projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 8d016ef1 | 1 | /* |
| 835c34a1 | 2 | * 8253/PIT functions |
| 8d016ef1 | 3 | * |
| 4 | */ | |
| e9e2cdb4 | 5 | #include <linux/clockchips.h> |
| 8d016ef1 | 6 | #include <linux/module.h> |
| 08604bd9 | 7 | #include <linux/timex.h> |
| 334955ef | 8 | #include <linux/i8253.h> |
| 8d016ef1 | 9 | |
| 4713e22c | 10 | #include <asm/hpet.h> |
| 16f871bc | 11 | #include <asm/time.h> |
| c8344bc2 | 12 | #include <asm/smp.h> |
| 8d016ef1 | 13 | |
| e9e2cdb4 TG |
14 | /* |
| 15 | * HPET replaces the PIT, when enabled. So we need to know, which of | |
| 16 | * the two timers is used | |
| 17 | */ | |
| 18 | struct clock_event_device *global_clock_event; | |
| 19 | ||
| e9e2cdb4 TG |
20 | void __init setup_pit_timer(void) |
| 21 | { | |
| 0a779c57 TG |
22 | clockevent_i8253_init(true); |
| 23 | global_clock_event = &i8253_clockevent; | |
| 8d016ef1 | 24 | } |
| 5d0cf410 | 25 | |
| f5e0e93f | 26 | #ifndef CONFIG_X86_64 |
| 5d0cf410 | 27 | static int __init init_pit_clocksource(void) |
| 28 | { | |
| 316da3b3 TG |
29 | /* |
| 30 | * Several reasons not to register PIT as a clocksource: | |
| 31 | * | |
| 32 | * - On SMP PIT does not scale due to i8253_lock | |
| 33 | * - when HPET is enabled | |
| 34 | * - when local APIC timer is active (PIT is switched off) | |
| 35 | */ | |
| 36 | if (num_possible_cpus() > 1 || is_hpet_enabled() || | |
| 8eda41b0 | 37 | !clockevent_state_periodic(&i8253_clockevent)) |
| 5d0cf410 | 38 | return 0; |
| 39 | ||
| 82491451 | 40 | return clocksource_i8253_init(); |
| 5d0cf410 | 41 | } |
| 6bb74df4 | 42 | arch_initcall(init_pit_clocksource); |
| c8344bc2 | 43 | #endif /* !CONFIG_X86_64 */ |