intel_th: Add Memory Storage Unit driver

Memory Storage Unit (MSU) is a trace output device that collects trace
data to system memory. It consists of 2 independent Memory Storage
Controllers (MSCs).

This driver provides userspace interfaces to configure in-memory tracing
parameters, such as contiguous (high-order allocation) buffer or multiblock
(scatter list) buffer mode, wrapping (data overwrite) and number and sizes
of windows in multiblock mode. Userspace can read the buffers via mmap()ing
or read()ing of the corresponding device node.

Signed-off-by: Laurent Fert <[email protected]>
Signed-off-by: Alexander Shishkin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: virtuoso

Documentation/ABI/testing/sysfs-bus-intel_th-devices-msc

@@ -0,0 +1,33 @@
+What:		/sys/bus/intel_th/devices/<intel_th_id>-msc<msc-id>/wrap
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <[email protected]>
+Description:	(RW) Configure MSC buffer wrapping. 1 == wrapping enabled.
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-msc<msc-id>/mode
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <[email protected]>
+Description:	(RW) Configure MSC operating mode:
+		  - "single", for contiguous buffer mode (high-order alloc);
+		  - "multi", for multiblock mode;
+		  - "ExI", for DCI handler mode;
+		  - "debug", for debug mode.
+		If operating mode changes, existing buffer is deallocated,
+		provided there are no active users and tracing is not enabled,
+		otherwise the write will fail.
+
+What:		/sys/bus/intel_th/devices/<intel_th_id>-msc<msc-id>/nr_pages
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <[email protected]>
+Description:	(RW) Configure MSC buffer size for "single" or "multi" modes.
+		In single mode, this is a single number of pages, has to be
+		power of 2. In multiblock mode, this is a comma-separated list
+		of numbers of pages for each window to be allocated. Number of
+		windows is not limited.
+		Writing to this file deallocates existing buffer (provided
+		there are no active users and tracing is not enabled) and then
+		allocates a new one.
+
+

drivers/hwtracing/intel_th/Kconfig

@@ -44,6 +44,16 @@ config INTEL_TH_STH
 
 	  Say Y here to enable STH subdevice of Intel(R) Trace Hub.
 
+config INTEL_TH_MSU
+	tristate "Intel(R) Trace Hub Memory Storage Unit"
+	help
+	  Memory Storage Unit (MSU) trace output device enables
+	  storing STP traces to system memory. It supports single
+	  and multiblock modes of operation and provides read()
+	  and mmap() access to the collected data.
+
+	  Say Y here to enable MSU output device for Intel TH.
+
 config INTEL_TH_DEBUG
 	bool "Intel(R) Trace Hub debugging"
 	depends on DEBUG_FS

drivers/hwtracing/intel_th/Makefile

@@ -10,3 +10,6 @@ intel_th_gth-y			:= gth.o
 
 obj-$(CONFIG_INTEL_TH_STH)	+= intel_th_sth.o
 intel_th_sth-y			:= sth.o
+
+obj-$(CONFIG_INTEL_TH_MSU)	+= intel_th_msu.o
+intel_th_msu-y			:= msu.o