[PATCH 2/7] thermal: stats: track number of change requests due to tz

[Eduardo Valentin <evalenti@kernel.org>]

From: Eduardo Valentin <eduval@amazon.com>

This patch improves the current cooling device
statistics by adding a new file under
cdev/stats/requests_of_thermal_zone

to represent the number of times each thermal zone
requested the cooling device to effectively change.
If the request associated was not serviced because
another thermal zone asked for a higher cooling level,
this counter does not increase.

The file format is:
thermal_zone: <type> <count>

Samples:
$ cat cdev0/stats/requests_of_thermal_zone
thermal_zone: amb0	2

In this example, it means the thermal zone 'amb0' has requested
2 times for cdev0 to change state.

Cc: "Rafael J. Wysocki" <rafael@kernel.org> (supporter:THERMAL)
Cc: Daniel Lezcano <daniel.lezcano@linaro.org> (supporter:THERMAL)
Cc: Amit Kucheria <amitk@kernel.org> (reviewer:THERMAL)
Cc: Zhang Rui <rui.zhang@intel.com> (reviewer:THERMAL)
Cc: Jonathan Corbet <corbet@lwn.net> (maintainer:DOCUMENTATION)
Cc: linux-pm@vger.kernel.org (open list:THERMAL)
Cc: linux-doc@vger.kernel.org (open list:DOCUMENTATION)
Cc: linux-kernel@vger.kernel.org (open list)

Signed-off-by: Eduardo Valentin <eduval@amazon.com>
---
 .../driver-api/thermal/sysfs-api.rst          |  2 +
 drivers/thermal/thermal_core.h                |  1 +
 drivers/thermal/thermal_sysfs.c               | 52 +++++++++++++++++++
 3 files changed, 55 insertions(+)

diff --git a/Documentation/driver-api/thermal/sysfs-api.rst b/Documentation/driver-api/thermal/sysfs-api.rst
index caa50d61a5bc..75309a51d9b3 100644
--- a/Documentation/driver-api/thermal/sysfs-api.rst
+++ b/Documentation/driver-api/thermal/sysfs-api.rst
@@ -369,6 +369,8 @@ Thermal cooling device sys I/F, created once it's registered::
     |---stats/trans_table:	Cooling state transition table
     |---stats/time_in_thermal_zone_ms:	Time that this cooling device was driven
                                 each associated thermal zone.
+    |---stats/requests_of_thermal_zone:	Total number of times this cooling device
+                                changed due to each associated thermal zone.
 
 
 Then next two dynamic attributes are created/removed in pairs. They represent
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 3cce60c6e065..ed6511c3b794 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -103,6 +103,7 @@ struct thermal_instance {
 	unsigned int weight; /* The weight of the cooling device */
 	bool upper_no_limit;
 #if IS_ENABLED(CONFIG_THERMAL_STATISTICS)
+	unsigned long total_requests;
 	ktime_t time_in; /* time spent in this instance */
 #endif
 };
diff --git a/drivers/thermal/thermal_sysfs.c b/drivers/thermal/thermal_sysfs.c
index a3b71f03db75..0bce1415f7e8 100644
--- a/drivers/thermal/thermal_sysfs.c
+++ b/drivers/thermal/thermal_sysfs.c
@@ -723,6 +723,7 @@ void thermal_cooling_device_stats_update(struct thermal_cooling_device *cdev,
 	stats->trans_table[stats->state * (cdev->max_state + 1) + new_state]++;
 	stats->state = new_state;
 	stats->total_trans++;
+	stats->curr_instance->total_requests++;
 
 unlock:
 	spin_unlock(&stats->lock);
@@ -867,6 +868,54 @@ time_in_thermal_zone_ms_show(struct device *dev, struct device_attribute *attr,
 	return ret < 0 ? ret : len;
 }
 
+static ssize_t
+requests_of_thermal_zone_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	LIST_HEAD(cdev_thermal_zone_list);
+	struct thermal_cooling_device *cdev = to_cooling_device(dev);
+	struct cooling_dev_stats *stats = cdev->stats;
+	struct cdev_thermal_zone_residency *res, *next;
+	struct thermal_instance *instance;
+	ssize_t len = 0, ret = 0;
+
+	mutex_lock(&cdev->lock);
+
+	spin_lock(&stats->lock);
+	update_time_in_state(stats, stats->curr_instance);
+	spin_unlock(&stats->lock);
+
+	build_cdev_thermal_zone_residency(&cdev_thermal_zone_list, cdev);
+
+	list_for_each_entry(instance, &cdev->thermal_instances, cdev_node)
+		list_for_each_entry(res, &cdev_thermal_zone_list, node)
+			if (strncmp(res->thermal_zone, instance->tz->type,
+				    THERMAL_NAME_LENGTH) == 0)
+				res->counter += instance->total_requests;
+
+	mutex_unlock(&cdev->lock);
+
+	list_for_each_entry_safe(res, next, &cdev_thermal_zone_list, node) {
+		ret = sprintf(buf + len, "thermal_zone: %s\t%lu\n",
+			      res->thermal_zone, res->counter);
+
+		if (ret == 0)
+			ret = -EOVERFLOW;
+
+		if (ret < 0)
+			break;
+
+		len += ret;
+	}
+
+	list_for_each_entry_safe(res, next, &cdev_thermal_zone_list, node) {
+		list_del(&res->node);
+		kfree(res);
+	}
+
+	return ret < 0 ? ret : len;
+}
+
 static ssize_t
 reset_store(struct device *dev, struct device_attribute *attr, const char *buf,
 	    size_t count)
@@ -897,6 +946,7 @@ reset_store(struct device *dev, struct device_attribute *attr, const char *buf,
 
 	/* Make sure we reset all counters per instance */
 	list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
+		instance->total_requests = 0;
 		instance->time_in = ktime_set(0, 0);
 	}
 
@@ -971,6 +1021,7 @@ static ssize_t trans_table_show(struct device *dev,
 static DEVICE_ATTR_RO(total_trans);
 static DEVICE_ATTR_RO(time_in_state_ms);
 static DEVICE_ATTR_RO(time_in_thermal_zone_ms);
+static DEVICE_ATTR_RO(requests_of_thermal_zone);
 static DEVICE_ATTR_WO(reset);
 static DEVICE_ATTR_RO(trans_table);
 
@@ -978,6 +1029,7 @@ static struct attribute *cooling_device_stats_attrs[] = {
 	&dev_attr_total_trans.attr,
 	&dev_attr_time_in_state_ms.attr,
 	&dev_attr_time_in_thermal_zone_ms.attr,
+	&dev_attr_requests_of_thermal_zone.attr,
 	&dev_attr_reset.attr,
 	&dev_attr_trans_table.attr,
 	NULL
-- 
2.34.1