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