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Commit dfba2174 authored by Lu Baolu's avatar Lu Baolu Committed by Greg Kroah-Hartman
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usb: xhci: Add DbC support in xHCI driver 



xHCI compatible USB host controllers(i.e. super-speed USB3 controllers)
can be implemented with the Debug Capability(DbC). It presents a debug
device which is fully compliant with the USB framework and provides the
equivalent of a very high performance full-duplex serial link. The debug
capability operation model and registers interface are defined in 7.6.8
of the xHCI specification, revision 1.1.

The DbC debug device shares a root port with the xHCI host. By default,
the debug capability is disabled and the root port is assigned to xHCI.
When the DbC is enabled, the root port will be assigned to the DbC debug
device, and the xHCI sees nothing on this port. This implementation uses
a sysfs node named <dbc> under the xHCI device to manage the enabling
and disabling of the debug capability.

When the debug capability is enabled, it will present a debug device
through the debug port. This debug device is fully compliant with the
USB3 framework, and it can be enumerated by a debug host on the other
end of the USB link. As soon as the debug device is configured, a TTY
serial device named /dev/ttyDBC0 will be created.

Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 67d2ea9f

Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd

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What:		/sys/bus/pci/drivers/xhci_hcd/.../dbc

Date:		June 2017

Contact:	Lu Baolu <baolu.lu@linux.intel.com>

Description:

		xHCI compatible USB host controllers (i.e. super-speed

		USB3 controllers) are often implemented with the Debug

		Capability (DbC). It can present a debug device which

		is fully compliant with the USB framework and provides

		the equivalent of a very high performance full-duplex

		serial link for debug purpose.



		The DbC debug device shares a root port with xHCI host.

		When the DbC is enabled, the root port will be assigned

		to the Debug Capability. Otherwise, it will be assigned

		to xHCI.



		Writing "enable" to this attribute will enable the DbC

		functionality and the shared root port will be assigned

		to the DbC device. Writing "disable" to this attribute

		will disable the DbC functionality and the shared root

		port will roll back to the xHCI.



		Reading this attribute gives the state of the DbC. It

		can be one of the following states: disabled, enabled,

		initialized, connected, configured and stalled.

drivers/usb/host/Kconfig

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@@ -27,6 +27,14 @@ config USB_XHCI_HCD 
	  module will be called xhci-hcd.



if USB_XHCI_HCD

config USB_XHCI_DBGCAP

	bool "xHCI support for debug capability"

	depends on TTY

	---help---

	  Say 'Y' to enable the support for the xHCI debug capability. Make

	  sure that your xHCI host supports the extended debug capability and

	  you want a TTY serial device based on the xHCI debug capability

	  before enabling this option. If unsure, say 'N'.



config USB_XHCI_PCI

       tristate

drivers/usb/host/Makefile

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@@ -14,6 +14,11 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o 
xhci-hcd-y := xhci.o xhci-mem.o

xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o

xhci-hcd-y += xhci-trace.o



ifneq ($(CONFIG_USB_XHCI_DBGCAP), )

	xhci-hcd-y += xhci-dbgcap.o xhci-dbgtty.o

endif



ifneq ($(CONFIG_USB_XHCI_MTK), )

	xhci-hcd-y += xhci-mtk-sch.o

endif

drivers/usb/host/xhci-dbgcap.c

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drivers/usb/host/xhci-dbgcap.h

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