[PATCH v9 3/7] thermal:boost: Automatic enable/disable of BOOST feature

[Lukasz Majewski <l.majewski@samsung.com>]

This patch provides auto disable/enable operation for boost. When any
defined trip point is passed, the boost is disabled.
In that moment thermal monitor workqueue is woken up and it monitors
if the device temperature drops below 75% of the smallest trip point.
When device cools down, the boost is enabled again.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>

---
Changes for v9:
- None

Changes for v8:
- Move cpufreq_boost_* stub functions definition (needed when cpufreq
  is not compiled in) to cpufreq.h at cpufreq core support commit

Changes for v7:
- None

Changes for v6:
- Disable boost only when supported and enabled
- Protect boost related thermal_zone_device struct fields with mutex
- Evaluate temperature trend during boost enable decision
- Create separate methods to handle boost enable/disable
  (thermal_boost_{enable|disable}) operations
- Boost is disabled at any trip point passage (not only the non critical one)
- Add stub definitions for cpufreq boost functions used when
  CONFIG_CPU_FREQ is NOT defined.

Changes for v5:
- Move boost disable code from cpu_cooling.c to thermal_core.c
  (to handle_non_critical_trips)
- Extent struct thermal_zone_device by adding overheated bool flag
- Implement auto enable of boost after device cools down
- Introduce boost_polling flag, which indicates if thermal uses it's predefined
  pool delay or has woken up thermal workqueue only to wait until device
  cools down.

Changes for v4:
- New patch

 drivers/thermal/thermal_core.c |   55 ++++++++++++++++++++++++++++++++++++++++
 include/linux/thermal.h        |    2 ++
 2 files changed, 57 insertions(+)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 4962a6a..a167ab9 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -34,6 +34,7 @@
 #include <linux/thermal.h>
 #include <linux/reboot.h>
 #include <linux/string.h>
+#include <linux/cpufreq.h>
 #include <net/netlink.h>
 #include <net/genetlink.h>
 
@@ -366,9 +367,59 @@ static void handle_critical_trips(struct thermal_zone_device *tz,
 	}
 }
 
+static int thermal_boost_enable(struct thermal_zone_device *tz)
+{
+	enum thermal_trend trend = get_tz_trend(tz, 0);
+	long trip_temp;
+
+	if (!tz->ops->get_trip_temp || !tz->overheated)
+		return -EPERM;
+	if (trend == THERMAL_TREND_RAISING || trend == THERMAL_TREND_RAISE_FULL)
+		return -EBUSY;
+
+	tz->ops->get_trip_temp(tz, 0, &trip_temp);
+	/*
+	 * Enable boost again only when current temperature is less
+	 * than 75% of trip_temp[0]
+	 */
+	if ((tz->temperature + (trip_temp >> 2)) < trip_temp) {
+		mutex_lock(&tz->lock);
+		tz->overheated = false;
+		if (tz->boost_polling) {
+			tz->boost_polling = false;
+			tz->polling_delay = 0;
+		}
+		mutex_unlock(&tz->lock);
+		cpufreq_boost_trigger_state(1);
+		return 0;
+	}
+	return -EBUSY;
+}
+
+static void thermal_boost_disable(struct thermal_zone_device *tz)
+{
+	cpufreq_boost_trigger_state(0);
+
+	/*
+	 * If no workqueue for monitoring is running - start one with
+	 * 1000 ms monitoring period
+	 * If workqueue already running - do not change its period and only
+	 * test if target CPU has cooled down
+	 */
+	mutex_lock(&tz->lock);
+	if (!tz->polling_delay) {
+		tz->boost_polling = true;
+		tz->polling_delay = 1000;
+	}
+	tz->overheated = true;
+	mutex_unlock(&tz->lock);
+}
+
 static void handle_thermal_trip(struct thermal_zone_device *tz, int trip)
 {
 	enum thermal_trip_type type;
+	if (cpufreq_boost_supported() && cpufreq_boost_enabled())
+		thermal_boost_disable(tz);
 
 	tz->ops->get_trip_type(tz, trip, &type);
 
@@ -467,6 +518,10 @@ static void thermal_zone_device_check(struct work_struct *work)
 	struct thermal_zone_device *tz = container_of(work, struct
 						      thermal_zone_device,
 						      poll_queue.work);
+	if (cpufreq_boost_supported())
+		if (!thermal_boost_enable(tz))
+			return;
+
 	thermal_zone_device_update(tz);
 }
 
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index b268d3c..b316bdf 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -172,6 +172,8 @@ struct thermal_zone_device {
 	int emul_temperature;
 	int passive;
 	unsigned int forced_passive;
+	bool overheated;
+	bool boost_polling;
 	const struct thermal_zone_device_ops *ops;
 	const struct thermal_zone_params *tzp;
 	struct thermal_governor *governor;
-- 
1.7.10.4