[Bluetooth] Add UART driver for Texas Instruments' BRF63xx chips

Add support for Texas Instruments' HCI Low Level (HCILL) Bluetooth
protocol, which is a power management extension to H4. The HCILL is
widely used by TI's BRF63xx Bluetooth chips.

Signed-off-by: Ohad Ben-Cohen <ohad@bencohen.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
index b9fbe6e..62b89b9 100644
--- a/drivers/bluetooth/Kconfig
+++ b/drivers/bluetooth/Kconfig
@@ -55,6 +55,17 @@
 
 	  Say Y here to compile support for HCI BCSP protocol.
 
+config BT_HCIUART_LL
+	bool "HCILL protocol support"
+	depends on BT_HCIUART
+	help
+	  HCILL (HCI Low Level) is a serial protocol for communication
+	  between Bluetooth device and host. This protocol is required for
+	  serial Bluetooth devices that are based on Texas Instruments'
+	  BRF chips.
+
+	  Say Y here to compile support for HCILL protocol.
+
 config BT_HCIBCM203X
 	tristate "HCI BCM203x USB driver"
 	depends on USB