arch/um/kernel/time.c

   1 /*
   2  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/kernel.h"
   7 #include "linux/module.h"
   8 #include "linux/unistd.h"
   9 #include "linux/stddef.h"
  10 #include "linux/spinlock.h"
  11 #include "linux/time.h"
  12 #include "linux/sched.h"
  13 #include "linux/interrupt.h"
  14 #include "linux/init.h"
  15 #include "linux/delay.h"
  16 #include "linux/hrtimer.h"
  17 #include "asm/irq.h"
  18 #include "asm/param.h"
  19 #include "asm/current.h"
  20 #include "kern_util.h"
  21 #include "user_util.h"
  22 #include "mode.h"
  23 #include "os.h"
  24
  25 int hz(void)
  26 {
  27         return(HZ);
  28 }
  29
  30 /*
  31  * Scheduler clock - returns current time in nanosec units.
  32  */
  33 unsigned long long sched_clock(void)
  34 {
  35         return (unsigned long long)jiffies_64 * (1000000000 / HZ);
  36 }
  37
  38 /* Changed at early boot */
  39 int timer_irq_inited = 0;
  40
  41 static unsigned long long prev_nsecs;
  42 #ifdef CONFIG_UML_REAL_TIME_CLOCK
  43 static long long delta;                 /* Deviation per interval */
  44 #endif
  45
  46 void timer_irq(union uml_pt_regs *regs)
  47 {
  48         unsigned long long ticks = 0;
  49
  50 #ifdef CONFIG_UML_REAL_TIME_CLOCK
  51         if(prev_nsecs){
  52                 /* We've had 1 tick */
  53                 unsigned long long nsecs = os_nsecs();
  54
  55                 delta += nsecs - prev_nsecs;
  56                 prev_nsecs = nsecs;
  57
  58                 /* Protect against the host clock being set backwards */
  59                 if(delta < 0)
  60                         delta = 0;
  61
  62                 ticks += (delta * HZ) / BILLION;
  63                 delta -= (ticks * BILLION) / HZ;
  64         }
  65         else prev_nsecs = os_nsecs();
  66 #else
  67         ticks = 1;
  68 #endif
  69         while(ticks > 0){
  70                 do_IRQ(TIMER_IRQ, regs);
  71                 ticks--;
  72         }
  73 }
  74
  75 static DEFINE_SPINLOCK(timer_spinlock);
  76
  77 static unsigned long long local_offset = 0;
  78
  79 static inline unsigned long long get_time(void)
  80 {
  81         unsigned long long nsecs;
  82         unsigned long flags;
  83
  84         spin_lock_irqsave(&timer_spinlock, flags);
  85         nsecs = os_nsecs();
  86         nsecs += local_offset;
  87         spin_unlock_irqrestore(&timer_spinlock, flags);
  88
  89         return nsecs;
  90 }
  91
  92 irqreturn_t um_timer(int irq, void *dev, struct pt_regs *regs)
  93 {
  94         unsigned long long nsecs;
  95         unsigned long flags;
  96
  97         write_seqlock_irqsave(&xtime_lock, flags);
  98
  99         do_timer(regs);
 100
 101         nsecs = get_time() + local_offset;
 102         xtime.tv_sec = nsecs / NSEC_PER_SEC;
 103         xtime.tv_nsec = nsecs - xtime.tv_sec * NSEC_PER_SEC;
 104
 105         write_sequnlock_irqrestore(&xtime_lock, flags);
 106
 107         return IRQ_HANDLED;
 108 }
 109
 110 static void register_timer(void)
 111 {
 112         int err;
 113
 114         err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
 115         if(err != 0)
 116                 printk(KERN_ERR "timer_init : request_irq failed - "
 117                        "errno = %d\n", -err);
 118
 119         timer_irq_inited = 1;
 120
 121         user_time_init();
 122 }
 123
 124 extern void (*late_time_init)(void);
 125
 126 void time_init(void)
 127 {
 128         long long nsecs;
 129
 130         nsecs = os_nsecs();
 131         set_normalized_timespec(&wall_to_monotonic, -nsecs / BILLION,
 132                                 -nsecs % BILLION);
 133         late_time_init = register_timer;
 134 }
 135
 136 void do_gettimeofday(struct timeval *tv)
 137 {
 138         unsigned long long nsecs = get_time();
 139
 140         tv->tv_sec = nsecs / NSEC_PER_SEC;
 141         /* Careful about calculations here - this was originally done as
 142          * (nsecs - tv->tv_sec * NSEC_PER_SEC) / NSEC_PER_USEC
 143          * which gave bogus (> 1000000) values.  Dunno why, suspect gcc
 144          * (4.0.0) miscompiled it, or there's a subtle 64/32-bit conversion
 145          * problem that I missed.
 146          */
 147         nsecs -= tv->tv_sec * NSEC_PER_SEC;
 148         tv->tv_usec = (unsigned long) nsecs / NSEC_PER_USEC;
 149 }
 150
 151 static inline void set_time(unsigned long long nsecs)
 152 {
 153         unsigned long long now;
 154         unsigned long flags;
 155
 156         spin_lock_irqsave(&timer_spinlock, flags);
 157         now = os_nsecs();
 158         local_offset = nsecs - now;
 159         spin_unlock_irqrestore(&timer_spinlock, flags);
 160
 161         clock_was_set();
 162 }
 163
 164 int do_settimeofday(struct timespec *tv)
 165 {
 166         set_time((unsigned long long) tv->tv_sec * NSEC_PER_SEC + tv->tv_nsec);
 167
 168         return 0;
 169 }
 170
 171 void timer_handler(int sig, union uml_pt_regs *regs)
 172 {
 173         local_irq_disable();
 174         irq_enter();
 175         update_process_times(CHOOSE_MODE(
 176                              (UPT_SC(regs) && user_context(UPT_SP(regs))),
 177                              (regs)->skas.is_user));
 178         irq_exit();
 179         local_irq_enable();
 180         if(current_thread->cpu == 0)
 181                 timer_irq(regs);
 182 }