// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Congatec Board Controller GPIO driver
 *
 * Copyright (C) 2024 Bootlin
 * Author: Thomas Richard <thomas.richard@bootlin.com>
 */

#include <linux/gpio/driver.h>
#include <linux/mfd/cgbc.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>

#define CGBC_GPIO_NGPIO 14

#define CGBC_GPIO_CMD_GET       0x64
#define CGBC_GPIO_CMD_SET       0x65
#define CGBC_GPIO_CMD_DIR_GET   0x66
#define CGBC_GPIO_CMD_DIR_SET   0x67

struct cgbc_gpio_data {
        struct gpio_chip        chip;
        struct cgbc_device_data *cgbc;
        struct mutex lock;
};

static int cgbc_gpio_cmd(struct cgbc_device_data *cgbc,
                         u8 cmd0, u8 cmd1, u8 cmd2, u8 *value)
{
        u8 cmd[3] = {cmd0, cmd1, cmd2};

        return cgbc_command(cgbc, cmd, sizeof(cmd), value, 1, NULL);
}

static int cgbc_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
        struct cgbc_device_data *cgbc = gpio->cgbc;
        int ret;
        u8 val;

        scoped_guard(mutex, &gpio->lock)
                ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_GET, (offset > 7) ? 1 : 0, 0, &val);

        offset %= 8;

        if (ret)
                return ret;
        else
                return (int)(val & (u8)BIT(offset));
}

static int __cgbc_gpio_set(struct gpio_chip *chip, unsigned int offset,
                           int value)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
        struct cgbc_device_data *cgbc = gpio->cgbc;
        u8 val;
        int ret;

        ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_GET, (offset > 7) ? 1 : 0, 0, &val);
        if (ret)
                return ret;

        if (value)
                val |= BIT(offset % 8);
        else
                val &= ~(BIT(offset % 8));

        return cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_SET, (offset > 7) ? 1 : 0, val, &val);
}

static int cgbc_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);

        guard(mutex)(&gpio->lock);

        return __cgbc_gpio_set(chip, offset, value);
}

static int cgbc_gpio_direction_set(struct gpio_chip *chip,
                                   unsigned int offset, int direction)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
        struct cgbc_device_data *cgbc = gpio->cgbc;
        int ret;
        u8 val;

        ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);
        if (ret)
                goto end;

        if (direction == GPIO_LINE_DIRECTION_IN)
                val &= ~(BIT(offset % 8));
        else
                val |= BIT(offset % 8);

        ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_SET, (offset > 7) ? 1 : 0, val, &val);

end:
        return ret;
}

static int cgbc_gpio_direction_input(struct gpio_chip *chip,
                                     unsigned int offset)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);

        guard(mutex)(&gpio->lock);
        return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_IN);
}

static int cgbc_gpio_direction_output(struct gpio_chip *chip,
                                      unsigned int offset, int value)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
        int ret;

        guard(mutex)(&gpio->lock);

        ret = __cgbc_gpio_set(chip, offset, value);
        if (ret)
                return ret;

        return cgbc_gpio_direction_set(chip, offset, GPIO_LINE_DIRECTION_OUT);
}

static int cgbc_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
{
        struct cgbc_gpio_data *gpio = gpiochip_get_data(chip);
        struct cgbc_device_data *cgbc = gpio->cgbc;
        int ret;
        u8 val;

        scoped_guard(mutex, &gpio->lock)
                ret = cgbc_gpio_cmd(cgbc, CGBC_GPIO_CMD_DIR_GET, (offset > 7) ? 1 : 0, 0, &val);

        if (ret)
                return ret;

        if (val & BIT(offset % 8))
                return GPIO_LINE_DIRECTION_OUT;
        else
                return GPIO_LINE_DIRECTION_IN;
}

static int cgbc_gpio_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cgbc_device_data *cgbc = dev_get_drvdata(dev->parent);
        struct cgbc_gpio_data *gpio;
        struct gpio_chip *chip;
        int ret;

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

        gpio->cgbc = cgbc;

        platform_set_drvdata(pdev, gpio);

        chip = &gpio->chip;
        chip->label = dev_name(&pdev->dev);
        chip->owner = THIS_MODULE;
        chip->parent = dev;
        chip->base = -1;
        chip->direction_input = cgbc_gpio_direction_input;
        chip->direction_output = cgbc_gpio_direction_output;
        chip->get_direction = cgbc_gpio_get_direction;
        chip->get = cgbc_gpio_get;
        chip->set = cgbc_gpio_set;
        chip->ngpio = CGBC_GPIO_NGPIO;

        ret = devm_mutex_init(dev, &gpio->lock);
        if (ret)
                return ret;

        ret = devm_gpiochip_add_data(dev, chip, gpio);
        if (ret)
                return dev_err_probe(dev, ret, "Could not register GPIO chip\n");

        return 0;
}

static struct platform_driver cgbc_gpio_driver = {
        .driver = {
                .name = "cgbc-gpio",
        },
        .probe  = cgbc_gpio_probe,
};

module_platform_driver(cgbc_gpio_driver);

MODULE_DESCRIPTION("Congatec Board Controller GPIO Driver");
MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:cgbc-gpio");