arch/um/kernel/time_kern.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 int first_tick;
  42 static unsigned long long prev_nsecs;
  43 #ifdef CONFIG_UML_REAL_TIME_CLOCK
  44 static long long delta;                 /* Deviation per interval */
  45 #endif
  46
  47 void timer_irq(union uml_pt_regs *regs)
  48 {
  49         unsigned long long ticks = 0;
  50
  51         if(!timer_irq_inited){
  52                 /* This is to ensure that ticks don't pile up when
  53                  * the timer handler is suspended */
  54                 first_tick = 0;
  55                 return;
  56         }
  57
  58         if(first_tick){
  59 #ifdef CONFIG_UML_REAL_TIME_CLOCK
  60                 /* We've had 1 tick */
  61                 unsigned long long nsecs = os_nsecs();
  62
  63                 delta += nsecs - prev_nsecs;
  64                 prev_nsecs = nsecs;
  65
  66                 /* Protect against the host clock being set backwards */
  67                 if(delta < 0)
  68                         delta = 0;
  69
  70                 ticks += (delta * HZ) / BILLION;
  71                 delta -= (ticks * BILLION) / HZ;
  72 #else
  73                 ticks = 1;
  74 #endif
  75         }
  76         else {
  77                 prev_nsecs = os_nsecs();
  78                 first_tick = 1;
  79         }
  80
  81         while(ticks > 0){
  82                 do_IRQ(TIMER_IRQ, regs);
  83                 ticks--;
  84         }
  85 }
  86
  87
  88 void time_init_kern(void)
  89 {
  90         long long nsecs;
  91
  92         nsecs = os_nsecs();
  93         set_normalized_timespec(&wall_to_monotonic, -nsecs / BILLION,
  94                                 -nsecs % BILLION);
  95 }
  96
  97 void do_boot_timer_handler(struct sigcontext * sc)
  98 {
  99         unsigned long flags;
 100         struct pt_regs regs;
 101
 102         CHOOSE_MODE((void) (UPT_SC(&regs.regs) = sc),
 103                     (void) (regs.regs.skas.is_user = 0));
 104
 105         write_seqlock_irqsave(&xtime_lock, flags);
 106         do_timer(&regs);
 107         write_sequnlock_irqrestore(&xtime_lock, flags);
 108 }
 109
 110 static DEFINE_SPINLOCK(timer_spinlock);
 111
 112 static unsigned long long local_offset = 0;
 113
 114 static inline unsigned long long get_time(void)
 115 {
 116         unsigned long long nsecs;
 117         unsigned long flags;
 118
 119         spin_lock_irqsave(&timer_spinlock, flags);
 120         nsecs = os_nsecs();
 121         nsecs += local_offset;
 122         spin_unlock_irqrestore(&timer_spinlock, flags);
 123
 124         return nsecs;
 125 }
 126
 127 irqreturn_t um_timer(int irq, void *dev, struct pt_regs *regs)
 128 {
 129         unsigned long long nsecs;
 130         unsigned long flags;
 131
 132         write_seqlock_irqsave(&xtime_lock, flags);
 133
 134         do_timer(regs);
 135
 136         nsecs = get_time() + local_offset;
 137         xtime.tv_sec = nsecs / NSEC_PER_SEC;
 138         xtime.tv_nsec = nsecs - xtime.tv_sec * NSEC_PER_SEC;
 139
 140         write_sequnlock_irqrestore(&xtime_lock, flags);
 141
 142         return IRQ_HANDLED;
 143 }
 144
 145 void do_gettimeofday(struct timeval *tv)
 146 {
 147         unsigned long long nsecs = get_time();
 148
 149         tv->tv_sec = nsecs / NSEC_PER_SEC;
 150         /* Careful about calculations here - this was originally done as
 151          * (nsecs - tv->tv_sec * NSEC_PER_SEC) / NSEC_PER_USEC
 152          * which gave bogus (> 1000000) values.  Dunno why, suspect gcc
 153          * (4.0.0) miscompiled it, or there's a subtle 64/32-bit conversion
 154          * problem that I missed.
 155          */
 156         nsecs -= tv->tv_sec * NSEC_PER_SEC;
 157         tv->tv_usec = (unsigned long) nsecs / NSEC_PER_USEC;
 158 }
 159
 160 static inline void set_time(unsigned long long nsecs)
 161 {
 162         unsigned long long now;
 163         unsigned long flags;
 164
 165         spin_lock_irqsave(&timer_spinlock, flags);
 166         now = os_nsecs();
 167         local_offset = nsecs - now;
 168         spin_unlock_irqrestore(&timer_spinlock, flags);
 169
 170         clock_was_set();
 171 }
 172
 173 int do_settimeofday(struct timespec *tv)
 174 {
 175         set_time((unsigned long long) tv->tv_sec * NSEC_PER_SEC + tv->tv_nsec);
 176
 177         return 0;
 178 }
 179
 180 void timer_handler(int sig, union uml_pt_regs *regs)
 181 {
 182         local_irq_disable();
 183         irq_enter();
 184         update_process_times(CHOOSE_MODE(
 185                              (UPT_SC(regs) && user_context(UPT_SP(regs))),
 186                              (regs)->skas.is_user));
 187         irq_exit();
 188         local_irq_enable();
 189         if(current_thread->cpu == 0)
 190                 timer_irq(regs);
 191 }
 192
 193 int __init timer_init(void)
 194 {
 195         int err;
 196
 197         user_time_init();
 198         err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
 199         if(err != 0)
 200                 printk(KERN_ERR "timer_init : request_irq failed - "
 201                        "errno = %d\n", -err);
 202         timer_irq_inited = 1;
 203         return(0);
 204 }
 205
 206 arch_initcall(timer_init);