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\n", __func__);
  80                return ret;
  81        }
  82
  83        gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
  84
  85        of_node_put(gg_data.gpiospec.np);
  86        pr_debug("%s exited with status %d\n", __func__, gg_data.out_gpio);
  87        return gg_data.out_gpio;
  88}
  89EXPORT_SYMBOL(of_get_named_gpio_flags);
  90
  91/**
  92 * of_gpio_named_count - Count GPIOs for a device
  93 * @np:         device node to count GPIOs for
  94 * @propname:   property name containing gpio specifier(s)
  95 *
  96 * The function returns the count of GPIOs specified for a node.
  97 *
  98 * Note that the empty GPIO specifiers counts too. For example,
  99 *
 100 * gpios = <0
 101 *          &pio1 1 2
 102 *          0
 103 *          &pio2 3 4>;
 104 *
 105 * defines four GPIOs (so this function will return 4), two of which
 106 * are not specified.
 107 */
 108unsigned int of_gpio_named_count(struct device_node *np, const char* propname)
 109{
 110        unsigned int cnt = 0;
 111
 112        do {
 113                int ret;
 114
 115                ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
 116                                                 cnt, NULL);
 117                /* A hole in the gpios = <> counts anyway. */
 118                if (ret < 0 && ret != -EEXIST)
 119                        break;
 120        } while (++cnt);
 121
 122        return cnt;
 123}
 124EXPORT_SYMBOL(of_gpio_named_count);
 125
 126/**
 127 * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
 128 * @gc:         pointer to the gpio_chip structure
 129 * @np:         device node of the GPIO chip
 130 * @gpio_spec:  gpio specifier as found in the device tree
 131 * @flags:      a flags pointer to fill in
 132 *
 133 * This is simple translation function, suitable for the most 1:1 mapped
 134 * gpio chips. This function performs only one sanity check: whether gpio
 135 * is less than ngpios (that is specified in the gpio_chip).
 136 */
 137int of_gpio_simple_xlate(struct gpio_chip *gc,
 138                         const struct of_phandle_args *gpiospec, u32 *flags)
 139{
 140        /*
 141         * We're discouraging gpio_cells < 2, since that way you'll have to
 142         * write your own xlate function (that will have to retrive the GPIO
 143         * number and the flags from a single gpio cell -- this is possible,
 144         * but not recommended).
 145         */
 146        if (gc->of_gpio_n_cells < 2) {
 147                WARN_ON(1);
 148                return -EINVAL;
 149        }
 150
 151        if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
 152                return -EINVAL;
 153
 154        if (gpiospec->args[0] >= gc->ngpio)
 155                return -EINVAL;
 156
 157        if (flags)
 158                *flags = gpiospec->args[1];
 159
 160        return gpiospec->args[0];
 161}
 162EXPORT_SYMBOL(of_gpio_simple_xlate);
 163
 164/**
 165 * of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
 166 * @np:         device node of the GPIO chip
 167 * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 168 *
 169 * To use this function you should allocate and fill mm_gc with:
 170 *
 171 * 1) In the gpio_chip structure:
 172 *    - all the callbacks
 173 *    - of_gpio_n_cells
 174 *    - of_xlate callback (optional)
 175 *
 176 * 3) In the of_mm_gpio_chip structure:
 177 *    - save_regs callback (optional)
 178 *
 179 * If succeeded, this function will map bank's memory and will
 180 * do all necessary work for you. Then you'll able to use .regs
 181 * to manage GPIOs from the callbacks.
 182 */
 183int of_mm_gpiochip_add(struct device_node *np,
 184                       struct of_mm_gpio_chip *mm_gc)
 185{
 186        int ret = -ENOMEM;
 187        struct gpio_chip *gc = &mm_gc->gc;
 188
 189        gc->label = kstrdup(np->full_name, GFP_KERNEL);
 190        if (!gc->label)
 191                goto err0;
 192
 193        mm_gc->regs = of_iomap(np, 0);
 194        if (!mm_gc->regs)
 195                goto err1;
 196
 197        gc->base = -1;
 198
 199        if (mm_gc->save_regs)
 200                mm_gc->save_regs(mm_gc);
 201
 202        mm_gc->gc.of_node = np;
 203
 204        ret = gpiochip_add(gc);
 205        if (ret)
 206                goto err2;
 207
 208        return 0;
 209err2:
 210        iounmap(mm_gc->regs);
 211err1:
 212        kfree(gc->label);
 213err0:
 214        pr_err("%s: GPIO chip registration failed with status %d\n",
 215               np->full_name, ret);
 216        return ret;
 217}
 218EXPORT_SYMBOL(of_mm_gpiochip_add);
 219
 220#ifdef CONFIG_PINCTRL
 221static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
 222{
 223        struct device_node *np = chip->of_node;
 224        struct of_phandle_args pinspec;
 225        struct pinctrl_dev *pctldev;
 226        int index = 0, ret;
 227
 228        if (!np)
 229                return;
 230
 231        do {
 232                ret = of_parse_phandle_with_args(np, "gpio-ranges",
 233                                "#gpio-range-cells", index, &pinspec);
 234                if (ret)
 235                        break;
 236
 237                pctldev = of_pinctrl_get(pinspec.np);
 238                if (!pctldev)
 239                        break;
 240
 241                /*
 242                 * This assumes that the n GPIO pins are consecutive in the
 243                 * GPIO number space, and that the pins are also consecutive
 244                 * in their local number space. Currently it is not possible
 245                 * to add different ranges for one and the same GPIO chip,
 246                 * as the code assumes that we have one consecutive range
 247                 * on both, mapping 1-to-1.
 248                 *
 249                 * TODO: make the OF bindings handle multiple sparse ranges
 250                 * on the same GPIO chip.
 251                 */
 252                ret = gpiochip_add_pin_range(chip,
 253                                             pinctrl_dev_get_name(pctldev),
 254                                             0, /* offset in gpiochip */
 255                                             pinspec.args[0],
 256                                             pinspec.args[1]);
 257
 258                if (ret)
 259                        break;
 260
 261        } while (index++);
 262}
 263
 264#else
 265static void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
 266#endif
 267
 268void of_gpiochip_add(struct gpio_chip *chip)
 269{
 270        if ((!chip->of_node) && (chip->dev))
 271                chip->of_node = chip->dev->of_node;
 272
 273        if (!chip->of_node)
 274                return;
 275
 276        if (!chip->of_xlate) {
 277                chip->of_gpio_n_cells = 2;
 278                chip->of_xlate = of_gpio_simple_xlate;
 279        }
 280
 281        of_gpiochip_add_pin_range(chip);
 282        of_node_get(chip->of_node);
 283}
 284
 285void of_gpiochip_remove(struct gpio_chip *chip)
 286{
 287        gpiochip_remove_pin_ranges(chip);
 288
 289        if (chip->of_node)
 290                of_node_put(chip->of_node);
 291}
 292
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