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 void timer_handler(int sig, struct uml_pt_regs *regs)
  17 {
  18         unsigned long flags;
  19
  20         local_irq_save(flags);
  21         do_IRQ(TIMER_IRQ, regs);
  22         local_irq_restore(flags);
  23 }
  24
  25 static void itimer_set_mode(enum clock_event_mode mode,
  26                             struct clock_event_device *evt)
  27 {
  28         switch (mode) {
  29         case CLOCK_EVT_MODE_PERIODIC:
  30                 set_interval();
  31                 break;
  32
  33         case CLOCK_EVT_MODE_SHUTDOWN:
  34         case CLOCK_EVT_MODE_UNUSED:
  35         case CLOCK_EVT_MODE_ONESHOT:
  36                 disable_timer();
  37                 break;
  38
  39         case CLOCK_EVT_MODE_RESUME:
  40                 break;
  41         }
  42 }
  43
  44 static int itimer_next_event(unsigned long delta,
  45                              struct clock_event_device *evt)
  46 {
  47         return timer_one_shot(delta + 1);
  48 }
  49
  50 static struct clock_event_device itimer_clockevent = {
  51         .name           = "itimer",
  52         .rating         = 250,
  53         .cpumask        = cpu_all_mask,
  54         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  55         .set_mode       = itimer_set_mode,
  56         .set_next_event = itimer_next_event,
  57         .shift          = 32,
  58         .irq            = 0,
  59 };
  60
  61 static irqreturn_t um_timer(int irq, void *dev)
  62 {
  63         (*itimer_clockevent.event_handler)(&itimer_clockevent);
  64
  65         return IRQ_HANDLED;
  66 }
  67
  68 static cycle_t itimer_read(void)
  69 {
  70         return os_nsecs() / 1000;
  71 }
  72
  73 static struct clocksource itimer_clocksource = {
  74         .name           = "itimer",
  75         .rating         = 300,
  76         .read           = itimer_read,
  77         .mask           = CLOCKSOURCE_MASK(64),
  78         .mult           = 1000,
  79         .shift          = 0,
  80         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  81 };
  82
  83 static void __init setup_itimer(void)
  84 {
  85         int err;
  86
  87         err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
  88         if (err != 0)
  89                 printk(KERN_ERR "register_timer : request_irq failed - "
  90                        "errno = %d\n", -err);
  91
  92         itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
  93         itimer_clockevent.max_delta_ns =
  94                 clockevent_delta2ns(60 * HZ, &itimer_clockevent);
  95         itimer_clockevent.min_delta_ns =
  96                 clockevent_delta2ns(1, &itimer_clockevent);
  97         err = clocksource_register(&itimer_clocksource);
  98         if (err) {
  99                 printk(KERN_ERR "clocksource_register returned %d\n", err);
 100                 return;
 101         }
 102         clockevents_register_device(&itimer_clockevent);
 103 }
 104
 105 void __init time_init(void)
 106 {
 107         long long nsecs;
 108
 109         timer_init();
 110
 111         nsecs = os_nsecs();
 112         set_normalized_timespec(&wall_to_monotonic, -nsecs / NSEC_PER_SEC,
 113                                 -nsecs % NSEC_PER_SEC);
 114         set_normalized_timespec(&xtime, nsecs / NSEC_PER_SEC,
 115                                 nsecs % NSEC_PER_SEC);
 116         late_time_init = setup_itimer;
 117 }