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 static struct irqaction irq0 = { 22 .handler = timer_interrupt, 23 .flags = IRQF_NOBALANCING | IRQF_TIMER, 24 .name = "timer" 25 }; 26 27 void __init setup_pit_timer(void) 28 { 29 clockevent_i8253_init(true); 30 setup_irq(0, &irq0); 31 } 32 33 static 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 } 41 arch_initcall(init_pit_clocksource); 42