drivers/power/supply/isp1704_charger.c - linux - Git at Google

 // 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_new = 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");
	// 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_new = 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");