bluetooth: avrcp: provide an API for net buffer allocation

Add bt_avrcp_create_pdu() to allocate net_buf with protocol headroom.

Signed-off-by: Make Shi <[email protected]>

Author: makeshi

include/zephyr/bluetooth/classic/avrcp.h

@@ -264,6 +264,19 @@ int bt_avrcp_connect(struct bt_conn *conn);
  */
 int bt_avrcp_disconnect(struct bt_conn *conn);
 
+/**
+ * @brief Allocate a net_buf for AVRCP PDU transmission, reserving headroom
+ *        for AVRCP, AVRCTP, L2CAP, and ACL headers.
+ *
+ * This function allocates a buffer from the specified pool and reserves
+ * sufficient headroom for protocol headers required by AVRCP over Bluetooth.
+ *
+ * @param pool The buffer pool to allocate from.
+ *
+ * @return A newly allocated net_buf with reserved headroom.
+ */
+struct net_buf *bt_avrcp_create_pdu(struct net_buf_pool *pool);
+
 /** @brief Register callback.
  *
  *  Register AVRCP callbacks to monitor the state and interact with the remote device.

subsys/bluetooth/host/classic/avrcp.c

@@ -814,6 +814,14 @@ int bt_avrcp_disconnect(struct bt_conn *conn)
 	return err;
 }
 
+struct net_buf *bt_avrcp_create_pdu(struct net_buf_pool *pool)
+{
+	return bt_conn_create_pdu(pool,
+				  sizeof(struct bt_l2cap_hdr) +
+				  sizeof(struct bt_avctp_header) +
+				  sizeof(struct bt_avrcp_header));
+}
+
 int bt_avrcp_ct_get_cap(struct bt_avrcp_ct *ct, uint8_t tid, uint8_t cap_id)
 {
 	struct net_buf *buf;