1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2d865bea4SRalf Baechle /* 3d865bea4SRalf Baechle * i8253.c 8253/PIT functions 4d865bea4SRalf Baechle * 5d865bea4SRalf Baechle */ 6d865bea4SRalf Baechle #include <linux/clockchips.h> 7334955efSRalf Baechle #include <linux/i8253.h> 873bc256dSPaul Gortmaker #include <linux/export.h> 9631330f5SRalf Baechle #include <linux/smp.h> 10ca4d3e67SDavid Howells #include <linux/irq.h> 11d865bea4SRalf Baechle 12dd3db6ebSRalf Baechle #include <asm/time.h> 13d865bea4SRalf Baechle timer_interrupt(int irq,void * dev_id)14dd3db6ebSRalf Baechlestatic irqreturn_t timer_interrupt(int irq, void *dev_id) 15d865bea4SRalf Baechle { 16ded7c1eeSThomas Gleixner i8253_clockevent.event_handler(&i8253_clockevent); 17d865bea4SRalf Baechle 18d865bea4SRalf Baechle return IRQ_HANDLED; 19d865bea4SRalf Baechle } 20d865bea4SRalf Baechle setup_pit_timer(void)21d865bea4SRalf Baechlevoid __init setup_pit_timer(void) 22d865bea4SRalf Baechle { 23*ac8fd122Safzal mohammed unsigned long flags = IRQF_NOBALANCING | IRQF_TIMER; 24*ac8fd122Safzal mohammed 252d02612fSThomas Gleixner clockevent_i8253_init(true); 26*ac8fd122Safzal mohammed if (request_irq(0, timer_interrupt, flags, "timer", NULL)) 27*ac8fd122Safzal mohammed pr_err("Failed to request irq 0 (timer)\n"); 28d865bea4SRalf Baechle } 29d865bea4SRalf Baechle init_pit_clocksource(void)30d865bea4SRalf Baechlestatic int __init init_pit_clocksource(void) 31d865bea4SRalf Baechle { 32a07e3324SThomas Bogendoerfer if (num_possible_cpus() > 1 || /* PIT does not scale! */ 33a07e3324SThomas Bogendoerfer !clockevent_state_periodic(&i8253_clockevent)) 34d865bea4SRalf Baechle return 0; 35d865bea4SRalf Baechle 36798778b8SRussell King return clocksource_i8253_init(); 37d865bea4SRalf Baechle } 38d865bea4SRalf Baechle arch_initcall(init_pit_clocksource); 39