Bluetooth: Add support for sending system notes to monitor channel

The monitor channel can be used to send generic system notes as text
strings for debugging purposes. This adds the system note monitor code
and uses it for including kernel and subsystem version into traces.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/bluetooth/bluetooth.h

@@ -29,6 +29,8 @@
 #include <net/sock.h>
 #include <linux/seq_file.h>
 
+#define BT_SUBSYS_VERSION "2.21"
+
 #ifndef AF_BLUETOOTH
 #define AF_BLUETOOTH	31
 #define PF_BLUETOOTH	AF_BLUETOOTH

include/net/bluetooth/hci_mon.h

@@ -43,6 +43,7 @@ struct hci_mon_hdr {
 #define HCI_MON_CLOSE_INDEX	9
 #define HCI_MON_INDEX_INFO	10
 #define HCI_MON_VENDOR_DIAG	11
+#define HCI_MON_SYSTEM_NOTE	12
 
 struct hci_mon_new_index {
 	__u8		type;