gnss: add receiver type support

Add a "type" device attribute and a "GNSS_TYPE" uevent variable which
can be used to determine the type of a GNSS receiver. The currently
identified types reflect the protocol(s) supported by a receiver:

	"NMEA"	NMEA 0183
	"SiRF"	SiRF Binary
	"UBX"	UBX

Note that both SiRF and UBX type receivers typically support a subset of
NMEA 0183 with vendor extensions (e.g. to allow switching to the vendor
protocol).

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/gnss.h b/include/linux/gnss.h
index e26aeac..4354697 100644
--- a/include/linux/gnss.h
+++ b/include/linux/gnss.h
@@ -18,6 +18,14 @@
 
 struct gnss_device;
 
+enum gnss_type {
+	GNSS_TYPE_NMEA = 0,
+	GNSS_TYPE_SIRF,
+	GNSS_TYPE_UBX,
+
+	GNSS_TYPE_COUNT
+};
+
 struct gnss_operations {
 	int (*open)(struct gnss_device *gdev);
 	void (*close)(struct gnss_device *gdev);
@@ -30,6 +38,7 @@ struct gnss_device {
 	struct cdev cdev;
 	int id;
 
+	enum gnss_type type;
 	unsigned long flags;
 
 	struct rw_semaphore rwsem;