linux-kernel - [RFC PATCH 4/4] docs: ABI: Add sysfs documentation interface of hardware prefetch driver

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Date:   Mon, 11 Oct 2021 13:39:52 +0900
From:   Kohei Tarumizu <tarumizu.kohei@...itsu.com>
To:     hpa@...or.com, tglx@...utronix.de, mingo@...hat.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Cc:     tarumizu.kohei@...itsu.com
Subject: [RFC PATCH 4/4] docs: ABI: Add sysfs documentation interface of hardware prefetch driver

This descrives the sysfs interface implemented on the hardware prefetch
driver.

Signed-off-by: Kohei Tarumizu <tarumizu.kohei@...itsu.com>
---
 .../ABI/testing/sysfs-devices-system-cpu      | 58 +++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index b46ef1476..caeefd320 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -666,3 +666,61 @@ Description:	Preferred MTE tag checking mode
 		================  ==============================================
 
 		See also: Documentation/arm64/memory-tagging-extension.rst
+
+What:		/sys/devices/system/cpu/cpu*/hwpf/l*/enable
+		/sys/devices/system/cpu/cpu*/hwpf/l*/available_dist
+		/sys/devices/system/cpu/cpu*/hwpf/l*/dist
+		/sys/devices/system/cpu/cpu*/hwpf/l*/reliable
+Date:		October 2021
+Contact:	Kohei Tarumizu <tarumizu.kohei@...itsu.com>
+		Linux kernel mailing list <linux-kernel@...r.kernel.org>
+Description:	Parameters for the hardware prefetch driver
+
+		This sysfs interface provides Hardware Prefetch (HWPF) tunable
+		attribute files by using implementation defined registers.
+		These attribute files are corresponding to the cache level of
+		the parent directory.
+
+		enable:
+			Read/write interface to change hardware prefetch
+			enablement.
+			Read returns hardware prefetch enablement status:
+				0: hardware prefetch is enabled
+				1: hardware prefetch is disabled
+
+			Write '0' to enable Hardware Prefetch.
+			Write '1' to disable Hardware Prefetch.
+
+		available_dist:
+			Read only interface to get a list of values that can be
+			written to dist.
+
+		dist:
+			Read/write interface to specify the hardware prefetch
+			distance.
+			Read return the current hardware prefetch distance value
+			in bytes or the string "auto".
+
+			Write either a value in byte read from available_dist,
+			or the string "auto" to this attribuite. If you write
+			a value less than these, the value is rounded up.
+
+			The value 0 and the string "auto" are the same and have
+			a special meaning. This means that instead of setting
+			dist to a user-specified value, it operates using
+			hardware-specific values.
+
+		strong:
+			Read/write interface to change hardware prefetch
+			strongness.
+			Strong prefetch operation is surely executed, if there
+			is no corresponding data in cache.
+			Weak prefetch operation allows the hardware not to
+			execute operation depending on hardware state.
+
+			Read returns hardware prefetch strongness status:
+				0: hardware prefetch is generated strong
+				1: hardware prefetch is generated weak
+
+			Write '0' to hardware prefetch generate strong.
+			Write '1' to hardware prefetch generate weak.
-- 
2.27.0