[PATCH] thermal: add interface to support tune governor in run-time

[Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

The governers are not static, so added a new function
thermal_update_governor() to update a new one and throw away
old ones in run-time. And added start/stop callback to tuning governor
parameters at any time.

Signed-off-by: Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 drivers/thermal/thermal_core.c |  103 ++++++++++++++++++++++++++++++++++++----
 drivers/thermal/thermal_core.h |    1 +
 include/linux/thermal.h        |   11 +++++
 3 files changed, 106 insertions(+), 9 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 89e0637..be93f43 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -93,10 +93,17 @@ int thermal_register_governor(struct thermal_governor *governor)
 			name = pos->tzp->governor_name;
 		else
 			name = DEFAULT_THERMAL_GOVERNOR;
-		if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH))
+		if (!strnicmp(name, governor->name, THERMAL_NAME_LENGTH)) {
+			if (governor->start) {
+				err = governor->start(pos);
+				if (err < 0)
+					goto exit;
+			}
 			pos->governor = governor;
+		}
 	}
 
+exit:
 	mutex_unlock(&thermal_list_lock);
 	mutex_unlock(&thermal_governor_lock);
 
@@ -119,8 +126,11 @@ void thermal_unregister_governor(struct thermal_governor *governor)
 
 	list_for_each_entry(pos, &thermal_tz_list, node) {
 		if (!strnicmp(pos->governor->name, governor->name,
-						THERMAL_NAME_LENGTH))
+						THERMAL_NAME_LENGTH)) {
+			if (pos->governor->stop)
+				pos->governor->stop(pos);
 			pos->governor = NULL;
+		}
 	}
 
 	mutex_unlock(&thermal_list_lock);
@@ -130,6 +140,49 @@ exit:
 	return;
 }
 
+/**
+ * thermal_update_governor() - update the thermal zone device's governor
+ * to a new one.
+ * @tzd: pointer of thermal zone device, which need to update governor.
+ * @name: thermal zone name to fetch the temperature
+ *
+ * Return: On success returns 0, an error code otherwise
+ */
+int thermal_update_governor(struct thermal_zone_device *tzd,
+			    const char *name)
+{
+	struct thermal_governor *old_gov, *new_gov;
+	int ret = 0;
+
+	mutex_lock(&thermal_governor_lock);
+
+	new_gov = __find_governor(name);
+	if (!new_gov) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	old_gov = tzd->governor;
+
+	if (old_gov && old_gov->stop)
+		old_gov->stop(tzd);
+
+	if (new_gov->start) {
+		ret = new_gov->start(tzd);
+		if (ret < 0) {
+			if (old_gov && old_gov->start)
+				old_gov->start(tzd);
+			goto exit;
+		}
+	}
+
+	tzd->governor = new_gov;
+
+exit:
+	mutex_unlock(&thermal_governor_lock);
+	return ret;
+}
+
 static int get_idr(struct idr *idr, struct mutex *lock, int *id)
 {
 	int ret;
@@ -734,22 +787,17 @@ policy_store(struct device *dev, struct device_attribute *attr,
 {
 	int ret = -EINVAL;
 	struct thermal_zone_device *tz = to_thermal_zone(dev);
-	struct thermal_governor *gov;
 	char name[THERMAL_NAME_LENGTH];
 
 	snprintf(name, sizeof(name), "%s", buf);
 
-	mutex_lock(&thermal_governor_lock);
-
-	gov = __find_governor(strim(name));
-	if (!gov)
+	ret = thermal_update_governor(tz, strim(name));
+	if (ret < 0)
 		goto exit;
 
-	tz->governor = gov;
 	ret = count;
 
 exit:
-	mutex_unlock(&thermal_governor_lock);
 	return ret;
 }
 
@@ -761,6 +809,24 @@ policy_show(struct device *dev, struct device_attribute *devattr, char *buf)
 	return sprintf(buf, "%s\n", tz->governor->name);
 }
 
+static ssize_t
+available_policies_show(struct device *dev, struct device_attribute *devattr,
+			char *buf)
+{
+	struct thermal_governor *pos;
+	ssize_t count = 0;
+
+	mutex_lock(&thermal_governor_lock);
+
+	list_for_each_entry(pos, &thermal_governor_list, governor_list)
+		count += sprintf(buf + count, "%s ", pos->name);
+	count += sprintf(buf + count, "\n");
+
+	mutex_unlock(&thermal_governor_lock);
+
+	return count;
+}
+
 #ifdef CONFIG_THERMAL_EMULATION
 static ssize_t
 emul_temp_store(struct device *dev, struct device_attribute *attr,
@@ -794,6 +860,7 @@ static DEVICE_ATTR(temp, 0444, temp_show, NULL);
 static DEVICE_ATTR(mode, 0644, mode_show, mode_store);
 static DEVICE_ATTR(passive, S_IRUGO | S_IWUSR, passive_show, passive_store);
 static DEVICE_ATTR(policy, S_IRUGO | S_IWUSR, policy_show, policy_store);
+static DEVICE_ATTR(available_policies, S_IRUGO, available_policies_show, NULL);
 
 /* sys I/F for cooling device */
 #define to_cooling_device(_dev)	\
@@ -1527,6 +1594,11 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	if (result)
 		goto unregister;
 
+	/* Create available_policies attribute */
+	result = device_create_file(&tz->device, &dev_attr_available_policies);
+	if (result)
+		goto unregister;
+
 	/* Update 'this' zone's governor information */
 	mutex_lock(&thermal_governor_lock);
 
@@ -1535,6 +1607,12 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	else
 		tz->governor = __find_governor(DEFAULT_THERMAL_GOVERNOR);
 
+	if (tz->governor->start) {
+		result = tz->governor->start(tz);
+		if (result < 0)
+			tz->governor = NULL;
+	}
+
 	mutex_unlock(&thermal_governor_lock);
 
 	if (!tz->tzp || !tz->tzp->no_hwmon) {
@@ -1561,6 +1639,9 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 		return tz;
 
 unregister:
+	if (tz->governor && tz->governor->stop)
+		tz->governor->stop(tz);
+	tz->governor = NULL;
 	release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
 	device_unregister(&tz->device);
 	return ERR_PTR(result);
@@ -1622,7 +1703,11 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 	if (tz->ops->get_mode)
 		device_remove_file(&tz->device, &dev_attr_mode);
 	device_remove_file(&tz->device, &dev_attr_policy);
+	device_remove_file(&tz->device, &dev_attr_available_policies);
 	remove_trip_attrs(tz);
+
+	if (tz->governor && tz->governor->stop)
+		tz->governor->stop(tz);
 	tz->governor = NULL;
 
 	thermal_remove_hwmon_sysfs(tz);
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 3db339f..89bcfe7 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -52,6 +52,7 @@ struct thermal_instance {
 
 int thermal_register_governor(struct thermal_governor *);
 void thermal_unregister_governor(struct thermal_governor *);
+int thermal_update_governor(struct thermal_zone_device *, const char *);
 
 #ifdef CONFIG_THERMAL_GOV_STEP_WISE
 int thermal_gov_step_wise_register(void);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 37e4e03..ad9ab14 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -178,6 +178,7 @@ struct thermal_zone_device {
 	struct thermal_zone_device_ops *ops;
 	const struct thermal_zone_params *tzp;
 	struct thermal_governor *governor;
+	void *governor_data;
 	struct list_head thermal_instances;
 	struct idr idr;
 	struct mutex lock; /* protect thermal_instances list */
@@ -188,6 +189,15 @@ struct thermal_zone_device {
 /* Structure that holds thermal governor information */
 struct thermal_governor {
 	char name[THERMAL_NAME_LENGTH];
+
+	/*
+	 * The start and stop operations will be called when thermal zone is
+	 * registered and when change governor via sysfs or driver in running
+	 * time.
+	 */
+	int (*start)(struct thermal_zone_device *tz);
+	void (*stop)(struct thermal_zone_device *tz);
+
 	int (*throttle)(struct thermal_zone_device *tz, int trip);
 	struct list_head	governor_list;
 };
@@ -235,6 +245,7 @@ struct thermal_zone_params {
 	 */
 	bool no_hwmon;
 
+	void *governor_params;
 	int num_tbps;	/* Number of tbp entries */
 	struct thermal_bind_params *tbp;
 };
-- 
1.7.9.5