arch/mips/kernel/i8253.c

   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);