blob: 6ebe00cb4a3b704d19eca6a75dce913135446262 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
/*
* 8253/PIT functions
*
*/
#include <linux/clockchips.h>
#include <linux/init.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() ||
!clockevent_state_periodic(&i8253_clockevent))
return 0;
return clocksource_i8253_init();
}
arch_initcall(init_pit_clocksource);
#endif /* !CONFIG_X86_64 */
|
