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/*
 * Moschip MCS814x GPIO support
 *
 * Copyright (C) 2012, Florian Fainelli <florian@openwrt.org>
 *
 * Licensed under the GPLv2
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>

struct mcs814x_gpio_chip {
        void __iomem *regs;
        struct gpio_chip chip;
};

#define GPIO_PIN        0x00
#define GPIO_DIR        0x04

#define to_mcs814x_gpio_chip(x) container_of(x, struct mcs814x_gpio_chip, chip)

static int mcs814x_gpio_get(struct gpio_chip *chip, unsigned offset)
{
        struct mcs814x_gpio_chip *mcs814x = to_mcs814x_gpio_chip(chip);

        return readl_relaxed(mcs814x->regs + GPIO_PIN) & (1 << offset);
}

static void mcs814x_gpio_set(struct gpio_chip *chip,
                                unsigned offset, int value)
{
        struct mcs814x_gpio_chip *mcs814x = to_mcs814x_gpio_chip(chip);
        u32 mask;

        mask = readl_relaxed(mcs814x->regs + GPIO_PIN);
        if (value)
                mask |= (1 << offset);
        else
                mask &= ~(1 << offset);
        writel_relaxed(mask, mcs814x->regs + GPIO_PIN);
}

static int mcs814x_gpio_direction_output(struct gpio_chip *chip,
                                        unsigned offset, int value)
{
        struct mcs814x_gpio_chip *mcs814x = to_mcs814x_gpio_chip(chip);
        u32 mask;

        mask = readl_relaxed(mcs814x->regs + GPIO_DIR);
        mask &= ~(1 << offset);
        writel_relaxed(mask, mcs814x->regs + GPIO_DIR);

        return 0;
}

static int mcs814x_gpio_direction_input(struct gpio_chip *chip,
                                        unsigned offset)
{
        struct mcs814x_gpio_chip *mcs814x = to_mcs814x_gpio_chip(chip);
        u32 mask;

        mask = readl_relaxed(mcs814x->regs + GPIO_DIR);
        mask |= (1 << offset);
        writel_relaxed(mask, mcs814x->regs + GPIO_DIR);

        return 0;
}

static int mcs814x_gpio_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct mcs814x_gpio_chip *mcs814x_chip;
        int ret;
        const unsigned int *num_gpios;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENODEV;

        num_gpios = of_get_property(pdev->dev.of_node, "num-gpios", NULL);
        if (!num_gpios)
                dev_err(&pdev->dev, "FIXME: no num-gpios property\n");

        mcs814x_chip = kzalloc(sizeof(*mcs814x_chip), GFP_KERNEL);
        if (!mcs814x_chip)
                return -ENOMEM;

        mcs814x_chip->regs = devm_ioremap_resource(&pdev->dev, res);
        if (!mcs814x_chip->regs) {
                ret = -ENOMEM;
                goto out;
        }

        platform_set_drvdata(pdev, mcs814x_chip);

#ifdef CONFIG_OF_GPIO
        mcs814x_chip->chip.of_node = pdev->dev.of_node;
#endif

        mcs814x_chip->chip.label = pdev->name;
        mcs814x_chip->chip.get = mcs814x_gpio_get;
        mcs814x_chip->chip.set = mcs814x_gpio_set;
        mcs814x_chip->chip.direction_input = mcs814x_gpio_direction_input;
        mcs814x_chip->chip.direction_output = mcs814x_gpio_direction_output;
        mcs814x_chip->chip.ngpio = be32_to_cpup(num_gpios);
        /* we want dynamic base allocation */
        mcs814x_chip->chip.base = -1;

        ret = gpiochip_add(&mcs814x_chip->chip);
        if (ret) {
                dev_err(&pdev->dev, "failed to register gpiochip\n");
                goto out;
        }

        return 0;

out:
        platform_set_drvdata(pdev, NULL);
        kfree(mcs814x_chip);
        return ret;
}

static struct of_device_id mcs814x_gpio_ids[] = {
        { .compatible = "moschip,mcs814x-gpio" },
        { /* sentinel */ },
};

static struct platform_driver mcs814x_gpio_driver = {
        .driver = {
                .name   = "mcs814x-gpio",
                .owner  = THIS_MODULE,
                .of_match_table = mcs814x_gpio_ids,
        },
        .probe  = mcs814x_gpio_probe,
};

int __init mcs814x_gpio_init(void)
{
        return platform_driver_register(&mcs814x_gpio_driver);
}
postcore_initcall(mcs814x_gpio_init);