// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * ISP1704 USB Charger Detection driver
 *
 * Copyright (C) 2010 Nokia Corporation
 * Copyright (C) 2012 - 2013 Pali Rohár <pali@kernel.org>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/sysfs.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/delay.h>
#include <linux/of.h>

#include <linux/gpio/consumer.h>
#include <linux/usb/otg.h>
#include <linux/usb/ulpi.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

/* Vendor specific Power Control register */
#define ISP1704_PWR_CTRL                0x3d
#define ISP1704_PWR_CTRL_SWCTRL         (1 << 0)
#define ISP1704_PWR_CTRL_DET_COMP       (1 << 1)
#define ISP1704_PWR_CTRL_BVALID_RISE    (1 << 2)
#define ISP1704_PWR_CTRL_BVALID_FALL    (1 << 3)
#define ISP1704_PWR_CTRL_DP_WKPU_EN     (1 << 4)
#define ISP1704_PWR_CTRL_VDAT_DET       (1 << 5)
#define ISP1704_PWR_CTRL_DPVSRC_EN      (1 << 6)
#define ISP1704_PWR_CTRL_HWDETECT       (1 << 7)

#define NXP_VENDOR_ID                   0x04cc

static u16 isp170x_id[] = {
        0x1704,
        0x1707,
};

struct isp1704_charger {
        struct device                   *dev;
        struct power_supply             *psy;
        struct power_supply_desc        psy_desc;
        struct gpio_desc                *enable_gpio;
        struct usb_phy                  *phy;
        struct notifier_block           nb;
        struct work_struct              work;

        /* properties */
        char                    model[8];
        unsigned                present:1;
        unsigned                online:1;
        unsigned                current_max;
};

static inline int isp1704_read(struct isp1704_charger *isp, u32 reg)
{
        return usb_phy_io_read(isp->phy, reg);
}

static inline int isp1704_write(struct isp1704_charger *isp, u32 reg, u32 val)
{
        return usb_phy_io_write(isp->phy, val, reg);
}

static void isp1704_charger_set_power(struct isp1704_charger *isp, bool on)
{
        gpiod_set_value(isp->enable_gpio, on);
}

/*
 * Determine is the charging port DCP (dedicated charger) or CDP (Host/HUB
 * chargers).
 *
 * REVISIT: The method is defined in Battery Charging Specification and is
 * applicable to any ULPI transceiver. Nothing isp170x specific here.
 */
static inline int isp1704_charger_type(struct isp1704_charger *isp)
{
        u8 reg;
        u8 func_ctrl;
        u8 otg_ctrl;
        int type = POWER_SUPPLY_TYPE_USB_DCP;

        func_ctrl = isp1704_read(isp, ULPI_FUNC_CTRL);
        otg_ctrl = isp1704_read(isp, ULPI_OTG_CTRL);

        /* disable pulldowns */
        reg = ULPI_OTG_CTRL_DM_PULLDOWN | ULPI_OTG_CTRL_DP_PULLDOWN;
        isp1704_write(isp, ULPI_CLR(ULPI_OTG_CTRL), reg);

        /* full speed */
        isp1704_write(isp, ULPI_CLR(ULPI_FUNC_CTRL),
                        ULPI_FUNC_CTRL_XCVRSEL_MASK);
        isp1704_write(isp, ULPI_SET(ULPI_FUNC_CTRL),
                        ULPI_FUNC_CTRL_FULL_SPEED);

        /* Enable strong pull-up on DP (1.5K) and reset */
        reg = ULPI_FUNC_CTRL_TERMSELECT | ULPI_FUNC_CTRL_RESET;
        isp1704_write(isp, ULPI_SET(ULPI_FUNC_CTRL), reg);
        usleep_range(1000, 2000);

        reg = isp1704_read(isp, ULPI_DEBUG);
        if ((reg & 3) != 3)
                type = POWER_SUPPLY_TYPE_USB_CDP;

        /* recover original state */
        isp1704_write(isp, ULPI_FUNC_CTRL, func_ctrl);
        isp1704_write(isp, ULPI_OTG_CTRL, otg_ctrl);

        return type;
}

/*
 * ISP1704 detects PS/2 adapters as charger. To make sure the detected charger
 * is actually a dedicated charger, the following steps need to be taken.
 */
static inline int isp1704_charger_verify(struct isp1704_charger *isp)
{
        int     ret = 0;
        u8      r;

        /* Reset the transceiver */
        r = isp1704_read(isp, ULPI_FUNC_CTRL);
        r |= ULPI_FUNC_CTRL_RESET;
        isp1704_write(isp, ULPI_FUNC_CTRL, r);
        usleep_range(1000, 2000);

        /* Set normal mode */
        r &= ~(ULPI_FUNC_CTRL_RESET | ULPI_FUNC_CTRL_OPMODE_MASK);
        isp1704_write(isp, ULPI_FUNC_CTRL, r);

        /* Clear the DP and DM pull-down bits */
        r = ULPI_OTG_CTRL_DP_PULLDOWN | ULPI_OTG_CTRL_DM_PULLDOWN;
        isp1704_write(isp, ULPI_CLR(ULPI_OTG_CTRL), r);

        /* Enable strong pull-up on DP (1.5K) and reset */
        r = ULPI_FUNC_CTRL_TERMSELECT | ULPI_FUNC_CTRL_RESET;
        isp1704_write(isp, ULPI_SET(ULPI_FUNC_CTRL), r);
        usleep_range(1000, 2000);

        /* Read the line state */
        if (!isp1704_read(isp, ULPI_DEBUG)) {
                /* Disable strong pull-up on DP (1.5K) */
                isp1704_write(isp, ULPI_CLR(ULPI_FUNC_CTRL),
                                ULPI_FUNC_CTRL_TERMSELECT);
                return 1;
        }

        /* Is it a charger or PS/2 connection */

        /* Enable weak pull-up resistor on DP */
        isp1704_write(isp, ULPI_SET(ISP1704_PWR_CTRL),
                        ISP1704_PWR_CTRL_DP_WKPU_EN);

        /* Disable strong pull-up on DP (1.5K) */
        isp1704_write(isp, ULPI_CLR(ULPI_FUNC_CTRL),
                        ULPI_FUNC_CTRL_TERMSELECT);

        /* Enable weak pull-down resistor on DM */
        isp1704_write(isp, ULPI_SET(ULPI_OTG_CTRL),
                        ULPI_OTG_CTRL_DM_PULLDOWN);

        /* It's a charger if the line states are clear */
        if (!(isp1704_read(isp, ULPI_DEBUG)))
                ret = 1;

        /* Disable weak pull-up resistor on DP */
        isp1704_write(isp, ULPI_CLR(ISP1704_PWR_CTRL),
                        ISP1704_PWR_CTRL_DP_WKPU_EN);

        return ret;
}

static inline int isp1704_charger_detect(struct isp1704_charger *isp)
{
        unsigned long   timeout;
        u8              pwr_ctrl;
        int             ret = 0;

        pwr_ctrl = isp1704_read(isp, ISP1704_PWR_CTRL);

        /* set SW control bit in PWR_CTRL register */
        isp1704_write(isp, ISP1704_PWR_CTRL,
                        ISP1704_PWR_CTRL_SWCTRL);

        /* enable manual charger detection */
        isp1704_write(isp, ULPI_SET(ISP1704_PWR_CTRL),
                        ISP1704_PWR_CTRL_SWCTRL
                        | ISP1704_PWR_CTRL_DPVSRC_EN);
        usleep_range(1000, 2000);

        timeout = jiffies + msecs_to_jiffies(300);
        do {
                /* Check if there is a charger */
                if (isp1704_read(isp, ISP1704_PWR_CTRL)
                                & ISP1704_PWR_CTRL_VDAT_DET) {
                        ret = isp1704_charger_verify(isp);
                        break;
                }
        } while (!time_after(jiffies, timeout) && isp->online);

        /* recover original state */
        isp1704_write(isp, ISP1704_PWR_CTRL, pwr_ctrl);

        return ret;
}

static inline int isp1704_charger_detect_dcp(struct isp1704_charger *isp)
{
        if (isp1704_charger_detect(isp) &&
                        isp1704_charger_type(isp) == POWER_SUPPLY_TYPE_USB_DCP)
                return true;
        else
                return false;
}

static void isp1704_charger_work(struct work_struct *data)
{
        struct isp1704_charger  *isp =
                container_of(data, struct isp1704_charger, work);
        static DEFINE_MUTEX(lock);

        mutex_lock(&lock);

        switch (isp->phy->last_event) {
        case USB_EVENT_VBUS:
                /* do not call wall charger detection more times */
                if (!isp->present) {
                        isp->online = true;
                        isp->present = 1;
                        isp1704_charger_set_power(isp, 1);

                        /* detect wall charger */
                        if (isp1704_charger_detect_dcp(isp)) {
                                isp->psy_desc.type = POWER_SUPPLY_TYPE_USB_DCP;
                                isp->current_max = 1800;
                        } else {
                                isp->psy_desc.type = POWER_SUPPLY_TYPE_USB;
                                isp->current_max = 500;
                        }

                        /* enable data pullups */
                        if (isp->phy->otg->gadget)
                                usb_gadget_connect(isp->phy->otg->gadget);
                }

                if (isp->psy_desc.type != POWER_SUPPLY_TYPE_USB_DCP) {
                        /*
                         * Only 500mA here or high speed chirp
                         * handshaking may break
                         */
                        if (isp->current_max > 500)
                                isp->current_max = 500;

                        if (isp->current_max > 100)
                                isp->psy_desc.type = POWER_SUPPLY_TYPE_USB_CDP;
                }
                break;
        case USB_EVENT_NONE:
                isp->online = false;
                isp->present = 0;
                isp->current_max = 0;
                isp->psy_desc.type = POWER_SUPPLY_TYPE_USB;

                /*
                 * Disable data pullups. We need to prevent the controller from
                 * enumerating.
                 *
                 * FIXME: This is here to allow charger detection with Host/HUB
                 * chargers. The pullups may be enabled elsewhere, so this can
                 * not be the final solution.
                 */
                if (isp->phy->otg->gadget)
                        usb_gadget_disconnect(isp->phy->otg->gadget);

                isp1704_charger_set_power(isp, 0);
                break;
        default:
                goto out;
        }

        power_supply_changed(isp->psy);
out:
        mutex_unlock(&lock);
}

static int isp1704_notifier_call(struct notifier_block *nb,
                unsigned long val, void *v)
{
        struct isp1704_charger *isp =
                container_of(nb, struct isp1704_charger, nb);

        schedule_work(&isp->work);

        return NOTIFY_OK;
}

static int isp1704_charger_get_property(struct power_supply *psy,
                                enum power_supply_property psp,
                                union power_supply_propval *val)
{
        struct isp1704_charger *isp = power_supply_get_drvdata(psy);

        switch (psp) {
        case POWER_SUPPLY_PROP_PRESENT:
                val->intval = isp->present;
                break;
        case POWER_SUPPLY_PROP_ONLINE:
                val->intval = isp->online;
                break;
        case POWER_SUPPLY_PROP_CURRENT_MAX:
                val->intval = isp->current_max;
                break;
        case POWER_SUPPLY_PROP_MODEL_NAME:
                val->strval = isp->model;
                break;
        case POWER_SUPPLY_PROP_MANUFACTURER:
                val->strval = "NXP";
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

static enum power_supply_property power_props[] = {
        POWER_SUPPLY_PROP_PRESENT,
        POWER_SUPPLY_PROP_ONLINE,
        POWER_SUPPLY_PROP_CURRENT_MAX,
        POWER_SUPPLY_PROP_MODEL_NAME,
        POWER_SUPPLY_PROP_MANUFACTURER,
};

static inline int isp1704_test_ulpi(struct isp1704_charger *isp)
{
        int vendor;
        int product;
        int i;
        int ret;

        /* Test ULPI interface */
        ret = isp1704_write(isp, ULPI_SCRATCH, 0xaa);
        if (ret < 0)
                return ret;

        ret = isp1704_read(isp, ULPI_SCRATCH);
        if (ret < 0)
                return ret;

        if (ret != 0xaa)
                return -ENODEV;

        /* Verify the product and vendor id matches */
        vendor = isp1704_read(isp, ULPI_VENDOR_ID_LOW);
        vendor |= isp1704_read(isp, ULPI_VENDOR_ID_HIGH) << 8;
        if (vendor != NXP_VENDOR_ID)
                return -ENODEV;

        product = isp1704_read(isp, ULPI_PRODUCT_ID_LOW);
        product |= isp1704_read(isp, ULPI_PRODUCT_ID_HIGH) << 8;

        for (i = 0; i < ARRAY_SIZE(isp170x_id); i++) {
                if (product == isp170x_id[i]) {
                        sprintf(isp->model, "isp%x", product);
                        return product;
                }
        }

        dev_err(isp->dev, "product id %x not matching known ids", product);

        return -ENODEV;
}

static int isp1704_charger_probe(struct platform_device *pdev)
{
        struct isp1704_charger  *isp;
        int                     ret = -ENODEV;
        struct power_supply_config psy_cfg = {};

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

        isp->enable_gpio = devm_gpiod_get(&pdev->dev, "nxp,enable",
                                          GPIOD_OUT_HIGH);
        if (IS_ERR(isp->enable_gpio)) {
                ret = PTR_ERR(isp->enable_gpio);
                dev_err(&pdev->dev, "Could not get reset gpio: %d\n", ret);
                return ret;
        }

        if (pdev->dev.of_node)
                isp->phy = devm_usb_get_phy_by_phandle(&pdev->dev, "usb-phy", 0);
        else
                isp->phy = devm_usb_get_phy(&pdev->dev, USB_PHY_TYPE_USB2);

        if (IS_ERR(isp->phy)) {
                ret = PTR_ERR(isp->phy);
                dev_err(&pdev->dev, "usb_get_phy failed\n");
                goto fail0;
        }

        isp->dev = &pdev->dev;
        platform_set_drvdata(pdev, isp);

        isp1704_charger_set_power(isp, 1);

        ret = isp1704_test_ulpi(isp);
        if (ret < 0) {
                dev_err(&pdev->dev, "isp1704_test_ulpi failed\n");
                goto fail1;
        }

        isp->psy_desc.name              = "isp1704";
        isp->psy_desc.type              = POWER_SUPPLY_TYPE_USB;
        isp->psy_desc.properties        = power_props;
        isp->psy_desc.num_properties    = ARRAY_SIZE(power_props);
        isp->psy_desc.get_property      = isp1704_charger_get_property;

        psy_cfg.drv_data                = isp;

        isp->psy = power_supply_register(isp->dev, &isp->psy_desc, &psy_cfg);
        if (IS_ERR(isp->psy)) {
                ret = PTR_ERR(isp->psy);
                dev_err(&pdev->dev, "power_supply_register failed\n");
                goto fail1;
        }

        /*
         * REVISIT: using work in order to allow the usb notifications to be
         * made atomically in the future.
         */
        INIT_WORK(&isp->work, isp1704_charger_work);

        isp->nb.notifier_call = isp1704_notifier_call;

        ret = usb_register_notifier(isp->phy, &isp->nb);
        if (ret) {
                dev_err(&pdev->dev, "usb_register_notifier failed\n");
                goto fail2;
        }

        dev_info(isp->dev, "registered with product id %s\n", isp->model);

        /*
         * Taking over the D+ pullup.
         *
         * FIXME: The device will be disconnected if it was already
         * enumerated. The charger driver should be always loaded before any
         * gadget is loaded.
         */
        if (isp->phy->otg->gadget)
                usb_gadget_disconnect(isp->phy->otg->gadget);

        if (isp->phy->last_event == USB_EVENT_NONE)
                isp1704_charger_set_power(isp, 0);

        /* Detect charger if VBUS is valid (the cable was already plugged). */
        if (isp->phy->last_event == USB_EVENT_VBUS &&
                        !isp->phy->otg->default_a)
                schedule_work(&isp->work);

        return 0;
fail2:
        power_supply_unregister(isp->psy);
fail1:
        isp1704_charger_set_power(isp, 0);
fail0:
        dev_err(&pdev->dev, "failed to register isp1704 with error %d\n", ret);

        return ret;
}

static void isp1704_charger_remove(struct platform_device *pdev)
{
        struct isp1704_charger *isp = platform_get_drvdata(pdev);

        usb_unregister_notifier(isp->phy, &isp->nb);
        power_supply_unregister(isp->psy);
        isp1704_charger_set_power(isp, 0);
}

#ifdef CONFIG_OF
static const struct of_device_id omap_isp1704_of_match[] = {
        { .compatible = "nxp,isp1704", },
        { .compatible = "nxp,isp1707", },
        {},
};
MODULE_DEVICE_TABLE(of, omap_isp1704_of_match);
#endif

static struct platform_driver isp1704_charger_driver = {
        .driver = {
                .name = "isp1704_charger",
                .of_match_table = of_match_ptr(omap_isp1704_of_match),
        },
        .probe = isp1704_charger_probe,
        .remove = isp1704_charger_remove,
};

module_platform_driver(isp1704_charger_driver);

MODULE_ALIAS("platform:isp1704_charger");
MODULE_AUTHOR("Nokia Corporation");
MODULE_DESCRIPTION("ISP170x USB Charger driver");
MODULE_LICENSE("GPL");