arch/um/kernel/time.c

   1 /*
   2  * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
   3  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
   4  * Copyright (C) 2012-2014 Cisco Systems
   5  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   6  * Licensed under the GPL
   7  */
   8
   9 #include <linux/clockchips.h>
  10 #include <linux/init.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/mm.h>
  14 #include <linux/sched.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/threads.h>
  17 #include <asm/irq.h>
  18 #include <asm/param.h>
  19 #include <kern_util.h>
  20 #include <os.h>
  21 #include <timer-internal.h>
  22
  23 void timer_handler(int sig, struct siginfo *unused_si, 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 int itimer_shutdown(struct clock_event_device *evt)
  33 {
  34         os_timer_disable();
  35         return 0;
  36 }
  37
  38 static int itimer_set_periodic(struct clock_event_device *evt)
  39 {
  40         os_timer_set_interval(NULL, NULL);
  41         return 0;
  42 }
  43
  44 static int itimer_next_event(unsigned long delta,
  45                              struct clock_event_device *evt)
  46 {
  47         return os_timer_one_shot(delta);
  48 }
  49
  50 static int itimer_one_shot(struct clock_event_device *evt)
  51 {
  52         os_timer_one_shot(1);
  53         return 0;
  54 }
  55
  56 static struct clock_event_device timer_clockevent = {
  57         .name                   = "posix-timer",
  58         .rating                 = 250,
  59         .cpumask                = cpu_all_mask,
  60         .features               = CLOCK_EVT_FEAT_PERIODIC |
  61                                   CLOCK_EVT_FEAT_ONESHOT,
  62         .set_state_shutdown     = itimer_shutdown,
  63         .set_state_periodic     = itimer_set_periodic,
  64         .set_state_oneshot      = itimer_one_shot,
  65         .set_next_event         = itimer_next_event,
  66         .shift                  = 0,
  67         .max_delta_ns           = 0xffffffff,
  68         .min_delta_ns           = TIMER_MIN_DELTA, //microsecond resolution should be enough for anyone, same as 640K RAM
  69         .irq                    = 0,
  70         .mult                   = 1,
  71 };
  72
  73 static irqreturn_t um_timer(int irq, void *dev)
  74 {
  75         if (get_current()->mm != NULL)
  76         {
  77         /* userspace - relay signal, results in correct userspace timers */
  78                 os_alarm_process(get_current()->mm->context.id.u.pid);
  79         }
  80
  81         (*timer_clockevent.event_handler)(&timer_clockevent);
  82
  83         return IRQ_HANDLED;
  84 }
  85
  86 static u64 timer_read(struct clocksource *cs)
  87 {
  88         return os_nsecs() / TIMER_MULTIPLIER;
  89 }
  90
  91 static struct clocksource timer_clocksource = {
  92         .name           = "timer",
  93         .rating         = 300,
  94         .read           = timer_read,
  95         .mask           = CLOCKSOURCE_MASK(64),
  96         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  97 };
  98
  99 static void __init timer_setup(void)
 100 {
 101         int err;
 102
 103         err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL);
 104         if (err != 0)
 105                 printk(KERN_ERR "register_timer : request_irq failed - "
 106                        "errno = %d\n", -err);
 107
 108         err = os_timer_create(NULL);
 109         if (err != 0) {
 110                 printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
 111                 return;
 112         }
 113
 114         err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER);
 115         if (err) {
 116                 printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
 117                 return;
 118         }
 119         clockevents_register_device(&timer_clockevent);
 120 }
 121
 122 void read_persistent_clock(struct timespec *ts)
 123 {
 124         long long nsecs = os_persistent_clock_emulation();
 125
 126         set_normalized_timespec(ts, nsecs / NSEC_PER_SEC,
 127                                 nsecs % NSEC_PER_SEC);
 128 }
 129
 130 void __init time_init(void)
 131 {
 132         timer_set_signal_handler();
 133         late_time_init = timer_setup;
 134 }