coresight-etm4x: Adding CoreSight ETM4x driver

This driver manages the CoreSight ETMv4 (Embedded Trace Macrocell) IP block
to support HW assisted tracing on ARMv7 and ARMv8 architectures.
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>
Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x

+What:		/sys/bus/coresight/devices/<memory_map>.etm/enable_source
+Date:		April 2015
+KernelVersion:  4.01
+Contact:        Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Enable/disable tracing on this specific trace entiry.
+		Enabling a source implies the source has been configured
+		properly and a sink has been identidifed for it.  The path
+		of coresight components linking the source to the sink is
+		configured and managed automatically by the coresight framework.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/cpu
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) The CPU this tracing entity is associated with.

drivers/hwtracing/coresight/Kconfig

@@ -58,4 +58,15 @@ config CORESIGHT_SOURCE_ETM3X
 	  which allows tracing the instructions that a processor is executing
 	  This is primarily useful for instruction level tracing.  Depending
 	  the ETM version data tracing may also be available.
+
+config CORESIGHT_SOURCE_ETM4X
+	bool "CoreSight Embedded Trace Macrocell 4.x driver"
+	depends on ARM64
+	select CORESIGHT_LINKS_AND_SINKS
+	help
+	  This driver provides support for the ETM4.x tracer module, tracing the
+	  instructions that a processor is executing. This is primarily useful
+	  for instruction level tracing. Depending on the implemented version
+	  data tracing may also be available.
+
 endif

drivers/hwtracing/coresight/Makefile

@@ -9,3 +9,4 @@ obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
 obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
 					   coresight-replicator.o
 obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o coresight-etm-cp14.o
+obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o