LXR linux/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
  14static irqreturn_t timer_interrupt(int irq, void *dev_id)
  15{
  16        i8253_clockevent.event_handler(&i8253_clockevent);
  17
  18        return IRQ_HANDLED;
  19}
  20
  21void __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
  30static 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}
  38arch_initcall(init_pit_clocksource);
  39