Poll HTIF console on timer interrupt

2 files changed, 20 insertions, 8 deletions

diff --git a/machine/mentry.S b/machine/mentry.S
index 4895227..6bdc7e6 100644
--- a/machine/mentry.S
+++ b/machine/mentry.S
@@ -20,7 +20,9 @@ trap_table:
   .word bad_trap
 #define SOFTWARE_INTERRUPT_VECTOR 12
   .word software_interrupt
-#define TRAP_FROM_MACHINE_MODE_VECTOR 13
+#define TIMER_INTERRUPT_VECTOR 13
+  .word timer_interrupt
+#define TRAP_FROM_MACHINE_MODE_VECTOR 14
   .word __trap_from_machine_mode
 
   .option norvc
@@ -49,11 +51,8 @@ trap_vector:
   # Is it a machine timer interrupt?
   li a0, IRQ_M_TIMER * 2
   bne a0, a1, 1f
-  # Yes.  Post a supervisor timer interrupt.
-  li a0, MIP_MTIP
-  csrc mie, a0
-  li a0, MIP_STIP
-  csrs mip, a0
+  li a1, TIMER_INTERRUPT_VECTOR
+  j .Lhandle_trap_in_machine_mode
 
 .Lmret:
   # Go back whence we came.
diff --git a/machine/mtrap.c b/machine/mtrap.c
index 5c835cb..9560948 100644
--- a/machine/mtrap.c
+++ b/machine/mtrap.c
@@ -30,6 +30,8 @@ static void htif_interrupt()
 {
   // we should only be interrupted by keypresses
   uint64_t fh = fromhost;
+  if (!fh)
+    return;
   if (!(FROMHOST_DEV(fh) == 1 && FROMHOST_CMD(fh) == 0))
     die("unexpected htif interrupt");
   HLS()->console_ibuf = 1 + (uint8_t)FROMHOST_DATA(fh);
@@ -40,8 +42,7 @@ static void htif_interrupt()
 static void do_tohost_fromhost(uintptr_t dev, uintptr_t cmd, uintptr_t data)
 {
   while (tohost)
-    if (fromhost)
-      htif_interrupt();
+    htif_interrupt();
   tohost = TOHOST_CMD(dev, cmd, data);
 
   while (1) {
@@ -56,6 +57,18 @@ static void do_tohost_fromhost(uintptr_t dev, uintptr_t cmd, uintptr_t data)
   }
 }
 
+uintptr_t timer_interrupt()
+{
+  // just send the timer interrupt to the supervisor
+  clear_csr(mie, MIP_MTIP);
+  set_csr(mip, MIP_STIP);
+
+  // and poll the HTIF console
+  htif_interrupt();
+
+  return 0;
+}
+
 static uintptr_t mcall_console_putchar(uint8_t ch)
 {
   do_tohost_fromhost(1, 1, ch);