[PATCH v6 7/7] Documentation: Add sysfs documentation for PSCRR reboot reason tracking

[Oleksij Rempel]

Add documentation for the Power State Change Reason Recorder (PSCRR)
sysfs interface, which allows tracking of system shutdown and reboot
reasons. The documentation provides details on available sysfs entries
under `/sys/kernel/pscrr/`, explaining their functionality, example usage,
and how they interact with different backend storage options (e.g., NVMEM).

Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
 .../ABI/testing/sysfs-kernel-reboot-pscrr     | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-reboot-pscrr

diff --git a/Documentation/ABI/testing/sysfs-kernel-reboot-pscrr b/Documentation/ABI/testing/sysfs-kernel-reboot-pscrr
new file mode 100644
index 000000000000..7cc643f89675
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-reboot-pscrr
@@ -0,0 +1,46 @@
+What:		/sys/kernel/pscrr/reason
+Date:		April 2025
+KernelVersion:  6.15
+Contact:	Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
+Description:
+		This file provides access to the last recorded power state
+		change reason. The storage backend is configurable and, if
+		supported, the reason may be stored persistently in an
+		NVMEM cell or another backend.
+
+		Reading this file returns an integer representing the last
+		recorded shutdown or reboot cause.
+
+		Writing an integer value to this file sets the reason to be
+		stored and recorded for system analysis.
+
+		Example usage (values are for illustration and may not reflect
+		actual reasons used in a given system):
+		  Read:
+			$ cat /sys/kernel/pscrr/reason
+			3   # (Example: Power loss event, may differ per system)
+
+		  Write:
+			$ echo 5 > /sys/kernel/pscrr/reason
+			# Sets the reason to 5 (Example: User-triggered reboot,
+			# this may not be a real value in your system)
+
+		Values are defined in:
+		  - `include/linux/reboot.h` (enum psc_reason)
+
+What:		/sys/kernel/pscrr/reason_boot
+Date:		April 2025
+KernelVersion:  6.15
+Contact:	Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
+Description:
+		This file provides the last recorded power state change reason
+		from before the current system boot. If a supported backend
+		(e.g., NVMEM) is configured, this value is retained across
+		reboots.
+
+		Example usage (values are for illustration and may not reflect
+		actual reasons used in a given system):
+		  Read:
+			$ cat /sys/kernel/pscrr/reason_boot
+			2   # (Example: Over-temperature shutdown, may differ per system)
+
-- 
2.39.5