Gigabeat: Add timer functionality. Rework tick timer setup to be exactly 100Hz. Metronome should work now but some pcm changes are needed to have faster tocks work correctly (in the works).

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13806 a1c6a512-1295-4272-9138-f99709370657

firmware/export/timer.h

@@ -25,7 +25,6 @@
 
 #ifndef SIMULATOR
 
-
 #if defined(CPU_PP)
  /* Portalplayer chips use a microsecond timer. */
  #define TIMER_FREQ 1000000
@@ -34,6 +33,8 @@
  #define TIMER_FREQ (CPU_FREQ/2)
 #elif CONFIG_CPU == PNX0101
  #define TIMER_FREQ 3000000
+#elif CONFIG_CPU == S3C2440
+ #include "timer-target.h"
 #else
  #define TIMER_FREQ CPU_FREQ
 #endif
@@ -46,5 +47,9 @@ void timers_adjust_prescale(int multiplier, bool enable_irq);
 #endif
 void timer_unregister(void);
 
+/* For target-specific interface use */
+extern void (*pfn_timer)(void);
+extern void (*pfn_unregister)(void);
+
 #endif /* !SIMULATOR */
 #endif /* __TIMER_H__ */