coresight-etm4x: Read only access to the tracer's ID registers

ETM ID registers contain valuable information about the capabilities
of the implementation and are very useful when configuring the device for
various trace scenarios.
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

@@ -358,3 +358,93 @@ KernelVersion:	4.01
 Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
 Description:	(R) Print the content of the Peripheral ID3 Register
 		(0xFEC).  The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr0
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the tracing capabilities of the trace unit (0x1E0).
+		The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr1
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the tracing capabilities of the trace unit (0x1E4).
+		The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr2
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the maximum size of the data value, data address,
+		VMID, context ID and instuction address in the trace unit
+		(0x1E8).  The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr3
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the value associated with various resources
+		available to the trace unit.  See the Trace Macrocell
+		architecture specification for more details (0x1E8).
+		The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr4
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns how many resources the trace unit supports (0x1F0).
+		The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr5
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns how many resources the trace unit supports (0x1F4).
+		The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr8
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the maximum speculation depth of the instruction
+		trace stream. (0x180).  The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr9
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the number of P0 right-hand keys that the trace unit
+		can use (0x184).  The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr10
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the number of P1 right-hand keys that the trace unit
+		can use (0x188).  The value is taken directly from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr11
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the number of special P1 right-hand keys that the
+		trace unit can use (0x18C).  The value is taken directly from
+		the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr12
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the number of conditional P1 right-hand keys that
+		the trace unit can use (0x190).  The value is taken directly
+		from the HW.
+
+What:		/sys/bus/coresight/devices/<memory_map>.etm/trcidr/trcidr13
+Date:		April 2015
+KernelVersion:	4.01
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) Returns the number of special conditional P1 right-hand keys
+		that the trace unit can use (0x194).  The value is taken
+		directly from the HW.

drivers/hwtracing/coresight/coresight-etm4x.c

@@ -2238,6 +2238,37 @@ static struct attribute *coresight_etmv4_mgmt_attrs[] = {
 	NULL,
 };
 
+coresight_simple_func(trcidr0, TRCIDR0);
+coresight_simple_func(trcidr1, TRCIDR1);
+coresight_simple_func(trcidr2, TRCIDR2);
+coresight_simple_func(trcidr3, TRCIDR3);
+coresight_simple_func(trcidr4, TRCIDR4);
+coresight_simple_func(trcidr5, TRCIDR5);
+/* trcidr[6,7] are reserved */
+coresight_simple_func(trcidr8, TRCIDR8);
+coresight_simple_func(trcidr9, TRCIDR9);
+coresight_simple_func(trcidr10, TRCIDR10);
+coresight_simple_func(trcidr11, TRCIDR11);
+coresight_simple_func(trcidr12, TRCIDR12);
+coresight_simple_func(trcidr13, TRCIDR13);
+
+static struct attribute *coresight_etmv4_trcidr_attrs[] = {
+	&dev_attr_trcidr0.attr,
+	&dev_attr_trcidr1.attr,
+	&dev_attr_trcidr2.attr,
+	&dev_attr_trcidr3.attr,
+	&dev_attr_trcidr4.attr,
+	&dev_attr_trcidr5.attr,
+	/* trcidr[6,7] are reserved */
+	&dev_attr_trcidr8.attr,
+	&dev_attr_trcidr9.attr,
+	&dev_attr_trcidr10.attr,
+	&dev_attr_trcidr11.attr,
+	&dev_attr_trcidr12.attr,
+	&dev_attr_trcidr13.attr,
+	NULL,
+};
+
 static const struct attribute_group coresight_etmv4_group = {
 	.attrs = coresight_etmv4_attrs,
 };
@@ -2247,9 +2278,15 @@ static const struct attribute_group coresight_etmv4_mgmt_group = {
 	.name = "mgmt",
 };
 
+static const struct attribute_group coresight_etmv4_trcidr_group = {
+	.attrs = coresight_etmv4_trcidr_attrs,
+	.name = "trcidr",
+};
+
 static const struct attribute_group *coresight_etmv4_groups[] = {
 	&coresight_etmv4_group,
 	&coresight_etmv4_mgmt_group,
+	&coresight_etmv4_trcidr_group,
 	NULL,
 };