[PATCH 3/3] Documentation: Document sysfs interfaces purr, spurr, idle_purr, idle_spurr

[Gautham R. Shenoy]

From: "Gautham R. Shenoy" <ego at linux.vnet.ibm.com>

Add documentation for the following sysfs interfaces:
/sys/devices/system/cpu/cpuX/purr
/sys/devices/system/cpu/cpuX/spurr
/sys/devices/system/cpu/cpuX/idle_purr
/sys/devices/system/cpu/cpuX/idle_spurr

Signed-off-by: Gautham R. Shenoy <ego at linux.vnet.ibm.com>
---
 Documentation/ABI/testing/sysfs-devices-system-cpu | 39 ++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index fc20cde..ecd23fb 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -574,3 +574,42 @@ Description:	Secure Virtual Machine
 		If 1, it means the system is using the Protected Execution
 		Facility in POWER9 and newer processors. i.e., it is a Secure
 		Virtual Machine.
+
+What: 		/sys/devices/system/cpu/cpuX/purr
+Date:		Apr 2005
+Contact:	Linux for PowerPC mailing list <linuxppc-dev at ozlabs.org>
+Description:	PURR ticks for this CPU since the system boot.
+
+		The Processor Utilization Resources Register (PURR) is
+		a 64-bit counter which provides an estimate of the
+		resources used by the CPU thread. The contents of this
+		register increases monotonically. This sysfs interface
+		exposes the number of PURR ticks for cpuX.
+
+What: 		/sys/devices/system/cpu/cpuX/spurr
+Date:		Dec 2006
+Contact:	Linux for PowerPC mailing list <linuxppc-dev at ozlabs.org>
+Description:	SPURR ticks for this CPU since the system boot.
+
+		The Scaled Processor Utilization Resources Register
+		(SPURR) is a 64-bit counter that provides a frequency
+		invariant estimate of the resources used by the CPU
+		thread. The contents of this register increases
+		monotonically. This sysfs interface exposes the number
+		of SPURR ticks for cpuX.
+
+What: 		/sys/devices/system/cpu/cpuX/idle_purr
+Date:		Nov 2019
+Contact:	Linux for PowerPC mailing list <linuxppc-dev at ozlabs.org>
+Description:	PURR ticks for cpuX when it was idle.
+
+		This sysfs interface exposes the number of PURR ticks
+		for cpuX when it was idle.
+
+What: 		/sys/devices/system/cpu/cpuX/spurr
+Date:		Nov 2019
+Contact:	Linux for PowerPC mailing list <linuxppc-dev at ozlabs.org>
+Description:	SPURR ticks for cpuX when it was idle.
+
+		This sysfs interface exposes the number of SPURR ticks
+		for cpuX when it was idle.
-- 
1.9.4