// SPDX-License-Identifier: GPL-2.0-only
/*
 * GPIO Driver for Loongson 1 SoC
 *
 * Copyright (C) 2015-2023 Keguang Zhang <keguang.zhang@gmail.com>
 */

#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/generic.h>
#include <linux/platform_device.h>

/* Loongson 1 GPIO Register Definitions */
#define GPIO_CFG                0x0
#define GPIO_DIR                0x10
#define GPIO_DATA               0x20
#define GPIO_OUTPUT             0x30

struct ls1x_gpio_chip {
        struct gpio_generic_chip chip;
        void __iomem *reg_base;
};

static int ls1x_gpio_request(struct gpio_chip *gc, unsigned int offset)
{
        struct ls1x_gpio_chip *ls1x_gc = gpiochip_get_data(gc);

        guard(gpio_generic_lock_irqsave)(&ls1x_gc->chip);

        __raw_writel(__raw_readl(ls1x_gc->reg_base + GPIO_CFG) | BIT(offset),
                     ls1x_gc->reg_base + GPIO_CFG);

        return 0;
}

static void ls1x_gpio_free(struct gpio_chip *gc, unsigned int offset)
{
        struct ls1x_gpio_chip *ls1x_gc = gpiochip_get_data(gc);

        guard(gpio_generic_lock_irqsave)(&ls1x_gc->chip);

        __raw_writel(__raw_readl(ls1x_gc->reg_base + GPIO_CFG) & ~BIT(offset),
                     ls1x_gc->reg_base + GPIO_CFG);
}

static int ls1x_gpio_probe(struct platform_device *pdev)
{
        struct gpio_generic_chip_config config;
        struct device *dev = &pdev->dev;
        struct ls1x_gpio_chip *ls1x_gc;
        int ret;

        ls1x_gc = devm_kzalloc(dev, sizeof(*ls1x_gc), GFP_KERNEL);
        if (!ls1x_gc)
                return -ENOMEM;

        ls1x_gc->reg_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(ls1x_gc->reg_base))
                return PTR_ERR(ls1x_gc->reg_base);

        config = (struct gpio_generic_chip_config) {
                .dev = dev,
                .sz = 4,
                .dat = ls1x_gc->reg_base + GPIO_DATA,
                .set = ls1x_gc->reg_base + GPIO_OUTPUT,
                .dirin = ls1x_gc->reg_base + GPIO_DIR,
        };

        ret = gpio_generic_chip_init(&ls1x_gc->chip, &config);
        if (ret)
                goto err;

        ls1x_gc->chip.gc.owner = THIS_MODULE;
        ls1x_gc->chip.gc.request = ls1x_gpio_request;
        ls1x_gc->chip.gc.free = ls1x_gpio_free;
        /*
         * Clear ngpio to let gpiolib get the correct number
         * by reading ngpios property
         */
        ls1x_gc->chip.gc.ngpio = 0;

        ret = devm_gpiochip_add_data(dev, &ls1x_gc->chip.gc, ls1x_gc);
        if (ret)
                goto err;

        platform_set_drvdata(pdev, ls1x_gc);

        dev_info(dev, "GPIO controller registered with %d pins\n",
                 ls1x_gc->chip.gc.ngpio);

        return 0;
err:
        dev_err(dev, "failed to register GPIO controller\n");
        return ret;
}

static const struct of_device_id ls1x_gpio_dt_ids[] = {
        { .compatible = "loongson,ls1x-gpio" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ls1x_gpio_dt_ids);

static struct platform_driver ls1x_gpio_driver = {
        .probe  = ls1x_gpio_probe,
        .driver = {
                .name   = "ls1x-gpio",
                .of_match_table = ls1x_gpio_dt_ids,
        },
};

module_platform_driver(ls1x_gpio_driver);

MODULE_AUTHOR("Keguang Zhang <keguang.zhang@gmail.com>");
MODULE_DESCRIPTION("Loongson1 GPIO driver");
MODULE_LICENSE("GPL");