Re: [PATCH v7 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
new file mode 100644
index 000000000000..daf146efbb35
--- /dev/null
+++ b/drivers/usb/cdns3/core.c

@@ -0,0 +1,529 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cadence USBSS 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/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+
+#include "gadget.h"
+#include "core.h"
+#include "host-export.h"
+#include "gadget-export.h"
+#include "drd.h"
+#include "debug.h"
+
+/**
+ * cdns3_handshake - spin reading  until handshake completes or fails
+ * @ptr: address of device controller register to be read
+ * @mask: bits to look at in result of read
+ * @done: value of those bits when handshake succeeds
+ * @usec: timeout in microseconds
+ *
+ * Returns negative errno, or zero on success
+ *
+ * Success happens when the "mask" bits have the specified value (hardware
+ * handshake done). There are two failure modes: "usec" have passed (major
+ * hardware flakeout), or the register reads as all-ones (hardware removed).
+ */
+int cdns3_handshake(void __iomem *ptr, u32 mask, u32 done, int usec)
+{
+	u32 result;
+
+	do {
+		result = readl(ptr);
+		if (result == ~(u32)0)  /* card removed */
+			return -ENODEV;
+
+		result &= mask;
+		if (result == done)
+			return 0;
+
+		udelay(1);
+		usec--;
+	} while (usec > 0);
+
+	return -ETIMEDOUT;
+}
+
+static inline
+struct cdns3_role_driver *cdns3_get_current_role_driver(struct cdns3 *cdns)
+{
+	WARN_ON(cdns->role >= CDNS3_ROLE_END || !cdns->roles[cdns->role]);
+	return cdns->roles[cdns->role];
+}
+
+static int cdns3_role_start(struct cdns3 *cdns, enum cdns3_roles role)
+{
+	int ret;
+
+	if (WARN_ON(role >= CDNS3_ROLE_END))
+		return 0;
+
+	if (!cdns->roles[role])
+		return -ENXIO;
+
+	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_ACTIVE)
+		return 0;
+
+	mutex_lock(&cdns->mutex);
+	cdns->role = role;
+	ret = cdns->roles[role]->start(cdns);
+	if (!ret)
+		cdns->roles[role]->state = CDNS3_ROLE_STATE_ACTIVE;
+	mutex_unlock(&cdns->mutex);
+	return ret;
+}
+
+void cdns3_role_stop(struct cdns3 *cdns)
+{
+	enum cdns3_roles role = cdns->role;
+
+	if (role >= CDNS3_ROLE_END) {
+		WARN_ON(role > CDNS3_ROLE_END);
+		return;
+	}
+
+	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_INACTIVE)
+		return;
+
+	mutex_lock(&cdns->mutex);
+	cdns->roles[role]->stop(cdns);
+	cdns->roles[role]->state = CDNS3_ROLE_STATE_INACTIVE;
+	mutex_unlock(&cdns->mutex);
+}
+
+static void cdns3_exit_roles(struct cdns3 *cdns)
+{
+	cdns3_role_stop(cdns);
+	cdns3_drd_exit(cdns);
+}
+
+enum cdns3_roles cdsn3_get_real_role(struct cdns3 *cdns);
+
+static int cdns3_idle_role_start(struct cdns3 *cnds)
+{	/* Hold PHY in RESET */
+	return 0;
+}
+
+static void cdns3_idle_role_stop(struct cdns3 *cnds)
+{
+	/* Program Lane swap and bring PHY out of RESET */
+}
+
+static int cdns3_idle_init(struct cdns3 *cdns)
+{
+	struct cdns3_role_driver *rdrv;
+
+	rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL);
+	if (!rdrv)
+		return -ENOMEM;
+
+	rdrv->start = cdns3_idle_role_start;
+	rdrv->stop = cdns3_idle_role_stop;
+	rdrv->state = CDNS3_ROLE_STATE_INACTIVE;
+	rdrv->suspend = NULL;
+	rdrv->resume = NULL;
+	rdrv->name = "idle";
+
+	cdns->roles[CDNS3_ROLE_IDLE] = rdrv;
+
+	return 0;
+}
+
+/**
+ * cdns3_core_init_role - initialize role of operation
+ * @cdns: Pointer to cdns3 structure
+ *
+ * Returns 0 on success otherwise negative errno
+ */
+static int cdns3_core_init_role(struct cdns3 *cdns)
+{
+	struct device *dev = cdns->dev;
+	enum usb_dr_mode best_dr_mode;
+	enum usb_dr_mode dr_mode;
+	int ret = 0;
+
+	dr_mode = usb_get_dr_mode(dev);
+	cdns->role = CDNS3_ROLE_END;
+
+	/*
+	 * 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 (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 = cdns3_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) {
+		ret = cdns3_host_init(cdns);
+		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) {
+		ret = cdns3_gadget_init(cdns);
+		if (ret) {
+			dev_err(dev, "Device initialization failed with %d\n",
+				ret);
+			goto err;
+		}
+	}
+
+	cdns->desired_dr_mode = dr_mode;
+	cdns->dr_mode = dr_mode;
+
+	/*
+	 * desired_dr_mode might have changed so we need to update
+	 * the controller configuration"?
+	 */
+	ret = cdns3_drd_update_mode(cdns);
+	if (ret)
+		goto err;
+
+	cdns->role = cdsn3_get_real_role(cdns);
+
+	ret = cdns3_role_start(cdns, cdns->role);
+	if (ret) {
+		dev_err(dev, "can't start %s role\n",
+			cdns3_get_current_role_driver(cdns)->name);
+		goto err;
+	}
+
+	return ret;
+err:
+	cdns3_exit_roles(cdns);
+	return ret;
+}
+
+/**
+ * cdsn3_get_real_role - get real role of controller based on hardware settings.
+ * @cdns: Pointer to cdns3 structure
+ *
+ * Returns role
+ */
+enum cdns3_roles cdsn3_get_real_role(struct cdns3 *cdns)
+{
+	enum cdns3_roles role;
+	int id, vbus;
+
+	if (cdns->current_dr_mode != USB_DR_MODE_OTG)
+		goto not_otg;
+
+	id = cdns3_get_id(cdns);
+	vbus = cdns3_get_vbus(cdns);
+
+	/*
+	 * Role change state machine
+	 * Inputs: ID, VBUS
+	 * Previous state: cdns->role
+	 * Next state: role
+	 */
+	role = cdns->role;
+
+	switch (role) {
+	case CDNS3_ROLE_IDLE: /* from IDLE, we can change to HOST or GADGET */
+		if (!id)
+			role = CDNS3_ROLE_HOST;
+		else if (vbus)
+			role = CDNS3_ROLE_GADGET;
+		break;
+	case CDNS3_ROLE_HOST: /* from HOST, we can only change to IDLE */
+		if (id)
+			role = CDNS3_ROLE_IDLE;
+		break;
+	case CDNS3_ROLE_GADGET: /* from GADGET, we can only change to IDLE */
+		if (!vbus)
+			role = CDNS3_ROLE_IDLE;
+		break;
+	case CDNS3_ROLE_END: /* only at initialization, move to IDLE */
+		role = CDNS3_ROLE_IDLE;
+		break;
+	}
+
+	dev_info(cdns->dev, "role %d -> %d\n", cdns->role, role);

+	if (ret) {
+		dev_err(dev, "error setting dma mask: %d\n", ret);
+		return -ENODEV;
+	}
+
+	cdns = devm_kzalloc(dev, sizeof(*cdns), GFP_KERNEL);
+	if (!cdns)
+		return -ENOMEM;
+
+	cdns->dev = dev;
+
+	platform_set_drvdata(pdev, cdns);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_IRQ, "host");
+	if (!res) {
+		dev_err(dev, "missing host IRQ\n");
+		return -ENODEV;
+	}
+
+	cdns->xhci_res[0] = *res;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "xhci");
+	if (!res) {
+		dev_err(dev, "couldn't get xhci resource\n");
+		return -ENXIO;
+	}
+
+	cdns->xhci_res[1] = *res;
+
+	cdns->dev_irq = platform_get_irq_byname(pdev, "peripheral");
+	if (cdns->dev_irq == -EPROBE_DEFER)
+		return cdns->dev_irq;
+
+	if (cdns->dev_irq < 0)
+		dev_err(dev, "couldn't get peripheral irq\n");
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dev");
+	regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(regs)) {
+		dev_err(dev, "couldn't iomap dev resource\n");
+		return PTR_ERR(regs);
+	}
+	cdns->dev_regs	= regs;
+
+	cdns->otg_irq = platform_get_irq_byname(pdev, "otg");
+	if (cdns->otg_irq == -EPROBE_DEFER)
+		return cdns->otg_irq;
+
+	if (cdns->otg_irq < 0) {
+		dev_err(dev, "couldn't get otg irq\n");
+		return cdns->otg_irq;
+	}
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "otg");
+	if (!res) {
+		dev_err(dev, "couldn't get otg resource\n");
+		return -ENXIO;
+	}
+
+	cdns->otg_res = *res;
+
+	mutex_init(&cdns->mutex);
+
+	cdns->phy = devm_phy_optional_get(dev, "cdns3,usbphy");
+	if (IS_ERR(cdns->phy))
+		return PTR_ERR(cdns->phy);
+
+	phy_init(cdns->phy);
+	ret = phy_init(cdns->phy);
+	if (ret) {
+		dev_err(dev, "phy_init error\n");
+		return ret;
+	}
+
+	ret = phy_power_on(cdns->phy);
+	if (ret) {
+		dev_err(dev, "phy_power_on error\n");
+		phy_exit(cdns->phy);
+		return ret;
+	}
+
+	INIT_WORK(&cdns->role_switch_wq, cdns3_role_switch);
+
+	ret = cdns3_drd_init(cdns);
+	if (ret)
+		goto err;
+
+	ret = cdns3_core_init_role(cdns);
+	if (ret)
+		goto err;
+
+	cdns3_debugfs_init(cdns);
+	device_set_wakeup_capable(dev, true);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
+	/*
+	 * The controller needs less time between bus and controller suspend,
+	 * and we also needs a small delay to avoid frequently entering low
+	 * power mode.
+	 */
+	pm_runtime_set_autosuspend_delay(dev, 20);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_use_autosuspend(dev);
+	dev_dbg(dev, "Cadence USB3 core: probe succeed\n");
+
+	return 0;
+
+err:
+	phy_power_off(cdns->phy);
+	phy_exit(cdns->phy);
+	return ret;
+}
+
+/**
+ * cdns3_remove - unbind drd driver and clean up
+ * @pdev: Pointer to Linux platform device
+ *
+ * Returns 0 on success otherwise negative errno
+ */
+static int cdns3_remove(struct platform_device *pdev)
+{
+	struct cdns3 *cdns = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+	cdns3_debugfs_exit(cdns);
+	cdns3_exit_roles(cdns);
+	phy_power_off(cdns->phy);
+	phy_exit(cdns->phy);
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id of_cdns3_match[] = {
+	{ .compatible = "cdns,usb3-1.0.0" },
+	{ .compatible = "cdns,usb3-1.0.1" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, of_cdns3_match);
+#endif
+
+static struct platform_driver cdns3_driver = {
+	.probe		= cdns3_probe,
+	.remove		= cdns3_remove,
+	.driver		= {
+		.name	= "cdns-usb3",
+		.of_match_table	= of_match_ptr(of_cdns3_match),
+	},
+};
+
+module_platform_driver(cdns3_driver);
+
+MODULE_ALIAS("platform:cdns3");
+MODULE_AUTHOR("Pawel Laszczak [off-list ref]");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Cadence USB3 DRD Controller Driver");

diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
new file mode 100644
index 000000000000..83fc5f6f60c5
--- /dev/null
+++ b/drivers/usb/cdns3/core.h

@@ -0,0 +1,121 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Cadence USBSS DRD Header File.
+ *
+ * Copyright (C) 2017-2018 NXP
+ * Copyright (C) 2018-2019 Cadence.
+ *
+ * Authors: Peter Chen <peter.chen@nxp.com>
+ *          Pawel Laszczak <pawell@cadence.com>
+ */
+#include <linux/usb/otg.h>
+
+#ifndef __LINUX_CDNS3_CORE_H
+#define __LINUX_CDNS3_CORE_H
+
+struct cdns3;
+enum cdns3_roles {
+	CDNS3_ROLE_IDLE = 0,
+	CDNS3_ROLE_HOST,
+	CDNS3_ROLE_GADGET,
+	CDNS3_ROLE_END,
+};
+
+/**
+ * struct cdns3_role_driver - host/gadget role driver
+ * @start: start this role
+ * @stop: stop this role
+ * @suspend: suspend callback for this role
+ * @resume: resume callback for this role
+ * @irq: irq handler for this role
+ * @name: role name string (host/gadget)
+ * @state: current state
+ */
+struct cdns3_role_driver {
+	int (*start)(struct cdns3 *cdns);
+	void (*stop)(struct cdns3 *cdns);
+	int (*suspend)(struct cdns3 *cdns, bool do_wakeup);
+	int (*resume)(struct cdns3 *cdns, bool hibernated);
+	const char *name;
+#define CDNS3_ROLE_STATE_INACTIVE	0
+#define CDNS3_ROLE_STATE_ACTIVE		1
+	int state;
+};
+
+#define CDNS3_XHCI_RESOURCES_NUM	2
+/**
+ * struct cdns3 - Representation of Cadence USB3 DRD controller.
+ * @dev: pointer to Cadence device struct
+ * @xhci_regs: pointer to base of xhci registers
+ * @xhci_res: the resource for xhci
+ * @dev_regs: pointer to base of dev registers
+ * @otg_res: the resource for otg
+ * @otg_v0_regs: pointer to base of v0 otg registers
+ * @otg_v1_regs: pointer to base of v1 otg registers
+ * @otg_regs: pointer to base of otg registers
+ * @otg_irq: irq number for otg controller
+ * @dev_irq: irq number for device controller
+ * @roles: array of supported roles for this controller
+ * @role: current role
+ * @host_dev: the child host device pointer for cdns3 core
+ * @gadget_dev: the child gadget device pointer for cdns3 core
+ * @usb: phy for this controller
+ * @role_switch_wq: work queue item for role switch
+ * @in_lpm: the controller in low power mode
+ * @wakeup_int: the wakeup interrupt
+ * @mutex: the mutex for concurrent code at driver
+ * @dr_mode: supported mode of operation it can be only Host, only Device
+ *           or OTG mode that allow to switch between Device and Host mode.
+ *           This field based on firmware setting, kernel configuration
+ *           and hardware configuration.
+ * @current_dr_mode: current mode of operation when in dual-role mode
+ * @desired_dr_mode: desired mode of operation when in dual-role mode.
+ *           This value can be changed during runtime.
+ *           Available options depends on  dr_mode:
+ *           dr_mode                 |  desired_dr_mode and current_dr_mode
+ *           ----------------------------------------------------------------
+ *           USB_DR_MODE_HOST        | only USB_DR_MODE_HOST
+ *           USB_DR_MODE_PERIPHERAL  | only USB_DR_MODE_PERIPHERAL
+ *           USB_DR_MODE_OTG         | USB_DR_MODE_OTG or USB_DR_MODE_HOST or
+ *                                   | USB_DR_MODE_PERIPHERAL
+ *           Desired_dr_role can be changed by means of debugfs.
+ * @root: debugfs root folder pointer
+ * @debug_disable:
+ */
+struct cdns3 {
+	struct device			*dev;
+	void __iomem			*xhci_regs;
+	struct resource			xhci_res[CDNS3_XHCI_RESOURCES_NUM];
+	struct cdns3_usb_regs __iomem	*dev_regs;
+
+	struct resource			otg_res;
+	struct cdns3_otg_legacy_regs	*otg_v0_regs;
+	struct cdns3_otg_regs		*otg_v1_regs;
+	struct cdns3_otg_common_regs	*otg_regs;
+#define CDNS3_CONTROLLER_V0	0
+#define CDNS3_CONTROLLER_V1	1
+	u32				version;
+
+	int				otg_irq;
+	int				dev_irq;
+	struct cdns3_role_driver	*roles[CDNS3_ROLE_END];
+	enum cdns3_roles		role;
+	struct platform_device		*host_dev;
+	struct cdns3_device		*gadget_dev;
+	struct phy			*phy;
+	struct work_struct		role_switch_wq;
+	int				in_lpm:1;
+	int				wakeup_int:1;
+	/* mutext used in workqueue*/
+	struct mutex			mutex;
+	enum usb_dr_mode		dr_mode;
+	enum usb_dr_mode		current_dr_mode;
+	enum usb_dr_mode		desired_dr_mode;
+	struct dentry			*root;
+	int				debug_disable:1;
+};
+
+void cdns3_role_stop(struct cdns3 *cdns);
+int cdns3_handshake(void __iomem *ptr, u32 mask, u32 done, int usec);
+
+#endif /* __LINUX_CDNS3_CORE_H */

diff --git a/drivers/usb/cdns3/debug.h b/drivers/usb/cdns3/debug.h
new file mode 100644
index 000000000000..65c3d8a6cd62
--- /dev/null
+++ b/drivers/usb/cdns3/debug.h

@@ -0,0 +1,173 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Cadence USBSS DRD Driver.
+ * Debug header file.
+ *
+ * Copyright (C) 2018-2019 Cadence.
+ *
+ * Author: Pawel Laszczak <pawell@cadence.com>
+ */
+#ifndef __LINUX_CDNS3_DEBUG
+#define __LINUX_CDNS3_DEBUG
+
+#include "core.h"
+
+static inline char *cdns3_decode_usb_irq(char *str,
+					 enum usb_device_speed speed,
+					 u32 usb_ists)
+{
+	int ret;
+
+	ret = sprintf(str, "IRQ %08x = ", usb_ists);
+
+	if (usb_ists & (USB_ISTS_CON2I | USB_ISTS_CONI)) {
+		ret += sprintf(str + ret, "Connection %s\n",
+			       usb_speed_string(speed));
+	}
+	if (usb_ists & USB_ISTS_DIS2I || usb_ists & USB_ISTS_DISI)
+		ret += sprintf(str + ret, "Disconnection ");
+	if (usb_ists & USB_ISTS_L2ENTI)
+		ret += sprintf(str + ret, "suspended ");
+	if (usb_ists & USB_ISTS_L1ENTI)
+		ret += sprintf(str + ret, "L1 enter ");
+	if (usb_ists & USB_ISTS_L1EXTI)
+		ret += sprintf(str + ret, "L1 exit ");
+	if (usb_ists & USB_ISTS_L2ENTI)
+		ret += sprintf(str + ret, "L2 enter ");
+	if (usb_ists & USB_ISTS_L2EXTI)
+		ret += sprintf(str + ret, "L2 exit ");
+	if (usb_ists & USB_ISTS_U3EXTI)
+		ret += sprintf(str + ret, "U3 exit ");
+	if (usb_ists & USB_ISTS_UWRESI)
+		ret += sprintf(str + ret, "Warm Reset ");
+	if (usb_ists & USB_ISTS_UHRESI)
+		ret += sprintf(str + ret, "Hot Reset ");
+	if (usb_ists & USB_ISTS_U2RESI)
+		ret += sprintf(str + ret, "Reset");
+
+	return str;
+}
+
+static inline  char *cdns3_decode_ep_irq(char *str,
+					 u32 ep_sts,
+					 const char *ep_name)
+{
+	int ret;
+
+	ret = sprintf(str, "IRQ for %s: %08x ", ep_name, ep_sts);
+
+	if (ep_sts & EP_STS_SETUP)
+		ret += sprintf(str + ret, "SETUP ");
+	if (ep_sts & EP_STS_IOC)
+		ret += sprintf(str + ret, "IOC ");
+	if (ep_sts & EP_STS_ISP)
+		ret += sprintf(str + ret, "ISP ");
+	if (ep_sts & EP_STS_DESCMIS)
+		ret += sprintf(str + ret, "DESCMIS ");
+	if (ep_sts & EP_STS_STREAMR)
+		ret += sprintf(str + ret, "STREAMR ");
+	if (ep_sts & EP_STS_MD_EXIT)
+		ret += sprintf(str + ret, "MD_EXIT ");
+	if (ep_sts & EP_STS_TRBERR)
+		ret += sprintf(str + ret, "TRBERR ");
+	if (ep_sts & EP_STS_NRDY)
+		ret += sprintf(str + ret, "NRDY ");
+	if (ep_sts & EP_STS_PRIME)
+		ret += sprintf(str + ret, "PRIME ");
+	if (ep_sts & EP_STS_SIDERR)
+		ret += sprintf(str + ret, "SIDERRT ");
+	if (ep_sts & EP_STS_OUTSMM)
+		ret += sprintf(str + ret, "OUTSMM ");
+	if (ep_sts & EP_STS_ISOERR)
+		ret += sprintf(str + ret, "ISOERR ");
+	if (ep_sts & EP_STS_IOT)
+		ret += sprintf(str + ret, "IOT ");
+
+	return str;
+}
+
+static inline char *cdns3_decode_epx_irq(char *str,
+					 char *ep_name,
+					 u32 ep_sts)
+{
+	return cdns3_decode_ep_irq(str, ep_sts, ep_name);
+}
+
+static inline char *cdns3_decode_ep0_irq(char *str,
+					 int dir,
+					 u32 ep_sts)
+{
+	return cdns3_decode_ep_irq(str, ep_sts,
+				   dir ? "ep0IN" : "ep0OUT");
+}
+
+/**
+ * Debug a transfer ring.
+ *
+ * Prints out all TRBs in the endpoint ring, even those after the Link TRB.
+ *.
+ */
+static inline char *cdns3_dbg_ring(struct cdns3_endpoint *priv_ep,
+				   struct cdns3_trb *ring, char *str)
+{
+	dma_addr_t addr = priv_ep->trb_pool_dma;
+	struct cdns3_trb *trb;
+	int trb_per_sector;
+	int ret = 0;
+	int i;
+
+	trb_per_sector = GET_TRBS_PER_SEGMENT(priv_ep->type);
+
+	trb = &priv_ep->trb_pool[priv_ep->dequeue];
+	ret += sprintf(str + ret, "\n\t\tRing contents for %s:", priv_ep->name);
+
+	ret += sprintf(str + ret,
+		       "\n\t\tRing deq index: %d, trb: %p (virt), 0x%llx (dma)\n",
+		       priv_ep->dequeue, trb,
+		       (unsigned long long)cdns3_trb_virt_to_dma(priv_ep, trb));
+
+	trb = &priv_ep->trb_pool[priv_ep->enqueue];
+	ret += sprintf(str + ret,
+		       "\t\tRing enq index: %d, trb: %p (virt), 0x%llx (dma)\n",
+		       priv_ep->enqueue, trb,
+		       (unsigned long long)cdns3_trb_virt_to_dma(priv_ep, trb));
+
+	ret += sprintf(str + ret,
+		       "\t\tfree trbs: %d, CCS=%d, PCS=%d\n",
+		       priv_ep->free_trbs, priv_ep->ccs, priv_ep->pcs);
+
+	if (trb_per_sector > TRBS_PER_SEGMENT)
+		trb_per_sector = TRBS_PER_SEGMENT;
+
+	if (trb_per_sector > TRBS_PER_SEGMENT) {
+		sprintf(str + ret, "\t\tTo big transfer ring %d\n",
+			trb_per_sector);
+		return str;
+	}
+
+	for (i = 0; i < trb_per_sector; ++i) {
+		trb = &ring[i];
+		ret += sprintf(str + ret,
+			"\t\t@%pad %08x %08x %08x\n", &addr,
+			le32_to_cpu(trb->buffer),
+			le32_to_cpu(trb->length),
+			le32_to_cpu(trb->control));
+		addr += sizeof(*trb);
+	}
+
+	return str;
+}
+
+void cdns3_dbg(struct cdns3_device *priv_dev, const char *fmt, ...);
+
+#ifdef CONFIG_DEBUG_FS
+void cdns3_debugfs_init(struct cdns3 *cdns);
+void cdns3_debugfs_exit(struct cdns3 *cdns);
+#else
+void cdns3_debugfs_init(struct cdns3 *cdns);
+{  }
+void cdns3_debugfs_exit(struct cdns3 *cdns);
+{  }
+#endif
+
+#endif /*__LINUX_CDNS3_DEBUG*/

diff --git a/drivers/usb/cdns3/debugfs.c b/drivers/usb/cdns3/debugfs.c
new file mode 100644
index 000000000000..dfcbeb5e14f8
--- /dev/null
+++ b/drivers/usb/cdns3/debugfs.c

@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cadence USBSS DRD Controller DebugFS filer.
+ *
+ * Copyright (C) 2018-2019 Cadence.
+ *
+ * Author: Pawel Laszczak <pawell@cadence.com>
+ */
+
+#include <linux/types.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+
+#include "core.h"
+#include "gadget.h"
+#include "drd.h"
+
+static int cdns3_mode_show(struct seq_file *s, void *unused)
+{
+	struct cdns3 *cdns = s->private;
+
+	switch (cdns->current_dr_mode) {
+	case USB_DR_MODE_HOST:
+		seq_puts(s, "host\n");
+		break;
+	case USB_DR_MODE_PERIPHERAL:
+		seq_puts(s, "device\n");
+		break;
+	case USB_DR_MODE_OTG:
+		seq_puts(s, "otg\n");
+		break;
+	default:
+		seq_puts(s, "UNKNOWN mode\n");
+	}
+
+	return 0;
+}
+
+static int cdns3_mode_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, cdns3_mode_show, inode->i_private);
+}
+
+static ssize_t cdns3_mode_write(struct file *file,
+				const char __user *ubuf,
+				size_t count, loff_t *ppos)
+{
+	struct seq_file	 *s = file->private_data;
+	struct cdns3 *cdns = s->private;
+	u32 mode = USB_DR_MODE_UNKNOWN;
+	char buf[32];
+	int ret = 0;
+
+	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
+	if (cdns->debug_disable) {
+		dev_err(cdns->dev,
+			"Mode can't be changed when disable is set\n");
+		return -EFAULT;
+	}
+
+	if (!strncmp(buf, "host", 4)) {
+		if (cdns->dr_mode == USB_DR_MODE_HOST ||
+		    cdns->dr_mode == USB_DR_MODE_OTG) {
+			mode = USB_DR_MODE_HOST;
+		}
+	}
+
+	if (!strncmp(buf, "device", 6))
+		if (cdns->dr_mode == USB_DR_MODE_PERIPHERAL ||
+		    cdns->dr_mode == USB_DR_MODE_OTG)
+			mode = USB_DR_MODE_PERIPHERAL;
+
+	if (!strncmp(buf, "otg", 3) && cdns->dr_mode == USB_DR_MODE_OTG)
+		mode = USB_DR_MODE_OTG;
+
+	if (mode == USB_DR_MODE_UNKNOWN) {
+		dev_err(cdns->dev, "Failed: incorrect mode setting\n");
+		return -EFAULT;
+	}
+
+	if (cdns->current_dr_mode != mode) {
+		cdns->desired_dr_mode = mode;
+		cdns3_role_stop(cdns);
+		ret = cdns3_drd_update_mode(cdns);
+		if (ret)
+			return ret;
+
+		queue_work(system_freezable_wq, &cdns->role_switch_wq);
+	}
+
+	return count;
+}
+
+static const struct file_operations cdns3_mode_fops = {
+	.open			= cdns3_mode_open,
+	.write			= cdns3_mode_write,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
+static int cdns3_disable_show(struct seq_file *s, void *unused)
+{
+	struct cdns3 *cdns = s->private;
+
+	if (!cdns->debug_disable)
+		seq_puts(s, "0\n");
+	else
+		seq_puts(s, "1\n");
+
+	return 0;
+}
+
+static ssize_t cdns3_disable_write(struct file *file,
+				   const char __user *ubuf,
+				   size_t count, loff_t *ppos)
+{
+	struct seq_file	 *s = file->private_data;
+	struct cdns3 *cdns = s->private;
+	bool disable;
+	char buf[16];
+
+	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
+	if (kstrtobool(buf, &disable)) {
+		dev_err(cdns->dev, "wrong setting\n");
+		return -EINVAL;
+	}
+
+	if (disable != cdns->debug_disable) {
+		cdns->debug_disable = disable;
+		queue_work(system_freezable_wq, &cdns->role_switch_wq);
+	}
+
+	return count;
+}
+
+static int cdns3_disable_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, cdns3_disable_show, inode->i_private);
+}
+
+static const struct file_operations cdns3_disable_fops = {
+	.open			= cdns3_disable_open,
+	.write			= cdns3_disable_write,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
+void cdns3_debugfs_init(struct cdns3 *cdns)
+{
+	struct dentry *root;
+
+	root = debugfs_create_dir(dev_name(cdns->dev), NULL);
+	cdns->root = root;
+	if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET) &&
+	    IS_ENABLED(CONFIG_USB_CDNS3_HOST))
+		debugfs_create_file("mode", 0644, root, cdns,
+				    &cdns3_mode_fops);
+
+	debugfs_create_file("disable", 0644, root, cdns,
+			    &cdns3_disable_fops);
+}
+
+void cdns3_debugfs_exit(struct cdns3 *cdns)
+{
+	debugfs_remove_recursive(cdns->root);
+}

diff --git a/drivers/usb/cdns3/drd.c b/drivers/usb/cdns3/drd.c
new file mode 100644
index 000000000000..2daef0746ddd
--- /dev/null
+++ b/drivers/usb/cdns3/drd.c

@@ -0,0 +1,379 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cadence USBSS DRD Driver.
+ *
+ * Copyright (C) 2018-2019 Cadence.
+ * Copyright (C) 2019 Texas Instruments
+ *
+ * Author: Pawel Laszczak <pawell@cadence.com>
+ *         Roger Quadros <rogerq@ti.com>
+ *
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/usb/otg.h>
+
+#include "gadget.h"
+#include "drd.h"
+#include "core.h"
+
+/**
+ * cdns3_set_mode - change mode of OTG Core
+ * @cdns: pointer to context structure
+ * @mode: selected mode from cdns_role
+ *
+ * Returns 0 on success otherwise negative errno
+ */
+int cdns3_set_mode(struct cdns3 *cdns, enum usb_dr_mode mode)
+{
+	int ret = 0;
+	u32 reg;
+
+	cdns->current_dr_mode = mode;
+
+	switch (mode) {
+	case USB_DR_MODE_PERIPHERAL:
+		break;
+	case USB_DR_MODE_HOST:
+		break;
+	case USB_DR_MODE_OTG:
+		dev_dbg(cdns->dev, "Set controller to OTG mode\n");
+		if (cdns->version == CDNS3_CONTROLLER_V1) {
+			reg = readl(&cdns->otg_v1_regs->override);
+			reg |= OVERRIDE_IDPULLUP;
+			writel(reg, &cdns->otg_v1_regs->override);
+		} else {
+			reg = readl(&cdns->otg_v0_regs->ctrl1);
+			reg |= OVERRIDE_IDPULLUP_V0;
+			writel(reg, &cdns->otg_v0_regs->ctrl1);
+		}
+
+		/*
+		 * Hardware specification says: "ID_VALUE must be valid within
+		 * 50ms after idpullup is set to '1" so driver must wait
+		 * 50ms before reading this pin.
+		 */
+		usleep_range(50000, 60000);
+		break;
+	default:
+		cdns->current_dr_mode = USB_DR_MODE_UNKNOWN;
+		dev_err(cdns->dev, "Unsupported mode of operation %d\n", mode);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+int cdns3_get_id(struct cdns3 *cdns)
+{
+	int id;
+
+	id = readl(&cdns->otg_regs->sts) & OTGSTS_ID_VALUE;
+	dev_dbg(cdns->dev, "OTG ID: %d", id);
+
+	return id;
+}
+
+int cdns3_get_vbus(struct cdns3 *cdns)
+{
+	int vbus;
+
+	vbus = !!(readl(&cdns->otg_regs->sts) & OTGSTS_VBUS_VALID);
+	dev_dbg(cdns->dev, "OTG VBUS: %d", vbus);
+	return vbus;
+}
+
+int cdns3_is_host(struct cdns3 *cdns)
+{
+	if (cdns->current_dr_mode == USB_DR_MODE_HOST)
+		return 1;
+	else if (!cdns3_get_id(cdns))
+		return 1;
+
+	return 0;
+}
+
+int cdns3_is_device(struct cdns3 *cdns)
+{
+	if (cdns->current_dr_mode == USB_DR_MODE_PERIPHERAL)
+		return 1;
+	else if (cdns->current_dr_mode == USB_DR_MODE_OTG)
+		if (cdns3_get_id(cdns))
+			return 1;
+
+	return 0;
+}
+
+/**
+ * cdns3_otg_disable_irq - Disable all OTG interrupts
+ * @cdns: Pointer to controller context structure
+ */
+static void cdns3_otg_disable_irq(struct cdns3 *cdns)
+{
+	writel(0, &cdns->otg_regs->ien);
+}
+
+/**
+ * cdns3_otg_enable_irq - enable id and sess_valid interrupts
+ * @cdns: Pointer to controller context structure
+ */
+static void cdns3_otg_enable_irq(struct cdns3 *cdns)
+{
+	writel(OTGIEN_ID_CHANGE_INT | OTGIEN_VBUSVALID_RISE_INT |
+	       OTGIEN_VBUSVALID_FALL_INT, &cdns->otg_regs->ien);
+}
+
+/**
+ * cdns3_drd_switch_host - start/stop host
+ * @cdns: Pointer to controller context structure
+ * @on: 1 for start, 0 for stop
+ *
+ * Returns 0 on success otherwise negative errno
+ */
+int cdns3_drd_switch_host(struct cdns3 *cdns, int on)
+{
+	int ret;
+	u32 reg = OTGCMD_OTG_DIS;
+
+	/* switch OTG core */
+	if (on) {
+		writel(OTGCMD_HOST_BUS_REQ | reg, &cdns->otg_regs->cmd);
+
+		dev_info(cdns->dev, "Waiting till Host mode is turned on\n");