// SPDX-License-Identifier: GPL-2.0-only
/*
 * TI/National Semiconductor LP3943 GPIO driver
 *
 * Copyright 2013 Texas Instruments
 *
 * Author: Milo Kim <milo.kim@ti.com>
 */

#include <linux/bitops.h>
#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/i2c.h>
#include <linux/mfd/lp3943.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

enum lp3943_gpios {
        LP3943_GPIO1,
        LP3943_GPIO2,
        LP3943_GPIO3,
        LP3943_GPIO4,
        LP3943_GPIO5,
        LP3943_GPIO6,
        LP3943_GPIO7,
        LP3943_GPIO8,
        LP3943_GPIO9,
        LP3943_GPIO10,
        LP3943_GPIO11,
        LP3943_GPIO12,
        LP3943_GPIO13,
        LP3943_GPIO14,
        LP3943_GPIO15,
        LP3943_GPIO16,
        LP3943_MAX_GPIO,
};

struct lp3943_gpio {
        struct gpio_chip chip;
        struct lp3943 *lp3943;
        u16 input_mask;         /* 1 = GPIO is input direction, 0 = output */
};

static int lp3943_gpio_request(struct gpio_chip *chip, unsigned int offset)
{
        struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
        struct lp3943 *lp3943 = lp3943_gpio->lp3943;

        /* Return an error if the pin is already assigned */
        if (test_and_set_bit(offset, &lp3943->pin_used))
                return -EBUSY;

        return 0;
}

static void lp3943_gpio_free(struct gpio_chip *chip, unsigned int offset)
{
        struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
        struct lp3943 *lp3943 = lp3943_gpio->lp3943;

        clear_bit(offset, &lp3943->pin_used);
}

static int lp3943_gpio_set_mode(struct lp3943_gpio *lp3943_gpio, u8 offset,
                                u8 val)
{
        struct lp3943 *lp3943 = lp3943_gpio->lp3943;
        const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;

        return lp3943_update_bits(lp3943, mux[offset].reg, mux[offset].mask,
                                  val << mux[offset].shift);
}

static int lp3943_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
{
        struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);

        lp3943_gpio->input_mask |= BIT(offset);

        return lp3943_gpio_set_mode(lp3943_gpio, offset, LP3943_GPIO_IN);
}

static int lp3943_get_gpio_in_status(struct lp3943_gpio *lp3943_gpio,
                                     struct gpio_chip *chip, unsigned int offset)
{
        u8 addr, read;
        int err;

        switch (offset) {
        case LP3943_GPIO1 ... LP3943_GPIO8:
                addr = LP3943_REG_GPIO_A;
                break;
        case LP3943_GPIO9 ... LP3943_GPIO16:
                addr = LP3943_REG_GPIO_B;
                offset = offset - 8;
                break;
        default:
                return -EINVAL;
        }

        err = lp3943_read_byte(lp3943_gpio->lp3943, addr, &read);
        if (err)
                return err;

        return !!(read & BIT(offset));
}

static int lp3943_get_gpio_out_status(struct lp3943_gpio *lp3943_gpio,
                                      struct gpio_chip *chip, unsigned int offset)
{
        struct lp3943 *lp3943 = lp3943_gpio->lp3943;
        const struct lp3943_reg_cfg *mux = lp3943->mux_cfg;
        u8 read;
        int err;

        err = lp3943_read_byte(lp3943, mux[offset].reg, &read);
        if (err)
                return err;

        read = (read & mux[offset].mask) >> mux[offset].shift;

        if (read == LP3943_GPIO_OUT_HIGH)
                return 1;
        else if (read == LP3943_GPIO_OUT_LOW)
                return 0;
        else
                return -EINVAL;
}

static int lp3943_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
        struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);

        /*
         * Limitation:
         *   LP3943 doesn't have the GPIO direction register. It provides
         *   only input and output status registers.
         *   So, direction info is required to handle the 'get' operation.
         *   This variable is updated whenever the direction is changed and
         *   it is used here.
         */

        if (lp3943_gpio->input_mask & BIT(offset))
                return lp3943_get_gpio_in_status(lp3943_gpio, chip, offset);
        else
                return lp3943_get_gpio_out_status(lp3943_gpio, chip, offset);
}

static int lp3943_gpio_set(struct gpio_chip *chip, unsigned int offset,
                           int value)
{
        struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
        u8 data;

        if (value)
                data = LP3943_GPIO_OUT_HIGH;
        else
                data = LP3943_GPIO_OUT_LOW;

        return lp3943_gpio_set_mode(lp3943_gpio, offset, data);
}

static int lp3943_gpio_direction_output(struct gpio_chip *chip, unsigned int offset,
                                        int value)
{
        struct lp3943_gpio *lp3943_gpio = gpiochip_get_data(chip);
        int ret;

        ret = lp3943_gpio_set(chip, offset, value);
        if (ret)
                return ret;

        lp3943_gpio->input_mask &= ~BIT(offset);

        return 0;
}

static const struct gpio_chip lp3943_gpio_chip = {
        .label                  = "lp3943",
        .owner                  = THIS_MODULE,
        .request                = lp3943_gpio_request,
        .free                   = lp3943_gpio_free,
        .direction_input        = lp3943_gpio_direction_input,
        .get                    = lp3943_gpio_get,
        .direction_output       = lp3943_gpio_direction_output,
        .set                    = lp3943_gpio_set,
        .base                   = -1,
        .ngpio                  = LP3943_MAX_GPIO,
        .can_sleep              = 1,
};

static int lp3943_gpio_probe(struct platform_device *pdev)
{
        struct lp3943 *lp3943 = dev_get_drvdata(pdev->dev.parent);
        struct lp3943_gpio *lp3943_gpio;

        lp3943_gpio = devm_kzalloc(&pdev->dev, sizeof(*lp3943_gpio),
                                GFP_KERNEL);
        if (!lp3943_gpio)
                return -ENOMEM;

        lp3943_gpio->lp3943 = lp3943;
        lp3943_gpio->chip = lp3943_gpio_chip;
        lp3943_gpio->chip.parent = &pdev->dev;

        return devm_gpiochip_add_data(&pdev->dev, &lp3943_gpio->chip,
                                      lp3943_gpio);
}

static const struct of_device_id lp3943_gpio_of_match[] = {
        { .compatible = "ti,lp3943-gpio", },
        { }
};
MODULE_DEVICE_TABLE(of, lp3943_gpio_of_match);

static struct platform_driver lp3943_gpio_driver = {
        .probe = lp3943_gpio_probe,
        .driver = {
                .name = "lp3943-gpio",
                .of_match_table = lp3943_gpio_of_match,
        },
};
module_platform_driver(lp3943_gpio_driver);

MODULE_DESCRIPTION("LP3943 GPIO driver");
MODULE_ALIAS("platform:lp3943-gpio");
MODULE_AUTHOR("Milo Kim");
MODULE_LICENSE("GPL");