arch/parisc/kernel/time.c

   1 /*
   2  *  linux/arch/parisc/kernel/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *  Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
   6  *  Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
   7  *
   8  * 1994-07-02  Alan Modra
   9  *             fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
  10  * 1998-12-20  Updated NTP code according to technical memorandum Jan '96
  11  *             "A Kernel Model for Precision Timekeeping" by Dave Mills
  12  */
  13 #include <linux/config.h>
  14 #include <linux/errno.h>
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/param.h>
  19 #include <linux/string.h>
  20 #include <linux/mm.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/time.h>
  23 #include <linux/init.h>
  24 #include <linux/smp.h>
  25 #include <linux/profile.h>
  26
  27 #include <asm/uaccess.h>
  28 #include <asm/io.h>
  29 #include <asm/irq.h>
  30 #include <asm/param.h>
  31 #include <asm/pdc.h>
  32 #include <asm/led.h>
  33
  34 #include <linux/timex.h>
  35
  36 u64 jiffies_64 = INITIAL_JIFFIES;
  37
  38 EXPORT_SYMBOL(jiffies_64);
  39
  40 /* xtime and wall_jiffies keep wall-clock time */
  41 extern unsigned long wall_jiffies;
  42
  43 static long clocktick;  /* timer cycles per tick */
  44 static long halftick;
  45
  46 #ifdef CONFIG_SMP
  47 extern void smp_do_timer(struct pt_regs *regs);
  48 #endif
  49
  50 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  51 {
  52         long now;
  53         long next_tick;
  54         int nticks;
  55         int cpu = smp_processor_id();
  56
  57         profile_tick(CPU_PROFILING, regs);
  58
  59         now = mfctl(16);
  60         /* initialize next_tick to time at last clocktick */
  61         next_tick = cpu_data[cpu].it_value;
  62
  63         /* since time passes between the interrupt and the mfctl()
  64          * above, it is never true that last_tick + clocktick == now.  If we
  65          * never miss a clocktick, we could set next_tick = last_tick + clocktick
  66          * but maybe we'll miss ticks, hence the loop.
  67          *
  68          * Variables are *signed*.
  69          */
  70
  71         nticks = 0;
  72         while((next_tick - now) < halftick) {
  73                 next_tick += clocktick;
  74                 nticks++;
  75         }
  76         mtctl(next_tick, 16);
  77         cpu_data[cpu].it_value = next_tick;
  78
  79         while (nticks--) {
  80 #ifdef CONFIG_SMP
  81                 smp_do_timer(regs);
  82 #else
  83                 update_process_times(user_mode(regs));
  84 #endif
  85                 if (cpu == 0) {
  86                         write_seqlock(&xtime_lock);
  87                         do_timer(regs);
  88                         write_sequnlock(&xtime_lock);
  89                 }
  90         }
  91
  92 #ifdef CONFIG_CHASSIS_LCD_LED
  93         /* Only schedule the led tasklet on cpu 0, and only if it
  94          * is enabled.
  95          */
  96         if (cpu == 0 && !atomic_read(&led_tasklet.count))
  97                 tasklet_schedule(&led_tasklet);
  98 #endif
  99
 100         /* check soft power switch status */
 101         if (cpu == 0 && !atomic_read(&power_tasklet.count))
 102                 tasklet_schedule(&power_tasklet);
 103
 104         return IRQ_HANDLED;
 105 }
 106
 107 /*** converted from ia64 ***/
 108 /*
 109  * Return the number of micro-seconds that elapsed since the last
 110  * update to wall time (aka xtime aka wall_jiffies).  The xtime_lock
 111  * must be at least read-locked when calling this routine.
 112  */
 113 static inline unsigned long
 114 gettimeoffset (void)
 115 {
 116 #ifndef CONFIG_SMP
 117         /*
 118          * FIXME: This won't work on smp because jiffies are updated by cpu 0.
 119          *    Once parisc-linux learns the cr16 difference between processors,
 120          *    this could be made to work.
 121          */
 122         long last_tick;
 123         long elapsed_cycles;
 124
 125         /* it_value is the intended time of the next tick */
 126         last_tick = cpu_data[smp_processor_id()].it_value;
 127
 128         /* Subtract one tick and account for possible difference between
 129          * when we expected the tick and when it actually arrived.
 130          * (aka wall vs real)
 131          */
 132         last_tick -= clocktick * (jiffies - wall_jiffies + 1);
 133         elapsed_cycles = mfctl(16) - last_tick;
 134
 135         /* the precision of this math could be improved */
 136         return elapsed_cycles / (PAGE0->mem_10msec / 10000);
 137 #else
 138         return 0;
 139 #endif
 140 }
 141
 142 void
 143 do_gettimeofday (struct timeval *tv)
 144 {
 145         unsigned long flags, seq, usec, sec;
 146
 147         do {
 148                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 149                 usec = gettimeoffset();
 150                 sec = xtime.tv_sec;
 151                 usec += (xtime.tv_nsec / 1000);
 152         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 153
 154         while (usec >= 1000000) {
 155                 usec -= 1000000;
 156                 ++sec;
 157         }
 158
 159         tv->tv_sec = sec;
 160         tv->tv_usec = usec;
 161 }
 162
 163 EXPORT_SYMBOL(do_gettimeofday);
 164
 165 int
 166 do_settimeofday (struct timespec *tv)
 167 {
 168         time_t wtm_sec, sec = tv->tv_sec;
 169         long wtm_nsec, nsec = tv->tv_nsec;
 170
 171         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 172                 return -EINVAL;
 173
 174         write_seqlock_irq(&xtime_lock);
 175         {
 176                 /*
 177                  * This is revolting. We need to set "xtime"
 178                  * correctly. However, the value in this location is
 179                  * the value at the most recent update of wall time.
 180                  * Discover what correction gettimeofday would have
 181                  * done, and then undo it!
 182                  */
 183                 nsec -= gettimeoffset() * 1000;
 184
 185                 wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 186                 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 187
 188                 set_normalized_timespec(&xtime, sec, nsec);
 189                 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 190
 191                 time_adjust = 0;                /* stop active adjtime() */
 192                 time_status |= STA_UNSYNC;
 193                 time_maxerror = NTP_PHASE_LIMIT;
 194                 time_esterror = NTP_PHASE_LIMIT;
 195         }
 196         write_sequnlock_irq(&xtime_lock);
 197         clock_was_set();
 198         return 0;
 199 }
 200 EXPORT_SYMBOL(do_settimeofday);
 201
 202 /*
 203  * XXX: We can do better than this.
 204  * Returns nanoseconds
 205  */
 206
 207 unsigned long long sched_clock(void)
 208 {
 209         return (unsigned long long)jiffies * (1000000000 / HZ);
 210 }
 211
 212
 213 void __init time_init(void)
 214 {
 215         unsigned long next_tick;
 216         static struct pdc_tod tod_data;
 217
 218         clocktick = (100 * PAGE0->mem_10msec) / HZ;
 219         halftick = clocktick / 2;
 220
 221         /* Setup clock interrupt timing */
 222
 223         next_tick = mfctl(16);
 224         next_tick += clocktick;
 225         cpu_data[smp_processor_id()].it_value = next_tick;
 226
 227         /* kick off Itimer (CR16) */
 228         mtctl(next_tick, 16);
 229
 230         if(pdc_tod_read(&tod_data) == 0) {
 231                 write_seqlock_irq(&xtime_lock);
 232                 xtime.tv_sec = tod_data.tod_sec;
 233                 xtime.tv_nsec = tod_data.tod_usec * 1000;
 234                 set_normalized_timespec(&wall_to_monotonic,
 235                                         -xtime.tv_sec, -xtime.tv_nsec);
 236                 write_sequnlock_irq(&xtime_lock);
 237         } else {
 238                 printk(KERN_ERR "Error reading tod clock\n");
 239                 xtime.tv_sec = 0;
 240                 xtime.tv_nsec = 0;
 241         }
 242 }
 243