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 void do_boot_timer_handler(struct sigcontext * sc)
  88 {
  89         struct pt_regs regs;
  90
  91         CHOOSE_MODE((void) (UPT_SC(&regs.regs) = sc),
  92                     (void) (regs.regs.skas.is_user = 0));
  93         do_timer(&regs);
  94 }
  95
  96 static DEFINE_SPINLOCK(timer_spinlock);
  97
  98 static unsigned long long local_offset = 0;
  99
 100 static inline unsigned long long get_time(void)
 101 {
 102         unsigned long long nsecs;
 103         unsigned long flags;
 104
 105         spin_lock_irqsave(&timer_spinlock, flags);
 106         nsecs = os_nsecs();
 107         nsecs += local_offset;
 108         spin_unlock_irqrestore(&timer_spinlock, flags);
 109
 110         return nsecs;
 111 }
 112
 113 irqreturn_t um_timer(int irq, void *dev, struct pt_regs *regs)
 114 {
 115         unsigned long long nsecs;
 116         unsigned long flags;
 117
 118         do_timer(regs);
 119
 120         write_seqlock_irqsave(&xtime_lock, flags);
 121         nsecs = get_time() + local_offset;
 122         xtime.tv_sec = nsecs / NSEC_PER_SEC;
 123         xtime.tv_nsec = nsecs - xtime.tv_sec * NSEC_PER_SEC;
 124         write_sequnlock_irqrestore(&xtime_lock, flags);
 125
 126         return(IRQ_HANDLED);
 127 }
 128
 129 long um_time(int __user *tloc)
 130 {
 131         long ret = get_time() / NSEC_PER_SEC;
 132
 133         if((tloc != NULL) && put_user(ret, tloc))
 134                 return -EFAULT;
 135
 136         return ret;
 137 }
 138
 139 void do_gettimeofday(struct timeval *tv)
 140 {
 141         unsigned long long nsecs = get_time();
 142
 143         tv->tv_sec = nsecs / NSEC_PER_SEC;
 144         /* Careful about calculations here - this was originally done as
 145          * (nsecs - tv->tv_sec * NSEC_PER_SEC) / NSEC_PER_USEC
 146          * which gave bogus (> 1000000) values.  Dunno why, suspect gcc
 147          * (4.0.0) miscompiled it, or there's a subtle 64/32-bit conversion
 148          * problem that I missed.
 149          */
 150         nsecs -= tv->tv_sec * NSEC_PER_SEC;
 151         tv->tv_usec = (unsigned long) nsecs / NSEC_PER_USEC;
 152 }
 153
 154 static inline void set_time(unsigned long long nsecs)
 155 {
 156         unsigned long long now;
 157         unsigned long flags;
 158
 159         spin_lock_irqsave(&timer_spinlock, flags);
 160         now = os_nsecs();
 161         local_offset = nsecs - now;
 162         spin_unlock_irqrestore(&timer_spinlock, flags);
 163
 164         clock_was_set();
 165 }
 166
 167 long um_stime(int __user *tptr)
 168 {
 169         int value;
 170
 171         if (get_user(value, tptr))
 172                 return -EFAULT;
 173
 174         set_time((unsigned long long) value * NSEC_PER_SEC);
 175
 176         return 0;
 177 }
 178
 179 int do_settimeofday(struct timespec *tv)
 180 {
 181         set_time((unsigned long long) tv->tv_sec * NSEC_PER_SEC + tv->tv_nsec);
 182
 183         return 0;
 184 }
 185
 186 void timer_handler(int sig, union uml_pt_regs *regs)
 187 {
 188         local_irq_disable();
 189         irq_enter();
 190         update_process_times(CHOOSE_MODE(
 191                              (UPT_SC(regs) && user_context(UPT_SP(regs))),
 192                              (regs)->skas.is_user));
 193         irq_exit();
 194         local_irq_enable();
 195         if(current_thread->cpu == 0)
 196                 timer_irq(regs);
 197 }
 198
 199 int __init timer_init(void)
 200 {
 201         int err;
 202
 203         user_time_init();
 204         err = request_irq(TIMER_IRQ, um_timer, SA_INTERRUPT, "timer", NULL);
 205         if(err != 0)
 206                 printk(KERN_ERR "timer_init : request_irq failed - "
 207                        "errno = %d\n", -err);
 208         timer_irq_inited = 1;
 209         return(0);
 210 }
 211
 212 __initcall(timer_init);