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
14 static irqreturn_t timer_interrupt(int irq, void *dev_id)
15 {
16 i8253_clockevent.event_handler(&i8253_clockevent);
17
18 return IRQ_HANDLED;
19 }
20
21 void __init setup_pit_timer(void)
22 {
23 unsigned long flags = IRQF_NOBALANCING | IRQF_TIMER;
24
25 clockevent_i8253_init(true);
26 if (request_irq(0, timer_interrupt, flags, "timer", NULL))
27 pr_err("Failed to request irq 0 (timer)\n");
28 }
29
30 static int __init init_pit_clocksource(void)
31 {
32 if (num_possible_cpus() > 1 || /* PIT does not scale! */
33 !clockevent_state_periodic(&i8253_clockevent))
34 return 0;
35
36 return clocksource_i8253_init();
37 }
38 arch_initcall(init_pit_clocksource);
39
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