Bluetooth: btusb: Add shutdown routine for BTUSB_INTEL_NEW devices

If BT operations (BREDR inquiry/LE scan) were triggered
through the stack, followed by BT turn off through
'hciconfig hci0 down', the controller would still be active
and consume power.
Also, there is a possibility that a race condition/
synchronization issue might arise on the subsequent BT turn
on, as the controller might try to push the
events that were queued up before processing the HCI Reset
command.

btusb_shutdown_intel_new routine shall reset the controller
and stop all BT operation.
Advantages:
	1. Power save on the platform
	2. Host and controller will be in Sync.

Signed-off-by: Raghuram Hegde <[email protected]>
Signed-off-by: Chethan T N <[email protected]>
Signed-off-by: Marcel Holtmann <[email protected]>

Author: Raghuram Hegde

drivers/bluetooth/btusb.c

@@ -2434,6 +2434,24 @@ static int btusb_shutdown_intel(struct hci_dev *hdev)
 	return 0;
 }
 
+static int btusb_shutdown_intel_new(struct hci_dev *hdev)
+{
+	struct sk_buff *skb;
+
+	/* Send HCI Reset to the controller to stop any BT activity which
+	 * were triggered. This will help to save power and maintain the
+	 * sync b/w Host and controller
+	 */
+	skb = __hci_cmd_sync(hdev, HCI_OP_RESET, 0, NULL, HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb)) {
+		bt_dev_err(hdev, "HCI reset during shutdown failed");
+		return PTR_ERR(skb);
+	}
+	kfree_skb(skb);
+
+	return 0;
+}
+
 #ifdef CONFIG_PM
 /* Configure an out-of-band gpio as wake-up pin, if specified in device tree */
 static int marvell_config_oob_wake(struct hci_dev *hdev)
@@ -3139,6 +3157,7 @@ static int btusb_probe(struct usb_interface *intf,
 		hdev->manufacturer = 2;
 		hdev->send = btusb_send_frame_intel;
 		hdev->setup = btusb_setup_intel_new;
+		hdev->shutdown = btusb_shutdown_intel_new;
 		hdev->hw_error = btintel_hw_error;
 		hdev->set_diag = btintel_set_diag;
 		hdev->set_bdaddr = btintel_set_bdaddr;