+/**\r
+\r
+ This function registers the handler NotifyFunction so it is called every time\r
+ the timer interrupt fires. It also passes the amount of time since the last\r
+ handler call to the NotifyFunction. If NotifyFunction is NULL, then the\r
+ handler is unregistered. If the handler is registered, then EFI_SUCCESS is\r
+ returned. If the CPU does not support registering a timer interrupt handler,\r
+ then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler\r
+ when a handler is already registered, then EFI_ALREADY_STARTED is returned.\r
+ If an attempt is made to unregister a handler when a handler is not registered,\r
+ then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to\r
+ register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR\r
+ is returned.\r
+\r
+\r
+ @param This The EFI_TIMER_ARCH_PROTOCOL instance.\r
+ @param NotifyFunction The function to call when a timer interrupt fires. This\r
+ function executes at TPL_HIGH_LEVEL. The DXE Core will\r
+ register a handler for the timer interrupt, so it can know\r
+ how much time has passed. This information is used to\r
+ signal timer based events. NULL will unregister the handler.\r
+\r
+ @retval EFI_SUCCESS The timer handler was registered.\r
+ @retval EFI_UNSUPPORTED The platform does not support timer interrupts.\r
+ @retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already\r
+ registered.\r
+ @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not\r
+ previously registered.\r
+ @retval EFI_DEVICE_ERROR The timer handler could not be registered.\r
+\r
+**/\r