diff options
Diffstat (limited to 'kernel/arch/x86/kernel/i8253.c')
-rw-r--r-- | kernel/arch/x86/kernel/i8253.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/kernel/arch/x86/kernel/i8253.c b/kernel/arch/x86/kernel/i8253.c new file mode 100644 index 000000000..f2b96de3c --- /dev/null +++ b/kernel/arch/x86/kernel/i8253.c @@ -0,0 +1,43 @@ +/* + * 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 */ |