1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * i8253.c  8253/PIT functions
 4 *
 5 */
 6#include <linux/clockchips.h>
 7#include <linux/i8253.h>
 8#include <linux/export.h>
 9#include <linux/smp.h>
10#include <linux/irq.h>
11
12#include <asm/time.h>
13
14static irqreturn_t timer_interrupt(int irq, void *dev_id)
15{
16	i8253_clockevent.event_handler(&i8253_clockevent);
17
18	return IRQ_HANDLED;
19}
20
21static struct irqaction irq0  = {
22	.handler = timer_interrupt,
23	.flags = IRQF_NOBALANCING | IRQF_TIMER,
24	.name = "timer"
25};
26
27void __init setup_pit_timer(void)
28{
29	clockevent_i8253_init(true);
30	setup_irq(0, &irq0);
31}
32
33static int __init init_pit_clocksource(void)
34{
35	if (num_possible_cpus() > 1) /* PIT does not scale! */
 
36		return 0;
37
38	return clocksource_i8253_init();
39}
40arch_initcall(init_pit_clocksource);

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * i8253.c  8253/PIT functions
 4 *
 5 */
 6#include <linux/clockchips.h>
 7#include <linux/i8253.h>
 8#include <linux/export.h>
 9#include <linux/smp.h>
10#include <linux/irq.h>
11
12#include <asm/time.h>
13
14static irqreturn_t timer_interrupt(int irq, void *dev_id)
15{
16	i8253_clockevent.event_handler(&i8253_clockevent);
17
18	return IRQ_HANDLED;
19}
20
21static struct irqaction irq0  = {
22	.handler = timer_interrupt,
23	.flags = IRQF_NOBALANCING | IRQF_TIMER,
24	.name = "timer"
25};
26
27void __init setup_pit_timer(void)
28{
29	clockevent_i8253_init(true);
30	setup_irq(0, &irq0);
31}
32
33static int __init init_pit_clocksource(void)
34{
35	if (num_possible_cpus() > 1 || /* PIT does not scale! */
36	    !clockevent_state_periodic(&i8253_clockevent))
37		return 0;
38
39	return clocksource_i8253_init();
40}
41arch_initcall(init_pit_clocksource);