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* OF helpers for the GPIO API
* Copyright (c) 2007-2008 MontaVista Software, Inc.
* Author: Anton Vorontsov <>
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
/* Private data structure for of_gpiochip_find_and_xlate */
struct gg_data {
enum of_gpio_flags *flags;
struct of_phandle_args gpiospec;
int out_gpio;
/* Private function for resolving node pointer to gpio_chip */
static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
struct gg_data *gg_data = data;
int ret;
if ((gc->of_node != gg_data-> ||
(gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
return false;
ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
if (ret < 0)
return false;
gg_data->out_gpio = ret + gc->base;
return true;
* of_get_named_gpio_flags() - Get a GPIO number and flags to use with GPIO API
* @np: device node to get GPIO from
* @propname: property name containing gpio specifier(s)
* @index: index of the GPIO
* @flags: a flags pointer to fill in
* Returns GPIO number to use with Linux generic GPIO API, or one of the errno
* value on the error condition. If @flags is not NULL the function also fills
* in flags for the GPIO.
int of_get_named_gpio_flags(struct device_node *np, const char *propname,
int index, enum of_gpio_flags *flags)
/* Return -EPROBE_DEFER to support probe() functions to be called
* later when the GPIO actually becomes available
struct gg_data gg_data = { .flags = flags, .out_gpio = -EPROBE_DEFER };
int ret;
/* .of_xlate might decide to not fill in the flags, so clear it. */
if (flags)
*flags = 0;
ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
if (ret) {
pr_debug("%s: can't parse gpios property\n", __func__);
return ret;
gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
pr_debug("%s exited with status %d\n", __func__, gg_data.out_gpio);
return gg_data.out_gpio;
* of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
* @gc: pointer to the gpio_chip structure
* @np: device node of the GPIO chip
* @gpio_spec: gpio specifier as found in the device tree
* @flags: a flags pointer to fill in
* This is simple translation function, suitable for the most 1:1 mapped
* gpio chips. This function performs only one sanity check: whether gpio
* is less than ngpios (that is specified in the gpio_chip).
int of_gpio_simple_xlate(struct gpio_chip *gc,
const struct of_phandle_args *gpiospec, u32 *flags)
* We're discouraging gpio_cells < 2, since that way you'll have to
* write your own xlate function (that will have to retrive the GPIO
* number and the flags from a single gpio cell -- this is possible,
* but not recommended).
if (gc->of_gpio_n_cells < 2) {
return -EINVAL;
if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
return -EINVAL;
if (gpiospec->args[0] >= gc->ngpio)
return -EINVAL;
if (flags)
*flags = gpiospec->args[1];
return gpiospec->args[0];
* of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
* @np: device node of the GPIO chip
* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
* To use this function you should allocate and fill mm_gc with:
* 1) In the gpio_chip structure:
* - all the callbacks
* - of_gpio_n_cells
* - of_xlate callback (optional)
* 3) In the of_mm_gpio_chip structure:
* - save_regs callback (optional)
* If succeeded, this function will map bank's memory and will
* do all necessary work for you. Then you'll able to use .regs
* to manage GPIOs from the callbacks.
int of_mm_gpiochip_add(struct device_node *np,
struct of_mm_gpio_chip *mm_gc)
int ret = -ENOMEM;
struct gpio_chip *gc = &mm_gc->gc;
gc->label = kstrdup(np->full_name, GFP_KERNEL);
if (!gc->label)
goto err0;
mm_gc->regs = of_iomap(np, 0);
if (!mm_gc->regs)
goto err1;
gc->base = -1;
if (mm_gc->save_regs)
mm_gc->gc.of_node = np;
ret = gpiochip_add(gc);
if (ret)
goto err2;
return 0;
pr_err("%s: GPIO chip registration failed with status %d\n",
np->full_name, ret);
return ret;
static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
struct device_node *np = chip->of_node;
struct of_phandle_args pinspec;
struct pinctrl_dev *pctldev;
int index = 0, ret;
if (!np)
for (;; index++) {
ret = of_parse_phandle_with_args(np, "gpio-ranges",
"#gpio-range-cells", index, &pinspec);
if (ret)
pctldev = of_pinctrl_get(;
if (!pctldev)
ret = gpiochip_add_pin_range(chip,
if (ret)
static void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
void of_gpiochip_add(struct gpio_chip *chip)
if ((!chip->of_node) && (chip->dev))
chip->of_node = chip->dev->of_node;
if (!chip->of_node)
if (!chip->of_xlate) {
chip->of_gpio_n_cells = 2;
chip->of_xlate = of_gpio_simple_xlate;
void of_gpiochip_remove(struct gpio_chip *chip)
if (chip->of_node)