tmu: fix freeze when using sleep_us_spin() with interrupts on

Because of timing the interrupt handler could run before the flag is
checked.

include/gint/timer.h

@@ -162,10 +162,11 @@ void timer_stop(int timer);
    it may have only paused. If the timer never stops, you're in trouble. */
 void timer_wait(int timer);
 
-/* timer_spinwait(): Actively wait for a timer to raise UNF
+/* timer_spinwait(): Start a timer and actively wait for UNF
    Waits until the timer raises UNF, without sleeping. This is useful for
-   delays in driver code that is run when interrupts are disabled. This relies
+   delays in driver code that is run when interrupts are disabled. UNIE is
-   neither on the interrupt signal nor on the UNIE flag. */
+   disabled before starting the timer and waiting, so the callback is never
+   called. */
 void timer_spinwait(int timer);
 
 //---

src/tmu/sleep.c

@@ -13,12 +13,14 @@ static void do_sleep(uint64_t delay_us, int spin)
 		GINT_CALL_SET_STOP(&flag));
 	if(timer < 0) return;
 
-	timer_start(timer);
 	if(spin) {
 		timer_spinwait(timer);
 		timer_stop(timer);
 	}
-	else timer_wait(timer);
+	else {
+		timer_start(timer);
+		timer_wait(timer);
+	}
 }
 
 /* sleep_us(): Sleep for a fixed duration in microseconds */

src/tmu/tmu.c

@@ -209,6 +209,7 @@ void timer_stop(int id)
 	if(id < 3)
 	{
 		TMU[id].TCR.UNIE = 0;
+		TMU[id].TCR.UNF = 0;
 		TMU[id].TCOR = 0xffffffff;
 		TMU[id].TCNT = 0xffffffff;
 	}
@@ -240,17 +241,21 @@ void timer_wait(int id)
 	}
 }
 
-/* timer_spinwait(): Actively wait for a timer to raise UNF */
+/* timer_spinwait(): Start a timer and actively wait for UNF */
 void timer_spinwait(int id)
 {
 	if(id < 3)
 	{
 		tmu_t *T = &TMU[id];
+		T->TCR.UNIE = 0;
+		timer_start(id);
 		while(!T->TCR.UNF) {}
 	}
 	else
 	{
 		etmu_t *T = &ETMU[id-3];
+		set(T->TCR.UNIE, 0);
+		timer_start(id);
 		while(!T->TCR.UNF) {}
 	}
 }