/*
 * OF helpers for the GPIO API
 *
 * Copyright (c) 2007-2008  MontaVista Software, Inc.
 *
 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * 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->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;
}

/**
 * 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,
                                         &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);

/**
 * of_gpio_named_count - Count GPIOs for a device
 * @np:         device node to count GPIOs for
 * @propname:   property name containing gpio specifier(s)
 *
 * The function returns the count of GPIOs specified for a node.
 *
 * Note that the empty GPIO specifiers counts too. For example,
 *
 * gpios = <0
 *          &pio1 1 2
 *          0
 *          &pio2 3 4>;
 *
 * defines four GPIOs (so this function will return 4), two of which
 * are not specified.
 */
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);

/**
 * 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) {
                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);

/**
 * 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->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);

#ifdef CONFIG_PINCTRL
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)
                return;

        do {
                ret = of_parse_phandle_with_args(np, "gpio-ranges",
                                "#gpio-range-cells", index, &pinspec);
                if (ret)
                        break;

                pctldev = of_pinctrl_get(pinspec.np);
                if (!pctldev)
                        break;

                /*
                 * This assumes that the n GPIO pins are consecutive in the
                 * GPIO number space, and that the pins are also consecutive
                 * in their local number space. Currently it is not possible
                 * to add different ranges for one and the same GPIO chip,
                 * as the code assumes that we have one consecutive range
                 * on both, mapping 1-to-1.
                 *
                 * TODO: make the OF bindings handle multiple sparse ranges
                 * on the same GPIO chip.
                 */
                ret = gpiochip_add_pin_range(chip,
                                             pinctrl_dev_get_name(pctldev),
                                             0, /* offset in gpiochip */
                                             pinspec.args[0],
                                             pinspec.args[1]);

                if (ret)
                        break;

        } while (index++);
}

#else
static void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
#endif

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_gpiochip_add_pin_range(chip);
        of_node_get(chip->of_node);
}

void of_gpiochip_remove(struct gpio_chip *chip)
{
        gpiochip_remove_pin_ranges(chip);

        if (chip->of_node)
                of_node_put(chip->of_node);
}