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/interrupt.h>
   8 #include <linux/jiffies.h>
   9 #include <linux/threads.h>
  10 #include <asm/irq.h>
  11 #include <asm/param.h>
  12 #include "kern_util.h"
  13 #include "os.h"
  14
  15 /*
  16  * Scheduler clock - returns current time in nanosec units.
  17  */
  18 unsigned long long sched_clock(void)
  19 {
  20         return (unsigned long long)jiffies_64 * (NSEC_PER_SEC / HZ);
  21 }
  22
  23 void timer_handler(int sig, struct uml_pt_regs *regs)
  24 {
  25         unsigned long flags;
  26
  27         local_irq_save(flags);
  28         do_IRQ(TIMER_IRQ, regs);
  29         local_irq_restore(flags);
  30 }
  31
  32 static void itimer_set_mode(enum clock_event_mode mode,
  33                             struct clock_event_device *evt)
  34 {
  35         switch (mode) {
  36         case CLOCK_EVT_MODE_PERIODIC:
  37                 set_interval();
  38                 break;
  39
  40         case CLOCK_EVT_MODE_SHUTDOWN:
  41         case CLOCK_EVT_MODE_UNUSED:
  42         case CLOCK_EVT_MODE_ONESHOT:
  43                 disable_timer();
  44                 break;
  45
  46         case CLOCK_EVT_MODE_RESUME:
  47                 break;
  48         }
  49 }
  50
  51 static int itimer_next_event(unsigned long delta,
  52                              struct clock_event_device *evt)
  53 {
  54         return timer_one_shot(delta + 1);
  55 }
  56
  57 static struct clock_event_device itimer_clockevent = {
  58         .name           = "itimer",
  59         .rating         = 250,
  60         .cpumask        = CPU_MASK_ALL,
  61         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  62         .set_mode       = itimer_set_mode,
  63         .set_next_event = itimer_next_event,
  64         .shift          = 32,
  65         .irq            = 0,
  66 };
  67
  68 static irqreturn_t um_timer(int irq, void *dev)
  69 {
  70         (*itimer_clockevent.event_handler)(&itimer_clockevent);
  71
  72         return IRQ_HANDLED;
  73 }
  74
  75 static cycle_t itimer_read(void)
  76 {
  77         return os_nsecs();
  78 }
  79
  80 static struct clocksource itimer_clocksource = {
  81         .name           = "itimer",
  82         .rating         = 300,
  83         .read           = itimer_read,
  84         .mask           = CLOCKSOURCE_MASK(64),
  85         .mult           = 1,
  86         .shift          = 0,
  87         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  88 };
  89
  90 static void __init setup_itimer(void)
  91 {
  92         int err;
  93
  94         err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
  95         if (err != 0)
  96                 printk(KERN_ERR "register_timer : request_irq failed - "
  97                        "errno = %d\n", -err);
  98
  99         itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
 100         itimer_clockevent.max_delta_ns =
 101                 clockevent_delta2ns(60 * HZ, &itimer_clockevent);
 102         itimer_clockevent.min_delta_ns =
 103                 clockevent_delta2ns(1, &itimer_clockevent);
 104         err = clocksource_register(&itimer_clocksource);
 105         if (err) {
 106                 printk(KERN_ERR "clocksource_register returned %d\n", err);
 107                 return;
 108         }
 109         clockevents_register_device(&itimer_clockevent);
 110 }
 111
 112 extern void (*late_time_init)(void);
 113
 114 void __init time_init(void)
 115 {
 116         long long nsecs;
 117
 118         timer_init();
 119
 120         nsecs = os_nsecs();
 121         set_normalized_timespec(&wall_to_monotonic, -nsecs / NSEC_PER_SEC,
 122                                 -nsecs % NSEC_PER_SEC);
 123         set_normalized_timespec(&xtime, nsecs / NSEC_PER_SEC,
 124                                 nsecs % NSEC_PER_SEC);
 125         late_time_init = setup_itimer;
 126 }