linux-kernel - [PATCH v4 6/8] cpufreq: CPPC: Add sysfs for min/max_perf and perf

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Message-ID: <20251105113844.4086250-7-sumitg@nvidia.com>
Date: Wed, 5 Nov 2025 17:08:42 +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>, <rdunlap@...radead.org>, <ray.huang@....com>,
	<gautham.shenoy@....com>, <mario.limonciello@....com>, <perry.yuan@....com>,
	<ionela.voinescu@....com>, <zhanjie9@...ilicon.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>, <nhartman@...dia.com>, <bbasu@...dia.com>,
	<sumitg@...dia.com>
Subject: [PATCH v4 6/8] 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.

Reviewed-by: Randy Dunlap <rdunlap@...radead.org>
Signed-off-by: Sumit Gupta <sumitg@...dia.com>
---
 .../ABI/testing/sysfs-devices-system-cpu      | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 8aed6d94c4cd..6f1f70696000 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -327,6 +327,52 @@ 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:		December 2025
+Contact:	linux-pm@...r.kernel.org
+Description:	Minimum Performance Frequency
+
+		Read/write a frequency value in kHz from/to this file. This
+		file conveys the minimum performance level (as frequency) at
+		which the platform may run. The frequency value is internally
+		converted to a performance value and must correspond to a
+		performance level in the range [Lowest Performance, Highest
+		Performance], inclusive. The minimum must be less than or equal
+		to the maximum performance. The performance range can be checked
+		from nodes:
+			/sys/devices/system/cpu/cpuX/acpi_cppc/highest_perf
+			/sys/devices/system/cpu/cpuX/acpi_cppc/lowest_perf
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/max_perf
+Date:		December 2025
+Contact:	linux-pm@...r.kernel.org
+Description:	Maximum Performance Frequency
+
+		Read/write a frequency value in kHz from/to this file. This
+		file conveys the maximum performance level (as frequency) at
+		which the platform may run. The frequency value is internally
+		converted to a performance value and must correspond to a
+		performance level in the range [Lowest Performance, Highest
+		Performance], inclusive. The performance range can be checked
+		from nodes:
+			/sys/devices/system/cpu/cpuX/acpi_cppc/highest_perf
+			/sys/devices/system/cpu/cpuX/acpi_cppc/lowest_perf
+
+		This file is only present if the cppc-cpufreq driver is in use.
+
+What:		/sys/devices/system/cpu/cpuX/cpufreq/perf_limited
+Date:		December 2025
+Contact:	linux-pm@...r.kernel.org
+Description:	Performance Limited
+
+		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