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 - Get a GPIO number from the device tree to use with GPIO API
  23  * @np:         device node to get GPIO from
  24  * @index:      index of the GPIO
  25  *
  26  * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
  27  * value on the error condition.
  28  */
  29 int of_get_gpio(struct device_node *np, int index)
  30 {
  31         int ret;
  32         struct device_node *gc;
  33         struct of_gpio_chip *of_gc = NULL;
  34         int size;
  35         const void *gpio_spec;
  36         const u32 *gpio_cells;
  37
  38         ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells", index,
  39                                           &gc, &gpio_spec);
  40         if (ret) {
  41                 pr_debug("%s: can't parse gpios property\n", __func__);
  42                 goto err0;
  43         }
  44
  45         of_gc = gc->data;
  46         if (!of_gc) {
  47                 pr_debug("%s: gpio controller %s isn't registered\n",
  48                          np->full_name, gc->full_name);
  49                 ret = -ENODEV;
  50                 goto err1;
  51         }
  52
  53         gpio_cells = of_get_property(gc, "#gpio-cells", &size);
  54         if (!gpio_cells || size != sizeof(*gpio_cells) ||
  55                         *gpio_cells != of_gc->gpio_cells) {
  56                 pr_debug("%s: wrong #gpio-cells for %s\n",
  57                          np->full_name, gc->full_name);
  58                 ret = -EINVAL;
  59                 goto err1;
  60         }
  61
  62         ret = of_gc->xlate(of_gc, np, gpio_spec);
  63         if (ret < 0)
  64                 goto err1;
  65
  66         ret += of_gc->gc.base;
  67 err1:
  68         of_node_put(gc);
  69 err0:
  70         pr_debug("%s exited with status %d\n", __func__, ret);
  71         return ret;
  72 }
  73 EXPORT_SYMBOL(of_get_gpio);
  74
  75 /**
  76  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number
  77  * @of_gc:      pointer to the of_gpio_chip structure
  78  * @np:         device node of the GPIO chip
  79  * @gpio_spec:  gpio specifier as found in the device tree
  80  *
  81  * This is simple translation function, suitable for the most 1:1 mapped
  82  * gpio chips. This function performs only one sanity check: whether gpio
  83  * is less than ngpios (that is specified in the gpio_chip).
  84  */
  85 int of_gpio_simple_xlate(struct of_gpio_chip *of_gc, struct device_node *np,
  86                          const void *gpio_spec)
  87 {
  88         const u32 *gpio = gpio_spec;
  89
  90         if (*gpio > of_gc->gc.ngpio)
  91                 return -EINVAL;
  92
  93         return *gpio;
  94 }
  95 EXPORT_SYMBOL(of_gpio_simple_xlate);
  96
  97 /**
  98  * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
  99  * @np:         device node of the GPIO chip
 100  * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 101  *
 102  * To use this function you should allocate and fill mm_gc with:
 103  *
 104  * 1) In the gpio_chip structure:
 105  *    - all the callbacks
 106  *
 107  * 2) In the of_gpio_chip structure:
 108  *    - gpio_cells
 109  *    - xlate callback (optional)
 110  *
 111  * 3) In the of_mm_gpio_chip structure:
 112  *    - save_regs callback (optional)
 113  *
 114  * If succeeded, this function will map bank's memory and will
 115  * do all necessary work for you. Then you'll able to use .regs
 116  * to manage GPIOs from the callbacks.
 117  */
 118 int of_mm_gpiochip_add(struct device_node *np,
 119                        struct of_mm_gpio_chip *mm_gc)
 120 {
 121         int ret = -ENOMEM;
 122         struct of_gpio_chip *of_gc = &mm_gc->of_gc;
 123         struct gpio_chip *gc = &of_gc->gc;
 124
 125         gc->label = kstrdup(np->full_name, GFP_KERNEL);
 126         if (!gc->label)
 127                 goto err0;
 128
 129         mm_gc->regs = of_iomap(np, 0);
 130         if (!mm_gc->regs)
 131                 goto err1;
 132
 133         gc->base = -1;
 134
 135         if (!of_gc->xlate)
 136                 of_gc->xlate = of_gpio_simple_xlate;
 137
 138         if (mm_gc->save_regs)
 139                 mm_gc->save_regs(mm_gc);
 140
 141         np->data = of_gc;
 142
 143         ret = gpiochip_add(gc);
 144         if (ret)
 145                 goto err2;
 146
 147         /* We don't want to lose the node and its ->data */
 148         of_node_get(np);
 149
 150         pr_debug("%s: registered as generic GPIO chip, base is %d\n",
 151                  np->full_name, gc->base);
 152         return 0;
 153 err2:
 154         np->data = NULL;
 155         iounmap(mm_gc->regs);
 156 err1:
 157         kfree(gc->label);
 158 err0:
 159         pr_err("%s: GPIO chip registration failed with status %d\n",
 160                np->full_name, ret);
 161         return ret;
 162 }
 163 EXPORT_SYMBOL(of_mm_gpiochip_add);