linux/drivers/gpio/gpiolib-of.c
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   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/pinctrl/pinctrl.h>
  23#include <linux/slab.h>
  24
  25/* Private data structure for of_gpiochip_find_and_xlate */
  26struct gg_data {
  27        enum of_gpio_flags *flags;
  28        struct of_phandle_args gpiospec;
  29
  30        int out_gpio;
  31};
  32
  33/* Private function for resolving node pointer to gpio_chip */
  34static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
  35{
  36        struct gg_data *gg_data = data;
  37        int ret;
  38
  39        if ((gc->of_node != gg_data->gpiospec.np) ||
  40            (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
  41            (!gc->of_xlate))
  42                return false;
  43
  44        ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
  45        if (ret < 0)
  46                return false;
  47
  48        gg_data->out_gpio = ret + gc->base;
  49        return true;
  50}
  51
  52/**
  53 * of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
  54 * @np:         device node to get GPIO from
  55 * @propname:   property name containing gpio specifier(s)
  56 * @index:      index of the GPIO
  57 * @flags:      a flags pointer to fill in
  58 *
  59 * Returns GPIO number to use with Linux generic GPIO API, or one of the errno
  60 * value on the error condition. If @flags is not NULL the function also fills
  61 * in flags for the GPIO.
  62 */
  63int of_get_named_gpio_flags(struct device_node *np, const char *propname,
  64                           int index, enum of_gpio_flags *flags)
  65{
  66        /* Return -EPROBE_DEFER to support probe() functions to be called
  67         * later when the GPIO actually becomes available
  68         */
  69        struct gg_data gg_data = { .flags = flags, .out_gpio = -EPROBE_DEFER };
  70        int ret;
  71
  72        /* .of_xlate might decide to not fill in the flags, so clear it. */
  73        if (flags)
  74                *flags = 0;
  75
  76        ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
  77                                         &gg_data.gpiospec);
  78        if (ret) {
  79                pr_debug("%s: can't parse gpios property of node '%s[%d]'\n",
  80                        __func__, np->full_name, index);
  81                return ret;
  82        }
  83
  84        gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
  85
  86        of_node_put(gg_data.gpiospec.np);
  87        pr_debug("%s exited with status %d\n", __func__, gg_data.out_gpio);
  88        return gg_data.out_gpio;
  89}
  90EXPORT_SYMBOL(of_get_named_gpio_flags);
  91
  92/**
  93 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
  94 * @gc:         pointer to the gpio_chip structure
  95 * @np:         device node of the GPIO chip
  96 * @gpio_spec:  gpio specifier as found in the device tree
  97 * @flags:      a flags pointer to fill in
  98 *
  99 * This is simple translation function, suitable for the most 1:1 mapped
 100 * gpio chips. This function performs only one sanity check: whether gpio
 101 * is less than ngpios (that is specified in the gpio_chip).
 102 */
 103int of_gpio_simple_xlate(struct gpio_chip *gc,
 104                         const struct of_phandle_args *gpiospec, u32 *flags)
 105{
 106        /*
 107         * We're discouraging gpio_cells < 2, since that way you'll have to
 108         * write your own xlate function (that will have to retrive the GPIO
 109         * number and the flags from a single gpio cell -- this is possible,
 110         * but not recommended).
 111         */
 112        if (gc->of_gpio_n_cells < 2) {
 113                WARN_ON(1);
 114                return -EINVAL;
 115        }
 116
 117        if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
 118                return -EINVAL;
 119
 120        if (gpiospec->args[0] >= gc->ngpio)
 121                return -EINVAL;
 122
 123        if (flags)
 124                *flags = gpiospec->args[1];
 125
 126        return gpiospec->args[0];
 127}
 128EXPORT_SYMBOL(of_gpio_simple_xlate);
 129
 130/**
 131 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 132 * @np:         device node of the GPIO chip
 133 * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 134 *
 135 * To use this function you should allocate and fill mm_gc with:
 136 *
 137 * 1) In the gpio_chip structure:
 138 *    - all the callbacks
 139 *    - of_gpio_n_cells
 140 *    - of_xlate callback (optional)
 141 *
 142 * 3) In the of_mm_gpio_chip structure:
 143 *    - save_regs callback (optional)
 144 *
 145 * If succeeded, this function will map bank's memory and will
 146 * do all necessary work for you. Then you'll able to use .regs
 147 * to manage GPIOs from the callbacks.
 148 */
 149int of_mm_gpiochip_add(struct device_node *np,
 150                       struct of_mm_gpio_chip *mm_gc)
 151{
 152        int ret = -ENOMEM;
 153        struct gpio_chip *gc = &mm_gc->gc;
 154
 155        gc->label = kstrdup(np->full_name, GFP_KERNEL);
 156        if (!gc->label)
 157                goto err0;
 158
 159        mm_gc->regs = of_iomap(np, 0);
 160        if (!mm_gc->regs)
 161                goto err1;
 162
 163        gc->base = -1;
 164
 165        if (mm_gc->save_regs)
 166                mm_gc->save_regs(mm_gc);
 167
 168        mm_gc->gc.of_node = np;
 169
 170        ret = gpiochip_add(gc);
 171        if (ret)
 172                goto err2;
 173
 174        return 0;
 175err2:
 176        iounmap(mm_gc->regs);
 177err1:
 178        kfree(gc->label);
 179err0:
 180        pr_err("%s: GPIO chip registration failed with status %d\n",
 181               np->full_name, ret);
 182        return ret;
 183}
 184EXPORT_SYMBOL(of_mm_gpiochip_add);
 185
 186#ifdef CONFIG_PINCTRL
 187static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
 188{
 189        struct device_node *np = chip->of_node;
 190        struct of_phandle_args pinspec;
 191        struct pinctrl_dev *pctldev;
 192        int index = 0, ret;
 193
 194        if (!np)
 195                return;
 196
 197        for (;; index++) {
 198                ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
 199                                index, &pinspec);
 200                if (ret)
 201                        break;
 202
 203                pctldev = of_pinctrl_get(pinspec.np);
 204                if (!pctldev)
 205                        break;
 206
 207                ret = gpiochip_add_pin_range(chip,
 208                                             pinctrl_dev_get_devname(pctldev),
 209                                             pinspec.args[0],
 210                                             pinspec.args[1],
 211                                             pinspec.args[2]);
 212
 213                if (ret)
 214                        break;
 215        }
 216}
 217
 218#else
 219static void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
 220#endif
 221
 222void of_gpiochip_add(struct gpio_chip *chip)
 223{
 224        if ((!chip->of_node) && (chip->dev))
 225                chip->of_node = chip->dev->of_node;
 226
 227        if (!chip->of_node)
 228                return;
 229
 230        if (!chip->of_xlate) {
 231                chip->of_gpio_n_cells = 2;
 232                chip->of_xlate = of_gpio_simple_xlate;
 233        }
 234
 235        of_gpiochip_add_pin_range(chip);
 236        of_node_get(chip->of_node);
 237}
 238
 239void of_gpiochip_remove(struct gpio_chip *chip)
 240{
 241        gpiochip_remove_pin_ranges(chip);
 242
 243        if (chip->of_node)
 244                of_node_put(chip->of_node);
 245}
 246
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