coresight: etm4x: Expose trcdevarch via sysfs

mainline inclusion
from mainline-v5.11-rc5
commit 4211bfce
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YCYK
CVE: NA

Reference: https://lore.kernel.org/r/20210201181351.1475223-23-mathieu.poirier@linaro.org

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Expose the TRCDEVARCH register via the sysfs for component
detection. Given that the TRCIDR1 may not completely identify
the ETM component and instead need to use TRCDEVARCH, expose
this via sysfs for tools to use it for identification.

Link: https://lore.kernel.org/r/20210110224850.1880240-21-suzuki.poulose@arm.com
Cc: Mike Leach <mike.leach@linaro.org>
Signed-off-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20210201181351.1475223-23-mathieu.poirier@linaro.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -371,6 +371,14 @@ Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
 Description:	(Read) Print the content of the Device ID Register
 		(0xFC8).  The value is taken directly from the HW.
 
+What:		/sys/bus/coresight/devices/etm<N>/mgmt/trcdevarch
+Date:		January 2021
+KernelVersion:	5.12
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(Read) Print the content of the Device Architecture Register
+		(offset 0xFBC).  The value is taken directly read
+		from the HW.
+
 What:		/sys/bus/coresight/devices/etm<N>/mgmt/trcdevtype
 Date:		April 2015
 KernelVersion:	4.01

drivers/hwtracing/coresight/coresight-etm4x-sysfs.c

@@ -2459,6 +2459,7 @@ static struct attribute *coresight_etmv4_mgmt_attrs[] = {
 	coresight_etm4x_reg(trcoslsr, TRCOSLSR),
 	coresight_etm4x_reg(trcconfig, TRCCONFIGR),
 	coresight_etm4x_reg(trctraceid, TRCTRACEIDR),
+	coresight_etm4x_reg(trcdevarch, TRCDEVARCH),
 	NULL,
 };