// SPDX-License-Identifier: GPL-2.0
/*
 * Renesas RZ/V2H(P) USB2PHY Port reset control driver
 *
 * Copyright (C) 2025 Renesas Electronics Corporation
 */

#include <linux/cleanup.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/reset-controller.h>

struct rzv2h_usb2phy_regval {
        u16 reg;
        u16 val;
};

struct rzv2h_usb2phy_reset_of_data {
        const struct rzv2h_usb2phy_regval *init_vals;
        unsigned int init_val_count;

        u16 reset_reg;
        u16 reset_assert_val;
        u16 reset_deassert_val;
        u16 reset_status_bits;
        u16 reset_release_val;

        u16 reset2_reg;
        u16 reset2_acquire_val;
        u16 reset2_release_val;
};

struct rzv2h_usb2phy_reset_priv {
        const struct rzv2h_usb2phy_reset_of_data *data;
        void __iomem *base;
        struct device *dev;
        struct reset_controller_dev rcdev;
        spinlock_t lock; /* protects register accesses */
};

static inline struct rzv2h_usb2phy_reset_priv
*rzv2h_usbphy_rcdev_to_priv(struct reset_controller_dev *rcdev)
{
        return container_of(rcdev, struct rzv2h_usb2phy_reset_priv, rcdev);
}

/* This function must be called only after pm_runtime_resume_and_get() has been called */
static void rzv2h_usbphy_assert_helper(struct rzv2h_usb2phy_reset_priv *priv)
{
        const struct rzv2h_usb2phy_reset_of_data *data = priv->data;

        scoped_guard(spinlock, &priv->lock) {
                writel(data->reset2_acquire_val, priv->base + data->reset2_reg);
                writel(data->reset_assert_val, priv->base + data->reset_reg);
        }

        usleep_range(11, 20);
}

static int rzv2h_usbphy_reset_assert(struct reset_controller_dev *rcdev,
                                     unsigned long id)
{
        struct rzv2h_usb2phy_reset_priv *priv = rzv2h_usbphy_rcdev_to_priv(rcdev);
        struct device *dev = priv->dev;
        int ret;

        ret = pm_runtime_resume_and_get(dev);
        if (ret) {
                dev_err(dev, "pm_runtime_resume_and_get failed\n");
                return ret;
        }

        rzv2h_usbphy_assert_helper(priv);

        pm_runtime_put(dev);

        return 0;
}

static int rzv2h_usbphy_reset_deassert(struct reset_controller_dev *rcdev,
                                       unsigned long id)
{
        struct rzv2h_usb2phy_reset_priv *priv = rzv2h_usbphy_rcdev_to_priv(rcdev);
        const struct rzv2h_usb2phy_reset_of_data *data = priv->data;
        struct device *dev = priv->dev;
        int ret;

        ret = pm_runtime_resume_and_get(dev);
        if (ret) {
                dev_err(dev, "pm_runtime_resume_and_get failed\n");
                return ret;
        }

        scoped_guard(spinlock, &priv->lock) {
                writel(data->reset_deassert_val, priv->base + data->reset_reg);
                writel(data->reset2_release_val, priv->base + data->reset2_reg);
                writel(data->reset_release_val, priv->base + data->reset_reg);
        }

        pm_runtime_put(dev);

        return 0;
}

static int rzv2h_usbphy_reset_status(struct reset_controller_dev *rcdev,
                                     unsigned long id)
{
        struct rzv2h_usb2phy_reset_priv *priv = rzv2h_usbphy_rcdev_to_priv(rcdev);
        struct device *dev = priv->dev;
        int ret;
        u32 reg;

        ret = pm_runtime_resume_and_get(dev);
        if (ret) {
                dev_err(dev, "pm_runtime_resume_and_get failed\n");
                return ret;
        }

        reg = readl(priv->base + priv->data->reset_reg);

        pm_runtime_put(dev);

        return (reg & priv->data->reset_status_bits) == priv->data->reset_status_bits;
}

static const struct reset_control_ops rzv2h_usbphy_reset_ops = {
        .assert = rzv2h_usbphy_reset_assert,
        .deassert = rzv2h_usbphy_reset_deassert,
        .status = rzv2h_usbphy_reset_status,
};

static int rzv2h_usb2phy_reset_of_xlate(struct reset_controller_dev *rcdev,
                                        const struct of_phandle_args *reset_spec)
{
        /* No special handling needed, we have only one reset line per device */
        return 0;
}

static int rzv2h_usb2phy_reset_probe(struct platform_device *pdev)
{
        const struct rzv2h_usb2phy_reset_of_data *data;
        struct rzv2h_usb2phy_reset_priv *priv;
        struct device *dev = &pdev->dev;
        struct reset_control *rstc;
        int error;

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

        data = of_device_get_match_data(dev);
        priv->data = data;
        priv->dev = dev;
        priv->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(priv->base))
                return PTR_ERR(priv->base);

        rstc = devm_reset_control_get_shared_deasserted(dev, NULL);
        if (IS_ERR(rstc))
                return dev_err_probe(dev, PTR_ERR(rstc),
                                     "failed to get deasserted reset\n");

        spin_lock_init(&priv->lock);

        error = devm_pm_runtime_enable(dev);
        if (error)
                return dev_err_probe(dev, error, "Failed to enable pm_runtime\n");

        error = pm_runtime_resume_and_get(dev);
        if (error)
                return dev_err_probe(dev, error, "pm_runtime_resume_and_get failed\n");

        for (unsigned int i = 0; i < data->init_val_count; i++)
                writel(data->init_vals[i].val, priv->base + data->init_vals[i].reg);

        /* keep usb2phy in asserted state */
        rzv2h_usbphy_assert_helper(priv);

        pm_runtime_put(dev);

        priv->rcdev.ops = &rzv2h_usbphy_reset_ops;
        priv->rcdev.of_reset_n_cells = 0;
        priv->rcdev.nr_resets = 1;
        priv->rcdev.of_xlate = rzv2h_usb2phy_reset_of_xlate;
        priv->rcdev.of_node = dev->of_node;
        priv->rcdev.dev = dev;

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

/*
 * initialization values required to prepare the PHY to receive
 * assert and deassert requests.
 */
static const struct rzv2h_usb2phy_regval rzv2h_init_vals[] = {
        { .reg = 0xc10, .val = 0x67c },
        { .reg = 0xc14, .val = 0x1f },
        { .reg = 0x600, .val = 0x909 },
};

static const struct rzv2h_usb2phy_reset_of_data rzv2h_reset_of_data = {
        .init_vals = rzv2h_init_vals,
        .init_val_count = ARRAY_SIZE(rzv2h_init_vals),
        .reset_reg = 0,
        .reset_assert_val = 0x206,
        .reset_status_bits = BIT(2),
        .reset_deassert_val = 0x200,
        .reset_release_val = 0x0,
        .reset2_reg = 0xb04,
        .reset2_acquire_val = 0x303,
        .reset2_release_val = 0x3,
};

static const struct of_device_id rzv2h_usb2phy_reset_of_match[] = {
        { .compatible = "renesas,r9a09g057-usb2phy-reset", .data = &rzv2h_reset_of_data },
        { /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, rzv2h_usb2phy_reset_of_match);

static struct platform_driver rzv2h_usb2phy_reset_driver = {
        .driver = {
                .name           = "rzv2h_usb2phy_reset",
                .of_match_table = rzv2h_usb2phy_reset_of_match,
        },
        .probe = rzv2h_usb2phy_reset_probe,
};
module_platform_driver(rzv2h_usb2phy_reset_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
MODULE_DESCRIPTION("Renesas RZ/V2H(P) USB2PHY Control");