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-rw-r--r--src/arch/riscv/trap_handler.c61
1 files changed, 9 insertions, 52 deletions
diff --git a/src/arch/riscv/trap_handler.c b/src/arch/riscv/trap_handler.c
index 772be64f40..8029218fb2 100644
--- a/src/arch/riscv/trap_handler.c
+++ b/src/arch/riscv/trap_handler.c
@@ -20,9 +20,6 @@
#include <string.h>
#include <vm.h>
-static uint64_t *time;
-static uint64_t *timecmp;
-
static const char *const exception_names[] = {
"Instruction address misaligned",
"Instruction access fault",
@@ -78,62 +75,22 @@ static void print_trap_information(const trapframe *tf)
printk(BIOS_DEBUG, "Stored sp: %p\n", (void*) tf->gpr[2]);
}
-static void gettimer(void)
-{
- /*
- * FIXME: This hard-coded value (currently) works on spike, but we
- * should really read it from the device tree.
- */
- uintptr_t clint = 0x02000000;
-
- time = (void *)(clint + 0xbff8);
- timecmp = (void *)(clint + 0x4000);
-
- if (!time)
- die("Got timer interrupt but found no timer.");
- if (!timecmp)
- die("Got timer interrupt but found no timecmp.");
-}
-
static void interrupt_handler(trapframe *tf)
{
uint64_t cause = tf->cause & ~0x8000000000000000ULL;
- uint32_t msip, ssie;
switch (cause) {
case IRQ_M_TIMER:
- // The only way to reset the timer interrupt is to
- // write mtimecmp. But we also have to ensure the
- // comparison fails, for a long time, to let
- // supervisor interrupt handler compute a new value
- // and set it. Finally, it fires if mtimecmp is <=
- // mtime, not =, so setting mtimecmp to 0 won't work
- // to clear the interrupt and disable a new one. We
- // have to set the mtimecmp far into the future.
- // Akward!
- //
- // Further, maybe the platform doesn't have the
- // hardware or the payload never uses it. We hold off
- // querying some things until we are sure we need
- // them. What to do if we can not find them? There are
- // no good options.
-
- // This hart may have disabled timer interrupts. If
- // so, just return. Kernels should only enable timer
- // interrupts on one hart, and that should be hart 0
- // at present, as we only search for
- // "core{0{0{timecmp" above.
- ssie = read_csr(sie);
- if (!(ssie & SIP_STIP))
- break;
+ /*
+ * Set interrupt pending for supervisor mode and disable timer
+ * interrupt in machine mode.
+ * To receive another timer interrupt just set timecmp and
+ * enable machine mode timer interrupt again.
+ */
+
+ clear_csr(mie, MIP_MTIP);
+ set_csr(mip, MIP_STIP);
- if (!timecmp)
- gettimer();
- //printk(BIOS_SPEW, "timer interrupt\n");
- *timecmp = (uint64_t) -1;
- msip = read_csr(mip);
- msip |= SIP_STIP;
- write_csr(mip, msip);
break;
default:
printk(BIOS_EMERG, "======================================\n");