thermal: add available policies sysfs attribute

The Linux thermal framework support to change thermal governor
policy in userspace, but it can't show what available policies
supported.

This patch adds available_policies attribute to the thermal
framework, it can list the thermal governors which can be
used for a particular zone. This attribute is read only.

Signed-off-by: Wei Ni <wni@nvidia.com>
Reviewed-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index c1f6864..10f062e 100644 (file)
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -180,6 +180,7 @@ Thermal zone device sys I/F, created once it's registered:
     |---temp:                  Current temperature
     |---mode:                  Working mode of the thermal zone
     |---policy:                        Thermal governor used for this zone
+    |---available_policies:    Available thermal governors for this zone
     |---trip_point_[0-*]_temp: Trip point temperature
     |---trip_point_[0-*]_type: Trip point type
     |---trip_point_[0-*]_hyst: Hysteresis value for this trip point
@@ -256,6 +257,10 @@ policy
        One of the various thermal governors used for a particular zone.
        RW, Required
 
+available_policies
+       Available thermal governors which can be used for a particular zone.
+       RO, Required
+
 trip_point_[0-*]_temp
        The temperature above which trip point will be fired.
        Unit: millidegree Celsius
@@ -417,6 +422,7 @@ method, the sys I/F structure will be built like this:
     |---temp:                  37000
     |---mode:                  enabled
     |---policy:                        step_wise
+    |---available_policies:    step_wise fair_share
     |---trip_point_0_temp:     100000
     |---trip_point_0_type:     critical
     |---trip_point_1_temp:     80000

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 04659bf..c470095 100644 (file)
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -847,6 +847,27 @@ 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;
+       ssize_t size = PAGE_SIZE;
+
+       mutex_lock(&thermal_governor_lock);
+
+       list_for_each_entry(pos, &thermal_governor_list, governor_list) {
+               size = PAGE_SIZE - count;
+               count += scnprintf(buf + count, size, "%s ", pos->name);
+       }
+       count += scnprintf(buf + count, size, "\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,
@@ -1032,6 +1053,7 @@ 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)        \
@@ -1817,6 +1839,11 @@ 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);
 
@@ -1917,6 +1944,7 @@ 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);
        thermal_set_governor(tz, NULL);