On Tue, Aug 29, 2023 at 9:42 PM Fabio Estevam <festevam@xxxxxxxxx> wrote:
>
> From: Fabio Estevam <festevam@xxxxxxx>
>
> 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.
>
> Tested on a i.MX8MM board with the following devicetree changes:
>
> thermal-zones {
> cpu-thermal {
> critical-action = "reboot";
> };
> };
>
> Signed-off-by: Fabio Estevam <festevam@xxxxxxx>
> ---
> Changes since v4:
> - Simplify the logic inside thermal_zone_device_critical(). (Rafael)
> - Declare THERMAL_CRITICAL_ACTION_SHUTDOWN = 0 so it is clear what happens
> on non-DT platforms. (Rafael)
>
> drivers/thermal/thermal_core.c | 6 +++++-
> drivers/thermal/thermal_of.c | 27 +++++++++++++++++++++++++++
> include/linux/thermal.h | 6 ++++++
> 3 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index a59700593d32..062114608667 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -320,11 +320,15 @@ void thermal_zone_device_critical(struct thermal_zone_device *tz)
> * Its a must for forced_emergency_poweroff_work to be scheduled.
> */
> int poweroff_delay_ms = CONFIG_THERMAL_EMERGENCY_POWEROFF_DELAY_MS;
> + static const char *msg = "Temperature too high";
>
> dev_emerg(&tz->device, "%s: critical temperature reached, "
> "shutting down\n", tz->type);
>
> - hw_protection_shutdown("Temperature too high", poweroff_delay_ms);
> + if (tz->action == THERMAL_CRITICAL_ACTION_REBOOT)
> + hw_protection_reboot(msg, poweroff_delay_ms);
> + else
> + hw_protection_shutdown(msg, poweroff_delay_ms);
> }
> EXPORT_SYMBOL(thermal_zone_device_critical);
>
> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> index 4ca905723429..8bc28cba7406 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -218,6 +218,31 @@ static struct device_node *of_thermal_zone_find(struct device_node *sensor, int
> return tz;
> }
>
> +static const char * const critical_actions[] = {
> + [THERMAL_CRITICAL_ACTION_SHUTDOWN] = "shutdown",
> + [THERMAL_CRITICAL_ACTION_REBOOT] = "reboot",
> +};
> +
> +static void thermal_of_get_critical_action(struct device_node *np,
> + enum thermal_action *action)
> +{
> + const char *action_string;
> + int i, ret;
> +
> + ret = of_property_read_string(np, "critical-action", &action_string);
> + if (ret < 0)
> + goto out_default_action;
> +
> + for (i = 0; i < ARRAY_SIZE(critical_actions); i++)
> + if (!strcasecmp(action_string, critical_actions[i])) {
> + *action = i;
> + return;
> + }
This looks somewhat artificial and is a bit questionable (the index
variable should arguably start at THERMAL_CRITICAL_ACTION_SHUTDOWN,
for instance, and the "shutdown" item is redundant).
There are only two values and you want to carry out an emergency
shutdown anyway if the value is not "reboot".
I would just do
if (!strcasecmp(action_string, "reboot")) {
*action = THERMAL_CRITICAL_ACTION_REBOOT;
return;
}
> +
> +out_default_action:
> + *action = THERMAL_CRITICAL_ACTION_SHUTDOWN;
> +}
> +
> static int thermal_of_monitor_init(struct device_node *np, int *delay, int *pdelay)
> {
> int ret;
> @@ -516,6 +541,8 @@ static struct thermal_zone_device *thermal_of_zone_register(struct device_node *
> goto out_kfree_trips;
> }
>
> + thermal_of_get_critical_action(np, &tz->action);
> +
> ret = thermal_zone_device_enable(tz);
> if (ret) {
> pr_err("Failed to enabled thermal zone '%s', id=%d: %d\n",
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index b449a46766f5..b68e5734823d 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -34,6 +34,11 @@ struct thermal_cooling_device;
> struct thermal_instance;
> struct thermal_attr;
>
> +enum thermal_action {
> + THERMAL_CRITICAL_ACTION_SHUTDOWN = 0, /* shutdown when crit temperature is reached */
> + THERMAL_CRITICAL_ACTION_REBOOT, /* reboot when crit temperature is reached */
> +};
> +
> enum thermal_trend {
> THERMAL_TREND_STABLE, /* temperature is stable */
> THERMAL_TREND_RAISING, /* temperature is raising */
> @@ -187,6 +192,7 @@ struct thermal_zone_device {
> struct list_head node;
> struct delayed_work poll_queue;
> enum thermal_notify_event notify_event;
> + enum thermal_action action;
> };
>
> /**
> --
