accel-location: add helper functions for ACCEL_LOCATION udev property

src/Makefile.am

@@ -28,6 +28,8 @@ iio_sensor_proxy_SOURCES =			\
 	iio-buffer-utils.c			\
 	accel-mount-matrix.h			\
 	accel-mount-matrix.c			\
+	accel-location.h				\
+	accel-location.c				\
 	$(BUILT_SOURCES)
 
 iio_sensor_proxy_CPPFLAGS =			\

src/accel-location.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2019 Luís Ferreira <luis@aurorafoss.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 3 as published by
+ * the Free Software Foundation.
+ *
+ */
+
+#include "accel-location.h"
+
+AccelLocation
+setup_accel_location (GUdevDevice *device)
+{
+	AccelLocation ret;
+	const char *location;
+
+	location = g_udev_device_get_property (device, "ACCEL_LOCATION");
+	if (location) {
+		if (parse_accel_location (location, &ret))
+			return ret;
+
+		g_warning ("Failed to parse ACCEL_LOCATION ('%s') from udev",
+			   location);
+	} else {
+		g_debug ("No autodetected location, falling back to display location");
+	}
+
+	ret = ACCEL_LOCATION_DISPLAY;
+	return ret;
+}
+
+gboolean
+parse_accel_location (const char *location, AccelLocation *value)
+{
+	/* Empty string means we use the display location */
+	if (location == NULL ||
+		*location == '\0' ||
+		(g_strcmp0 (location, "display") == 0)) {
+		*value = ACCEL_LOCATION_DISPLAY;
+		return TRUE;
+	} else if (g_strcmp0 (location, "base") == 0) {
+		*value = ACCEL_LOCATION_BASE;
+		return TRUE;
+	} else {
+		g_warning ("Failed to parse '%s' as a location", location);
+		return FALSE;
+	}
+}

src/accel-location.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2019 Luís Ferreira <luis@aurorafoss.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 3 as published by
+ * the Free Software Foundation.
+ *
+ */
+
+#include <glib.h>
+#include <gudev/gudev.h>
+
+typedef enum {
+	ACCEL_LOCATION_DISPLAY,
+	ACCEL_LOCATION_BASE,
+} AccelLocation;
+
+AccelLocation setup_accel_location (GUdevDevice *device);
+
+gboolean parse_accel_location (const char    *location,
+                               AccelLocation *value);