[PATCH 04/10] ASoC: SDCA: Add support for Entity 0

[Charles Keepax <ckeepax@opensource.cirrus.com>]

Within SDCA there is a special Entity called Entity 0 which is used
to hold Function level controls. Whilst Entity 0 isn't a full SDCA
Entity, it is helpful to add an sdca_entity structure for it. This
will allow it to be treated identically in the code that handles
SDCA Controls.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---
 include/sound/sdca_function.h   |  4 ++++
 sound/soc/sdca/sdca_functions.c | 14 +++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/sound/sdca_function.h b/include/sound/sdca_function.h
index 47fc1da8e4f33..a51e3a459e361 100644
--- a/include/sound/sdca_function.h
+++ b/include/sound/sdca_function.h
@@ -117,6 +117,9 @@ enum sdca_entity0_controls {
 
 /**
  * enum sdca_entity_type - SDCA Entity Type codes
+ * @SDCA_ENTITY_TYPE_ENTITY_0: Entity 0, not actually from the
+ * specification but useful internally as an Entity structure
+ * is allocated for Entity 0, to hold Entity 0 controls.
  * @SDCA_ENTITY_TYPE_IT: Input Terminal.
  * @SDCA_ENTITY_TYPE_OT: Output Terminal.
  * @SDCA_ENTITY_TYPE_MU: Mixer Unit.
@@ -141,6 +144,7 @@ enum sdca_entity0_controls {
  * all Entity Types not described are reserved.
  */
 enum sdca_entity_type {
+	SDCA_ENTITY_TYPE_ENTITY_0			= 0x00,
 	SDCA_ENTITY_TYPE_IT				= 0x02,
 	SDCA_ENTITY_TYPE_OT				= 0x03,
 	SDCA_ENTITY_TYPE_MU				= 0x05,
diff --git a/sound/soc/sdca/sdca_functions.c b/sound/soc/sdca/sdca_functions.c
index f914ec3f86c9a..b0ca92f1bc57f 100644
--- a/sound/soc/sdca/sdca_functions.c
+++ b/sound/soc/sdca/sdca_functions.c
@@ -293,7 +293,8 @@ static int find_sdca_entities(struct device *dev,
 		return -EINVAL;
 	}
 
-	entities = devm_kcalloc(dev, num_entities, sizeof(*entities), GFP_KERNEL);
+	/* Add 1 to make space for Entity 0 */
+	entities = devm_kcalloc(dev, num_entities + 1, sizeof(*entities), GFP_KERNEL);
 	if (!entities)
 		return -ENOMEM;
 
@@ -331,7 +332,13 @@ static int find_sdca_entities(struct device *dev,
 			return ret;
 	}
 
-	function->num_entities = num_entities;
+	/*
+	 * Add Entity 0 at end of the array, makes it easy to skip during
+	 * all the Entity searches involved in creating connections.
+	 */
+	entities[num_entities].label = "entity0";
+
+	function->num_entities = num_entities + 1;
 	function->entities = entities;
 
 	return 0;
@@ -440,7 +447,8 @@ static int find_sdca_connections(struct device *dev,
 {
 	int i;
 
-	for (i = 0; i < function->num_entities; i++) {
+	/* Entity 0 cannot have connections */
+	for (i = 0; i < function->num_entities - 1; i++) {
 		struct sdca_entity *entity = &function->entities[i];
 		char entity_property[SDCA_PROPERTY_LENGTH];
 		struct fwnode_handle *entity_node;
-- 
2.39.5