thermal: allow registering without .get_temp

This patch changes the thermal core driver to allow
registration of thermal zones without the .get_temp callback.

The idea behind this change is to allow lazy registration
of sensor callbacks.

The thermal zone will be disabled whenever the ops
does not contain a .get_temp callback. The sysfs interface
will be returning -EINVAL on any temperature read operation.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index f1d511a9475b..0e43dc208fc6 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -403,7 +403,7 @@ int thermal_zone_get_temp(struct thermal_zone_device *tz, unsigned long *temp)
         enum thermal_trip_type type;
 #endif
 
-        if (!tz || IS_ERR(tz))
+        if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
                 goto exit;
 
         mutex_lock(&tz->lock);
@@ -456,6 +456,9 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 {
         int count;
 
+        if (!tz->ops->get_temp)
+                return;
+
         update_temperature(tz);
 
         for (count = 0; count < tz->trips; count++)
@@ -1386,7 +1389,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
         if (trips > THERMAL_MAX_TRIPS || trips < 0 || mask >> trips)
                 return ERR_PTR(-EINVAL);
 
-        if (!ops || !ops->get_temp)
+        if (!ops)
                 return ERR_PTR(-EINVAL);
 
         if (trips > 0 && (!ops->get_trip_type || !ops->get_trip_temp))
@@ -1490,6 +1493,9 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 
         INIT_DELAYED_WORK(&(tz->poll_queue), thermal_zone_device_check);
 
+        if (!tz->ops->get_temp)
+                thermal_zone_device_set_polling(tz, 0);
+
         thermal_zone_device_update(tz);
 
         if (!result)