samples: Bluetooth: hci_uart: Implement NOP Command Complete

Implement the Controller counterpart to CONFIG_BT_WAIT_NOP so that it
issues a NOP Command Complete event after booting up, to signal to the
Host that it is ready to receive HCI traffic.

Fixes #15333

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

include/bluetooth/hci.h

@@ -337,6 +337,9 @@ struct bt_hci_cmd_hdr {
 /* Construct OpCode from OGF and OCF */
 #define BT_OP(ogf, ocf)                         ((ocf) | ((ogf) << 10))
 
+/* Invalid opcode */
+#define BT_OP_NOP				0x0000
+
 /* Obtain OGF from OpCode */
 #define BT_OGF(opcode)                          (((opcode) >> 10) & BIT_MASK(6))
 /* Obtain OCF from OpCode */

samples/bluetooth/hci_uart/src/main.c

@@ -357,6 +357,33 @@ void main(void)
 
 	/* Enable the raw interface, this will in turn open the HCI driver */
 	bt_enable_raw(&rx_queue);
+
+	if (IS_ENABLED(CONFIG_BT_WAIT_NOP)) {
+		/* Issue a Command Complete with NOP */
+		int i;
+
+		const struct {
+			const u8_t h4;
+			const struct bt_hci_evt_hdr hdr;
+			const struct bt_hci_evt_cmd_complete cc;
+		} __packed cc_evt = {
+			.h4 = H4_EVT,
+			.hdr = {
+				.evt = BT_HCI_EVT_CMD_COMPLETE,
+				.len = sizeof(struct bt_hci_evt_cmd_complete),
+			},
+			.cc = {
+				.ncmd = 1,
+				.opcode = sys_cpu_to_le16(BT_OP_NOP),
+			},
+		};
+
+		for (i = 0; i < sizeof(cc_evt); i++) {
+			uart_poll_out(hci_uart_dev,
+				      *(((const u8_t *)&cc_evt)+i));
+		}
+	}
+
 	/* Spawn the TX thread and start feeding commands and data to the
 	 * controller
 	 */

subsys/bluetooth/common/Kconfig

@@ -46,6 +46,13 @@ config BT_HCI_MESH_EXT
 	help
 	  Enable support for the Bluetooth Mesh HCI Commands.
 
+config BT_WAIT_NOP
+	bool "Wait for \"NOP\" Command Complete event during init"
+	help
+	  Emit a Command Complete event from the Controller (and wait for it
+	  from the Host) for the NOP opcode to indicate that the Controller is
+	  ready to receive commands.
+
 config BT_RPA
 	# Virtual/hidden option
 	bool

subsys/bluetooth/host/Kconfig

@@ -70,14 +70,6 @@ config BT_HCI_TX_PRIO
 	int
 	default 7
 
-config BT_WAIT_NOP
-	bool "Wait for \"NOP\" Command Complete event during init"
-	help
-	  Some controllers emit a Command Complete event for the NOP
-	  opcode to indicate that they're ready to receive commands.
-	  This option should be selected if the controller used
-	  exhibits such behavior.
-
 config BT_HCI_RESERVE
 	int
 	default 0 if BT_H4