diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/arch/riscv/trap_handler.c | 61 |
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"); |