                 ret = -EINVAL;
  63                 goto err1;
  64         }
  65
  66         /* .xlate might decide to not fill in the flags, so clear it. */
  67         if (flags)
  68                 *flags = 0;
  69
  70         ret = of_gc->xlate(of_gc, np, gpio_spec, flags);
  71         if (ret < 0)
  72                 goto err1;
  73
  74         ret += of_gc->gc.base;
  75 err1:
  76         of_node_put(gc);
  77 err0:
  78         pr_debug("%s exited with status %d\n", __func__, ret);
  79         return ret;
  80 }
  81 EXPORT_SYMBOL(of_get_gpio_flags);
  82
  83 /**
  84  * of_gpio_count - Count GPIOs for a device
  85  * @np:         device node to count GPIOs for
  86  *
  87  * The function returns the count of GPIOs specified for a node.
  88  *
  89  * Note that the empty GPIO specifiers counts too. For example,
  90  *
  91  * gpios = <0
  92  *          &pio1 1 2
  93  *          0
  94  *          &pio2 3 4>;
  95  *
  96  * defines four GPIOs (so this function will return 4), two of which
  97  * are not specified.
  98  */
  99 unsigned int of_gpio_count(struct device_node *np)
 100 {
 101         unsigned int cnt = 0;
 102
 103         do {
 104                 int ret;
 105
 106                 ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
 107                                                   cnt, NULL, NULL);
 108                 /* A hole in the gpios = <> counts anyway. */
 109                 if (ret < 0 && ret != -EEXIST)
 110                         break;
 111         } while (++cnt);
 112
 113         return cnt;
 114 }
 115 EXPORT_SYMBOL(of_gpio_count);
 116
 117 /**
 118  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 119  * @of_gc:      pointer to the of_gpio_chip structure
 120  * @np:         device node of the GPIO chip
 121  * @gpio_spec:  gpio specifier as found in the device tree
 122  * @flags:      a flags pointer to fill in
 123  *
 124  * This is simple translation function, suitable for the most 1:1 mapped
 125  * gpio chips. This function performs only one sanity check: whether gpio
 126  * is less than ngpios (that is specified in the gpio_chip).
 127  */
 128 int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
 129                          const void *gpio_spec, enum of_gpio_flags *flags)
 130 {
 131         const __be32 *gpio = gpio_spec;
 132         const u32 n = be32_to_cpup(gpio);
 133
 134         /*
 135          * We're discouraging gpio_cells < 2, since that way you'll have to
 136          * write your own xlate function (that will have to retrive the GPIO
 137          * number and the flags from a single gpio cell -- this is possible,
 138          * but not recommended).
 139          */
 140         if (of_gc->gpio_cells < 2) {
 141                 WARN_ON(1);
 142                 return -EINVAL;
 143         }
 144
 145         if (n > of_gc->gc.ngpio)
 146                 return -EINVAL;
 147
 148         if (flags)
 149                 *flags = be32_to_cpu(gpio[1]);
 150
 151         return n;
 152 }
 153 EXPORT_SYMBOL(of_gpio_simple_xlate);
 154
 155 /**
 156  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 157  * @np:         device node of the GPIO chip
 158  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 159  *
 160  * To use this function you should allocate and fill mm_gc with:
 161  *
 162  * 1) In the gpio_chip structure:
 163  *    - all the callbacks
 164  *
 165  * 2) In the of_gpio_chip structure:
 166  *    - gpio_cells
 167  *    - xlate callback (optional)
 168  *
 169  * 3) In the of_mm_gpio_chip structure:
 170  *    - save_regs callback (optional)
 171  *
 172  * If succeeded, this function will map bank's memory and will
 173  * do all necessary work for you. Then you'll able to use .regs
 174  * to manage GPIOs from the callbacks.
 175  */
 176 int of_mm_gpiochip_add(struct device_node *np,
 177                        struct of_mm_gpio_chip *mm_gc)
 178 {
 179         int ret = -ENOMEM;
 180         struct of_gpio_chip *of_gc = &mm_gc->of_gc;
 181         struct gpio_chip *gc = &of_gc->gc;
 182
 183         gc->label = kstrdup(np->full_name, GFP_KERNEL);
 184         if (!gc->label)
 185                 goto err0;
 186
 187         mm_gc->regs = of_iomap(np, 0);
 188         if (!mm_gc->regs)
 189                 goto err1;
 190
 191         gc->base = -1;
 192
 193         if (!of_gc->xlate)
 194                 of_gc->xlate = of_gpio_simple_xlate;
 195
 196         if (mm_gc->save_regs)
 197                 mm_gc->save_regs(mm_gc);
 198
 199         np->data = of_gc;
 200
 201         ret = gpiochip_add(gc);
 202         if (ret)
 203                 goto err2;
 204
 205         /* We don't want to lose the node and its ->data */
 206         of_node_get(np);
 207
 208         pr_debug("%s: registered as generic GPIO chip, base is %d\n",
 209                  np->full_name, gc->base);
 210         return 0;
 211 err2:
 212         np->data = NULL;
 213         iounmap(mm_gc->regs);
 214 err1:
 215         kfree(gc->label);
 216 err0:
 217         pr_err("%s: GPIO chip registration failed with status %d\n",
 218                np->full_name, ret);
 219         return ret;
 220 }
 221 EXPORT_SYMBOL(of_mm_gpiochip_add);