arch/um/kernel/time.c

   1 /*
   2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <linux/clockchips.h>
   7 #include <linux/init.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/jiffies.h>
  10 #include <linux/threads.h>
  11 #include <asm/irq.h>
  12 #include <asm/param.h>
  13 #include "kern_util.h"
  14 #include "os.h"
  15
  16 /*
  17  * Scheduler clock - returns current time in nanosec units.
  18  */
  19 unsigned long long sched_clock(void)
  20 {
  21         return (unsigned long long)jiffies_64 * (NSEC_PER_SEC / HZ);
  22 }
  23
  24 void timer_handler(int sig, struct uml_pt_regs *regs)
  25 {
  26         unsigned long flags;
  27
  28         local_irq_save(flags);
  29         do_IRQ(TIMER_IRQ, regs);
  30         local_irq_restore(flags);
  31 }
  32
  33 static void itimer_set_mode(enum clock_event_mode mode,
  34                             struct clock_event_device *evt)
  35 {
  36         switch (mode) {
  37         case CLOCK_EVT_MODE_PERIODIC:
  38                 set_interval();
  39                 break;
  40
  41         case CLOCK_EVT_MODE_SHUTDOWN:
  42         case CLOCK_EVT_MODE_UNUSED:
  43         case CLOCK_EVT_MODE_ONESHOT:
  44                 disable_timer();
  45                 break;
  46
  47         case CLOCK_EVT_MODE_RESUME:
  48                 break;
  49         }
  50 }
  51
  52 static int itimer_next_event(unsigned long delta,
  53                              struct clock_event_device *evt)
  54 {
  55         return timer_one_shot(delta + 1);
  56 }
  57
  58 static struct clock_event_device itimer_clockevent = {
  59         .name           = "itimer",
  60         .rating         = 250,
  61         .cpumask        = CPU_MASK_ALL,
  62         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  63         .set_mode       = itimer_set_mode,
  64         .set_next_event = itimer_next_event,
  65         .shift          = 32,
  66         .irq            = 0,
  67 };
  68
  69 static irqreturn_t um_timer(int irq, void *dev)
  70 {
  71         (*itimer_clockevent.event_handler)(&itimer_clockevent);
  72
  73         return IRQ_HANDLED;
  74 }
  75
  76 static cycle_t itimer_read(void)
  77 {
  78         return os_nsecs() / 1000;
  79 }
  80
  81 static struct clocksource itimer_clocksource = {
  82         .name           = "itimer",
  83         .rating         = 300,
  84         .read           = itimer_read,
  85         .mask           = CLOCKSOURCE_MASK(64),
  86         .mult           = 1000,
  87         .shift          = 0,
  88         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  89 };
  90
  91 static void __init setup_itimer(void)
  92 {
  93         int err;
  94
  95         err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
  96         if (err != 0)
  97                 printk(KERN_ERR "register_timer : request_irq failed - "
  98                        "errno = %d\n", -err);
  99
 100         itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
 101         itimer_clockevent.max_delta_ns =
 102                 clockevent_delta2ns(60 * HZ, &itimer_clockevent);
 103         itimer_clockevent.min_delta_ns =
 104                 clockevent_delta2ns(1, &itimer_clockevent);
 105         err = clocksource_register(&itimer_clocksource);
 106         if (err) {
 107                 printk(KERN_ERR "clocksource_register returned %d\n", err);
 108                 return;
 109         }
 110         clockevents_register_device(&itimer_clockevent);
 111 }
 112
 113 void __init time_init(void)
 114 {
 115         long long nsecs;
 116
 117         timer_init();
 118
 119         nsecs = os_nsecs();
 120         set_normalized_timespec(&wall_to_monotonic, -nsecs / NSEC_PER_SEC,
 121                                 -nsecs % NSEC_PER_SEC);
 122         set_normalized_timespec(&xtime, nsecs / NSEC_PER_SEC,
 123                                 nsecs % NSEC_PER_SEC);
 124         late_time_init = setup_itimer;
 125 }