[Bluetooth] Add HCIUARTGETDEVICE support for HCI line discipline

Adding HCIUARTGETDEVICE makes it possible to get the HCI device number
that is attached to a given serial device. This is required during the
initialization process of some Bluetooth chips.
Signed-off-by: NOhad Ben-Cohen <ohad@bencohen.org>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_ldisc.c

@@ -479,6 +479,11 @@ static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file * file,
 			return hu->proto->id;
 		return -EUNATCH;
 
+	case HCIUARTGETDEVICE:
+		if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
+			return hu->hdev->id;
+		return -EUNATCH;
+
 	default:
 		err = n_tty_ioctl(tty, file, cmd, arg);
 		break;

drivers/bluetooth/hci_uart.h

@@ -30,6 +30,7 @@
 /* Ioctls */
 #define HCIUARTSETPROTO		_IOW('U', 200, int)
 #define HCIUARTGETPROTO		_IOR('U', 201, int)
+#define HCIUARTGETDEVICE	_IOR('U', 202, int)
 
 /* UART protocols */
 #define HCI_UART_MAX_PROTO	4