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

[Roger Quadros <rogerq@ti.com>]

Hi,

On 11/08/2019 14:59, Pawel Laszczak wrote:
> 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. 
> 

I have not tested this series yet.
My understanding is that if user sets role to "host" or "device" then it should
remain in that role irrespective of ID/VBUS. Once user sets it to "none" then
port should set role based on ID/VBUS.

> 
>>> +};
>>> +
>>> +/**
>>> + * 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. 
> 

No. Only when user sets role to none then role should be based on HW.
>>

<snip>

cheers,
-roger
-- 
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