+extern int sensor_count;
+extern struct sensor_t sensor_desc[MAX_SENSORS];
+extern sensor_info_t sensor[MAX_SENSORS];
+extern sensor_catalog_entry_t sensor_catalog[];
+extern unsigned int catalog_size;
+
+/* Needed both in sensors and activity HALs */
+void check_trig_sensors (int i, char *sysfs_file, char map[catalog_size]);
+void check_poll_sensors (int i, char *sysfs_file, char map[catalog_size]);
+void check_event_sensors (int i, char *sysfs_file, char map[catalog_size]);
+void discover_sensors(int dev_num, char *sysfs_base_path, char map[catalog_size],
+ void (*discover_sensor)(int, char*, char*));
+
+/*
+ * Macros associating iio sysfs entries to to sensor types ; see
+ * linux/kernel/drivers/iio/industrialio-core.c and
+ * hardware/libhardware/include/hardware/sensor.h
+ */
+
+#define DECLARE_VOID_CHANNEL(tag) \
+ tag, \
+ "", \
+ "", \
+ "", \
+ "", \
+ "", \
+ "", \
+
+#define DECLARE_CHANNEL(tag, spacer, name) \
+ name, \
+ "in_"tag spacer name"_en", \
+ "in_"tag spacer name"_type", \
+ "in_"tag spacer name"_index", \
+ "in_"tag spacer name"_raw", \
+ "in_"tag spacer name"_input", \
+ "in_"tag spacer name"_scale", \
+ 0, {{0}},
+
+#define DECLARE_NAMED_CHANNEL(tag, name) DECLARE_CHANNEL(tag, "_", name)
+
+#define DECLARE_GENERIC_CHANNEL(tag) DECLARE_CHANNEL(tag, "", "")
+
+#define DECLARE_EVENT(tag, spacer1, name, spacer2, type, spacer3, dir) \
+ type, dir, \
+ "in_"tag spacer1 name spacer2 type spacer3 dir"_en", \
+ "in_"tag spacer1 name spacer2 type spacer3 dir"_value", \
+
+#define DECLARE_GENERIC_EVENT(tag, name, type, dir) \
+ DECLARE_EVENT(tag, "_", name, "_", type, "_", dir)
+#define DECLARE_NAMED_EVENT(tag, name) \
+ DECLARE_EVENT(tag, "_", name, "","","","")