// SPDX-License-Identifier: GPL-2.0

#include <linux/auxiliary_bus.h>
#include <linux/gpio/consumer.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/reset-controller.h>

struct reset_gpio_priv {
        struct reset_controller_dev rc;
        struct gpio_desc *reset;
};

static inline struct reset_gpio_priv
*rc_to_reset_gpio(struct reset_controller_dev *rc)
{
        return container_of(rc, struct reset_gpio_priv, rc);
}

static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned long id)
{
        struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);

        return gpiod_set_value_cansleep(priv->reset, 1);
}

static int reset_gpio_deassert(struct reset_controller_dev *rc,
                               unsigned long id)
{
        struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);

        return gpiod_set_value_cansleep(priv->reset, 0);
}

static int reset_gpio_status(struct reset_controller_dev *rc, unsigned long id)
{
        struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);

        return gpiod_get_value_cansleep(priv->reset);
}

static const struct reset_control_ops reset_gpio_ops = {
        .assert = reset_gpio_assert,
        .deassert = reset_gpio_deassert,
        .status = reset_gpio_status,
};

static int reset_gpio_of_xlate(struct reset_controller_dev *rcdev,
                               const struct of_phandle_args *reset_spec)
{
        return reset_spec->args[0];
}

static void reset_gpio_of_node_put(void *data)
{
        of_node_put(data);
}

static int reset_gpio_probe(struct auxiliary_device *adev,
                            const struct auxiliary_device_id *id)
{
        struct device *dev = &adev->dev;
        struct of_phandle_args *platdata = dev_get_platdata(dev);
        struct reset_gpio_priv *priv;
        int ret;

        if (!platdata)
                return -EINVAL;

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

        auxiliary_set_drvdata(adev, &priv->rc);

        priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(priv->reset))
                return dev_err_probe(dev, PTR_ERR(priv->reset),
                                     "Could not get reset gpios\n");

        priv->rc.ops = &reset_gpio_ops;
        priv->rc.owner = THIS_MODULE;
        priv->rc.dev = dev;
        priv->rc.of_args = platdata;
        ret = devm_add_action_or_reset(dev, reset_gpio_of_node_put,
                                       priv->rc.of_node);
        if (ret)
                return ret;

        /* Cells to match GPIO specifier, but it's not really used */
        priv->rc.of_reset_n_cells = 2;
        priv->rc.of_xlate = reset_gpio_of_xlate;
        priv->rc.nr_resets = 1;

        return devm_reset_controller_register(dev, &priv->rc);
}

static const struct auxiliary_device_id reset_gpio_ids[] = {
        { .name = "reset.gpio" },
        {}
};
MODULE_DEVICE_TABLE(auxiliary, reset_gpio_ids);

static struct auxiliary_driver reset_gpio_driver = {
        .probe          = reset_gpio_probe,
        .id_table       = reset_gpio_ids,
        .driver = {
                .name = "reset-gpio",
                .suppress_bind_attrs = true,
        },
};
module_auxiliary_driver(reset_gpio_driver);

MODULE_AUTHOR("Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>");
MODULE_DESCRIPTION("Generic GPIO reset driver");
MODULE_LICENSE("GPL");