/*
 * 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;
        const struct usb_phy_data *phy_data;
        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;

        phy_data = of_id->data;

        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");