spark: use LED display for time and volume

This is a first draft of code to display time and
volume percent on the 4 digit display on spark boxes.

src/driver/spark_led.h

@@ -0,0 +1,61 @@
+/* ugly: this is copied from frontcontroller utility, but the driver
+ * does not seem to provide userspace headers... :-( */
+
+
+/* this setups the mode temporarily (for one ioctl)
+ * to the desired mode. currently the "normal" mode
+ * is the compatible vfd mode
+ */
+struct set_mode_s {
+	int compat; /* 0 = compatibility mode to vfd driver; 1 = nuvoton mode */
+};
+
+struct set_brightness_s {
+	int level;
+};
+
+struct set_icon_s {
+	int icon_nr;
+	int on;
+};
+
+struct set_led_s {
+	int led_nr;
+	int on;
+};
+
+/* time must be given as follows:
+ * time[0] & time[1] = mjd ???
+ * time[2] = hour
+ * time[3] = min
+ * time[4] = sec
+ */
+struct set_standby_s {
+	char time[5];
+};
+
+struct set_time_s {
+	char time[5];
+};
+
+struct aotom_ioctl_data {
+	union
+	{
+		struct set_icon_s icon;
+		struct set_led_s led;
+		struct set_brightness_s brightness;
+		struct set_mode_s mode;
+		struct set_standby_s standby;
+		struct set_time_s time;
+	} u;
+};
+
+/* a strange way of defining ioctls... but anyway... */
+#define VFDGETTIME      0xc0425afa
+#define VFDSETTIME      0xc0425afb
+#define VFDSTANDBY      0xc0425afc
+#define VFDSETLED       0xc0425afe
+#define VFDDISPLAYCHARS 0xc0425a00
+#define VFDDISPLAYCLR   0xc0425b00
+#define VFDSETMODE      0xc0425aff
+