reboot: add support for configuring emergency hardware protection action

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

In the general case, however, the driver detecting the issue can't know
what the appropriate course of action is and shouldn't be dictating the
policy of dealing with it.

Therefore, add a global hw_protection toggle that allows the user to
specify whether shutdown or reboot should be the default action when the
driver doesn't set policy.

This introduces no functional change yet as hw_protection_trigger() has no
callers, but these will be added in subsequent commits.

[arnd@arndb.de: hide unused hw_protection_attr]
  Link: https://lkml.kernel.org/r/20250224141849.1546019-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-7-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 21 insertions, 1 deletions

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 53c64e31b3cf..79e02876f2ba 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -181,16 +181,36 @@ extern void orderly_reboot(void);
 /**
  * enum hw_protection_action - Hardware protection action
  *
+ * @HWPROT_ACT_DEFAULT:
+ *      The default action should be taken. This is HWPROT_ACT_SHUTDOWN
+ *      by default, but can be overridden.
  * @HWPROT_ACT_SHUTDOWN:
  *	The system should be shut down (powered off) for HW protection.
  * @HWPROT_ACT_REBOOT:
  *	The system should be rebooted for HW protection.
  */
-enum hw_protection_action { HWPROT_ACT_SHUTDOWN, HWPROT_ACT_REBOOT };
+enum hw_protection_action { HWPROT_ACT_DEFAULT, HWPROT_ACT_SHUTDOWN, HWPROT_ACT_REBOOT };
 
 void __hw_protection_trigger(const char *reason, int ms_until_forced,
 			     enum hw_protection_action action);
 
+/**
+ * hw_protection_trigger - Trigger default emergency system hardware protection action
+ *
+ * @reason:		Reason of emergency shutdown or reboot to be printed.
+ * @ms_until_forced:	Time to wait for orderly shutdown or reboot before
+ *			triggering it. Negative value disables the forced
+ *			shutdown or reboot.
+ *
+ * Initiate an emergency system shutdown or reboot in order to protect
+ * hardware from further damage. The exact action taken is controllable at
+ * runtime and defaults to shutdown.
+ */
+static inline void hw_protection_trigger(const char *reason, int ms_until_forced)
+{
+	__hw_protection_trigger(reason, ms_until_forced, HWPROT_ACT_DEFAULT);
+}
+
 static inline void hw_protection_reboot(const char *reason, int ms_until_forced)
 {
 	__hw_protection_trigger(reason, ms_until_forced, HWPROT_ACT_REBOOT);