/*
 * Renesas R-Car Gen2 USB phy driver
 *
 * Copyright (C) 2013 Renesas Solutions Corp.
 * Copyright (C) 2013 Cogent Embedded, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_data/usb-rcar-gen2-phy.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/usb/otg.h>

struct rcar_gen2_usb_phy_priv {
	struct usb_phy phy;
	void __iomem *base;
	struct clk *clk;
	spinlock_t lock;
	int usecount;
	u32 ugctrl2;
};

#define usb_phy_to_priv(p) container_of(p, struct rcar_gen2_usb_phy_priv, phy)

/* Low Power Status register */
#define USBHS_LPSTS_REG			0x02
#define USBHS_LPSTS_SUSPM		(1 << 14)

/* USB General control register */
#define USBHS_UGCTRL_REG		0x80
#define USBHS_UGCTRL_CONNECT		(1 << 2)
#define USBHS_UGCTRL_PLLRESET		(1 << 0)

/* USB General control register 2 */
#define USBHS_UGCTRL2_REG		0x84
#define USBHS_UGCTRL2_USB0_PCI		(1 << 4)
#define USBHS_UGCTRL2_USB0_HS		(3 << 4)
#define USBHS_UGCTRL2_USB2_PCI		(0 << 31)
#define USBHS_UGCTRL2_USB2_SS		(1 << 31)

/* USB General status register */
#define USBHS_UGSTS_REG			0x88
#define USBHS_UGSTS_LOCK		(3 << 8)

/* Enable USBHS internal phy */
static int __rcar_gen2_usbhs_phy_enable(void __iomem *base)
{
	u32 val;
	int i;

	/* USBHS PHY power on */
	val = ioread32(base + USBHS_UGCTRL_REG);
	val &= ~USBHS_UGCTRL_PLLRESET;
	iowrite32(val, base + USBHS_UGCTRL_REG);

	val = ioread16(base + USBHS_LPSTS_REG);
	val |= USBHS_LPSTS_SUSPM;
	iowrite16(val, base + USBHS_LPSTS_REG);

	for (i = 0; i < 20; i++) {
		val = ioread32(base + USBHS_UGSTS_REG);
		if ((val & USBHS_UGSTS_LOCK) == USBHS_UGSTS_LOCK) {
			val = ioread32(base + USBHS_UGCTRL_REG);
			val |= USBHS_UGCTRL_CONNECT;
			iowrite32(val, base + USBHS_UGCTRL_REG);
			return 0;
		}
		udelay(1);
	}

	/* Timed out waiting for the PLL lock */
	return -ETIMEDOUT;
}

/* Disable USBHS internal phy */
static int __rcar_gen2_usbhs_phy_disable(void __iomem *base)
{
	u32 val;

	/* USBHS PHY power off */
	val = ioread32(base + USBHS_UGCTRL_REG);
	val &= ~USBHS_UGCTRL_CONNECT;
	iowrite32(val, base + USBHS_UGCTRL_REG);

	val = ioread16(base + USBHS_LPSTS_REG);
	val &= ~USBHS_LPSTS_SUSPM;
	iowrite16(val, base + USBHS_LPSTS_REG);

	val = ioread32(base + USBHS_UGCTRL_REG);
	val |= USBHS_UGCTRL_PLLRESET;
	iowrite32(val, base + USBHS_UGCTRL_REG);
	return 0;
}

/* Setup USB channels */
static void __rcar_gen2_usb_phy_init(struct rcar_gen2_usb_phy_priv *priv)
{
	u32 val;

	clk_prepare_enable(priv->clk);

	/* Set USB channels in the USBHS UGCTRL2 register */
	val = ioread32(priv->base + USBHS_UGCTRL2_REG);
	val &= ~(USBHS_UGCTRL2_USB0_HS | USBHS_UGCTRL2_USB2_SS);
	val |= priv->ugctrl2;
	iowrite32(val, priv->base + USBHS_UGCTRL2_REG);
}

/* Shutdown USB channels */
static void __rcar_gen2_usb_phy_shutdown(struct rcar_gen2_usb_phy_priv *priv)
{
	__rcar_gen2_usbhs_phy_disable(priv->base);
	clk_disable_unprepare(priv->clk);
}

static int rcar_gen2_usb_phy_set_suspend(struct usb_phy *phy, int suspend)
{
	struct rcar_gen2_usb_phy_priv *priv = usb_phy_to_priv(phy);
	unsigned long flags;
	int retval;

	spin_lock_irqsave(&priv->lock, flags);
	retval = suspend ? __rcar_gen2_usbhs_phy_disable(priv->base) :
			   __rcar_gen2_usbhs_phy_enable(priv->base);
	spin_unlock_irqrestore(&priv->lock, flags);
	return retval;
}

static int rcar_gen2_usb_phy_init(struct usb_phy *phy)
{
	struct rcar_gen2_usb_phy_priv *priv = usb_phy_to_priv(phy);
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);
	/*
	 * Enable the clock and setup USB channels
	 * if it's the first user
	 */
	if (!priv->usecount++)
		__rcar_gen2_usb_phy_init(priv);
	spin_unlock_irqrestore(&priv->lock, flags);
	return 0;
}

static void rcar_gen2_usb_phy_shutdown(struct usb_phy *phy)
{
	struct rcar_gen2_usb_phy_priv *priv = usb_phy_to_priv(phy);
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);
	if (!priv->usecount) {
		dev_warn(phy->dev, "Trying to disable phy with 0 usecount\n");
		goto out;
	}

	/* Disable everything if it's the last user */
	if (!--priv->usecount)
		__rcar_gen2_usb_phy_shutdown(priv);
out:
	spin_unlock_irqrestore(&priv->lock, flags);
}

static int rcar_gen2_usb_phy_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct rcar_gen2_phy_platform_data *pdata;
	struct rcar_gen2_usb_phy_priv *priv;
	struct resource *res;
	void __iomem *base;
	struct clk *clk;
	int retval;

	pdata = dev_get_platdata(&pdev->dev);
	if (!pdata) {
		dev_err(dev, "No platform data\n");
		return -EINVAL;
	}

	clk = devm_clk_get(&pdev->dev, "usbhs");
	if (IS_ERR(clk)) {
		dev_err(&pdev->dev, "Can't get the clock\n");
		return PTR_ERR(clk);
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	base = devm_ioremap_resource(dev, res);
	if (IS_ERR(base))
		return PTR_ERR(base);

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		dev_err(dev, "Memory allocation failed\n");
		return -ENOMEM;
	}

	spin_lock_init(&priv->lock);
	priv->clk = clk;
	priv->base = base;
	priv->ugctrl2 = pdata->chan0_pci ?
			USBHS_UGCTRL2_USB0_PCI : USBHS_UGCTRL2_USB0_HS;
	priv->ugctrl2 |= pdata->chan2_pci ?
			USBHS_UGCTRL2_USB2_PCI : USBHS_UGCTRL2_USB2_SS;
	priv->phy.dev = dev;
	priv->phy.label = dev_name(dev);
	priv->phy.init = rcar_gen2_usb_phy_init;
	priv->phy.shutdown = rcar_gen2_usb_phy_shutdown;
	priv->phy.set_suspend = rcar_gen2_usb_phy_set_suspend;

	retval = usb_add_phy(&priv->phy, USB_PHY_TYPE_USB2);
	if (retval < 0) {
		dev_err(dev, "Failed to add USB phy\n");
		return retval;
	}

	platform_set_drvdata(pdev, priv);

	return retval;
}

static int rcar_gen2_usb_phy_remove(struct platform_device *pdev)
{
	struct rcar_gen2_usb_phy_priv *priv = platform_get_drvdata(pdev);

	usb_remove_phy(&priv->phy);

	return 0;
}

static struct platform_driver rcar_gen2_usb_phy_driver = {
	.driver = {
		.name = "usb_phy_rcar_gen2",
	},
	.probe = rcar_gen2_usb_phy_probe,
	.remove = rcar_gen2_usb_phy_remove,
};

module_platform_driver(rcar_gen2_usb_phy_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Renesas R-Car Gen2 USB phy");
MODULE_AUTHOR("Valentine Barshak <valentine.barshak@cogentembedded.com>");
