// SPDX-License-Identifier: GPL-2.0
/*
 * Renesas R-Car Gen3 PCIe PHY driver
 *
 * Copyright (C) 2018 Cogent Embedded, Inc.
 */

#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/phy/phy.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>

#define PHY_CTRL                0x4000          /* R8A77980 only */

/* PHY control register (PHY_CTRL) */
#define PHY_CTRL_PHY_PWDN       BIT(2)

struct rcar_gen3_phy {
        struct phy *phy;
        spinlock_t lock;
        void __iomem *base;
};

static void rcar_gen3_phy_pcie_modify_reg(struct phy *p, unsigned int reg,
                                          u32 clear, u32 set)
{
        struct rcar_gen3_phy *phy = phy_get_drvdata(p);
        void __iomem *base = phy->base;
        unsigned long flags;
        u32 value;

        spin_lock_irqsave(&phy->lock, flags);

        value = readl(base + reg);
        value &= ~clear;
        value |= set;
        writel(value, base + reg);

        spin_unlock_irqrestore(&phy->lock, flags);
}

static int r8a77980_phy_pcie_power_on(struct phy *p)
{
        /* Power on the PCIe PHY */
        rcar_gen3_phy_pcie_modify_reg(p, PHY_CTRL, PHY_CTRL_PHY_PWDN, 0);

        return 0;
}

static int r8a77980_phy_pcie_power_off(struct phy *p)
{
        /* Power off the PCIe PHY */
        rcar_gen3_phy_pcie_modify_reg(p, PHY_CTRL, 0, PHY_CTRL_PHY_PWDN);

        return 0;
}

static const struct phy_ops r8a77980_phy_pcie_ops = {
        .power_on       = r8a77980_phy_pcie_power_on,
        .power_off      = r8a77980_phy_pcie_power_off,
        .owner          = THIS_MODULE,
};

static const struct of_device_id rcar_gen3_phy_pcie_match_table[] = {
        { .compatible = "renesas,r8a77980-pcie-phy" },
        { }
};
MODULE_DEVICE_TABLE(of, rcar_gen3_phy_pcie_match_table);

static int rcar_gen3_phy_pcie_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct phy_provider *provider;
        struct rcar_gen3_phy *phy;
        void __iomem *base;
        int error;

        if (!dev->of_node) {
                dev_err(dev,
                        "This driver must only be instantiated from the device tree\n");
                return -EINVAL;
        }

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

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

        spin_lock_init(&phy->lock);

        phy->base = base;

        /*
         * devm_phy_create() will call pm_runtime_enable(&phy->dev);
         * And then, phy-core will manage runtime PM for this device.
         */
        pm_runtime_enable(dev);

        phy->phy = devm_phy_create(dev, NULL, &r8a77980_phy_pcie_ops);
        if (IS_ERR(phy->phy)) {
                dev_err(dev, "Failed to create PCIe PHY\n");
                error = PTR_ERR(phy->phy);
                goto error;
        }
        phy_set_drvdata(phy->phy, phy);

        provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
        if (IS_ERR(provider)) {
                dev_err(dev, "Failed to register PHY provider\n");
                error = PTR_ERR(provider);
                goto error;
        }

        return 0;

error:
        pm_runtime_disable(dev);

        return error;
}

static void rcar_gen3_phy_pcie_remove(struct platform_device *pdev)
{
        pm_runtime_disable(&pdev->dev);
}

static struct platform_driver rcar_gen3_phy_driver = {
        .driver = {
                .name = "phy_rcar_gen3_pcie",
                .of_match_table = rcar_gen3_phy_pcie_match_table,
        },
        .probe = rcar_gen3_phy_pcie_probe,
        .remove = rcar_gen3_phy_pcie_remove,
};

module_platform_driver(rcar_gen3_phy_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Renesas R-Car Gen3 PCIe PHY");
MODULE_AUTHOR("Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>");