intel_th: Add Global Trace Hub driver

Global Trace Hub (GTH) is the central component of Intel TH architecture;
it carries out switching between the trace sources and trace outputs, can
enable/disable tracing, perform STP encoding, internal buffering, control
backpressure from outputs to sources and so on.

This property is also reflected in the software model; GTH (switch) driver
is required for the other subdevices to probe, because it matches trace
output devices against its output ports and configures them accordingly.

It also implements an interface for output ports to request trace enabling
or disabling and a few other useful things.

For userspace, it provides an attribute group "masters", which allows
configuration of per-master trace output destinations for up to master 255
and "256+" meaning "masters 256 and above". It also provides an attribute
group to discover and configure some of the parameters of its output ports,
called "outputs". Via these the user can set up data retention policy for
an individual output port or check if it is in reset state.

Signed-off-by: Laurent Fert <laurent.fert@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-intel_th-devices-gth b/Documentation/ABI/testing/sysfs-bus-intel_th-devices-gth
new file mode 100644
index 000000000000..22d0843849a8
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-intel_th-devices-gth
@@ -0,0 +1,49 @@
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/masters/*
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RW) Configure output ports for STP masters. Writing -1
+		disables a master; any
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/outputs/[0-7]_port
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RO) Output port type:
+		  0: not present,
+		  1: MSU (Memory Storage Unit)
+		  2: CTP (Common Trace Port)
+		  4: PTI (MIPI PTI).
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/outputs/[0-7]_drop
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RW) Data retention policy setting: keep (0) or drop (1)
+		incoming data while output port is in reset.
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/outputs/[0-7]_null
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RW) STP NULL packet generation: enabled (1) or disabled (0).
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/outputs/[0-7]_flush
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RW) Force flush data from byte packing buffer for the output
+		port.
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/outputs/[0-7]_reset
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RO) Output port is in reset (1).
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-gth/outputs/[0-7]_smcfreq
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:	(RW) STP sync packet frequency for the port. Specifies the
+		number of clocks between mainenance packets.