On Wed, 2014-07-30 at 16:10 -0700, Matt Longnecker wrote:
> Some hardware can react autonomously at a programmed temperature.
if you have a temperature sensor, then you should have a thermal zone
device driver for it, right?
> For example, an SoC might implement a last ditch throttle or a
> hardware thermal shutdown.
And it should be handled by the thermal zone driver, who has the
knowledge of when to do throttle/shutdown.
> The driver for such a device can
> register itself as a cooling_device with the thermal framework.
>
cooling device just exports its cooling ability for thermal framework to
use. It never makes any decision about thermal control.
> With this change, the thermal framework notifies such a driver
> when userspace alters the relevant trip temperature so that
> the driver can reprogram its hardware
>
When user space alters the trip temperature, the thermal zone device
driver is aware is this change, and it can optionally program the
hardware.
thanks,
rui
> Signed-off-by: Matt Longnecker <mlongnec...@nvidia.com>
> ---
> drivers/thermal/thermal_core.c | 30 ++++++++++++++++++++++++++++++
> include/linux/thermal.h | 2 ++
> 2 files changed, 32 insertions(+)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 71b0ec0..f25272e 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -597,6 +597,7 @@ trip_point_temp_store(struct device *dev, struct
> device_attribute *attr,
> struct thermal_zone_device *tz = to_thermal_zone(dev);
> int trip, ret;
> unsigned long temperature;
> + struct thermal_instance *pos = NULL;
>
> if (!tz->ops->set_trip_temp)
> return -EPERM;
> @@ -609,6 +610,20 @@ trip_point_temp_store(struct device *dev, struct
> device_attribute *attr,
>
> ret = tz->ops->set_trip_temp(tz, trip, temperature);
>
> + /*
> + * Notify bound cooling devices that this trip point changed.
> + * This is useful for cooling devices which represent a behavior
> + * which trips in hardware (e.g. catastrophic shutdown)
> + */
> + list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
> + if (pos->tz == tz && pos->trip == trip && pos->cdev) {
> + if (pos->cdev->ops->trip_point_changed)
> + pos->cdev->ops->trip_point_changed(pos->cdev,
> + pos->tz,
> + trip);
> + }
> + }
> +
> return ret ? ret : count;
> }
>
> @@ -641,6 +656,7 @@ trip_point_hyst_store(struct device *dev, struct
> device_attribute *attr,
> struct thermal_zone_device *tz = to_thermal_zone(dev);
> int trip, ret;
> unsigned long temperature;
> + struct thermal_instance *pos = NULL;
>
> if (!tz->ops->set_trip_hyst)
> return -EPERM;
> @@ -658,6 +674,20 @@ trip_point_hyst_store(struct device *dev, struct
> device_attribute *attr,
> */
> ret = tz->ops->set_trip_hyst(tz, trip, temperature);
>
> + /*
> + * Notify bound cooling devices that this trip point changed.
> + * This is useful for cooling devices which represent a behavior
> + * which trips in hardware (e.g. catastrophic shutdown)
> + */
> + list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
> + if (pos->tz == tz && pos->trip == trip && pos->cdev) {
> + if (pos->cdev->ops->trip_point_changed)
> + pos->cdev->ops->trip_point_changed(pos->cdev,
> + pos->tz,
> + trip);
> + }
> + }
> +
> return ret ? ret : count;
> }
>
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index f7e11c7..7da7fc5 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -138,6 +138,8 @@ struct thermal_cooling_device_ops {
> int (*get_max_state) (struct thermal_cooling_device *, unsigned long *);
> int (*get_cur_state) (struct thermal_cooling_device *, unsigned long *);
> int (*set_cur_state) (struct thermal_cooling_device *, unsigned long);
> + void (*trip_point_changed) (struct thermal_cooling_device *,
> + struct thermal_zone_device *, int);
> };
>
> struct thermal_cooling_device {
--
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