[PATCH v11 1/4] dt-bindings: thermal-zones: Document critical-action

[PATCH v11 1/4] dt-bindings: thermal-zones: Document critical-action

[Fabio Estevam]

From: Fabio Estevam <festevam@denx.de>

Document the critical-action property to describe the thermal action
the OS should perform after the critical temperature is reached.

The possible values are "shutdown" and "reboot".

The motivation for introducing the critical-action property is that
different systems may need different thermal actions when the critical
temperature is reached.

For example, in a desktop PC, it is desired that a shutdown happens
after the critical temperature is reached.

However, in some embedded cases, such behavior does not suit well,
as the board may be unattended in the field and rebooting may be a
better approach.

The bootloader may also benefit from this new property as it can check
the SoC temperature and in case the temperature is above the critical
point, it can trigger a shutdown or reboot accordingly.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
Changes since v10:
- None

 .../bindings/thermal/thermal-zones.yaml          | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
index 4a8dabc48170..dbd52620d293 100644
--- a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
+++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
@@ -75,6 +75,22 @@ patternProperties:
           framework and assumes that the thermal sensors in this zone
           support interrupts.
 
+      critical-action:
+        $ref: /schemas/types.yaml#/definitions/string
+        description: |
+          The action the OS should perform after the critical temperature is reached.
+          By default the system will shutdown as a safe action to prevent damage
+          to the hardware, if the property is not set.
+          The shutdown action should be always the default and preferred one.
+          Choose 'reboot' with care, as the hardware may be in thermal stress,
+          thus leading to infinite reboots that may cause damage to the hardware.
+          Make sure the firmware/bootloader will act as the last resort and take
+          over the thermal control.
+
+        enum:
+          - shutdown
+          - reboot
+
       thermal-sensors:
         $ref: /schemas/types.yaml#/definitions/phandle-array
         maxItems: 1
-- 
2.34.1

[PATCH v11 2/4] thermal_core: Prepare for introduction of thermal reboot

[Fabio Estevam]

From: Fabio Estevam <festevam@denx.de>

Add some helper functions to make it easier introducing the support
for thermal reboot.

No functional change.

Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since v10:
- None

 drivers/thermal/thermal_core.c | 14 ++++++++++----
 include/linux/reboot.h         |  7 ++++++-
 kernel/reboot.c                |  8 ++++----
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 9c17d35ccbbd..8c808ff9ddfe 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -314,18 +314,24 @@ static void handle_non_critical_trips(struct thermal_zone_device *tz,
 		       def_governor->throttle(tz, trip);
 }
 
-void thermal_zone_device_critical(struct thermal_zone_device *tz)
+static void thermal_zone_device_halt(struct thermal_zone_device *tz, bool shutdown)
 {
 	/*
 	 * poweroff_delay_ms must be a carefully profiled positive value.
 	 * Its a must for forced_emergency_poweroff_work to be scheduled.
 	 */
 	int poweroff_delay_ms = CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS;
+	const char *msg = "Temperature too high";
+
+	dev_emerg(&tz->device, "%s: critical temperature reached\n", tz->type);
 
-	dev_emerg(&tz->device, "%s: critical temperature reached, "
-		  "shutting down\n", tz->type);
+	if (shutdown)
+		hw_protection_shutdown(msg, poweroff_delay_ms);
+}
 
-	hw_protection_shutdown("Temperature too high", poweroff_delay_ms);
+void thermal_zone_device_critical(struct thermal_zone_device *tz)
+{
+	thermal_zone_device_halt(tz, true);
 }
 EXPORT_SYMBOL(thermal_zone_device_critical);
 
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index c4cc3b89ced1..4586c663884e 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -177,7 +177,12 @@ void ctrl_alt_del(void);
 
 extern void orderly_poweroff(bool force);
 extern void orderly_reboot(void);
-void hw_protection_shutdown(const char *reason, int ms_until_forced);
+void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown);
+
+static inline void hw_protection_shutdown(const char *reason, int ms_until_forced)
+{
+	__hw_protection_shutdown(reason, ms_until_forced, true);
+}
 
 /*
  * Emergency restart, callable from an interrupt handler.
diff --git a/kernel/reboot.c b/kernel/reboot.c
index c3a3b82c4f64..07eb6537ed8b 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -970,7 +970,7 @@ static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
 }
 
 /**
- * hw_protection_shutdown - Trigger an emergency system poweroff
+ * __hw_protection_shutdown - Trigger an emergency system poweroff
  *
  * @reason:		Reason of emergency shutdown to be printed.
  * @ms_until_forced:	Time to wait for orderly shutdown before tiggering a
@@ -984,7 +984,7 @@ static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
  * if the previous request has given a large timeout for forced shutdown.
  * Can be called from any context.
  */
-void hw_protection_shutdown(const char *reason, int ms_until_forced)
+void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown)
 {
 	static atomic_t allow_proceed = ATOMIC_INIT(1);
 
@@ -999,9 +999,9 @@ void hw_protection_shutdown(const char *reason, int ms_until_forced)
 	 * orderly_poweroff failure
 	 */
 	hw_failure_emergency_poweroff(ms_until_forced);
-	orderly_poweroff(true);
+	if (shutdown)
+		orderly_poweroff(true);
 }
-EXPORT_SYMBOL_GPL(hw_protection_shutdown);
 
 static int __init reboot_setup(char *str)
 {
-- 
2.34.1

[PATCH v11 3/4] reboot: Introduce thermal_zone_device_critical_reboot()

[Fabio Estevam]

From: Fabio Estevam <festevam@denx.de>

Introduce thermal_zone_device_critical_reboot() to trigger an
emergency reboot.

It is a counterpart of thermal_zone_device_critical() with the
difference that it will force a reboot instead of shutdown.

The motivation for doing this is to allow the thermal subystem
to trigger a reboot when the temperature reaches the critical
temperature.

Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since v10:
- Rebased against 6.7-rc1 and fixed a conflict.

 drivers/thermal/thermal_core.c |  7 +++++++
 include/linux/reboot.h         |  5 +++++
 include/linux/thermal.h        |  1 +
 kernel/reboot.c                | 27 ++++++++++++++++-----------
 4 files changed, 29 insertions(+), 11 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 8c808ff9ddfe..1c735f858e50 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -327,6 +327,8 @@ static void thermal_zone_device_halt(struct thermal_zone_device *tz, bool shutdo
 
 	if (shutdown)
 		hw_protection_shutdown(msg, poweroff_delay_ms);
+	else
+		hw_protection_reboot(msg, poweroff_delay_ms);
 }
 
 void thermal_zone_device_critical(struct thermal_zone_device *tz)
@@ -335,6 +337,11 @@ void thermal_zone_device_critical(struct thermal_zone_device *tz)
 }
 EXPORT_SYMBOL(thermal_zone_device_critical);
 
+void thermal_zone_device_critical_reboot(struct thermal_zone_device *tz)
+{
+	thermal_zone_device_halt(tz, false);
+}
+
 static void handle_critical_trips(struct thermal_zone_device *tz,
 				  const struct thermal_trip *trip)
 {
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 4586c663884e..abcdde4df697 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -179,6 +179,11 @@ extern void orderly_poweroff(bool force);
 extern void orderly_reboot(void);
 void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown);
 
+static inline void hw_protection_reboot(const char *reason, int ms_until_forced)
+{
+	__hw_protection_shutdown(reason, ms_until_forced, false);
+}
+
 static inline void hw_protection_shutdown(const char *reason, int ms_until_forced)
 {
 	__hw_protection_shutdown(reason, ms_until_forced, true);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index cee814d5d1ac..3644326b18ac 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -361,6 +361,7 @@ int thermal_zone_get_offset(struct thermal_zone_device *tz);
 int thermal_zone_device_enable(struct thermal_zone_device *tz);
 int thermal_zone_device_disable(struct thermal_zone_device *tz);
 void thermal_zone_device_critical(struct thermal_zone_device *tz);
+void thermal_zone_device_critical_reboot(struct thermal_zone_device *tz);
 #else
 static inline struct thermal_zone_device *thermal_zone_device_register_with_trips(
 					const char *type,
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 07eb6537ed8b..f76814037f41 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -970,19 +970,22 @@ static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
 }
 
 /**
- * __hw_protection_shutdown - Trigger an emergency system poweroff
+ * __hw_protection_shutdown - Trigger an emergency system shutdown or reboot
  *
- * @reason:		Reason of emergency shutdown to be printed.
- * @ms_until_forced:	Time to wait for orderly shutdown before tiggering a
- *			forced shudown. Negative value disables the forced
- *			shutdown.
+ * @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.
+ * @shutdown:		If true, indicates that a shutdown will happen
+ *			after the critical tempeature is reached.
+ *			If false, indicates that a reboot will happen
+ *			after the critical tempeature is reached.
  *
- * Initiate an emergency system shutdown in order to protect hardware from
- * further damage. Usage examples include a thermal protection or a voltage or
- * current regulator failures.
- * NOTE: The request is ignored if protection shutdown is already pending even
- * if the previous request has given a large timeout for forced shutdown.
- * Can be called from any context.
+ * Initiate an emergency system shutdown or reboot in order to protect
+ * hardware from further damage. Usage examples include a thermal protection.
+ * NOTE: The request is ignored if protection shutdown or reboot is already
+ * pending even if the previous request has given a large timeout for forced
+ * shutdown/reboot.
  */
 void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown)
 {
@@ -1001,6 +1004,8 @@ void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shut
 	hw_failure_emergency_poweroff(ms_until_forced);
 	if (shutdown)
 		orderly_poweroff(true);
+	else
+		orderly_reboot();
 }
 
 static int __init reboot_setup(char *str)
-- 
2.34.1

[PATCH v11 4/4] thermal: thermal_of: Allow rebooting after critical temp

[Fabio Estevam]

From: Fabio Estevam <festevam@denx.de>

Currently, the default mechanism is to trigger a shutdown after the
critical temperature is reached.

In some embedded cases, such behavior does not suit well, as the board may
be unattended in the field and rebooting may be a better approach.

The bootloader may also check the temperature and only allow the boot to
proceed when the temperature is below a certain threshold.

Introduce support for allowing a reboot to be triggered after the
critical temperature is reached.

If the "critical-action" devicetree property is not found, fall back to
the shutdown action to preserve the existing default behavior.

If a custom ops->critical exists, then it takes preference over
critical-actions.

Tested on a i.MX8MM board with the following devicetree changes:

	thermal-zones {
		cpu-thermal {
			critical-action = "reboot";
		};
	};

Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since v10:
- None

 drivers/thermal/thermal_of.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
index 1e0655b63259..4d6c22e0ed85 100644
--- a/drivers/thermal/thermal_of.c
+++ b/drivers/thermal/thermal_of.c
@@ -475,6 +475,7 @@ static struct thermal_zone_device *thermal_of_zone_register(struct device_node *
 	struct thermal_zone_params tzp = {};
 	struct thermal_zone_device_ops *of_ops;
 	struct device_node *np;
+	const char *action;
 	int delay, pdelay;
 	int ntrips, mask;
 	int ret;
@@ -511,6 +512,11 @@ static struct thermal_zone_device *thermal_of_zone_register(struct device_node *
 
 	mask = GENMASK_ULL((ntrips) - 1, 0);
 
+	ret = of_property_read_string(np, "critical-action", &action);
+	if (!ret)
+		if (!of_ops->critical && !strcasecmp(action, "reboot"))
+			of_ops->critical = thermal_zone_device_critical_reboot;
+
 	tz = thermal_zone_device_register_with_trips(np->name, trips, ntrips,
 						     mask, data, of_ops, &tzp,
 						     pdelay, delay);
-- 
2.34.1

Re: [PATCH v11 3/4] reboot: Introduce thermal_zone_device_critical_reboot()

[Daniel Lezcano]

On 19/11/2023 14:05, Fabio Estevam wrote:
> From: Fabio Estevam <festevam@denx.de>
> 
> Introduce thermal_zone_device_critical_reboot() to trigger an
> emergency reboot.
> 
> It is a counterpart of thermal_zone_device_critical() with the
> difference that it will force a reboot instead of shutdown.
> 
> The motivation for doing this is to allow the thermal subystem
> to trigger a reboot when the temperature reaches the critical
> temperature.
> 
> Signed-off-by: Fabio Estevam <festevam@denx.de>
> ---

[ ... ]

> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index cee814d5d1ac..3644326b18ac 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -361,6 +361,7 @@ int thermal_zone_get_offset(struct thermal_zone_device *tz);
>   int thermal_zone_device_enable(struct thermal_zone_device *tz);
>   int thermal_zone_device_disable(struct thermal_zone_device *tz);
>   void thermal_zone_device_critical(struct thermal_zone_device *tz);
> +void thermal_zone_device_critical_reboot(struct thermal_zone_device *tz);

It is more relevant to keep it private to the thermal core as there is 
no user of it except in the thermal-of. IOW in thermal_core.h

[ ... ]


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