// SPDX-License-Identifier: GPL-2.0
/*
 * GPIO-controlled multiplexer driver
 *
 * Copyright (C) 2017 Axentia Technologies AB
 *
 * Author: Peter Rosin <peda@axentia.se>
 */

#include <linux/bitmap.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mux/driver.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>

struct mux_gpio {
        struct gpio_descs *gpios;
};

static int mux_gpio_set(struct mux_control *mux, int state)
{
        struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
        DECLARE_BITMAP(values, BITS_PER_TYPE(state));
        u32 value = state;

        bitmap_from_arr32(values, &value, BITS_PER_TYPE(value));

        gpiod_multi_set_value_cansleep(mux_gpio->gpios, values);

        return 0;
}

static const struct mux_control_ops mux_gpio_ops = {
        .set = mux_gpio_set,
};

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

static int mux_gpio_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct mux_chip *mux_chip;
        struct mux_gpio *mux_gpio;
        int pins;
        s32 idle_state;
        int ret;

        pins = gpiod_count(dev, "mux");
        if (pins < 0)
                return pins;

        mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
        if (IS_ERR(mux_chip))
                return PTR_ERR(mux_chip);

        mux_gpio = mux_chip_priv(mux_chip);
        mux_chip->ops = &mux_gpio_ops;

        mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
        if (IS_ERR(mux_gpio->gpios))
                return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios),
                                     "failed to get gpios\n");
        WARN_ON(pins != mux_gpio->gpios->ndescs);
        mux_chip->mux->states = BIT(pins);

        ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
        if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
                if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
                        dev_err(dev, "invalid idle-state %u\n", idle_state);
                        return -EINVAL;
                }

                mux_chip->mux->idle_state = idle_state;
        }

        ret = devm_regulator_get_enable_optional(dev, "mux");
        if (ret && ret != -ENODEV)
                return dev_err_probe(dev, ret, "failed to get/enable mux supply\n");

        ret = devm_mux_chip_register(dev, mux_chip);
        if (ret < 0)
                return ret;

        dev_info(dev, "%u-way mux-controller registered\n",
                 mux_chip->mux->states);

        return 0;
}

static struct platform_driver mux_gpio_driver = {
        .driver = {
                .name = "gpio-mux",
                .of_match_table = mux_gpio_dt_ids,
        },
        .probe = mux_gpio_probe,
};
module_platform_driver(mux_gpio_driver);

MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
MODULE_LICENSE("GPL v2");