gpiolib-of.c

Go to the documentation of this file.

/*
 * OF helpers for the GPIO API
 *
 * Copyright (c) 2007-2008  MontaVista Software, Inc.
 *
 * Author: Anton Vorontsov <[email protected]>
 *
 * 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/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->gpiospec.np) ||
        (gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
        (!gc->of_xlate))
        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;
}

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,
                     &gg_data.gpiospec);
    if (ret) {
        pr_debug("%s: can't parse gpios property\n", __func__);
        return ret;
    }

    gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);

    of_node_put(gg_data.gpiospec.np);
    pr_debug("%s exited with status %d\n", __func__, gg_data.out_gpio);
    return gg_data.out_gpio;
}
EXPORT_SYMBOL(of_get_named_gpio_flags);

unsigned int of_gpio_named_count(struct device_node *np, const char* propname)
{
    unsigned int cnt = 0;

    do {
        int ret;

        ret = of_parse_phandle_with_args(np, propname, "#gpio-cells",
                         cnt, NULL);
        /* A hole in the gpios = <> counts anyway. */
        if (ret < 0 && ret != -EEXIST)
            break;
    } while (++cnt);

    return cnt;
}
EXPORT_SYMBOL(of_gpio_named_count);

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) {
        WARN_ON(1);
        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];
}
EXPORT_SYMBOL(of_gpio_simple_xlate);

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->save_regs(mm_gc);

    mm_gc->gc.of_node = np;

    ret = gpiochip_add(gc);
    if (ret)
        goto err2;

    return 0;
err2:
    iounmap(mm_gc->regs);
err1:
    kfree(gc->label);
err0:
    pr_err("%s: GPIO chip registration failed with status %d\n",
           np->full_name, ret);
    return ret;
}
EXPORT_SYMBOL(of_mm_gpiochip_add);

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)
        return;

    if (!chip->of_xlate) {
        chip->of_gpio_n_cells = 2;
        chip->of_xlate = of_gpio_simple_xlate;
    }

    of_node_get(chip->of_node);
}

void of_gpiochip_remove(struct gpio_chip *chip)
{
    if (chip->of_node)
        of_node_put(chip->of_node);
}