drivers/usb/cdns3/core.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Cadence USBSS and USBSSP DRD Driver.
  *
  * Copyright (C) 2018-2019 Cadence.
  * Copyright (C) 2017-2018 NXP
  * Copyright (C) 2019 Texas Instruments
  *
  * Author: Peter Chen <peter.chen@nxp.com>
  *         Pawel Laszczak <pawell@cadence.com>
  *         Roger Quadros <rogerq@ti.com>
  */

 #include <linux/dma-mapping.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/pm_runtime.h>

 #include "core.h"
 #include "host-export.h"
 #include "drd.h"

 static int cdns_idle_init(struct cdns *cdns);

 static int cdns_role_start(struct cdns *cdns, enum usb_role role)
 {
 	int ret;

 	if (WARN_ON(role > USB_ROLE_DEVICE))
 		return 0;

 	mutex_lock(&cdns->mutex);
 	cdns->role = role;
 	mutex_unlock(&cdns->mutex);

 	if (!cdns->roles[role])
 		return -ENXIO;

 	if (cdns->roles[role]->state == CDNS_ROLE_STATE_ACTIVE)
 		return 0;

 	mutex_lock(&cdns->mutex);
 	ret = cdns->roles[role]->start(cdns);
 	if (!ret)
 		cdns->roles[role]->state = CDNS_ROLE_STATE_ACTIVE;
 	mutex_unlock(&cdns->mutex);

 	return ret;
 }

 static void cdns_role_stop(struct cdns *cdns)
 {
 	enum usb_role role = cdns->role;

 	if (WARN_ON(role > USB_ROLE_DEVICE))
 		return;

 	if (cdns->roles[role]->state == CDNS_ROLE_STATE_INACTIVE)
 		return;

 	mutex_lock(&cdns->mutex);
 	cdns->roles[role]->stop(cdns);
 	cdns->roles[role]->state = CDNS_ROLE_STATE_INACTIVE;
 	mutex_unlock(&cdns->mutex);
 }

 static void cdns_exit_roles(struct cdns *cdns)
 {
 	cdns_role_stop(cdns);
 	cdns_drd_exit(cdns);
 }

 /**
  * cdns_core_init_role - initialize role of operation
  * @cdns: Pointer to cdns structure
  *
  * Returns 0 on success otherwise negative errno
  */
 static int cdns_core_init_role(struct cdns *cdns)
 {
 	struct device *dev = cdns->dev;
 	enum usb_dr_mode best_dr_mode;
 	enum usb_dr_mode dr_mode;
 	int ret;

 	dr_mode = usb_get_dr_mode(dev);
 	cdns->role = USB_ROLE_NONE;

 	/*
 	 * If driver can't read mode by means of usb_get_dr_mode function then
 	 * chooses mode according with Kernel configuration. This setting
 	 * can be restricted later depending on strap pin configuration.
 	 */
 	if (dr_mode == USB_DR_MODE_UNKNOWN) {
 		if (cdns->version == CDNSP_CONTROLLER_V2) {
 			if (IS_ENABLED(CONFIG_USB_CDNSP_HOST) &&
 			    IS_ENABLED(CONFIG_USB_CDNSP_GADGET))
 				dr_mode = USB_DR_MODE_OTG;
 			else if (IS_ENABLED(CONFIG_USB_CDNSP_HOST))
 				dr_mode = USB_DR_MODE_HOST;
 			else if (IS_ENABLED(CONFIG_USB_CDNSP_GADGET))
 				dr_mode = USB_DR_MODE_PERIPHERAL;
 		} else {
 			if (IS_ENABLED(CONFIG_USB_CDNS3_HOST) &&
 			    IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
 				dr_mode = USB_DR_MODE_OTG;
 			else if (IS_ENABLED(CONFIG_USB_CDNS3_HOST))
 				dr_mode = USB_DR_MODE_HOST;
 			else if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
 				dr_mode = USB_DR_MODE_PERIPHERAL;
 		}
 	}

 	/*
 	 * At this point cdns->dr_mode contains strap configuration.
 	 * Driver try update this setting considering kernel configuration
 	 */
 	best_dr_mode = cdns->dr_mode;

 	ret = cdns_idle_init(cdns);
 	if (ret)
 		return ret;

 	if (dr_mode == USB_DR_MODE_OTG) {
 		best_dr_mode = cdns->dr_mode;
 	} else if (cdns->dr_mode == USB_DR_MODE_OTG) {
 		best_dr_mode = dr_mode;
 	} else if (cdns->dr_mode != dr_mode) {
 		dev_err(dev, "Incorrect DRD configuration\n");
 		return -EINVAL;
 	}

 	dr_mode = best_dr_mode;

 	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_HOST) {
 		if ((cdns->version == CDNSP_CONTROLLER_V2 &&
 		     IS_ENABLED(CONFIG_USB_CDNSP_HOST)) ||
 		    (cdns->version < CDNSP_CONTROLLER_V2 &&
 		     IS_ENABLED(CONFIG_USB_CDNS3_HOST)))
 			ret = cdns_host_init(cdns);
 		else
 			ret = -ENXIO;

 		if (ret) {
 			dev_err(dev, "Host initialization failed with %d\n",
 				ret);
 			goto err;
 		}
 	}

 	if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_PERIPHERAL) {
 		if (cdns->gadget_init)
 			ret = cdns->gadget_init(cdns);
 		else
 			ret = -ENXIO;

 		if (ret) {
 			dev_err(dev, "Device initialization failed with %d\n",
 				ret);
 			goto err;
 		}
 	}

 	cdns->dr_mode = dr_mode;

 	ret = cdns_drd_update_mode(cdns);
 	if (ret)
 		goto err;

 	/* Initialize idle role to start with */
 	ret = cdns_role_start(cdns, USB_ROLE_NONE);
 	if (ret)
 		goto err;

 	switch (cdns->dr_mode) {
 	case USB_DR_MODE_OTG:
 		ret = cdns_hw_role_switch(cdns);
 		if (ret)
 			goto err;
 		break;
 	case USB_DR_MODE_PERIPHERAL:
 		ret = cdns_role_start(cdns, USB_ROLE_DEVICE);
 		if (ret)
 			goto err;
 		break;
 	case USB_DR_MODE_HOST:
 		ret = cdns_role_start(cdns, USB_ROLE_HOST);
 		if (ret)
 			goto err;
 		break;
 	default:
 		ret = -EINVAL;
 		goto err;
 	}

 	return 0;
 err:
 	cdns_exit_roles(cdns);
 	return ret;
 }

 /**
  * cdns_hw_role_state_machine  - role switch state machine based on hw events.
  * @cdns: Pointer to controller structure.
  *
  * Returns next role to be entered based on hw events.
  */
 static enum usb_role cdns_hw_role_state_machine(struct cdns *cdns)
 {
 	enum usb_role role = USB_ROLE_NONE;
 	int id, vbus;

 	if (cdns->dr_mode != USB_DR_MODE_OTG) {
 		if (cdns_is_host(cdns))
 			role = USB_ROLE_HOST;
 		if (cdns_is_device(cdns))
 			role = USB_ROLE_DEVICE;

 		return role;
 	}

 	id = cdns_get_id(cdns);
 	vbus = cdns_get_vbus(cdns);

 	/*
 	 * Role change state machine
 	 * Inputs: ID, VBUS
 	 * Previous state: cdns->role
 	 * Next state: role
 	 */
 	role = cdns->role;

 	switch (role) {
 	case USB_ROLE_NONE:
 		/*
 		 * Driver treats USB_ROLE_NONE synonymous to IDLE state from
 		 * controller specification.
 		 */
 		if (!id)
 			role = USB_ROLE_HOST;
 		else if (vbus)
 			role = USB_ROLE_DEVICE;
 		break;
 	case USB_ROLE_HOST: /* from HOST, we can only change to NONE */
 		if (id)
 			role = USB_ROLE_NONE;
 		break;
 	case USB_ROLE_DEVICE: /* from GADGET, we can only change to NONE*/
 		if (!vbus)
 			role = USB_ROLE_NONE;
 		break;
 	}

 	dev_dbg(cdns->dev, "role %d -> %d\n", cdns->role, role);

 	return role;
 }

 static int cdns_idle_role_start(struct cdns *cdns)
 {
 	return 0;
 }

 static void cdns_idle_role_stop(struct cdns *cdns)
 {
 	/* Program Lane swap and bring PHY out of RESET */
 	phy_reset(cdns->usb3_phy);
 }

 static int cdns_idle_init(struct cdns *cdns)
 {
 	struct cdns_role_driver *rdrv;

 	rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL);
 	if (!rdrv)
 		return -ENOMEM;

 	rdrv->start = cdns_idle_role_start;
 	rdrv->stop = cdns_idle_role_stop;
 	rdrv->state = CDNS_ROLE_STATE_INACTIVE;
 	rdrv->suspend = NULL;
 	rdrv->resume = NULL;
 	rdrv->name = "idle";

 	cdns->roles[USB_ROLE_NONE] = rdrv;

 	return 0;
 }

 /**
  * cdns_hw_role_switch - switch roles based on HW state
  * @cdns: controller
  */
 int cdns_hw_role_switch(struct cdns *cdns)
 {
 	enum usb_role real_role, current_role;
 	int ret = 0;

 	/* Depends on role switch class */
 	if (cdns->role_sw)
 		return 0;

 	pm_runtime_get_sync(cdns->dev);

 	current_role = cdns->role;
 	real_role = cdns_hw_role_state_machine(cdns);

 	/* Do nothing if nothing changed */
 	if (current_role == real_role)
 		goto exit;

 	cdns_role_stop(cdns);

 	dev_dbg(cdns->dev, "Switching role %d -> %d", current_role, real_role);

 	ret = cdns_role_start(cdns, real_role);
 	if (ret) {
 		/* Back to current role */
 		dev_err(cdns->dev, "set %d has failed, back to %d\n",
 			real_role, current_role);
 		ret = cdns_role_start(cdns, current_role);
 		if (ret)
 			dev_err(cdns->dev, "back to %d failed too\n",
 				current_role);
 	}
 exit:
 	pm_runtime_put_sync(cdns->dev);
 	return ret;
 }

 /**
  * cdns_role_get - get current role of controller.
  *
  * @sw: pointer to USB role switch structure
  *
  * Returns role
  */
 static enum usb_role cdns_role_get(struct usb_role_switch *sw)
 {
 	struct cdns *cdns = usb_role_switch_get_drvdata(sw);

 	return cdns->role;
 }

 /**
  * cdns_role_set - set current role of controller.
  *
  * @sw: pointer to USB role switch structure
  * @role: the previous role
  * Handles below events:
  * - Role switch for dual-role devices
  * - USB_ROLE_GADGET <--> USB_ROLE_NONE for peripheral-only devices
  */
 static int cdns_role_set(struct usb_role_switch *sw, enum usb_role role)
 {
 	struct cdns *cdns = usb_role_switch_get_drvdata(sw);
 	int ret = 0;

 	pm_runtime_get_sync(cdns->dev);

 	if (cdns->role == role)
 		goto pm_put;

 	if (cdns->dr_mode == USB_DR_MODE_HOST) {
 		switch (role) {
 		case USB_ROLE_NONE:
 		case USB_ROLE_HOST:
 			break;
 		default:
 			goto pm_put;
 		}
 	}

 	if (cdns->dr_mode == USB_DR_MODE_PERIPHERAL) {
 		switch (role) {
 		case USB_ROLE_NONE:
 		case USB_ROLE_DEVICE:
 			break;
 		default:
 			goto pm_put;
 		}
 	}

 	cdns_role_stop(cdns);
 	ret = cdns_role_start(cdns, role);
 	if (ret)
 		dev_err(cdns->dev, "set role %d has failed\n", role);

 pm_put:
 	pm_runtime_put_sync(cdns->dev);
 	return ret;
 }


 /**
  * cdns_wakeup_irq - interrupt handler for wakeup events
  * @irq: irq number for cdns3/cdnsp core device
  * @data: structure of cdns
  *
  * Returns IRQ_HANDLED or IRQ_NONE
  */
 static irqreturn_t cdns_wakeup_irq(int irq, void *data)
 {
 	struct cdns *cdns = data;

 	if (cdns->in_lpm) {
 		disable_irq_nosync(irq);
 		cdns->wakeup_pending = true;
 		if ((cdns->role == USB_ROLE_HOST) && cdns->host_dev)
 			pm_request_resume(&cdns->host_dev->dev);

 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 /**
  * cdns_init - probe for cdns3/cdnsp core device
  * @cdns: Pointer to cdns structure.
  *
  * Returns 0 on success otherwise negative errno
  */
 int cdns_init(struct cdns *cdns)
 {
 	struct device *dev = cdns->dev;
 	int ret;

 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
 	if (ret) {
 		dev_err(dev, "error setting dma mask: %d\n", ret);
 		return ret;
 	}

 	mutex_init(&cdns->mutex);

 	if (device_property_read_bool(dev, "usb-role-switch")) {
 		struct usb_role_switch_desc sw_desc = { };

 		sw_desc.set = cdns_role_set;
 		sw_desc.get = cdns_role_get;
 		sw_desc.allow_userspace_control = true;
 		sw_desc.driver_data = cdns;
 		sw_desc.fwnode = dev->fwnode;

 		cdns->role_sw = usb_role_switch_register(dev, &sw_desc);
 		if (IS_ERR(cdns->role_sw)) {
 			dev_warn(dev, "Unable to register Role Switch\n");
 			return PTR_ERR(cdns->role_sw);
 		}
 	}

 	if (cdns->wakeup_irq) {
 		ret = devm_request_irq(cdns->dev, cdns->wakeup_irq,
 						cdns_wakeup_irq,
 						IRQF_SHARED,
 						dev_name(cdns->dev), cdns);

 		if (ret) {
 			dev_err(cdns->dev, "couldn't register wakeup irq handler\n");
 			goto role_switch_unregister;
 		}
 	}

 	ret = cdns_drd_init(cdns);
 	if (ret)
 		goto init_failed;

 	ret = cdns_core_init_role(cdns);
 	if (ret)
 		goto init_failed;

 	spin_lock_init(&cdns->lock);

 	dev_dbg(dev, "Cadence USB3 core: probe succeed\n");

 	return 0;
 init_failed:
 	cdns_drd_exit(cdns);
 role_switch_unregister:
 	if (cdns->role_sw)
 		usb_role_switch_unregister(cdns->role_sw);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(cdns_init);

 /**
  * cdns_remove - unbind drd driver and clean up
  * @cdns: Pointer to cdns structure.
  *
  * Returns 0 on success otherwise negative errno
  */
 int cdns_remove(struct cdns *cdns)
 {
 	cdns_exit_roles(cdns);
 	usb_role_switch_unregister(cdns->role_sw);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(cdns_remove);

 #ifdef CONFIG_PM_SLEEP
 int cdns_suspend(struct cdns *cdns)
 {
 	struct device *dev = cdns->dev;
 	unsigned long flags;

 	if (pm_runtime_status_suspended(dev))
 		pm_runtime_resume(dev);

 	if (cdns->roles[cdns->role]->suspend) {
 		spin_lock_irqsave(&cdns->lock, flags);
 		cdns->roles[cdns->role]->suspend(cdns, false);
 		spin_unlock_irqrestore(&cdns->lock, flags);
 	}

 	return 0;
 }
 EXPORT_SYMBOL_GPL(cdns_suspend);

 int cdns_resume(struct cdns *cdns)
 {
 	enum usb_role real_role;
 	bool role_changed = false;
 	int ret = 0;

 	if (cdns_power_is_lost(cdns)) {
 		if (cdns->role_sw) {
 			cdns->role = cdns_role_get(cdns->role_sw);
 		} else {
 			real_role = cdns_hw_role_state_machine(cdns);
 			if (real_role != cdns->role) {
 				ret = cdns_hw_role_switch(cdns);
 				if (ret)
 					return ret;
 				role_changed = true;
 			}
 		}

 		if (!role_changed) {
 			if (cdns->role == USB_ROLE_HOST)
 				ret = cdns_drd_host_on(cdns);
 			else if (cdns->role == USB_ROLE_DEVICE)
 				ret = cdns_drd_gadget_on(cdns);

 			if (ret)
 				return ret;
 		}
 	}

 	if (cdns->roles[cdns->role]->resume)
 		cdns->roles[cdns->role]->resume(cdns, cdns_power_is_lost(cdns));

 	return 0;
 }
 EXPORT_SYMBOL_GPL(cdns_resume);

 void cdns_set_active(struct cdns *cdns, u8 set_active)
 {
 	struct device *dev = cdns->dev;

 	if (set_active) {
 		pm_runtime_disable(dev);
 		pm_runtime_set_active(dev);
 		pm_runtime_enable(dev);
 	}

 	return;
 }
 EXPORT_SYMBOL_GPL(cdns_set_active);
 #endif /* CONFIG_PM_SLEEP */

 MODULE_AUTHOR("Peter Chen <peter.chen@nxp.com>");
 MODULE_AUTHOR("Pawel Laszczak <pawell@cadence.com>");
 MODULE_AUTHOR("Roger Quadros <rogerq@ti.com>");
 MODULE_DESCRIPTION("Cadence USBSS and USBSSP DRD Driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Cadence USBSS and USBSSP DRD Driver.
	*
	* Copyright (C) 2018-2019 Cadence.
	* Copyright (C) 2017-2018 NXP
	* Copyright (C) 2019 Texas Instruments
	*
	* Author: Peter Chen <peter.chen@nxp.com>
	* Pawel Laszczak <pawell@cadence.com>
	* Roger Quadros <rogerq@ti.com>
	*/

	#include <linux/dma-mapping.h>
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/pm_runtime.h>

	#include "core.h"
	#include "host-export.h"
	#include "drd.h"

	static int cdns_idle_init(struct cdns *cdns);

	static int cdns_role_start(struct cdns *cdns, enum usb_role role)
	{
	int ret;

	if (WARN_ON(role > USB_ROLE_DEVICE))
	return 0;

	mutex_lock(&cdns->mutex);
	cdns->role = role;
	mutex_unlock(&cdns->mutex);

	if (!cdns->roles[role])
	return -ENXIO;

	if (cdns->roles[role]->state == CDNS_ROLE_STATE_ACTIVE)
	return 0;

	mutex_lock(&cdns->mutex);
	ret = cdns->roles[role]->start(cdns);
	if (!ret)
	cdns->roles[role]->state = CDNS_ROLE_STATE_ACTIVE;
	mutex_unlock(&cdns->mutex);

	return ret;
	}

	static void cdns_role_stop(struct cdns *cdns)
	{
	enum usb_role role = cdns->role;

	if (WARN_ON(role > USB_ROLE_DEVICE))
	return;

	if (cdns->roles[role]->state == CDNS_ROLE_STATE_INACTIVE)
	return;

	mutex_lock(&cdns->mutex);
	cdns->roles[role]->stop(cdns);
	cdns->roles[role]->state = CDNS_ROLE_STATE_INACTIVE;
	mutex_unlock(&cdns->mutex);
	}

	static void cdns_exit_roles(struct cdns *cdns)
	{
	cdns_role_stop(cdns);
	cdns_drd_exit(cdns);
	}

	/**
	* cdns_core_init_role - initialize role of operation
	* @cdns: Pointer to cdns structure
	*
	* Returns 0 on success otherwise negative errno
	*/
	static int cdns_core_init_role(struct cdns *cdns)
	{
	struct device *dev = cdns->dev;
	enum usb_dr_mode best_dr_mode;
	enum usb_dr_mode dr_mode;
	int ret;

	dr_mode = usb_get_dr_mode(dev);
	cdns->role = USB_ROLE_NONE;

	/*
	* If driver can't read mode by means of usb_get_dr_mode function then
	* chooses mode according with Kernel configuration. This setting
	* can be restricted later depending on strap pin configuration.
	*/
	if (dr_mode == USB_DR_MODE_UNKNOWN) {
	if (cdns->version == CDNSP_CONTROLLER_V2) {
	if (IS_ENABLED(CONFIG_USB_CDNSP_HOST) &&
	IS_ENABLED(CONFIG_USB_CDNSP_GADGET))
	dr_mode = USB_DR_MODE_OTG;
	else if (IS_ENABLED(CONFIG_USB_CDNSP_HOST))
	dr_mode = USB_DR_MODE_HOST;
	else if (IS_ENABLED(CONFIG_USB_CDNSP_GADGET))
	dr_mode = USB_DR_MODE_PERIPHERAL;
	} else {
	if (IS_ENABLED(CONFIG_USB_CDNS3_HOST) &&
	IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
	dr_mode = USB_DR_MODE_OTG;
	else if (IS_ENABLED(CONFIG_USB_CDNS3_HOST))
	dr_mode = USB_DR_MODE_HOST;
	else if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
	dr_mode = USB_DR_MODE_PERIPHERAL;
	}
	}

	/*
	* At this point cdns->dr_mode contains strap configuration.
	* Driver try update this setting considering kernel configuration
	*/
	best_dr_mode = cdns->dr_mode;

	ret = cdns_idle_init(cdns);
	if (ret)
	return ret;

	if (dr_mode == USB_DR_MODE_OTG) {
	best_dr_mode = cdns->dr_mode;
	} else if (cdns->dr_mode == USB_DR_MODE_OTG) {
	best_dr_mode = dr_mode;
	} else if (cdns->dr_mode != dr_mode) {
	dev_err(dev, "Incorrect DRD configuration\n");
	return -EINVAL;
	}

	dr_mode = best_dr_mode;

	if (dr_mode == USB_DR_MODE_OTG \|\| dr_mode == USB_DR_MODE_HOST) {
	if ((cdns->version == CDNSP_CONTROLLER_V2 &&
	IS_ENABLED(CONFIG_USB_CDNSP_HOST)) \|\|
	(cdns->version < CDNSP_CONTROLLER_V2 &&
	IS_ENABLED(CONFIG_USB_CDNS3_HOST)))
	ret = cdns_host_init(cdns);
	else
	ret = -ENXIO;

	if (ret) {
	dev_err(dev, "Host initialization failed with %d\n",
	ret);
	goto err;
	}
	}

	if (dr_mode == USB_DR_MODE_OTG \|\| dr_mode == USB_DR_MODE_PERIPHERAL) {
	if (cdns->gadget_init)
	ret = cdns->gadget_init(cdns);
	else
	ret = -ENXIO;

	if (ret) {
	dev_err(dev, "Device initialization failed with %d\n",
	ret);
	goto err;
	}
	}

	cdns->dr_mode = dr_mode;

	ret = cdns_drd_update_mode(cdns);
	if (ret)
	goto err;

	/* Initialize idle role to start with */
	ret = cdns_role_start(cdns, USB_ROLE_NONE);
	if (ret)
	goto err;

	switch (cdns->dr_mode) {
	case USB_DR_MODE_OTG:
	ret = cdns_hw_role_switch(cdns);
	if (ret)
	goto err;
	break;
	case USB_DR_MODE_PERIPHERAL:
	ret = cdns_role_start(cdns, USB_ROLE_DEVICE);
	if (ret)
	goto err;
	break;
	case USB_DR_MODE_HOST:
	ret = cdns_role_start(cdns, USB_ROLE_HOST);
	if (ret)
	goto err;
	break;
	default:
	ret = -EINVAL;
	goto err;
	}

	return 0;
	err:
	cdns_exit_roles(cdns);
	return ret;
	}

	/**
	* cdns_hw_role_state_machine - role switch state machine based on hw events.
	* @cdns: Pointer to controller structure.
	*
	* Returns next role to be entered based on hw events.
	*/
	static enum usb_role cdns_hw_role_state_machine(struct cdns *cdns)
	{
	enum usb_role role = USB_ROLE_NONE;
	int id, vbus;

	if (cdns->dr_mode != USB_DR_MODE_OTG) {
	if (cdns_is_host(cdns))
	role = USB_ROLE_HOST;
	if (cdns_is_device(cdns))
	role = USB_ROLE_DEVICE;

	return role;
	}

	id = cdns_get_id(cdns);
	vbus = cdns_get_vbus(cdns);

	/*
	* Role change state machine
	* Inputs: ID, VBUS
	* Previous state: cdns->role
	* Next state: role
	*/
	role = cdns->role;

	switch (role) {
	case USB_ROLE_NONE:
	/*
	* Driver treats USB_ROLE_NONE synonymous to IDLE state from
	* controller specification.
	*/
	if (!id)
	role = USB_ROLE_HOST;
	else if (vbus)
	role = USB_ROLE_DEVICE;
	break;
	case USB_ROLE_HOST: /* from HOST, we can only change to NONE */
	if (id)
	role = USB_ROLE_NONE;
	break;
	case USB_ROLE_DEVICE: /* from GADGET, we can only change to NONE*/
	if (!vbus)
	role = USB_ROLE_NONE;
	break;
	}

	dev_dbg(cdns->dev, "role %d -> %d\n", cdns->role, role);

	return role;
	}

	static int cdns_idle_role_start(struct cdns *cdns)
	{
	return 0;
	}

	static void cdns_idle_role_stop(struct cdns *cdns)
	{
	/* Program Lane swap and bring PHY out of RESET */
	phy_reset(cdns->usb3_phy);
	}

	static int cdns_idle_init(struct cdns *cdns)
	{
	struct cdns_role_driver *rdrv;

	rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL);
	if (!rdrv)
	return -ENOMEM;

	rdrv->start = cdns_idle_role_start;
	rdrv->stop = cdns_idle_role_stop;
	rdrv->state = CDNS_ROLE_STATE_INACTIVE;
	rdrv->suspend = NULL;
	rdrv->resume = NULL;
	rdrv->name = "idle";

	cdns->roles[USB_ROLE_NONE] = rdrv;

	return 0;
	}

	/**
	* cdns_hw_role_switch - switch roles based on HW state
	* @cdns: controller
	*/
	int cdns_hw_role_switch(struct cdns *cdns)
	{
	enum usb_role real_role, current_role;
	int ret = 0;

	/* Depends on role switch class */
	if (cdns->role_sw)
	return 0;

	pm_runtime_get_sync(cdns->dev);

	current_role = cdns->role;
	real_role = cdns_hw_role_state_machine(cdns);

	/* Do nothing if nothing changed */
	if (current_role == real_role)
	goto exit;

	cdns_role_stop(cdns);

	dev_dbg(cdns->dev, "Switching role %d -> %d", current_role, real_role);

	ret = cdns_role_start(cdns, real_role);
	if (ret) {
	/* Back to current role */
	dev_err(cdns->dev, "set %d has failed, back to %d\n",
	real_role, current_role);
	ret = cdns_role_start(cdns, current_role);
	if (ret)
	dev_err(cdns->dev, "back to %d failed too\n",
	current_role);
	}
	exit:
	pm_runtime_put_sync(cdns->dev);
	return ret;
	}

	/**
	* cdns_role_get - get current role of controller.
	*
	* @sw: pointer to USB role switch structure
	*
	* Returns role
	*/
	static enum usb_role cdns_role_get(struct usb_role_switch *sw)
	{
	struct cdns *cdns = usb_role_switch_get_drvdata(sw);

	return cdns->role;
	}

	/**
	* cdns_role_set - set current role of controller.
	*
	* @sw: pointer to USB role switch structure
	* @role: the previous role
	* Handles below events:
	* - Role switch for dual-role devices
	* - USB_ROLE_GADGET <--> USB_ROLE_NONE for peripheral-only devices
	*/
	static int cdns_role_set(struct usb_role_switch *sw, enum usb_role role)
	{
	struct cdns *cdns = usb_role_switch_get_drvdata(sw);
	int ret = 0;

	pm_runtime_get_sync(cdns->dev);

	if (cdns->role == role)
	goto pm_put;

	if (cdns->dr_mode == USB_DR_MODE_HOST) {
	switch (role) {
	case USB_ROLE_NONE:
	case USB_ROLE_HOST:
	break;
	default:
	goto pm_put;
	}
	}

	if (cdns->dr_mode == USB_DR_MODE_PERIPHERAL) {
	switch (role) {
	case USB_ROLE_NONE:
	case USB_ROLE_DEVICE:
	break;
	default:
	goto pm_put;
	}
	}

	cdns_role_stop(cdns);
	ret = cdns_role_start(cdns, role);
	if (ret)
	dev_err(cdns->dev, "set role %d has failed\n", role);

	pm_put:
	pm_runtime_put_sync(cdns->dev);
	return ret;
	}


	/**
	* cdns_wakeup_irq - interrupt handler for wakeup events
	* @irq: irq number for cdns3/cdnsp core device
	* @data: structure of cdns
	*
	* Returns IRQ_HANDLED or IRQ_NONE
	*/
	static irqreturn_t cdns_wakeup_irq(int irq, void *data)
	{
	struct cdns *cdns = data;

	if (cdns->in_lpm) {
	disable_irq_nosync(irq);
	cdns->wakeup_pending = true;
	if ((cdns->role == USB_ROLE_HOST) && cdns->host_dev)
	pm_request_resume(&cdns->host_dev->dev);

	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	/**
	* cdns_init - probe for cdns3/cdnsp core device
	* @cdns: Pointer to cdns structure.
	*
	* Returns 0 on success otherwise negative errno
	*/
	int cdns_init(struct cdns *cdns)
	{
	struct device *dev = cdns->dev;
	int ret;

	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
	if (ret) {
	dev_err(dev, "error setting dma mask: %d\n", ret);
	return ret;
	}

	mutex_init(&cdns->mutex);

	if (device_property_read_bool(dev, "usb-role-switch")) {
	struct usb_role_switch_desc sw_desc = { };

	sw_desc.set = cdns_role_set;
	sw_desc.get = cdns_role_get;
	sw_desc.allow_userspace_control = true;
	sw_desc.driver_data = cdns;
	sw_desc.fwnode = dev->fwnode;

	cdns->role_sw = usb_role_switch_register(dev, &sw_desc);
	if (IS_ERR(cdns->role_sw)) {
	dev_warn(dev, "Unable to register Role Switch\n");
	return PTR_ERR(cdns->role_sw);
	}
	}

	if (cdns->wakeup_irq) {
	ret = devm_request_irq(cdns->dev, cdns->wakeup_irq,
	cdns_wakeup_irq,
	IRQF_SHARED,
	dev_name(cdns->dev), cdns);

	if (ret) {
	dev_err(cdns->dev, "couldn't register wakeup irq handler\n");
	goto role_switch_unregister;
	}
	}

	ret = cdns_drd_init(cdns);
	if (ret)
	goto init_failed;

	ret = cdns_core_init_role(cdns);
	if (ret)
	goto init_failed;

	spin_lock_init(&cdns->lock);

	dev_dbg(dev, "Cadence USB3 core: probe succeed\n");

	return 0;
	init_failed:
	cdns_drd_exit(cdns);
	role_switch_unregister:
	if (cdns->role_sw)
	usb_role_switch_unregister(cdns->role_sw);

	return ret;
	}
	EXPORT_SYMBOL_GPL(cdns_init);

	/**
	* cdns_remove - unbind drd driver and clean up
	* @cdns: Pointer to cdns structure.
	*
	* Returns 0 on success otherwise negative errno
	*/
	int cdns_remove(struct cdns *cdns)
	{
	cdns_exit_roles(cdns);
	usb_role_switch_unregister(cdns->role_sw);

	return 0;
	}
	EXPORT_SYMBOL_GPL(cdns_remove);

	#ifdef CONFIG_PM_SLEEP
	int cdns_suspend(struct cdns *cdns)
	{
	struct device *dev = cdns->dev;
	unsigned long flags;

	if (pm_runtime_status_suspended(dev))
	pm_runtime_resume(dev);

	if (cdns->roles[cdns->role]->suspend) {
	spin_lock_irqsave(&cdns->lock, flags);
	cdns->roles[cdns->role]->suspend(cdns, false);
	spin_unlock_irqrestore(&cdns->lock, flags);
	}

	return 0;
	}
	EXPORT_SYMBOL_GPL(cdns_suspend);

	int cdns_resume(struct cdns *cdns)
	{
	enum usb_role real_role;
	bool role_changed = false;
	int ret = 0;

	if (cdns_power_is_lost(cdns)) {
	if (cdns->role_sw) {
	cdns->role = cdns_role_get(cdns->role_sw);
	} else {
	real_role = cdns_hw_role_state_machine(cdns);
	if (real_role != cdns->role) {
	ret = cdns_hw_role_switch(cdns);
	if (ret)
	return ret;
	role_changed = true;
	}
	}

	if (!role_changed) {
	if (cdns->role == USB_ROLE_HOST)
	ret = cdns_drd_host_on(cdns);
	else if (cdns->role == USB_ROLE_DEVICE)
	ret = cdns_drd_gadget_on(cdns);

	if (ret)
	return ret;
	}
	}

	if (cdns->roles[cdns->role]->resume)
	cdns->roles[cdns->role]->resume(cdns, cdns_power_is_lost(cdns));

	return 0;
	}
	EXPORT_SYMBOL_GPL(cdns_resume);

	void cdns_set_active(struct cdns *cdns, u8 set_active)
	{
	struct device *dev = cdns->dev;

	if (set_active) {
	pm_runtime_disable(dev);
	pm_runtime_set_active(dev);
	pm_runtime_enable(dev);
	}

	return;
	}
	EXPORT_SYMBOL_GPL(cdns_set_active);
	#endif /* CONFIG_PM_SLEEP */

	MODULE_AUTHOR("Peter Chen <peter.chen@nxp.com>");
	MODULE_AUTHOR("Pawel Laszczak <pawell@cadence.com>");
	MODULE_AUTHOR("Roger Quadros <rogerq@ti.com>");
	MODULE_DESCRIPTION("Cadence USBSS and USBSSP DRD Driver");
	MODULE_LICENSE("GPL");