drivers: gnss: Add geoid separation to gnss_info

Currently altitude is only provided above MSL. Adding
geoid seperation allows for ellipsoidal height to be
determined.

Signed-off-by: Maxmillion McLaughlin <max@sorcerer.earth>

drivers/gnss/gnss_nmea0183.c

@@ -545,6 +545,16 @@ int gnss_nmea0183_parse_gga(const char **argv, uint16_t argc, struct gnss_data *
 	}
 
 	data->nav_data.altitude = (int32_t)tmp64;
+
+	/* Parse geoid separation */
+	if ((gnss_parse_dec_to_milli(argv[11], &tmp64) < 0) ||
+	    (tmp64 > INT32_MAX) ||
+	    (tmp64 < INT32_MIN)) {
+		return -EINVAL;
+	}
+
+	data->info.geoid_separation = (int32_t)tmp64;
+
 	return 0;
 }
 

include/zephyr/data/navigation.h

@@ -31,7 +31,7 @@ struct navigation_data {
 	uint32_t bearing;
 	/** Speed in millimeters per second */
 	uint32_t speed;
-	/** Altitude in millimeters */
+	/** Altitude above MSL in millimeters */
 	int32_t altitude;
 };
 

include/zephyr/drivers/gnss.h

@@ -140,6 +140,8 @@ struct gnss_info {
 	uint16_t satellites_cnt;
 	/** Horizontal dilution of precision in 1/1000 */
 	uint32_t hdop;
+	/** Geoid separation in millimeters */
+	int32_t geoid_separation;
 	/** The fix status */
 	enum gnss_fix_status fix_status;
 	/** The fix quality */