linux-kernel - [PATCH v2 6/7] cpufreq: CPPC: Add sysfs for min/max_perf and perf

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Message-ID: <20250823200121.1320197-7-sumitg@nvidia.com>
Date: Sun, 24 Aug 2025 01:31:19 +0530
From: Sumit Gupta <sumitg@...dia.com>
To: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <lenb@...nel.org>,
	<robert.moore@...el.com>, <corbet@....net>, <pierre.gondois@....com>,
	<zhenglifeng1@...wei.com>, <ray.huang@....com>, <gautham.shenoy@....com>,
	<mario.limonciello@....com>, <perry.yuan@....com>,
	<linux-pm@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <acpica-devel@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>
CC: <linux-tegra@...r.kernel.org>, <treding@...dia.com>,
	<jonathanh@...dia.com>, <vsethi@...dia.com>, <ksitaraman@...dia.com>,
	<sanjayc@...dia.com>, <bbasu@...dia.com>, <sumitg@...dia.com>
Subject: [PATCH v2 6/7] cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited

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

Signed-off-by: Sumit Gupta <sumitg@...dia.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..4bce0dbc48c9 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:           Aug 2025
+Contact:        linux-pm@...r.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:           Aug 2025
+Contact:        linux-pm@...r.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:           Aug 2025
+Contact:        linux-pm@...r.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