i8253.c 839 B

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  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. #include <asm/time.h>
  12. static irqreturn_t timer_interrupt(int irq, void *dev_id)
  13. {
  14. i8253_clockevent.event_handler(&i8253_clockevent);
  15. return IRQ_HANDLED;
  16. }
  17. void __init setup_pit_timer(void)
  18. {
  19. unsigned long flags = IRQF_NOBALANCING | IRQF_TIMER;
  20. clockevent_i8253_init(true);
  21. if (request_irq(0, timer_interrupt, flags, "timer", NULL))
  22. pr_err("Failed to request irq 0 (timer)\n");
  23. }
  24. static int __init init_pit_clocksource(void)
  25. {
  26. if (num_possible_cpus() > 1 || /* PIT does not scale! */
  27. !clockevent_state_periodic(&i8253_clockevent))
  28. return 0;
  29. return clocksource_i8253_init();
  30. }
  31. arch_initcall(init_pit_clocksource);