On Thursday, July 26, 2012, Zhang Rui wrote:
> According to ACPI spec, tc1 and tc2 are used by OSPM
> to anticipate the temperature trends.
> We introduced the same concept to the generic thermal layer
> for passive cooling, but now it seems that these values
> are hard to be used on other platforms.
>
> So We introduce .get_trend() as a more general solution.
>
> For the platform thermal drivers that have their own way to
> anticipate the temperature trends, they should provide
> their own .get_trend() callback.
> Or else, we will calculate the temperature trends by simply
> comparing the current temperature and the cached previous
> temperature reading.
As far as the code is concerned:
Reviewed-by: Rafael J. Wysocki <rjw@xxxxxxx>
I wonder, though, if there are any users of the thermal core currently in the
tree who should introduce their own .get_trend() callbacks?
Rafael
> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
> ---
> drivers/acpi/thermal.c | 33 +++++++++++++++++++++++++++++++++
> drivers/thermal/thermal_sys.c | 19 +++++++++++++++++--
> include/linux/thermal.h | 9 +++++++++
> 3 files changed, 59 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
> index b48ec3e..0c49e42 100644
> --- a/drivers/acpi/thermal.c
> +++ b/drivers/acpi/thermal.c
> @@ -704,6 +704,38 @@ static int thermal_get_crit_temp(struct thermal_zone_device *thermal,
> return -EINVAL;
> }
>
> +static int thermal_get_trend(struct thermal_zone_device *thermal,
> + int trip, enum thermal_trend *trend)
> +{
> + struct acpi_thermal *tz = thermal->devdata;
> + enum thermal_trip_type type;
> + int i;
> +
> + if (thermal_get_trip_type(thermal, trip, &type))
> + return -EINVAL;
> +
> + /* Only PASSIVE trip points need TREND */
> + if (type != THERMAL_TRIP_PASSIVE)
> + return -EINVAL;
> +
> + /*
> + * tz->temperature has already been updated by generic thermal layer,
> + * before this callback being invoked
> + */
> + i = (tz->trips.passive.tc1 * (tz->temperature - tz->last_temperature))
> + + (tz->trips.passive.tc2
> + * (tz->temperature - tz->trips.passive.temperature));
> +
> + if (i > 0)
> + *trend = THERMAL_TREND_RAISING;
> + else if (i < 0)
> + *trend = THERMAL_TREND_DROPPING;
> + else
> + *trend = THERMAL_TREND_STABLE;
> + return 0;
> +}
> +
> +
> static int thermal_notify(struct thermal_zone_device *thermal, int trip,
> enum thermal_trip_type trip_type)
> {
> @@ -836,6 +868,7 @@ static const struct thermal_zone_device_ops acpi_thermal_zone_ops = {
> .get_trip_type = thermal_get_trip_type,
> .get_trip_temp = thermal_get_trip_temp,
> .get_crit_temp = thermal_get_crit_temp,
> + .get_trend = thermal_get_trend,
> .notify = thermal_notify,
> };
>
> diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
> index 62b4279..68c93d4 100644
> --- a/drivers/thermal/thermal_sys.c
> +++ b/drivers/thermal/thermal_sys.c
> @@ -723,6 +723,20 @@ static void thermal_zone_device_passive(struct thermal_zone_device *tz,
> struct thermal_cooling_device *cdev;
> long state, max_state;
>
> + if (!tz->ops->get_trend ||
> + tz->ops->get_trend(tz, trip, (enum thermal_trend *)&trend)) {
> + /*
> + * compare the current temperature and previous temperature
> + * to get the thermal trend, if no special requirement
> + */
> + if (tz->temperature > tz->last_temperature)
> + trend = THERMAL_TREND_RAISING;
> + else if (tz->temperature < tz->last_temperature)
> + trend = THERMAL_TREND_DROPPING;
> + else
> + trend = THERMAL_TREND_STABLE;
> + }
> +
> /*
> * Above Trip?
> * -----------
> @@ -1091,6 +1105,9 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
> goto leave;
> }
>
> + tz->last_temperature = tz->temperature;
> + tz->temperature = temp;
> +
> for (count = 0; count < tz->trips; count++) {
> tz->ops->get_trip_type(tz, count, &trip_type);
> tz->ops->get_trip_temp(tz, count, &trip_temp);
> @@ -1150,8 +1167,6 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
> thermal_zone_device_passive(tz, temp, tz->forced_passive,
> THERMAL_TRIPS_NONE);
>
> - tz->last_temperature = temp;
> -
> leave:
> if (tz->passive)
> thermal_zone_device_set_polling(tz, tz->passive_delay);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index a43b12c..a01e3e6 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -44,6 +44,12 @@ enum thermal_trip_type {
> THERMAL_TRIP_CRITICAL,
> };
>
> +enum thermal_trend {
> + THERMAL_TREND_STABLE, /* temperature is stable */
> + THERMAL_TREND_RAISING, /* temperature is raising */
> + THERMAL_TREND_DROPPING, /* temperature is dropping */
> +};
> +
> struct thermal_zone_device_ops {
> int (*bind) (struct thermal_zone_device *,
> struct thermal_cooling_device *);
> @@ -65,6 +71,8 @@ struct thermal_zone_device_ops {
> int (*set_trip_hyst) (struct thermal_zone_device *, int,
> unsigned long);
> int (*get_crit_temp) (struct thermal_zone_device *, unsigned long *);
> + int (*get_trend) (struct thermal_zone_device *, int,
> + enum thermal_trend *);
> int (*notify) (struct thermal_zone_device *, int,
> enum thermal_trip_type);
> };
> @@ -111,6 +119,7 @@ struct thermal_zone_device {
> int tc2;
> int passive_delay;
> int polling_delay;
> + int temperature;
> int last_temperature;
> bool passive;
> unsigned int forced_passive;
>
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