thunderbolt: Add support for XDomain discovery protocol

When two hosts are connected over a Thunderbolt cable, there is a
protocol they can use to communicate capabilities supported by the host.
The discovery protocol uses automatically configured control channel
(ring 0) and is build on top of request/response transactions using
special XDomain primitives provided by the Thunderbolt base protocol.

The capabilities consists of a root directory block of basic properties
used for identification of the host, and then there can be zero or more
directories each describing a Thunderbolt service and its capabilities.

Once both sides have discovered what is supported the two hosts can
setup high-speed DMA paths and transfer data to the other side using
whatever protocol was agreed based on the properties. The software
protocol used to communicate which DMA paths to enable is service
specific.

This patch adds support for the XDomain discovery protocol to the
Thunderbolt bus. We model each remote host connection as a Linux XDomain
device. For each Thunderbolt service found supported on the XDomain
device, we create Linux Thunderbolt service device which Thunderbolt
service drivers can then bind to based on the protocol identification
information retrieved from the property directory describing the
service.

This code is based on the work done by Amir Levy and Michael Jamet.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 48 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-thunderbolt b/Documentation/ABI/testing/sysfs-bus-thunderbolt
index 392bef5bd399..93798c02e28b 100644
--- a/Documentation/ABI/testing/sysfs-bus-thunderbolt
+++ b/Documentation/ABI/testing/sysfs-bus-thunderbolt
@@ -110,3 +110,51 @@ Description:	When new NVM image is written to the non-active NVM
 		is directly the status value from the DMA configuration
 		based mailbox before the device is power cycled. Writing
 		0 here clears the status.
+
+What:		/sys/bus/thunderbolt/devices/<xdomain>.<service>/key
+Date:		Jan 2018
+KernelVersion:	4.15
+Contact:	thunderbolt-software@lists.01.org
+Description:	This contains name of the property directory the XDomain
+		service exposes. This entry describes the protocol in
+		question. Following directories are already reserved by
+		the Apple XDomain specification:
+
+		network:  IP/ethernet over Thunderbolt
+		targetdm: Target disk mode protocol over Thunderbolt
+		extdisp:  External display mode protocol over Thunderbolt
+
+What:		/sys/bus/thunderbolt/devices/<xdomain>.<service>/modalias
+Date:		Jan 2018
+KernelVersion:	4.15
+Contact:	thunderbolt-software@lists.01.org
+Description:	Stores the same MODALIAS value emitted by uevent for
+		the XDomain service. Format: tbtsvc:kSpNvNrN
+
+What:		/sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcid
+Date:		Jan 2018
+KernelVersion:	4.15
+Contact:	thunderbolt-software@lists.01.org
+Description:	This contains XDomain protocol identifier the XDomain
+		service supports.
+
+What:		/sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcvers
+Date:		Jan 2018
+KernelVersion:	4.15
+Contact:	thunderbolt-software@lists.01.org
+Description:	This contains XDomain protocol version the XDomain
+		service supports.
+
+What:		/sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcrevs
+Date:		Jan 2018
+KernelVersion:	4.15
+Contact:	thunderbolt-software@lists.01.org
+Description:	This contains XDomain software version the XDomain
+		service supports.
+
+What:		/sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcstns
+Date:		Jan 2018
+KernelVersion:	4.15
+Contact:	thunderbolt-software@lists.01.org
+Description:	This contains XDomain service specific settings as
+		bitmask. Format: %x