bluez5-init: disable the HW flow control for qca6564

Add a software workaround to disable the HW flow control because the SOM
revision 3 (and older) has swapped the bluetooth TX and RX lines so we need
to operate in DTE mode which implies that the HW control lines are swapped.
This also implies reducing the baudrate to avoid the need for HW flow control.

https://jira.digi.com/browse/DEL-2611

Signed-off-by: Isaac Hermida <isaac.hermida@digi.com>

meta-digi-dey/recipes-connectivity/bluez/bluez5-5.33/bluez-init

@@ -24,17 +24,31 @@ fi
 SCRIPTNAME="$(basename "${0}")"
 
 bt_init_qca6564() {
-	if hciattach -t120 ttyBt qca 3000000 flow 2>/dev/null; then
+	MOD_VERSION="$(($(cat /proc/device-tree/digi,hwid,hv 2>/dev/null || true)))"
+
+	# Module version older than revision 4 has swapped TX and RX lines
+	if [ "${MOD_VERSION}" -lt "4" ]; then
+		# Workaround to ignore the CTS flow control line
+		BT_GPIO_CTS="18"
+		echo "${BT_GPIO_CTS}" > /sys/class/gpio/export
+		echo "out" > /sys/class/gpio/gpio${BT_GPIO_CTS}/direction
+		echo "0" > /sys/class/gpio/gpio${BT_GPIO_CTS}/value
+		# Reduce the rate to avoid the need for HW flow control
+		BT_RATE="115200"
+		BT_FLOW="noflow"
+	fi
+
+	if hciattach -t120 ttyBt qca ${BT_RATE:-3000000} ${BT_FLOW:-flow} 2>/dev/null; then
 		:	# No-op
 	else
 		echo "${SCRIPTNAME}: FAILED (hciattach)"
 		exit
 	fi
+
 	if hciconfig hci0 up; then
 		echo "${SCRIPTNAME}: OK"
 	else
-		echo "${SCRIPTNAME}: FAILED (hciconfig)"
+		echo "${SCRIPTNAME}: FAILED"
-		exit
 	fi
 }
 
@@ -114,6 +128,7 @@ bt_init_ar3k() {
 
 # Check if this hardware does support Bluetooth
 if [ -d "/proc/device-tree/bluetooth" ]; then
+	# Initialize for the specific bluetooth chip
 	if grep -qs '\<digi,ccimx6ul\>' /proc/device-tree/compatible; then
 		bt_init_qca6564
 	else