RE: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

[Pawel Laszczak <pawell@cadence.com>]

Hi,

>
>On 21/07/2019 21:32, Pawel Laszczak wrote:
>> This patch introduce new Cadence USBSS DRD driver to Linux kernel.
>>
>> The Cadence USBSS DRD Controller is a highly configurable IP Core which
>> can be instantiated as Dual-Role Device (DRD), Peripheral Only and
>> Host Only (XHCI)configurations.
>>
>> The current driver has been validated with FPGA platform. We have
>> support for PCIe bus, which is used on FPGA prototyping.
>>
>> The host side of USBSS-DRD controller is compliant with XHCI
>> specification, so it works with standard XHCI Linux driver.
>>
>> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>> ---
>>  drivers/usb/Kconfig                |    2 +
>>  drivers/usb/Makefile               |    2 +
>>  drivers/usb/cdns3/Kconfig          |   46 +
>>  drivers/usb/cdns3/Makefile         |   17 +
>>  drivers/usb/cdns3/cdns3-pci-wrap.c |  203 +++
>>  drivers/usb/cdns3/core.c           |  554 +++++++
>>  drivers/usb/cdns3/core.h           |  109 ++
>>  drivers/usb/cdns3/debug.h          |  171 ++
>>  drivers/usb/cdns3/debugfs.c        |   87 ++
>>  drivers/usb/cdns3/drd.c            |  390 +++++
>>  drivers/usb/cdns3/drd.h            |  166 ++
>>  drivers/usb/cdns3/ep0.c            |  914 +++++++++++
>>  drivers/usb/cdns3/gadget-export.h  |   28 +
>>  drivers/usb/cdns3/gadget.c         | 2338 ++++++++++++++++++++++++++++
>>  drivers/usb/cdns3/gadget.h         | 1321 ++++++++++++++++
>>  drivers/usb/cdns3/host-export.h    |   28 +
>>  drivers/usb/cdns3/host.c           |   71 +
>>  drivers/usb/cdns3/trace.c          |   11 +
>>  drivers/usb/cdns3/trace.h          |  493 ++++++
>>  19 files changed, 6951 insertions(+)
>>  create mode 100644 drivers/usb/cdns3/Kconfig
>>  create mode 100644 drivers/usb/cdns3/Makefile
>>  create mode 100644 drivers/usb/cdns3/cdns3-pci-wrap.c
>>  create mode 100644 drivers/usb/cdns3/core.c
>>  create mode 100644 drivers/usb/cdns3/core.h
>>  create mode 100644 drivers/usb/cdns3/debug.h
>>  create mode 100644 drivers/usb/cdns3/debugfs.c
>>  create mode 100644 drivers/usb/cdns3/drd.c
>>  create mode 100644 drivers/usb/cdns3/drd.h
>>  create mode 100644 drivers/usb/cdns3/ep0.c
>>  create mode 100644 drivers/usb/cdns3/gadget-export.h
>>  create mode 100644 drivers/usb/cdns3/gadget.c
>>  create mode 100644 drivers/usb/cdns3/gadget.h
>>  create mode 100644 drivers/usb/cdns3/host-export.h
>>  create mode 100644 drivers/usb/cdns3/host.c
>>  create mode 100644 drivers/usb/cdns3/trace.c
>>  create mode 100644 drivers/usb/cdns3/trace.h
>>
>> diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
>> index e4b27413f528..c2e78882f8c2 100644
>> --- a/drivers/usb/Kconfig
>> +++ b/drivers/usb/Kconfig
>> @@ -113,6 +113,8 @@ source "drivers/usb/usbip/Kconfig"
>>
>>  endif
>>
>> +source "drivers/usb/cdns3/Kconfig"
>> +
>>  source "drivers/usb/mtu3/Kconfig"
>>
>>  source "drivers/usb/musb/Kconfig"
>> diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
>> index 7d1b8c82b208..ab125b966cac 100644
>> --- a/drivers/usb/Makefile
>> +++ b/drivers/usb/Makefile
>> @@ -12,6 +12,8 @@ obj-$(CONFIG_USB_DWC3)		+= dwc3/
>>  obj-$(CONFIG_USB_DWC2)		+= dwc2/
>>  obj-$(CONFIG_USB_ISP1760)	+= isp1760/
>>
>> +obj-$(CONFIG_USB_CDNS3)		+= cdns3/
>> +
>>  obj-$(CONFIG_USB_MON)		+= mon/
>>  obj-$(CONFIG_USB_MTU3)		+= mtu3/
>>
>> diff --git a/drivers/usb/cdns3/Kconfig b/drivers/usb/cdns3/Kconfig
>> new file mode 100644
>> index 000000000000..d0331613a355
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/Kconfig
>> @@ -0,0 +1,46 @@
>> +config USB_CDNS3
>> +	tristate "Cadence USB3 Dual-Role Controller"
>> +	depends on USB_SUPPORT && (USB || USB_GADGET) && HAS_DMA
>> +	select USB_XHCI_PLATFORM if USB_XHCI_HCD
>> +	select USB_ROLE_SWITCH
>> +	help
>> +	  Say Y here if your system has a Cadence USB3 dual-role controller.
>> +	  It supports: dual-role switch, Host-only, and Peripheral-only.
>> +
>> +	  If you choose to build this driver is a dynamically linked
>> +	  as module, the module will be called cdns3.ko.
>> +
>> +if USB_CDNS3
>> +
>> +config USB_CDNS3_GADGET
>> +	bool "Cadence USB3 device controller"
>> +	depends on USB_GADGET=y || USB_GADGET=USB_CDNS3
>> +	help
>> +	  Say Y here to enable device controller functionality of the
>> +	  Cadence USBSS-DEV driver.
>> +
>> +	  This controller supports FF, HS and SS mode. It doesn't support
>
>s/FF/FS
>
>> +	  LS and SSP mode.
>> +
>> +config USB_CDNS3_HOST
>> +	bool "Cadence USB3 host controller"
>> +	depends on USB=y || USB=USB_CDNS3
>> +	help
>> +	  Say Y here to enable host controller functionality of the
>> +	  Cadence driver.
>> +
>> +	  Host controller is compliant with XHCI so it will use
>> +	  standard XHCI driver.
>> +
>> +config USB_CDNS3_PCI_WRAP
>> +	tristate "Cadence USB3 support on PCIe-based platforms"
>> +	depends on USB_PCI && ACPI
>> +	default USB_CDNS3
>> +	help
>> +	  If you're using the USBSS Core IP with a PCIe, please say
>> +	  'Y' or 'M' here.
>> +
>> +	  If you choose to build this driver as module it will
>> +	  be dynamically linked and module will be called cdns3-pci.ko
>> +
>> +endif
>> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
>> new file mode 100644
>> index 000000000000..6c58660b9cd1
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/Makefile
>> @@ -0,0 +1,17 @@
>> +# SPDX-License-Identifier: GPL-2.0
>> +# define_trace.h needs to know how to find our header
>> +CFLAGS_trace.o				:= -I$(src)
>> +
>> +cdns3-y					:= core.o drd.o
>> +
>> +obj-$(CONFIG_USB_CDNS3)			+= cdns3.o
>> +cdns3-$(CONFIG_DEBUG_FS)		+= debugfs.o
>> +cdns3-$(CONFIG_USB_CDNS3_GADGET)	+= gadget.o ep0.o
>> +
>> +ifneq ($(CONFIG_USB_CDNS3_GADGET),)
>> +cdns3-$(CONFIG_TRACING)			+= trace.o
>> +endif
>> +
>> +cdns3-$(CONFIG_USB_CDNS3_HOST)		+= host.o
>> +
>> +obj-$(CONFIG_USB_CDNS3_PCI_WRAP)	+= cdns3-pci-wrap.o
>> diff --git a/drivers/usb/cdns3/cdns3-pci-wrap.c b/drivers/usb/cdns3/cdns3-pci-wrap.c
>> new file mode 100644
>> index 000000000000..c41ddb61b857
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/cdns3-pci-wrap.c
>> @@ -0,0 +1,203 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Cadence USBSS PCI Glue driver
>> + *
>> + * Copyright (C) 2018-2019 Cadence.
>> + *
>> + * Author: Pawel Laszczak <pawell@cadence.com>
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/slab.h>
>> +
>> +struct cdns3_wrap {
>> +	struct platform_device *plat_dev;
>> +	struct resource dev_res[6];
>> +	int devfn;
>> +};
>> +
>> +#define RES_IRQ_HOST_ID		0
>> +#define RES_IRQ_PERIPHERAL_ID	1
>> +#define RES_IRQ_OTG_ID		2
>> +#define RES_HOST_ID		3
>> +#define RES_DEV_ID		4
>> +#define RES_DRD_ID		5
>> +
>> +#define PCI_BAR_HOST		0
>> +#define PCI_BAR_DEV		2
>> +#define PCI_BAR_OTG		0
>> +
>> +#define PCI_DEV_FN_HOST_DEVICE	0
>> +#define PCI_DEV_FN_OTG		1
>> +
>> +#define PCI_DRIVER_NAME		"cdns3-pci-usbss"
>> +#define PLAT_DRIVER_NAME	"cdns-usb3"
>> +
>> +#define CDNS_VENDOR_ID		0x17cd
>> +#define CDNS_DEVICE_ID		0x0100
>> +
>> +static struct pci_dev *cdns3_get_second_fun(struct pci_dev *pdev)
>> +{
>> +	struct pci_dev *func;
>> +
>> +	/*
>> +	 * Gets the second function.
>> +	 * It's little tricky, but this platform has two function.
>> +	 * The fist keeps resources for Host/Device while the second
>> +	 * keeps resources for DRD/OTG.
>> +	 */
>> +	func = pci_get_device(pdev->vendor, pdev->device, NULL);
>> +	if (unlikely(!func))
>> +		return NULL;
>> +
>> +	if (func->devfn == pdev->devfn) {
>> +		func = pci_get_device(pdev->vendor, pdev->device, func);
>> +		if (unlikely(!func))
>> +			return NULL;
>> +	}
>> +
>> +	return func;
>> +}
>> +
>> +static int cdns3_pci_probe(struct pci_dev *pdev,
>> +			   const struct pci_device_id *id)
>> +{
>> +	struct platform_device_info plat_info;
>> +	struct cdns3_wrap *wrap;
>> +	struct resource *res;
>> +	struct pci_dev *func;
>> +	int err;
>> +
>> +	/*
>> +	 * for GADGET/HOST PCI (devfn) function number is 0,
>> +	 * for OTG PCI (devfn) function number is 1
>> +	 */
>> +	if (!id || (pdev->devfn != PCI_DEV_FN_HOST_DEVICE &&
>> +		    pdev->devfn != PCI_DEV_FN_OTG))
>> +		return -EINVAL;
>> +
>> +	func = cdns3_get_second_fun(pdev);
>> +	if (unlikely(!func))
>> +		return -EINVAL;
>> +
>> +	err = pcim_enable_device(pdev);
>> +	if (err) {
>> +		dev_err(&pdev->dev, "Enabling PCI device has failed %d\n", err);
>> +		return err;
>> +	}
>> +
>> +	pci_set_master(pdev);
>> +
>> +	if (pci_is_enabled(func)) {
>> +		wrap = pci_get_drvdata(func);
>> +	} else {
>> +		wrap = kzalloc(sizeof(*wrap), GFP_KERNEL);
>> +		if (!wrap) {
>> +			pci_disable_device(pdev);
>> +			return -ENOMEM;
>> +		}
>> +	}
>> +
>> +	res = wrap->dev_res;
>> +
>> +	if (pdev->devfn == PCI_DEV_FN_HOST_DEVICE) {
>> +		/* function 0: host(BAR_0) + device(BAR_1).*/
>> +		dev_dbg(&pdev->dev, "Initialize Device resources\n");
>> +		res[RES_DEV_ID].start = pci_resource_start(pdev, PCI_BAR_DEV);
>> +		res[RES_DEV_ID].end =   pci_resource_end(pdev, PCI_BAR_DEV);
>> +		res[RES_DEV_ID].name = "dev";
>> +		res[RES_DEV_ID].flags = IORESOURCE_MEM;
>> +		dev_dbg(&pdev->dev, "USBSS-DEV physical base addr: %pa\n",
>> +			&res[RES_DEV_ID].start);
>> +
>> +		res[RES_HOST_ID].start = pci_resource_start(pdev, PCI_BAR_HOST);
>> +		res[RES_HOST_ID].end = pci_resource_end(pdev, PCI_BAR_HOST);
>> +		res[RES_HOST_ID].name = "xhci";
>> +		res[RES_HOST_ID].flags = IORESOURCE_MEM;
>> +		dev_dbg(&pdev->dev, "USBSS-XHCI physical base addr: %pa\n",
>> +			&res[RES_HOST_ID].start);
>> +
>> +		/* Interrupt for XHCI */
>> +		wrap->dev_res[RES_IRQ_HOST_ID].start = pdev->irq;
>> +		wrap->dev_res[RES_IRQ_HOST_ID].name = "host";
>> +		wrap->dev_res[RES_IRQ_HOST_ID].flags = IORESOURCE_IRQ;
>> +
>> +		/* Interrupt device. It's the same as for HOST. */
>> +		wrap->dev_res[RES_IRQ_PERIPHERAL_ID].start = pdev->irq;
>> +		wrap->dev_res[RES_IRQ_PERIPHERAL_ID].name = "peripheral";
>> +		wrap->dev_res[RES_IRQ_PERIPHERAL_ID].flags = IORESOURCE_IRQ;
>> +	} else {
>> +		res[RES_DRD_ID].start = pci_resource_start(pdev, PCI_BAR_OTG);
>> +		res[RES_DRD_ID].end =   pci_resource_end(pdev, PCI_BAR_OTG);
>> +		res[RES_DRD_ID].name = "otg";
>> +		res[RES_DRD_ID].flags = IORESOURCE_MEM;
>> +		dev_dbg(&pdev->dev, "USBSS-DRD physical base addr: %pa\n",
>> +			&res[RES_DRD_ID].start);
>> +
>> +		/* Interrupt for OTG/DRD. */
>> +		wrap->dev_res[RES_IRQ_OTG_ID].start = pdev->irq;
>> +		wrap->dev_res[RES_IRQ_OTG_ID].name = "otg";
>> +		wrap->dev_res[RES_IRQ_OTG_ID].flags = IORESOURCE_IRQ;
>> +	}
>> +
>> +	if (pci_is_enabled(func)) {
>> +		/* set up platform device info */
>> +		memset(&plat_info, 0, sizeof(plat_info));
>> +		plat_info.parent = &pdev->dev;
>> +		plat_info.fwnode = pdev->dev.fwnode;
>> +		plat_info.name = PLAT_DRIVER_NAME;
>> +		plat_info.id = pdev->devfn;
>> +		wrap->devfn  = pdev->devfn;
>> +		plat_info.res = wrap->dev_res;
>> +		plat_info.num_res = ARRAY_SIZE(wrap->dev_res);
>> +		plat_info.dma_mask = pdev->dma_mask;
>> +		/* register platform device */
>> +		wrap->plat_dev = platform_device_register_full(&plat_info);
>> +		if (IS_ERR(wrap->plat_dev)) {
>> +			pci_disable_device(pdev);
>> +			kfree(wrap);
>> +			return PTR_ERR(wrap->plat_dev);
>> +		}
>> +	}
>> +
>> +	pci_set_drvdata(pdev, wrap);
>> +	return err;
>> +}
>> +
>> +static void cdns3_pci_remove(struct pci_dev *pdev)
>> +{
>> +	struct cdns3_wrap *wrap;
>> +	struct pci_dev *func;
>> +
>> +	func = cdns3_get_second_fun(pdev);
>> +
>> +	wrap = (struct cdns3_wrap *)pci_get_drvdata(pdev);
>> +	if (wrap->devfn == pdev->devfn)
>> +		platform_device_unregister(wrap->plat_dev);
>> +
>> +	if (!pci_is_enabled(func))
>> +		kfree(wrap);
>> +}
>> +
>> +static const struct pci_device_id cdns3_pci_ids[] = {
>> +	{ PCI_DEVICE(CDNS_VENDOR_ID, CDNS_DEVICE_ID), },
>> +	{ 0, }
>> +};
>> +
>> +static struct pci_driver cdns3_pci_driver = {
>> +	.name = PCI_DRIVER_NAME,
>> +	.id_table = cdns3_pci_ids,
>> +	.probe = cdns3_pci_probe,
>> +	.remove = cdns3_pci_remove,
>> +};
>> +
>> +module_pci_driver(cdns3_pci_driver);
>> +MODULE_DEVICE_TABLE(pci, cdns3_pci_ids);
>> +
>> +MODULE_AUTHOR("Pawel Laszczak <pawell@cadence.com>");
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_DESCRIPTION("Cadence USBSS PCI wrapperr");
>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>> new file mode 100644
>> index 000000000000..900b2ce08162
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/core.c
>> @@ -0,0 +1,554 @@
>> +// 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"
>> +
>> +static inline
>> +struct cdns3_role_driver *cdns3_get_current_role_driver(struct cdns3 *cdns)
>> +{
>> +	WARN_ON(!cdns->roles[cdns->role]);
>> +	return cdns->roles[cdns->role];
>> +}
>> +
>> +static int cdns3_role_start(struct cdns3 *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 (role == USB_ROLE_NONE)
>> +		return 0;
>> +
>> +	if (!cdns->roles[role])
>> +		return -ENXIO;
>> +
>> +	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_ACTIVE)
>> +		return 0;
>> +
>> +	mutex_lock(&cdns->mutex);
>> +	if (role == USB_ROLE_HOST)
>> +		cdns3_drd_switch_host(cdns, 1);
>> +	else
>> +		cdns3_drd_switch_gadget(cdns, 1);
>> +
>> +	ret = cdns->roles[role]->start(cdns);
>> +	if (!ret)
>> +		cdns->roles[role]->state = CDNS3_ROLE_STATE_ACTIVE;
>> +	mutex_unlock(&cdns->mutex);
>> +
>> +	return ret;
>> +}
>> +
>> +static void cdns3_role_stop(struct cdns3 *cdns)
>> +{
>> +	enum usb_role role = cdns->role;
>> +
>> +	if (WARN_ON(role > USB_ROLE_DEVICE))
>> +		return;
>> +
>> +	if (role == USB_ROLE_NONE)
>> +		return;
>> +
>> +	if (cdns->roles[role]->state == CDNS3_ROLE_STATE_INACTIVE)
>> +		return;
>> +
>> +	mutex_lock(&cdns->mutex);
>> +	cdns->roles[role]->stop(cdns);
>> +	if (role == USB_ROLE_HOST)
>> +		cdns3_drd_switch_host(cdns, 0);
>> +	else
>> +		cdns3_drd_switch_gadget(cdns, 0);
>> +
>> +	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 usb_role cdsn3_real_role_switch_get(struct device *dev);
>> +
>> +/**
>> + * 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 = 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 (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;
>> +
>> +	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_real_role_switch_get(cdns->dev);
>> +
>> +	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_real_role_switch_get - get real role of controller based on hardware
>> + *   settings.
>> + * @dev: Pointer to device structure
>> + *
>> + * Returns role
>> + */
>> +enum usb_role cdsn3_real_role_switch_get(struct device *dev)
>> +{
>> +	struct cdns3 *cdns = dev_get_drvdata(dev);
>> +	enum usb_role 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 USB_ROLE_NONE:
>> +		/*
>> +		 * Driver treat 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;
>> +
>> +not_otg:
>> +	if (cdns3_is_host(cdns))
>> +		role = USB_ROLE_HOST;
>> +	if (cdns3_is_device(cdns))
>> +		role = USB_ROLE_DEVICE;
>> +
>> +	return role;
>> +}
>> +
>> +/**
>> + * cdns3_role_switch_set - work queue handler for role switch
>> + *
>> + * @dev: pointer to device object
>> + * @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 cdns3_role_switch_set(struct device *dev, enum usb_role role)
>> +{
>> +	struct cdns3 *cdns = dev_get_drvdata(dev);
>> +	enum usb_role real_role = USB_ROLE_NONE;
>> +	enum usb_role current_role;
>> +	int ret = 0;
>> +
>> +	/* Check if dr_mode was changed.*/
>> +	ret = cdns3_drd_update_mode(cdns);
>> +	if (ret)
>> +		return ret;
>> +
>> +	pm_runtime_get_sync(cdns->dev);
>> +
>> +	real_role = cdsn3_real_role_switch_get(cdns->dev);
>> +
>> +	/* Do nothing if nothing changed */
>> +	if (cdns->role == real_role)
>> +		goto exit;
>> +
>> +	cdns3_role_stop(cdns);
>> +
>> +	real_role = cdsn3_real_role_switch_get(cdns->dev);
>> +
>> +	current_role = role;
>> +	dev_dbg(cdns->dev, "Switching role");
>> +
>> +	ret = cdns3_role_start(cdns, real_role);
>> +	if (ret) {
>> +		/* Back to current role */
>> +		dev_err(cdns->dev, "set %d has failed, back to %d\n",
>> +			role, current_role);
>> +		ret = cdns3_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;
>> +}
>> +
>> +static const struct usb_role_switch_desc cdns3_switch_desc = {
>> +	.set = cdns3_role_switch_set,
>> +	.get = cdsn3_real_role_switch_get,
>> +	.allow_userspace_control = true,
>
>how does user initiated cdns3_role_switch_set() via sysfs co-exist with role
>changes done by hardware events. e.g. ID/VBUS?
>

Do you expect any issues whit this,  have you seen any problem with this 
on your J7 platform ?

I assume that it should work in this way:
1. user change role by sysfs
2. Driver change the role according with user request.
3. If we receive correct ID/VBUS then role should not be changed
    because new role is the same as current set in point 2. 


>> +};
>> +
>> +/**
>> + * cdns3_probe - probe for cdns3 core device
>> + * @pdev: Pointer to cdns3 core platform device
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +static int cdns3_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct resource	*res;
>> +	struct cdns3 *cdns;
>> +	void __iomem *regs;
>> +	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 -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->usb2_phy = devm_phy_optional_get(dev, "cdns3,usb2-phy");
>> +	if (IS_ERR(cdns->usb2_phy))
>> +		return PTR_ERR(cdns->usb2_phy);
>> +
>> +	phy_init(cdns->usb2_phy);
>> +	ret = phy_init(cdns->usb2_phy);
>
>why phy_init() twice?
>
>> +	if (ret)
>> +		return ret;
>> +
>> +	cdns->usb3_phy = devm_phy_optional_get(dev, "cdns3,usb3-phy");
>> +	if (IS_ERR(cdns->usb3_phy))
>> +		return PTR_ERR(cdns->usb3_phye t);
>> +
>> +	phy_init(cdns->usb3_phy);
>> +	ret = phy_init(cdns->usb3_phy);
>
>here too.

My mistake. 

>
>> +	if (ret)
>
>phy_exit(usb2_phy);
>
>> +		return ret;
>> +
>> +	ret = phy_power_on(cdns->usb2_phy);
>> +	if (ret)
>
>phy_exit on cleanup.
>> +		return ret;
>> +
>> +	ret = phy_power_on(cdns->usb3_phy);
>> +	if (ret)
>> +		goto err1;
>> +
>> +	cdns->role_sw = usb_role_switch_register(dev, &cdns3_switch_desc);
>> +	if (IS_ERR(cdns->role_sw)) {
>> +		ret = PTR_ERR(cdns->role_sw);
>> +		dev_warn(dev, "Unable to register Role Switch\n");
>> +		goto err2;
>> +	}
>> +
>> +	ret = cdns3_drd_init(cdns);
>> +	if (ret)
>> +		goto err3;
>> +
>> +	ret = cdns3_core_init_role(cdns);
>> +	if (ret)
>
>cdns3_drd_exit();

Fixed issues in this function.


>> +		goto err3;
>> +
>> +	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;
>> +err3:
>> +	usb_role_switch_unregister(cdns->role_sw);
>> +err2:
>> +	phy_power_off(cdns->usb3_phy);
>> +
>> +err1:
>> +	phy_power_off(cdns->usb2_phy);
>> +	phy_exit(cdns->usb2_phy);
>> +	phy_exit(cdns->usb3_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);
>> +	usb_role_switch_unregister(cdns->role_sw);
>> +	phy_power_off(cdns->usb2_phy);
>> +	phy_power_off(cdns->usb3_phy);
>> +	phy_exit(cdns->usb2_phy);
>> +	phy_exit(cdns->usb3_phy);
>> +	return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +
>> +static int cdns3_suspend(struct device *dev)
>> +{
>> +	struct cdns3 *cdns = dev_get_drvdata(dev);
>> +	unsigned long flags;
>> +
>> +	if (cdns->role == USB_ROLE_HOST)
>> +		return 0;
>> +
>> +	if (pm_runtime_status_suspended(dev))
>> +		pm_runtime_resume(dev);
>> +
>> +	if (cdns->roles[cdns->role]->suspend) {
>> +		spin_lock_irqsave(&cdns->gadget_dev->lock, flags);
>
>Aren't interrupts disabled during system suspend?
>What is the purpose of this lock?

This lock is unlocked in cdns3_disconnect_gadget before 
calling priv_dev->gadget_driver->disconnect.  
It does not protect anything. 

I
>
>> +		cdns->roles[cdns->role]->suspend(cdns, false);
>> +		spin_unlock_irqrestore(&cdns->gadget_dev->lock, flags);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int cdns3_resume(struct device *dev)
>> +{
>> +	struct cdns3 *cdns = dev_get_drvdata(dev);
>> +	unsigned long flags;
>> +> +	if (cdns->role == USB_ROLE_HOST)
>> +		return 0;> +
>> +	if (cdns->roles[cdns->role]->resume) {
>> +		spin_lock_irqsave(&cdns->gadget_dev->lock, flags);
>> +		cdns->roles[cdns->role]->resume(cdns, false);
>> +		spin_unlock_irqrestore(&cdns->gadget_dev->lock, flags);
>> +	}
>> +
>> +	pm_runtime_disable(dev);
>> +	pm_runtime_set_active(dev);
>> +	pm_runtime_enable(dev);
>> +
>> +	return 0;
>> +}
>> +#endif
>> +
>> +static const struct dev_pm_ops cdns3_pm_ops = {
>> +	SET_SYSTEM_SLEEP_PM_OPS(cdns3_suspend, cdns3_resume)
>> +};
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id of_cdns3_match[] = {
>> +	{ .compatible = "cdns,usb3" },
>> +	{ },
>> +};
>> +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),
>> +		.pm	= &cdns3_pm_ops,
>> +	},
>> +};
>> +
>> +module_platform_driver(cdns3_driver);
>> +
>> +MODULE_ALIAS("platform:cdns3");
>> +MODULE_AUTHOR("Pawel Laszczak <pawell@cadence.com>");
>> +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..581a2f28aca4
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/core.h
>> @@ -0,0 +1,109 @@
>> +/* 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>
>> +#include <linux/usb/role.h>
>> +
>> +#ifndef __LINUX_CDNS3_CORE_H
>> +#define __LINUX_CDNS3_CORE_H
>> +
>> +struct cdns3;
>> +
>> +/**
>> + * 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
>> + * @usb2_phy: pointer to USB2 PHY
>> + * @usb3_phy: pointer to USB3 PHY
>> + * @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.
>> + * @role_sw: pointer to role switch object.
>> + * @root: debugfs root folder pointer
>> + */
>> +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[USB_ROLE_DEVICE + 1];
>> +	enum usb_role			role;
>> +	struct platform_device		*host_dev;
>> +	struct cdns3_device		*gadget_dev;
>> +	struct phy			*usb2_phy;
>> +	struct phy			*usb3_phy;
>> +	/* 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 usb_role_switch		*role_sw;
>> +	struct dentry			*root;
>> +};
>> +
>> +#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..4fcd826cf930
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/debug.h
>> @@ -0,0 +1,171 @@
>> +/* 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;
>> +}
>> +
>> +#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);
>static inline void ...
>> +{  }
>> +void cdns3_debugfs_exit(struct cdns3 *cdns);
>
>static inline void ...

Probably debugfs.c will be removed from next version.

>> +{  }
>> +#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..6a4dcde8dac9
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/debugfs.c
>> @@ -0,0 +1,87 @@
>> +// 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;
>> +
>> +	seq_printf(s, "%s\n", usb_dr_mode_to_string(cdns->current_dr_mode));
>> +	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;
>> +	char buf[32];
>> +	int ret;
>> +
>> +	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
>> +		return -EFAULT;
>> +
>> +	buf[count - 1] = '\0';
>> +
>> +	ret = usb_get_dr_mode_from_string(buf);
>> +	if (ret == USB_DR_MODE_UNKNOWN) {
>> +		dev_err(cdns->dev, "Failed: incorrect mode setting\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (cdns->current_dr_mode != ret) {
>> +		cdns->desired_dr_mode = ret;
>> +
>> +		if (cdns->role != USB_ROLE_NONE)
>> +			usb_role_switch_set_role(cdns->role_sw, cdns->role);
>> +
>> +		usb_role_switch_set_role(cdns->role_sw, cdns->role);
>> +	}
>> +
>> +	return count;
>> +}
>
>Why do we still need this debugfs interface?
>Doesn't the role switch sysfs do the same thing?
>
It's only for testing. I will tray to remove whole debugfs.c file. 
>> +
>> +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,
>> +};
>> +
>> +void cdns3_debugfs_init(struct cdns3 *cdns)
>> +{
>> +	struct dentry *root;
>> +
>> +	root = debugfs_create_dir(dev_name(cdns->dev), usb_debug_root);
>> +	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);
>> +}
>> +
>> +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..77f8a1516140
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/drd.c
>> @@ -0,0 +1,390 @@
>> +// 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/iopoll.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, val;
>> +	u32 reg = OTGCMD_OTG_DIS;
>> +
>> +	/* switch OTG core */
>> +	if (on) {
>> +		writel(OTGCMD_HOST_BUS_REQ | reg, &cdns->otg_regs->cmd);
>> +
>> +		dev_dbg(cdns->dev, "Waiting till Host mode is turned on\n");
>> +		ret = readl_poll_timeout_atomic(&cdns->otg_regs->sts, val,
>> +						val & OTGSTS_XHCI_READY,
>> +						1, 100000);
>> +		if (ret) {
>> +			dev_err(cdns->dev, "timeout waiting for xhci_ready\n");
>> +			return ret;
>> +		}
>> +	} else {
>> +		writel(OTGCMD_HOST_BUS_DROP | OTGCMD_DEV_BUS_DROP |
>> +		       OTGCMD_DEV_POWER_OFF | OTGCMD_HOST_POWER_OFF,
>> +		       &cdns->otg_regs->cmd);
>> +		/* Waiting till H_IDLE state.*/
>> +		readl_poll_timeout_atomic(&cdns->otg_regs->state, val,
>> +					  !(val & OTGSTATE_HOST_STATE_MASK),
>> +					  1, 2000000);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * cdns3_drd_switch_gadget - start/stop gadget
>> + * @cdns: Pointer to controller context structure
>> + * @on: 1 for start, 0 for stop
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +int cdns3_drd_switch_gadget(struct cdns3 *cdns, int on)
>> +{
>> +	int ret, val;
>> +	u32 reg = OTGCMD_OTG_DIS;
>> +
>> +	/* switch OTG core */
>> +	if (on) {
>> +		writel(OTGCMD_DEV_BUS_REQ | reg, &cdns->otg_regs->cmd);
>> +
>> +		dev_dbg(cdns->dev, "Waiting till Device mode is turned on\n");
>> +
>> +		ret = readl_poll_timeout_atomic(&cdns->otg_regs->sts, val,
>> +						val & OTGSTS_DEV_READY,
>> +						1, 100000);
>> +		if (ret) {
>> +			dev_err(cdns->dev, "timeout waiting for dev_ready\n");
>> +			return ret;
>> +		}
>> +	} else {
>> +		/*
>> +		 * driver should wait at least 10us after disabling Device
>> +		 * before turning-off Device (DEV_BUS_DROP)
>> +		 */
>> +		usleep_range(20, 30);
>> +		writel(OTGCMD_HOST_BUS_DROP | OTGCMD_DEV_BUS_DROP |
>> +		       OTGCMD_DEV_POWER_OFF | OTGCMD_HOST_POWER_OFF,
>> +		       &cdns->otg_regs->cmd);
>> +		/* Waiting till DEV_IDLE state.*/
>> +		readl_poll_timeout_atomic(&cdns->otg_regs->state, val,
>> +					  !(val & OTGSTATE_DEV_STATE_MASK),
>> +					  1, 2000000);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * cdns3_init_otg_mode - initialize drd controller
>> + * @cdns: Pointer to controller context structure
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +static int cdns3_init_otg_mode(struct cdns3 *cdns)
>> +{
>> +	int ret = 0;
>> +
>> +	cdns3_otg_disable_irq(cdns);
>> +	/* clear all interrupts */
>> +	writel(~0, &cdns->otg_regs->ivect);
>> +
>> +	ret = cdns3_set_mode(cdns, USB_DR_MODE_OTG);
>> +	if (ret)
>> +		return ret;
>> +
>> +	cdns3_otg_enable_irq(cdns);
>> +	return ret;
>> +}
>> +
>> +/**
>> + * cdns3_drd_update_mode - initialize mode of operation
>> + * @cdns: Pointer to controller context structure
>> + *
>> + * Returns 0 on success otherwise negative errno
>> + */
>> +int cdns3_drd_update_mode(struct cdns3 *cdns)
>> +{
>> +	int ret = 0;
>> +
>> +	if (cdns->desired_dr_mode == cdns->current_dr_mode)
>> +		return ret;
>> +
>> +	switch (cdns->desired_dr_mode) {
>> +	case USB_DR_MODE_PERIPHERAL:
>> +		ret = cdns3_set_mode(cdns, USB_DR_MODE_PERIPHERAL);
>> +		break;
>> +	case USB_DR_MODE_HOST:
>> +		ret = cdns3_set_mode(cdns, USB_DR_MODE_HOST);
>> +		break;
>> +	case USB_DR_MODE_OTG:
>> +		ret = cdns3_init_otg_mode(cdns);
>> +		break;
>> +	default:
>> +		dev_err(cdns->dev, "Unsupported mode of operation %d\n",
>> +			cdns->dr_mode);
>> +		return -EINVAL;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static irqreturn_t cdns3_drd_thread_irq(int irq, void *data)
>> +{
>> +	struct cdns3 *cdns = data;
>> +
>> +	usb_role_switch_set_role(cdns->role_sw, cdns->role);
>
>How to ensure that HW events don't step over user chosen role?

I need to think about this and find out how to test it and eventually force 
such cases. 

But I assume that after attaching/detaching plug the user chosen role can 
be forgotten. 

>
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +/**
>> + * cdns3_drd_irq - interrupt handler for OTG events
>> + *
>> + * @irq: irq number for cdns3 core device
>> + * @data: structure of cdns3
>> + *
>> + * Returns IRQ_HANDLED or IRQ_NONE
>> + */
>> +static irqreturn_t cdns3_drd_irq(int irq, void *data)
>> +{
>> +	irqreturn_t ret = IRQ_NONE;
>> +	struct cdns3 *cdns = data;
>> +	u32 reg;
>> +
>> +	if (cdns->dr_mode != USB_DR_MODE_OTG)
>> +		return ret;
>> +
>> +	reg = readl(&cdns->otg_regs->ivect);
>> +
>> +	if (!reg)
>> +		return ret;
>> +
>> +	if (reg & OTGIEN_ID_CHANGE_INT) {
>> +		dev_dbg(cdns->dev, "OTG IRQ: new ID: %d\n",
>> +			cdns3_get_id(cdns));
>> +
>> +		ret = IRQ_WAKE_THREAD;
>> +	}
>> +
>> +	if (reg & (OTGIEN_VBUSVALID_RISE_INT | OTGIEN_VBUSVALID_FALL_INT)) {
>> +		dev_dbg(cdns->dev, "OTG IRQ: new VBUS: %d\n",
>> +			cdns3_get_vbus(cdns));
>> +
>> +		ret = IRQ_WAKE_THREAD;
>> +	}
>> +
>> +	writel(~0, &cdns->otg_regs->ivect);
>
>Do we need to keep the events masked till IRQ thread handler completes?
>Else we can get a new hard irq even before previous event is handled by the thread.

This line only clear the interrupts. It doesn’t mask events.

>
>> +	return ret;
>> +}
>> +
>> +int cdns3_drd_init(struct cdns3 *cdns)
>> +{
>> +	void __iomem *regs;
>> +	int ret = 0;
>> +	u32 state;
>> +
>> +	regs = devm_ioremap_resource(cdns->dev, &cdns->otg_res);
>> +	if (IS_ERR(regs))
>> +		return PTR_ERR(regs);
>> +
>> +	/* Detection of DRD version. Controller has been released
>> +	 * in two versions. Both are similar, but they have same changes
>> +	 * in register maps.
>> +	 * The first register in old version is command register and it's read
>> +	 * only, so driver should read 0 from it. On the other hand, in v1
>> +	 * the first register contains device ID number which is not set to 0.
>> +	 * Driver uses this fact to detect the proper version of
>> +	 * controller.
>> +	 */
>> +	cdns->otg_v0_regs = regs;
>> +	if (!readl(&cdns->otg_v0_regs->cmd)) {
>> +		cdns->version  = CDNS3_CONTROLLER_V0;
>> +		cdns->otg_v1_regs = NULL;
>> +		cdns->otg_regs = regs;
>> +		writel(1, &cdns->otg_v0_regs->simulate);
>> +		dev_info(cdns->dev, "DRD version v0 (%08x)\n",
>> +			 readl(&cdns->otg_v0_regs->version));
>> +	} else {
>> +		cdns->otg_v0_regs = NULL;
>> +		cdns->otg_v1_regs = regs;
>> +		cdns->otg_regs = (void *)&cdns->otg_v1_regs->cmd;
>> +		cdns->version  = CDNS3_CONTROLLER_V1;
>> +		writel(1, &cdns->otg_v1_regs->simulate);
>> +		dev_info(cdns->dev, "DRD version v1 (ID: %08x, rev: %08x)\n",
>> +			 readl(&cdns->otg_v1_regs->did),
>> +			 readl(&cdns->otg_v1_regs->rid));
>> +	}
>> +
>> +	state = OTGSTS_STRAP(readl(&cdns->otg_regs->sts));
>> +
>> +	/* Update dr_mode according to STRAP configuration. */
>> +	cdns->dr_mode = USB_DR_MODE_OTG;
>> +	if (state == OTGSTS_STRAP_HOST) {
>> +		dev_dbg(cdns->dev, "Controller strapped to HOST\n");
>> +		cdns->dr_mode = USB_DR_MODE_HOST;
>> +	} else if (state == OTGSTS_STRAP_GADGET) {
>> +		dev_dbg(cdns->dev, "Controller strapped to PERIPHERAL\n");
>> +		cdns->dr_mode = USB_DR_MODE_PERIPHERAL;
>> +	}
>> +
>> +	cdns->desired_dr_mode = cdns->dr_mode;
>> +	cdns->current_dr_mode = USB_DR_MODE_UNKNOWN;
>> +
>> +	ret = devm_request_threaded_irq(cdns->dev, cdns->otg_irq,
>> +					cdns3_drd_irq,
>> +					cdns3_drd_thread_irq,
>> +					IRQF_SHARED,
>> +					dev_name(cdns->dev), cdns);
>> +
>> +	if (ret) {
>> +		dev_err(cdns->dev, "couldn't get otg_irq\n");
>> +		return ret;
>> +	}
>> +
>> +	state = readl(&cdns->otg_regs->sts);
>> +	if (OTGSTS_OTG_NRDY(state) != 0) {
>> +		dev_err(cdns->dev, "Cadence USB3 OTG device not ready\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +int cdns3_drd_exit(struct cdns3 *cdns)
>> +{
>> +	cdns3_otg_disable_irq(cdns);
>> +	return 0;
>> +}
>> diff --git a/drivers/usb/cdns3/drd.h b/drivers/usb/cdns3/drd.h
>> new file mode 100644
>> index 000000000000..bf6c7bc41b58
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/drd.h
>> @@ -0,0 +1,166 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Cadence USB3 DRD header file.
>> + *
>> + * Copyright (C) 2018-2019 Cadence.
>> + *
>> + * Author: Pawel Laszczak <pawell@cadence.com>
>> + */
>> +#ifndef __LINUX_CDNS3_DRD
>> +#define __LINUX_CDNS3_DRD
>> +
>> +#include <linux/usb/otg.h>
>> +#include <linux/phy/phy.h>
>> +#include "core.h"
>> +
>> +/*  DRD register interface for version v1. */
>> +struct cdns3_otg_regs {
>> +	__le32 did;
>> +	__le32 rid;
>> +	__le32 capabilities;
>> +	__le32 reserved1;
>> +	__le32 cmd;
>> +	__le32 sts;
>> +	__le32 state;
>> +	__le32 reserved2;
>> +	__le32 ien;
>> +	__le32 ivect;
>> +	__le32 refclk;
>> +	__le32 tmr;
>> +	__le32 reserved3[4];
>> +	__le32 simulate;
>> +	__le32 override;
>> +	__le32 susp_ctrl;
>> +	__le32 reserved4;
>> +	__le32 anasts;
>> +	__le32 adp_ramp_time;
>> +	__le32 ctrl1;
>> +	__le32 ctrl2;
>> +};
>> +
>> +/*  DRD register interface for version v0. */
>> +struct cdns3_otg_legacy_regs {
>> +	__le32 cmd;
>> +	__le32 sts;
>> +	__le32 state;
>> +	__le32 refclk;
>> +	__le32 ien;
>> +	__le32 ivect;
>> +	__le32 reserved1[3];
>> +	__le32 tmr;
>> +	__le32 reserved2[2];
>> +	__le32 version;
>> +	__le32 capabilities;
>> +	__le32 reserved3[2];
>> +	__le32 simulate;
>> +	__le32 reserved4[5];
>> +	__le32 ctrl1;
>> +};
>> +
>> +/*
>> + * Common registers interface for both version of DRD.
>> + */
>> +struct cdns3_otg_common_regs {
>> +	__le32 cmd;
>> +	__le32 sts;
>> +	__le32 state;
>> +	__le32 different1;
>> +	__le32 ien;
>> +	__le32 ivect;
>> +};
>> +
>> +/* CDNS_RID - bitmasks */
>> +#define CDNS_RID(p)			((p) & GENMASK(15, 0))
>> +
>> +/* CDNS_VID - bitmasks */
>> +#define CDNS_DID(p)			((p) & GENMASK(31, 0))
>> +
>> +/* OTGCMD - bitmasks */
>> +/* "Request the bus for Device mode. */
>> +#define OTGCMD_DEV_BUS_REQ		BIT(0)
>> +/* Request the bus for Host mode */
>> +#define OTGCMD_HOST_BUS_REQ		BIT(1)
>> +/* Enable OTG mode. */
>> +#define OTGCMD_OTG_EN			BIT(2)
>> +/* Disable OTG mode */
>> +#define OTGCMD_OTG_DIS			BIT(3)
>> +/*"Configure OTG as A-Device. */
>> +#define OTGCMD_A_DEV_EN			BIT(4)
>> +/*"Configure OTG as A-Device. */
>> +#define OTGCMD_A_DEV_DIS		BIT(5)
>> +/* Drop the bus for Device mod	e. */
>> +#define OTGCMD_DEV_BUS_DROP		BIT(8)
>> +/* Drop the bus for Host mode*/
>> +#define OTGCMD_HOST_BUS_DROP		BIT(9)
>> +/* Power Down USBSS-DEV. */
>> +#define OTGCMD_DEV_POWER_OFF		BIT(11)
>> +/* Power Down CDNSXHCI. */
>> +#define OTGCMD_HOST_POWER_OFF		BIT(12)
>> +
>> +/* OTGIEN - bitmasks */
>> +/* ID change interrupt enable */
>> +#define OTGIEN_ID_CHANGE_INT		BIT(0)
>> +/* Vbusvalid fall detected interrupt enable.*/
>> +#define OTGIEN_VBUSVALID_RISE_INT	BIT(4)
>> +/* Vbusvalid fall detected interrupt enable */
>> +#define OTGIEN_VBUSVALID_FALL_INT	BIT(5)
>> +
>> +/* OTGSTS - bitmasks */
>> +/*
>> + * Current value of the ID pin. It is only valid when idpullup in
>> + *  OTGCTRL1_TYPE register is set to '1'.
>> + */
>> +#define OTGSTS_ID_VALUE			BIT(0)
>> +/* Current value of the vbus_valid */
>> +#define OTGSTS_VBUS_VALID		BIT(1)
>> +/* Current value of the b_sess_vld */
>> +#define OTGSTS_SESSION_VALID		BIT(2)
>> +/*Device mode is active*/
>> +#define OTGSTS_DEV_ACTIVE		BIT(3)
>> +/* Host mode is active. */
>> +#define OTGSTS_HOST_ACTIVE		BIT(4)
>> +/* OTG Controller not ready. */
>> +#define OTGSTS_OTG_NRDY_MASK		BIT(11)
>> +#define OTGSTS_OTG_NRDY(p)		((p) & OTGSTS_OTG_NRDY_MASK)
>> +/*
>> + * Value of the strap pins.
>> + * 000 - no default configuration
>> + * 010 - Controller initiall configured as Host
>> + * 100 - Controller initially configured as Device
>> + */
>> +#define OTGSTS_STRAP(p)			(((p) & GENMASK(14, 12)) >> 12)
>> +#define OTGSTS_STRAP_NO_DEFAULT_CFG	0x00
>> +#define OTGSTS_STRAP_HOST_OTG		0x01
>> +#define OTGSTS_STRAP_HOST		0x02
>> +#define OTGSTS_STRAP_GADGET		0x04
>> +/* Host mode is turned on. */
>> +#define OTGSTS_XHCI_READY		BIT(26)
>> +/* "Device mode is turned on .*/
>> +#define OTGSTS_DEV_READY		BIT(27)
>> +
>> +/* OTGSTATE- bitmasks */
>> +#define OTGSTATE_DEV_STATE_MASK		GENMASK(2, 0)
>> +#define OTGSTATE_HOST_STATE_MASK	GENMASK(5, 3)
>> +#define OTGSTATE_HOST_STATE_IDLE	0x0
>> +#define OTGSTATE_HOST_STATE_VBUS_FALL	0x7
>> +#define OTGSTATE_HOST_STATE(p)		(((p) & OTGSTATE_HOST_STATE_MASK) >> 3)
>> +
>> +/* OTGREFCLK - bitmasks */
>> +#define OTGREFCLK_STB_CLK_SWITCH_EN	BIT(31)
>> +
>> +/* OVERRIDE - bitmasks */
>> +#define OVERRIDE_IDPULLUP		BIT(0)
>> +/* Only for CDNS3_CONTROLLER_V0 version */
>> +#define OVERRIDE_IDPULLUP_V0		BIT(24)
>> +
>> +int cdns3_is_host(struct cdns3 *cdns);
>> +int cdns3_is_device(struct cdns3 *cdns);
>> +int cdns3_get_id(struct cdns3 *cdns);
>> +int cdns3_get_vbus(struct cdns3 *cdns);
>> +int cdns3_drd_init(struct cdns3 *cdns);
>> +int cdns3_drd_exit(struct cdns3 *cdns);
>> +int cdns3_drd_update_mode(struct cdns3 *cdns);
>> +int cdns3_drd_switch_gadget(struct cdns3 *cdns, int on);
>> +int cdns3_drd_switch_host(struct cdns3 *cdns, int on);
>> +
>> +#endif /* __LINUX_CDNS3_DRD */
>
><snip>
>
>> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
>> new file mode 100644
>> index 000000000000..291f08be56fe
>> --- /dev/null
>> +++ b/drivers/usb/cdns3/gadget.c
>> @@ -0,0 +1,2338 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Cadence USBSS DRD Driver - gadget side.
>> + *
>> + * Copyright (C) 2018-2019 Cadence Design Systems.
>> + * Copyright (C) 2017-2018 NXP
>> + *
>> + * Authors: Pawel Jez <pjez@cadence.com>,
>> + *          Pawel Laszczak <pawell@cadence.com>
>> + *          Peter Chen <peter.chen@nxp.com>
>> + */
>> +
>
><snip>
>
>> +/**
>> + * cdns3_device_irq_handler- interrupt handler for device part of controller
>> + *
>> + * @irq: irq number for cdns3 core device
>> + * @data: structure of cdns3
>> + *
>> + * Returns IRQ_HANDLED or IRQ_NONE
>> + */
>> +static irqreturn_t cdns3_device_irq_handler(int irq, void *data)
>> +{
>> +	struct cdns3_device *priv_dev;
>> +	struct cdns3 *cdns = data;
>> +	irqreturn_t ret = IRQ_NONE;
>> +	unsigned long flags;
>> +	u32 reg;
>> +
>> +	priv_dev = cdns->gadget_dev;
>> +	spin_lock_irqsave(&priv_dev->lock, flags);
>> +
>> +	/* check USB device interrupt */
>> +	reg = readl(&priv_dev->regs->usb_ists);
>> +
>> +	if (reg) {
>> +		writel(reg, &priv_dev->regs->usb_ists);
>
>Do we need to mask device interrupts till thread handler has done processing
>current set of events?

Yes, we need do this to avoid raising the next the same interrupts. 
If we return back from hard irq handler without clearing reported interrupts,
then system report them again. The solution for this is to use IRQF_ONESHOT
flag during registering interrupt, but I can't use this flag 
because I have shared interrupt line with other component. 

In this version these (usb_ists) interrupts are handled in hard irq, but in next version
will be moved to thread handler. 

>> +		cdns3_check_usb_interrupt_proceed(priv_dev, reg);
>> +		ret = IRQ_HANDLED;
>> +	}
>> +
>> +	/* check endpoint interrupt */
>> +	reg = readl(&priv_dev->regs->ep_ists);
>> +
>> +	if (reg) {
>> +		priv_dev->shadow_ep_en |= reg;
>> +		reg = ~reg & readl(&priv_dev->regs->ep_ien);
>> +		/* mask deferred interrupt. */
>> +		writel(reg, &priv_dev->regs->ep_ien);
>> +		ret = IRQ_WAKE_THREAD;
>> +	}
>> +
>> +	spin_unlock_irqrestore(&priv_dev->lock, flags);
>> +	return ret;
>> +}
>> +
>
><snip>
>
>> +
>> +static int cdns3_gadget_start(struct cdns3 *cdns)
>> +{
>> +	struct cdns3_device *priv_dev;
>> +	u32 max_speed;
>> +	int ret;
>> +
>> +	priv_dev = kzalloc(sizeof(*priv_dev), GFP_KERNEL);
>> +	if (!priv_dev)
>> +		return -ENOMEM;
>> +
>> +	cdns->gadget_dev = priv_dev;
>> +	priv_dev->sysdev = cdns->dev;
>> +	priv_dev->dev = cdns->dev;
>> +	priv_dev->regs = cdns->dev_regs;
>> +
>> +	device_property_read_u16(priv_dev->dev, "cdns,on-chip-buff-size",
>> +				 &priv_dev->onchip_buffers);
>> +
>> +	if (priv_dev->onchip_buffers <=  0) {
>> +		u32 reg = readl(&priv_dev->regs->usb_cap2);
>> +
>> +		priv_dev->onchip_buffers = USB_CAP2_ACTUAL_MEM_SIZE(reg);
>> +	}
>> +
>> +	if (!priv_dev->onchip_buffers)
>> +		priv_dev->onchip_buffers = 256;
>> +
>> +	max_speed = usb_get_maximum_speed(cdns->dev);
>> +
>> +	/* Check the maximum_speed parameter */
>> +	switch (max_speed) {
>> +	case USB_SPEED_FULL:
>
>In this case we need to limit controller max speed to full-speed as system
>integrator would expect that. e.g. in DT node, maximum-speed = "full-speed";
>
>I suppose we need to set the force Full-speed bit here?
>
>> +	case USB_SPEED_HIGH:
>
>Here we need to restrict device controller max-speed to high-speed.
>

Why system integrator would limit the speed of controller? 
For debugging purpose it's  ok, but in production system it's better 
to use higher speed.
Do we relay need such functionality ?

>> +	case USB_SPEED_SUPER:
>> +		break;
>> +	default:
>> +		dev_err(cdns->dev, "invalid maximum_speed parameter %d\n",
>> +			max_speed);
>> +		/* fall through */
>> +	case USB_SPEED_UNKNOWN:
>> +		/* default to superspeed */
>> +		max_speed = USB_SPEED_SUPER;
>> +		break;
>> +	}
>> +
>> +	/* fill gadget fields */
>> +	priv_dev->gadget.max_speed = max_speed;
>> +	priv_dev->gadget.speed = USB_SPEED_UNKNOWN;
>> +	priv_dev->gadget.ops = &cdns3_gadget_ops;
>> +	priv_dev->gadget.name = "usb-ss-gadget";
>> +	priv_dev->gadget.sg_supported = 1;
>> +
>> +	spin_lock_init(&priv_dev->lock);
>> +	INIT_WORK(&priv_dev->pending_status_wq,
>> +		  cdns3_pending_setup_status_handler);
>> +
>> +	/* initialize endpoint container */
>> +	INIT_LIST_HEAD(&priv_dev->gadget.ep_list);
>> +	INIT_LIST_HEAD(&priv_dev->aligned_buf_list);
>> +
>> +	ret = cdns3_init_eps(priv_dev);
>> +	if (ret) {
>> +		dev_err(priv_dev->dev, "Failed to create endpoints\n");
>> +		goto err1;
>> +	}
>> +
>> +	/* allocate memory for setup packet buffer */
>> +	priv_dev->setup_buf = dma_alloc_coherent(priv_dev->sysdev, 8,
>> +						 &priv_dev->setup_dma, GFP_DMA);
>> +	if (!priv_dev->setup_buf) {
>> +		ret = -ENOMEM;
>> +		goto err2;
>> +	}
>> +
>> +	priv_dev->dev_ver = readl(&priv_dev->regs->usb_cap6);
>> +
>> +	dev_dbg(priv_dev->dev, "Device Controller version: %08x\n",
>> +		readl(&priv_dev->regs->usb_cap6));
>> +	dev_dbg(priv_dev->dev, "USB Capabilities:: %08x\n",
>> +		readl(&priv_dev->regs->usb_cap1));
>> +	dev_dbg(priv_dev->dev, "On-Chip memory cnfiguration: %08x\n",
>> +		readl(&priv_dev->regs->usb_cap2));
>> +
>> +	priv_dev->dev_ver = GET_DEV_BASE_VERSION(priv_dev->dev_ver);
>> +
>> +	priv_dev->zlp_buf = kzalloc(CDNS3_EP_ZLP_BUF_SIZE, GFP_KERNEL);
>> +	if (!priv_dev->zlp_buf) {
>> +		ret = -ENOMEM;
>> +		goto err3;
>> +	}
>> +
>> +	/* add USB gadget device */
>> +	ret = usb_add_gadget_udc(priv_dev->dev, &priv_dev->gadget);
>> +	if (ret < 0) {
>> +		dev_err(priv_dev->dev,
>> +			"Failed to register USB device controller\n");
>> +		goto err4;
>> +	}
>> +
>> +	return 0;
>> +err4:
>> +	kfree(priv_dev->zlp_buf);
>> +err3:
>> +	dma_free_coherent(priv_dev->sysdev, 8, priv_dev->setup_buf,
>> +			  priv_dev->setup_dma);
>> +err2:
>> +	cdns3_free_all_eps(priv_dev);
>> +err1:
>> +	cdns->gadget_dev = NULL;
>> +	return ret;
>> +}
>> +
>
><snip>
>
Cheers,
Pawell