cpufreq: CPPC: Add support for autonomous selection

Add sysfs interfaces for CPPC autonomous selection in the cppc_cpufreq
driver.

Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Reviewed-by: Sumit Gupta <sumitg@nvidia.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://patch.msgid.link/20250507031941.2812701-1-zhenglifeng1@huawei.com
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 206079d3bd5b..37065e1b8ebc 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -268,6 +268,60 @@ Description:	Discover CPUs in the same CPU frequency coordination domain
 		This file is only present if the acpi-cpufreq or the cppc-cpufreq
 		drivers are in use.
 
+What:		/sys/devices/system/cpu/cpuX/cpufreq/auto_select
+Date:		May 2025
+Contact:	linux-pm@vger.kernel.org
+Description:	Autonomous selection enable
+
+		Read/write interface to control autonomous selection enable
+			Read returns autonomous selection status:
+				0: autonomous selection is disabled
+				1: autonomous selection is enabled
+
+			Write 'y' or '1' or 'on' to enable autonomous selection.
+			Write 'n' or '0' or 'off' to disable autonomous selection.
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/auto_act_window
+Date:		May 2025
+Contact:	linux-pm@vger.kernel.org
+Description:	Autonomous activity window
+
+		This file indicates a moving utilization sensitivity window to
+		the platform's autonomous selection policy.
+
+		Read/write an integer represents autonomous activity window (in
+		microseconds) from/to this file. The max value to write is
+		1270000000 but the max significand is 127. This means that if 128
+		is written to this file, 127 will be stored. If the value is
+		greater than 130, only the first two digits will be saved as
+		significand.
+
+		Writing a zero value to this file enable the platform to
+		determine an appropriate Activity Window depending on the workload.
+
+		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/energy_performance_preference_val
+Date:		May 2025
+Contact:	linux-pm@vger.kernel.org
+Description:	Energy performance preference
+
+		Read/write an 8-bit integer from/to this file. This file
+		represents a range of values from 0 (performance preference) to
+		0xFF (energy efficiency preference) that influences the rate of
+		performance increase/decrease and the result of the hardware's
+		energy efficiency and performance optimization policies.
+
+		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/cpu*/cache/index3/cache_disable_{0,1}
 Date:		August 2008