[PATCH v3 6/8] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited

[Sumit Gupta <sumitg@nvidia.com>]

Add sysfs interfaces for Minimum Performance, Maximum Performance
and Performance Limited Register in the cppc_cpufreq driver.

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 .../ABI/testing/sysfs-devices-system-cpu      | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index ab8cd337f43a..82141b45d58c 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -327,6 +327,49 @@ Description:	Energy performance preference
 
 		This file is only present if the cppc-cpufreq driver is in use.
 
+What:		/sys/devices/system/cpu/cpuX/cpufreq/min_perf
+Date:		September 2025
+Contact:	linux-pm@vger.kernel.org
+Description:	Minimum Performance
+
+		Read/write a 32 bits value from/to this file. This file
+		conveys the minimum performance level at which the platform
+		may run. Minimum performance may be set to any performance
+		value in the range [Lowest Performance, Highest Performance],
+		inclusive but must be set to a value that is less than or
+		equal to that specified by the Maximum Performance Register.
+
+		Writing to this file only has meaning when Autonomous Selection
+		is enabled.
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/max_perf
+Date:		September 2025
+Contact:	linux-pm@vger.kernel.org
+Description:	Minimum Performance
+
+		Read/write a 32 bits value from/to this file. This file conveys
+		the maximum performance level at which the platform may run.
+		Maximum performance may be set to any performance value in the
+		range [Lowest Performance, Highest Performance], inclusive.
+
+		Writing to this file only has meaning when Autonomous Selection is
+		enabled.
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/perf_limited
+Date:		September 2025
+Contact:	linux-pm@vger.kernel.org
+Description:	Minimum Performance
+
+		Read/write a 32 bits value from/to this file. This file indicates
+		to OSPM that an unpredictable event has limited processor
+		performance, and the delivered performance may be less than
+		desired/minimum performance.
+
+		This file is only present if the cppc-cpufreq driver is in use.
 
 What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
 Date:		August 2008
-- 
2.34.1