// SPDX-License-Identifier: GPL-2.0
/*
 * Renesas R-Car USB2.0 clock selector
 *
 * Copyright (C) 2017 Renesas Electronics Corp.
 *
 * Based on renesas-cpg-mssr.c
 *
 * Copyright (C) 2015 Glider bvba
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/slab.h>

#define USB20_CLKSET0           0x00
#define CLKSET0_INTCLK_EN       BIT(11)
#define CLKSET0_PRIVATE         BIT(0)
#define CLKSET0_EXTAL_ONLY      (CLKSET0_INTCLK_EN | CLKSET0_PRIVATE)

static const struct clk_bulk_data rcar_usb2_clocks[] = {
        { .id = "ehci_ohci", },
        { .id = "hs-usb-if", },
};

struct usb2_clock_sel_priv {
        void __iomem *base;
        struct clk_hw hw;
        struct clk_bulk_data clks[ARRAY_SIZE(rcar_usb2_clocks)];
        struct reset_control *rsts;
        bool extal;
        bool xtal;
};
#define to_priv(_hw)    container_of(_hw, struct usb2_clock_sel_priv, hw)

static void usb2_clock_sel_enable_extal_only(struct usb2_clock_sel_priv *priv)
{
        u16 val = readw(priv->base + USB20_CLKSET0);

        pr_debug("%s: enter %d %d %x\n", __func__,
                 priv->extal, priv->xtal, val);

        if (priv->extal && !priv->xtal && val != CLKSET0_EXTAL_ONLY)
                writew(CLKSET0_EXTAL_ONLY, priv->base + USB20_CLKSET0);
}

static void usb2_clock_sel_disable_extal_only(struct usb2_clock_sel_priv *priv)
{
        if (priv->extal && !priv->xtal)
                writew(CLKSET0_PRIVATE, priv->base + USB20_CLKSET0);
}

static int usb2_clock_sel_enable(struct clk_hw *hw)
{
        struct usb2_clock_sel_priv *priv = to_priv(hw);
        int ret;

        ret = reset_control_deassert(priv->rsts);
        if (ret)
                return ret;

        ret = clk_bulk_prepare_enable(ARRAY_SIZE(priv->clks), priv->clks);
        if (ret) {
                reset_control_assert(priv->rsts);
                return ret;
        }

        usb2_clock_sel_enable_extal_only(priv);

        return 0;
}

static void usb2_clock_sel_disable(struct clk_hw *hw)
{
        struct usb2_clock_sel_priv *priv = to_priv(hw);

        usb2_clock_sel_disable_extal_only(priv);

        clk_bulk_disable_unprepare(ARRAY_SIZE(priv->clks), priv->clks);
        reset_control_assert(priv->rsts);
}

/*
 * This module seems a mux, but this driver assumes a gate because
 * ehci/ohci platform drivers don't support clk_set_parent() for now.
 * If this driver acts as a gate, ehci/ohci-platform drivers don't need
 * any modification.
 */
static const struct clk_ops usb2_clock_sel_clock_ops = {
        .enable = usb2_clock_sel_enable,
        .disable = usb2_clock_sel_disable,
};

static const struct of_device_id rcar_usb2_clock_sel_match[] = {
        { .compatible = "renesas,rcar-gen3-usb2-clock-sel" },
        { }
};

static int rcar_usb2_clock_sel_suspend(struct device *dev)
{
        struct usb2_clock_sel_priv *priv = dev_get_drvdata(dev);

        usb2_clock_sel_disable_extal_only(priv);
        pm_runtime_put(dev);

        return 0;
}

static int rcar_usb2_clock_sel_resume(struct device *dev)
{
        struct usb2_clock_sel_priv *priv = dev_get_drvdata(dev);

        pm_runtime_get_sync(dev);
        usb2_clock_sel_enable_extal_only(priv);

        return 0;
}

static void rcar_usb2_clock_sel_remove(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;

        of_clk_del_provider(dev->of_node);
        pm_runtime_put(dev);
        pm_runtime_disable(dev);
}

static int rcar_usb2_clock_sel_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct usb2_clock_sel_priv *priv;
        struct clk *clk;
        struct clk_init_data init = {};
        int ret;

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

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

        memcpy(priv->clks, rcar_usb2_clocks, sizeof(priv->clks));
        ret = devm_clk_bulk_get(dev, ARRAY_SIZE(priv->clks), priv->clks);
        if (ret < 0)
                return ret;

        priv->rsts = devm_reset_control_array_get_shared(dev);
        if (IS_ERR(priv->rsts))
                return PTR_ERR(priv->rsts);

        clk = devm_clk_get(dev, "usb_extal");
        if (!IS_ERR(clk) && !clk_prepare_enable(clk)) {
                priv->extal = !!clk_get_rate(clk);
                clk_disable_unprepare(clk);
        }
        clk = devm_clk_get(dev, "usb_xtal");
        if (!IS_ERR(clk) && !clk_prepare_enable(clk)) {
                priv->xtal = !!clk_get_rate(clk);
                clk_disable_unprepare(clk);
        }

        if (!priv->extal && !priv->xtal) {
                dev_err(dev, "This driver needs usb_extal or usb_xtal\n");
                return -ENOENT;
        }

        pm_runtime_enable(dev);
        pm_runtime_get_sync(dev);
        platform_set_drvdata(pdev, priv);
        dev_set_drvdata(dev, priv);

        init.name = "rcar_usb2_clock_sel";
        init.ops = &usb2_clock_sel_clock_ops;
        priv->hw.init = &init;

        ret = devm_clk_hw_register(dev, &priv->hw);
        if (ret)
                goto pm_put;

        ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &priv->hw);
        if (ret)
                goto pm_put;

        return 0;

pm_put:
        pm_runtime_put(dev);
        pm_runtime_disable(dev);
        return ret;
}

static const struct dev_pm_ops rcar_usb2_clock_sel_pm_ops = {
        .suspend        = rcar_usb2_clock_sel_suspend,
        .resume         = rcar_usb2_clock_sel_resume,
};

static struct platform_driver rcar_usb2_clock_sel_driver = {
        .driver         = {
                .name   = "rcar-usb2-clock-sel",
                .of_match_table = rcar_usb2_clock_sel_match,
                .pm     = &rcar_usb2_clock_sel_pm_ops,
        },
        .probe          = rcar_usb2_clock_sel_probe,
        .remove         = rcar_usb2_clock_sel_remove,
};
builtin_platform_driver(rcar_usb2_clock_sel_driver);

MODULE_DESCRIPTION("Renesas R-Car USB2 clock selector Driver");
MODULE_LICENSE("GPL v2");