linux-kernel - [PATCH v2 8/8] thermal: core: Record PSCR before hw_protection

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Date: Wed, 24 Jan 2024 13:22:04 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Sebastian Reichel <sre@...nel.org>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	kernel@...gutronix.de,
	linux-kernel@...r.kernel.org,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Lukasz Luba <lukasz.luba@....com>,
	linux-pm@...r.kernel.org,
	devicetree@...r.kernel.org,
	Søren Andersen <san@...v.dk>
Subject: [PATCH v2 8/8] thermal: core: Record PSCR before hw_protection_shutdown()

Enhance the thermal core to record the Power State Change Reason (PSCR)
prior to invoking hw_protection_shutdown(). This change integrates the
PSCR framework with the thermal subsystem, ensuring that reasons for
power state changes, such as overtemperature events, are stored in a
dedicated non-volatile memory (NVMEM) cell.

This 'black box' recording is crucial for post-mortem analysis, enabling
a deeper understanding of system failures and abrupt shutdowns,
especially in scenarios where PMICs or watchdog timers are incapable of
logging such events.  The recorded data can be utilized during system
recovery routines in the bootloader or early kernel stages of subsequent
boots, significantly enhancing system diagnostics, reliability, and
debugging capabilities.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/thermal/thermal_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index dfaa6341694a..0511d82351c5 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -16,6 +16,7 @@
 #include <linux/kdev_t.h>
 #include <linux/idr.h>
 #include <linux/thermal.h>
+#include <linux/pscrr.h>
 #include <linux/reboot.h>
 #include <linux/string.h>
 #include <linux/of.h>
@@ -329,6 +330,8 @@ static void thermal_zone_device_halt(struct thermal_zone_device *tz, bool shutdo

 	dev_emerg(&tz->device, "%s: critical temperature reached\n", tz->type);

+	set_power_state_change_reason(PSCR_OVERTEMPERATURE);
+
 	if (shutdown)
 		hw_protection_shutdown(msg, poweroff_delay_ms);
 	else
-- 
2.39.2