[PATCH v4 09/10] thermal/of: Support cooling device ID in cooling-spec

[Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>]

Extend the cooling device specifier parsing to support an optional
cooling device identifier (cdev_id).

Two formats are now supported:

  - Legacy format:
        <&cdev lower upper>

  - Indexed format:
        <&cdev cdev_id lower upper>

When the indexed format is used, both the device node and the
cdev_id must match in order to bind a cooling device to a thermal
zone. The legacy format continues to match on the device node only,
preserving backward compatibility.

Update the parsing logic accordingly to handle both formats and
extract the mitigation limits from the appropriate arguments.

This is a preparatory step for upcoming DT bindings describing
cooling devices using (device node, id) tuples instead of child
nodes.

No functional change for existing device trees.

Signed-off-by: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
---
 drivers/thermal/thermal_of.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
index 3584024b76f5..100fd8a0c8ce 100644
--- a/drivers/thermal/thermal_of.c
+++ b/drivers/thermal/thermal_of.c
@@ -259,16 +259,34 @@ static bool thermal_of_get_cooling_spec(struct device_node *map_np, int index,
 
 	of_node_put(cooling_spec.np);
 
-	if (cooling_spec.args_count < 2) {
-		pr_err("wrong reference to cooling device, missing limits\n");
+	/*
+	 * There are two formats:
+	 * - Legacy format :	<&cdev lower upper>
+	 * - New format    :	<&cdev cdev_id lower upper>
+	 *
+	 * With the new format, along with the device node pointer,
+	 * the cdev_id must match with the cooling device cdev_id in
+	 * order to bind
+	 */
+	if (cooling_spec.args_count < 2 || cooling_spec.args_count > 3) {
+		pr_err("Invalid number of cooling device parameters\n");
 		return false;
 	}
 
 	if (cooling_spec.np != cdev->np)
 		return false;
 
-	c->lower = cooling_spec.args[0];
-	c->upper = cooling_spec.args[1];
+	if (cooling_spec.args_count == 3 &&
+	    cooling_spec.args[0] != cdev->cdev_id)
+		return false;
+
+	if (cooling_spec.args_count != 3) {
+		c->lower = cooling_spec.args[0];
+		c->upper = cooling_spec.args[1];
+	} else {
+		c->lower = cooling_spec.args[1];
+		c->upper = cooling_spec.args[2];
+	}
 	c->weight = weight;
 
 	return true;
-- 
2.43.0