improve timer handling

+ Previous code assumed a timer would only trigger when requested, but
  didn't explicitly disable timers during init. Newer versions of qemu
  (>= 10?) seem to have some kind of timer set, unsure if that's via
  OpenSBI or what exactly but some slower tests were failing because of
  it.

1 files changed, 13 insertions, 0 deletions

diff --git a/include/arch/timer.h b/include/arch/timer.h
index 8b832c9..8f235e6 100644
--- a/include/arch/timer.h
+++ b/include/arch/timer.h
@@ -30,6 +30,12 @@ ticks_t stat_timer(const void *fdt);
 
 /**
  * Set up timer interrupt for absolute ticks.
+ * At least currently assumes there is only one global timer, the kernel will
+ * ensure that the timer is scheduled to handle events in order.
+ *
+ * When setting a new timer, the current timer (if one is set) will
+ * not trigger an interrupt. For instance, if called from the interrupt handler
+ * of the existing interrupt, it won't re-trigger.
  *
  * @param ticks Time point for timer to trigger.
  * \todo Should maybe be stat_t?
@@ -37,6 +43,13 @@ ticks_t stat_timer(const void *fdt);
 void set_timer(ticks_t ticks);
 
 /**
+ * Stop the timer interrupts from happening altogether. Mainly called during
+ * init to avoid spurious interrupts and when all userspace timers have been
+ * handled.
+ */
+void clear_timer();
+
+/**
  * Get current ticks.
  *
  * @return Current tick count.