/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

#include <linux/slab.h>
#include <linux/of.h>
#include <linux/io.h>
#include <linux/usb/phy_companion.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/pm_runtime.h>
#include <linux/delay.h>
#include <linux/phy/phy.h>
#include <linux/of_platform.h>

#include <linux/mfd/syscon.h>

/*
 * TRM has two sets of USB_CTRL registers.. The correct register bits
 * are in TRM section 24.9.8.2 USB_CTRL Register. The TRM documents the
 * phy as being SR70LX Synopsys USB 2.0 OTG nanoPHY. It also seems at
 * least dm816x rev c ignores writes to USB_CTRL register, but the TI
 * kernel is writing to those so it's possible that later revisions
 * have worknig USB_CTRL register.
 *
 * Also note that At least USB_CTRL register seems to be dm816x specific
 * according to the TRM. It's possible that USBPHY_CTRL is more generic,
 * but that would have to be checked against the SR70LX documentation
 * which does not seem to be publicly available.
 *
 * Finally, the phy on dm814x and am335x is different from dm816x.
 */
#define DM816X_USB_CTRL_PHYCLKSRC	BIT(8)	/* 1 = PLL ref clock */
#define DM816X_USB_CTRL_PHYSLEEP1	BIT(1)	/* Enable the first phy */
#define DM816X_USB_CTRL_PHYSLEEP0	BIT(0)	/* Enable the second phy */

#define DM816X_USBPHY_CTRL_TXRISETUNE	1
#define DM816X_USBPHY_CTRL_TXVREFTUNE	0xc
#define DM816X_USBPHY_CTRL_TXPREEMTUNE	0x2

struct dm816x_usb_phy {
	struct regmap *syscon;
	struct device *dev;
	unsigned int instance;
	struct clk *refclk;
	struct usb_phy phy;
	unsigned int usb_ctrl;		/* Shared between phy0 and phy1 */
	unsigned int usbphy_ctrl;
};

static int dm816x_usb_phy_set_host(struct usb_otg *otg, struct usb_bus *host)
{
	otg->host = host;
	if (!host)
		otg->state = OTG_STATE_UNDEFINED;

	return 0;
}

static int dm816x_usb_phy_set_peripheral(struct usb_otg *otg,
					 struct usb_gadget *gadget)
{
	otg->gadget = gadget;
	if (!gadget)
		otg->state = OTG_STATE_UNDEFINED;

	return 0;
}

static int dm816x_usb_phy_init(struct phy *x)
{
	struct dm816x_usb_phy *phy = phy_get_drvdata(x);
	unsigned int val;
	int error;

	if (clk_get_rate(phy->refclk) != 24000000)
		dev_warn(phy->dev, "nonstandard phy refclk\n");

	/* Set PLL ref clock and put phys to sleep */
	error = regmap_update_bits(phy->syscon, phy->usb_ctrl,
				   DM816X_USB_CTRL_PHYCLKSRC |
				   DM816X_USB_CTRL_PHYSLEEP1 |
				   DM816X_USB_CTRL_PHYSLEEP0,
				   0);
	regmap_read(phy->syscon, phy->usb_ctrl, &val);
	if ((val & 3) != 0)
		dev_info(phy->dev,
			 "Working dm816x USB_CTRL! (0x%08x)\n",
			 val);

	/*
	 * TI kernel sets these values for "symmetrical eye diagram and
	 * better signal quality" so let's assume somebody checked the
	 * values with a scope and set them here too.
	 */
	regmap_read(phy->syscon, phy->usbphy_ctrl, &val);
	val |= DM816X_USBPHY_CTRL_TXRISETUNE |
		DM816X_USBPHY_CTRL_TXVREFTUNE |
		DM816X_USBPHY_CTRL_TXPREEMTUNE;
	regmap_write(phy->syscon, phy->usbphy_ctrl, val);

	return 0;
}

static const struct phy_ops ops = {
	.init		= dm816x_usb_phy_init,
	.owner		= THIS_MODULE,
};

static int __maybe_unused dm816x_usb_phy_runtime_suspend(struct device *dev)
{
	struct dm816x_usb_phy *phy = dev_get_drvdata(dev);
	unsigned int mask, val;
	int error = 0;

	mask = BIT(phy->instance);
	val = ~BIT(phy->instance);
	error = regmap_update_bits(phy->syscon, phy->usb_ctrl,
				   mask, val);
	if (error)
		dev_err(phy->dev, "phy%i failed to power off\n",
			phy->instance);
	clk_disable(phy->refclk);

	return 0;
}

static int __maybe_unused dm816x_usb_phy_runtime_resume(struct device *dev)
{
	struct dm816x_usb_phy *phy = dev_get_drvdata(dev);
	unsigned int mask, val;
	int error;

	error = clk_enable(phy->refclk);
	if (error)
		return error;

	/*
	 * Note that at least dm816x rev c does not seem to do
	 * anything with the USB_CTRL register. But let's follow
	 * what the TI tree is doing in case later revisions use
	 * USB_CTRL.
	 */
	mask = BIT(phy->instance);
	val = BIT(phy->instance);
	error = regmap_update_bits(phy->syscon, phy->usb_ctrl,
				   mask, val);
	if (error) {
		dev_err(phy->dev, "phy%i failed to power on\n",
			phy->instance);
		clk_disable(phy->refclk);
		return error;
	}

	return 0;
}

static UNIVERSAL_DEV_PM_OPS(dm816x_usb_phy_pm_ops,
			    dm816x_usb_phy_runtime_suspend,
			    dm816x_usb_phy_runtime_resume,
			    NULL);

#ifdef CONFIG_OF
static const struct of_device_id dm816x_usb_phy_id_table[] = {
	{
		.compatible = "ti,dm8168-usb-phy",
	},
	{},
};
MODULE_DEVICE_TABLE(of, dm816x_usb_phy_id_table);
#endif

static int dm816x_usb_phy_probe(struct platform_device *pdev)
{
	struct dm816x_usb_phy *phy;
	struct resource *res;
	struct phy *generic_phy;
	struct phy_provider *phy_provider;
	struct usb_otg *otg;
	const struct of_device_id *of_id;
	int error;

	of_id = of_match_device(of_match_ptr(dm816x_usb_phy_id_table),
				&pdev->dev);
	if (!of_id)
		return -EINVAL;

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

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENOENT;

	phy->syscon = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
						      "syscon");
	if (IS_ERR(phy->syscon))
		return PTR_ERR(phy->syscon);

	/*
	 * According to sprs614e.pdf, the first usb_ctrl is shared and
	 * the second instance for usb_ctrl is reserved.. Also the
	 * register bits are different from earlier TRMs.
	 */
	phy->usb_ctrl = 0x20;
	phy->usbphy_ctrl = (res->start & 0xff) + 4;
	if (phy->usbphy_ctrl == 0x2c)
		phy->instance = 1;

	otg = devm_kzalloc(&pdev->dev, sizeof(*otg), GFP_KERNEL);
	if (!otg)
		return -ENOMEM;

	phy->dev = &pdev->dev;
	phy->phy.dev = phy->dev;
	phy->phy.label = "dm8168_usb_phy";
	phy->phy.otg = otg;
	phy->phy.type = USB_PHY_TYPE_USB2;
	otg->set_host = dm816x_usb_phy_set_host;
	otg->set_peripheral = dm816x_usb_phy_set_peripheral;
	otg->usb_phy = &phy->phy;

	platform_set_drvdata(pdev, phy);

	phy->refclk = devm_clk_get(phy->dev, "refclk");
	if (IS_ERR(phy->refclk))
		return PTR_ERR(phy->refclk);
	error = clk_prepare(phy->refclk);
	if (error)
		return error;

	pm_runtime_enable(phy->dev);
	generic_phy = devm_phy_create(phy->dev, NULL, &ops);
	if (IS_ERR(generic_phy))
		return PTR_ERR(generic_phy);

	phy_set_drvdata(generic_phy, phy);

	phy_provider = devm_of_phy_provider_register(phy->dev,
						     of_phy_simple_xlate);
	if (IS_ERR(phy_provider))
		return PTR_ERR(phy_provider);

	usb_add_phy_dev(&phy->phy);

	return 0;
}

static int dm816x_usb_phy_remove(struct platform_device *pdev)
{
	struct dm816x_usb_phy *phy = platform_get_drvdata(pdev);

	usb_remove_phy(&phy->phy);
	pm_runtime_disable(phy->dev);
	clk_unprepare(phy->refclk);

	return 0;
}

static struct platform_driver dm816x_usb_phy_driver = {
	.probe		= dm816x_usb_phy_probe,
	.remove		= dm816x_usb_phy_remove,
	.driver		= {
		.name	= "dm816x-usb-phy",
		.pm	= &dm816x_usb_phy_pm_ops,
		.of_match_table = of_match_ptr(dm816x_usb_phy_id_table),
	},
};

module_platform_driver(dm816x_usb_phy_driver);

MODULE_ALIAS("platform:dm816x_usb");
MODULE_AUTHOR("Tony Lindgren <tony@atomide.com>");
MODULE_DESCRIPTION("dm816x usb phy driver");
MODULE_LICENSE("GPL v2");