Re: [PATCH] thermal: omap-thermal: Add notify function to thermal_zone_device_ops

[Keerthy <a0393675@ti.com>]

Eduardo,

On Tuesday 16 February 2016 10:35 AM, Keerthy wrote:
> notify function is used to notify when some temperature thresholds
> are crossed. In case we get notified for a critical trip point then
> schedule an emergency shutdown function to backup orderly_poweroff
> failures.
>
> orderly_poweroff is triggered when a graceful shutdown
> of system is desired. This may be used in many critical states of the
> kernel such as when subsystems detects conditions such as critical
> temperature conditions. However, in certain conditions in system
> boot up sequences like those in the middle of driver probes being
> initiated, userspace will be unable to power off the system in a clean
> manner and leaves the system in a critical state. In cases like these,
> the /sbin/poweroff will return success (having forked off to attempt
> powering off the system. However, the system overall will fail to
> completely poweroff (since other modules will be probed) and the system
> is still functional with no userspace (since that would have shut itself
> off).
>
> However, there is no clean way of detecting such failure of userspace
> powering off the system. In such scenarios, it is necessary for a backup
> workqueue to be able to force a shutdown of the system when orderly
> shutdown is not successful after a configurable time period.
>

A gentle ping on this.

> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
>
> The previous discussion:
>
> https://lkml.org/lkml/2016/1/28/989
>
> Making use of the notify ops to schedule a backup thermal shutdown.
>
>   drivers/thermal/ti-soc-thermal/Kconfig             | 13 +++++++
>   drivers/thermal/ti-soc-thermal/ti-thermal-common.c | 43 ++++++++++++++++++++++
>   2 files changed, 56 insertions(+)
>
> diff --git a/drivers/thermal/ti-soc-thermal/Kconfig b/drivers/thermal/ti-soc-thermal/Kconfig
> index ea8283f..b4b9668 100644
> --- a/drivers/thermal/ti-soc-thermal/Kconfig
> +++ b/drivers/thermal/ti-soc-thermal/Kconfig
> @@ -71,3 +71,16 @@ config DRA752_THERMAL
>
>   	  This includes alert interrupts generation and also the TSHUT
>   	  support.
> +
> +config TI_THERMAL_EMERGENCY_POWEROFF_DELAY_MS
> +	int "Emergency poweroff delay in milli-seconds"
> +	depends on TI_SOC_THERMAL
> +	default 0
> +	help
> +	  The number of milliseconds to delay before emergency
> +	  poweroff kicks in. The delay should be carefully profiled
> +	  so as to give adequate time for orderly_poweroff. In case
> +	  of failure of an orderly_poweroff the emergency poweroff
> +	  kicks in after the delay has elapsed and shuts down the system.
> +
> +	  If set to 0 poweroff will happen immediately.
> diff --git a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> index b213a12..d48eb5b1 100644
> --- a/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> +++ b/drivers/thermal/ti-soc-thermal/ti-thermal-common.c
> @@ -31,6 +31,7 @@
>   #include <linux/cpumask.h>
>   #include <linux/cpu_cooling.h>
>   #include <linux/of.h>
> +#include <linux/reboot.h>
>
>   #include "ti-thermal.h"
>   #include "ti-bandgap.h"
> @@ -286,6 +287,47 @@ static int ti_thermal_get_crit_temp(struct thermal_zone_device *thermal,
>   	return ti_thermal_get_trip_temp(thermal, OMAP_TRIP_NUMBER - 1, temp);
>   }
>
> +/**
> + * emergency_poweroff_func - emergency poweroff work after a known delay
> + * @work: work_struct associated with the emergency poweroff function
> + *
> + * This function is called in very critical situations to force
> + * a kernel poweroff after a configurable timeout value.
> + */
> +static void emergency_poweroff_func(struct work_struct *work)
> +{
> +	pr_warn("Attempting kernel_power_off\n");
> +	kernel_power_off();
> +
> +	pr_warn("kernel_power_off has failed! Attempting emergency_restart\n");
> +	emergency_restart();
> +}
> +
> +static DECLARE_DELAYED_WORK(emergency_poweroff_work, emergency_poweroff_func);
> +
> +/**
> + * emergency_poweroff - Trigger an emergency system poweroff
> + *
> + * This may be called from any critical situation to trigger a system shutdown
> + * after a known period of time. By default the delay is 0 millisecond
> + */
> +void ti_thermal_emergency_poweroff(void)
> +{
> +	schedule_delayed_work(&emergency_poweroff_work,
> +	msecs_to_jiffies(CONFIG_TI_THERMAL_EMERGENCY_POWEROFF_DELAY_MS));
> +}
> +
> +static int ti_thermal_notify(struct thermal_zone_device *thermal, int temp,
> +			     enum thermal_trip_type type)
> +{
> +	if (type == THERMAL_TRIP_CRITICAL) {
> +		pr_warn("critical temperature %d reached", temp);
> +		ti_thermal_emergency_poweroff();
> +	}
> +
> +	return 0;
> +}
> +
>   static const struct thermal_zone_of_device_ops ti_of_thermal_ops = {
>   	.get_temp = __ti_thermal_get_temp,
>   	.get_trend = __ti_thermal_get_trend,
> @@ -301,6 +343,7 @@ static struct thermal_zone_device_ops ti_thermal_ops = {
>   	.get_trip_type = ti_thermal_get_trip_type,
>   	.get_trip_temp = ti_thermal_get_trip_temp,
>   	.get_crit_temp = ti_thermal_get_crit_temp,
> +	.notify = ti_thermal_notify,
>   };
>
>   static struct ti_thermal_data
>