| /* |
| * 8253/PIT functions |
| * |
| */ |
| #include <linux/clockchips.h> |
| #include <linux/module.h> |
| #include <linux/timex.h> |
| #include <linux/i8253.h> |
| |
| #include <asm/hpet.h> |
| #include <asm/time.h> |
| #include <asm/smp.h> |
| |
| /* |
| * HPET replaces the PIT, when enabled. So we need to know, which of |
| * the two timers is used |
| */ |
| struct clock_event_device *global_clock_event; |
| |
| void __init setup_pit_timer(void) |
| { |
| clockevent_i8253_init(true); |
| global_clock_event = &i8253_clockevent; |
| } |
| |
| #ifndef CONFIG_X86_64 |
| static int __init init_pit_clocksource(void) |
| { |
| /* |
| * Several reasons not to register PIT as a clocksource: |
| * |
| * - On SMP PIT does not scale due to i8253_lock |
| * - when HPET is enabled |
| * - when local APIC timer is active (PIT is switched off) |
| */ |
| if (num_possible_cpus() > 1 || is_hpet_enabled() || |
| i8253_clockevent.mode != CLOCK_EVT_MODE_PERIODIC) |
| return 0; |
| |
| return clocksource_i8253_init(); |
| } |
| arch_initcall(init_pit_clocksource); |
| #endif /* !CONFIG_X86_64 */ |