[PATCH V13 2/5] thermal: of-thermal: add API for getting sensor ID from DT

[Anson . Huang]

From: Anson Huang <Anson.Huang@xxxxxxx>

On some platforms like i.MX8QXP, the thermal driver needs a
real HW sensor ID from DT thermal zone, the HW sensor ID is
used to get temperature from SCU firmware, and the virtual
sensor ID starting from 0 to N is NOT used at all, this patch
adds new API thermal_zone_of_get_sensor_id() to provide the
feature of getting sensor ID from DT thermal zone's node.

Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
---
Changes since V12:
	- allow the caller of thermal_zone_of_get_sensor_id() to pass NULL as second parameter
	  of_phandle_args structure, as some caller maybe ONLY need to read sensor ID.
---
 drivers/thermal/of-thermal.c | 59 +++++++++++++++++++++++++++++++++++---------
 include/linux/thermal.h      | 10 ++++++++
 2 files changed, 57 insertions(+), 12 deletions(-)

diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
index dc5093b..0466ab5 100644
--- a/drivers/thermal/of-thermal.c
+++ b/drivers/thermal/of-thermal.c
@@ -449,6 +449,52 @@ thermal_zone_of_add_sensor(struct device_node *zone,
 }
 
 /**
+ * thermal_zone_of_get_sensor_id - get sensor ID from a DT thermal zone
+ * @tz_np: a valid thermal zone device node.
+ * @sensor_specs: pointer to output arguments structure will be passed back,
+ *		  it can be NULL if the caller does NOT need the output
+ *		  arguments structure to be passed back.
+ * @id: a sensor ID pointer will be passed back.
+ *
+ * This function will get sensor ID from a given thermal zone node, use
+ * "thermal-sensors" as list name, and get sensor ID from first phandle's
+ * argument.
+ *
+ * Return: 0 on success, proper error code otherwise.
+ */
+
+int thermal_zone_of_get_sensor_id(struct device_node *tz_np,
+				  struct of_phandle_args *sensor_specs,
+				  u32 *id)
+{
+	struct of_phandle_args tmp_sensor_specs;
+	int ret;
+
+	if (!sensor_specs)
+		sensor_specs = &tmp_sensor_specs;
+
+	ret = of_parse_phandle_with_args(tz_np,
+					 "thermal-sensors",
+					 "#thermal-sensor-cells",
+					 0,
+					 sensor_specs);
+	if (ret)
+		return ret;
+
+	if (sensor_specs->args_count >= 1) {
+		*id = sensor_specs->args[0];
+		WARN(sensor_specs->args_count > 1,
+		     "%pOFn: too many cells in sensor specifier %d\n",
+		     sensor_specs->np, sensor_specs->args_count);
+	} else {
+		*id = 0;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(thermal_zone_of_get_sensor_id);
+
+/**
  * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
  * @dev: a valid struct device pointer of a sensor device. Must contain
  *       a valid .of_node, for the sensor node.
@@ -503,21 +549,10 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
 		int ret, id;
 
 		/* For now, thermal framework supports only 1 sensor per zone */
-		ret = of_parse_phandle_with_args(child, "thermal-sensors",
-						 "#thermal-sensor-cells",
-						 0, &sensor_specs);
+		ret = thermal_zone_of_get_sensor_id(child, &sensor_specs, &id);
 		if (ret)
 			continue;
 
-		if (sensor_specs.args_count >= 1) {
-			id = sensor_specs.args[0];
-			WARN(sensor_specs.args_count > 1,
-			     "%pOFn: too many cells in sensor specifier %d\n",
-			     sensor_specs.np, sensor_specs.args_count);
-		} else {
-			id = 0;
-		}
-
 		if (sensor_specs.np == sensor_np && id == sensor_id) {
 			tzd = thermal_zone_of_add_sensor(child, sensor_np,
 							 data, ops);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 15a4ca5..c994e3a 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -375,6 +375,9 @@ struct thermal_trip {
 
 /* Function declarations */
 #ifdef CONFIG_THERMAL_OF
+int thermal_zone_of_get_sensor_id(struct device_node *tz_np,
+				  struct of_phandle_args *sensor_specs,
+				  u32 *id);
 struct thermal_zone_device *
 thermal_zone_of_sensor_register(struct device *dev, int id, void *data,
 				const struct thermal_zone_of_device_ops *ops);
@@ -386,6 +389,13 @@ struct thermal_zone_device *devm_thermal_zone_of_sensor_register(
 void devm_thermal_zone_of_sensor_unregister(struct device *dev,
 					    struct thermal_zone_device *tz);
 #else
+
+static int thermal_zone_of_get_sensor_id(struct device_node *tz_np,
+					 struct of_phandle_args *sensor_specs,
+					 u32 *id)
+{
+	return -ENOENT;
+}
 static inline struct thermal_zone_device *
 thermal_zone_of_sensor_register(struct device *dev, int id, void *data,
 				const struct thermal_zone_of_device_ops *ops)
-- 
2.7.4