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/errno.h>
  14 #include <linux/module.h>
  15 #include <linux/sched.h>
  16 #include <linux/kernel.h>
  17 #include <linux/param.h>
  18 #include <linux/string.h>
  19 #include <linux/mm.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/time.h>
  22 #include <linux/init.h>
  23 #include <linux/smp.h>
  24 #include <linux/profile.h>
  25
  26 #include <asm/uaccess.h>
  27 #include <asm/io.h>
  28 #include <asm/irq.h>
  29 #include <asm/param.h>
  30 #include <asm/pdc.h>
  31 #include <asm/led.h>
  32
  33 #include <linux/timex.h>
  34
  35 /* xtime and wall_jiffies keep wall-clock time */
  36 extern unsigned long wall_jiffies;
  37
  38 static long clocktick __read_mostly;    /* timer cycles per tick */
  39 static long halftick __read_mostly;
  40
  41 #ifdef CONFIG_SMP
  42 extern void smp_do_timer(struct pt_regs *regs);
  43 #endif
  44
  45 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  46 {
  47         long now;
  48         long next_tick;
  49         int nticks;
  50         int cpu = smp_processor_id();
  51
  52         profile_tick(CPU_PROFILING, regs);
  53
  54         now = mfctl(16);
  55         /* initialize next_tick to time at last clocktick */
  56         next_tick = cpu_data[cpu].it_value;
  57
  58         /* since time passes between the interrupt and the mfctl()
  59          * above, it is never true that last_tick + clocktick == now.  If we
  60          * never miss a clocktick, we could set next_tick = last_tick + clocktick
  61          * but maybe we'll miss ticks, hence the loop.
  62          *
  63          * Variables are *signed*.
  64          */
  65
  66         nticks = 0;
  67         while((next_tick - now) < halftick) {
  68                 next_tick += clocktick;
  69                 nticks++;
  70         }
  71         mtctl(next_tick, 16);
  72         cpu_data[cpu].it_value = next_tick;
  73
  74         while (nticks--) {
  75 #ifdef CONFIG_SMP
  76                 smp_do_timer(regs);
  77 #else
  78                 update_process_times(user_mode(regs));
  79 #endif
  80                 if (cpu == 0) {
  81                         write_seqlock(&xtime_lock);
  82                         do_timer(1);
  83                         write_sequnlock(&xtime_lock);
  84                 }
  85         }
  86
  87         /* check soft power switch status */
  88         if (cpu == 0 && !atomic_read(&power_tasklet.count))
  89                 tasklet_schedule(&power_tasklet);
  90
  91         return IRQ_HANDLED;
  92 }
  93
  94
  95 unsigned long profile_pc(struct pt_regs *regs)
  96 {
  97         unsigned long pc = instruction_pointer(regs);
  98
  99         if (regs->gr[0] & PSW_N)
 100                 pc -= 4;
 101
 102 #ifdef CONFIG_SMP
 103         if (in_lock_functions(pc))
 104                 pc = regs->gr[2];
 105 #endif
 106
 107         return pc;
 108 }
 109 EXPORT_SYMBOL(profile_pc);
 110
 111
 112 /*** converted from ia64 ***/
 113 /*
 114  * Return the number of micro-seconds that elapsed since the last
 115  * update to wall time (aka xtime aka wall_jiffies).  The xtime_lock
 116  * must be at least read-locked when calling this routine.
 117  */
 118 static inline unsigned long
 119 gettimeoffset (void)
 120 {
 121 #ifndef CONFIG_SMP
 122         /*
 123          * FIXME: This won't work on smp because jiffies are updated by cpu 0.
 124          *    Once parisc-linux learns the cr16 difference between processors,
 125          *    this could be made to work.
 126          */
 127         long last_tick;
 128         long elapsed_cycles;
 129
 130         /* it_value is the intended time of the next tick */
 131         last_tick = cpu_data[smp_processor_id()].it_value;
 132
 133         /* Subtract one tick and account for possible difference between
 134          * when we expected the tick and when it actually arrived.
 135          * (aka wall vs real)
 136          */
 137         last_tick -= clocktick * (jiffies - wall_jiffies + 1);
 138         elapsed_cycles = mfctl(16) - last_tick;
 139
 140         /* the precision of this math could be improved */
 141         return elapsed_cycles / (PAGE0->mem_10msec / 10000);
 142 #else
 143         return 0;
 144 #endif
 145 }
 146
 147 void
 148 do_gettimeofday (struct timeval *tv)
 149 {
 150         unsigned long flags, seq, usec, sec;
 151
 152         do {
 153                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 154                 usec = gettimeoffset();
 155                 sec = xtime.tv_sec;
 156                 usec += (xtime.tv_nsec / 1000);
 157         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 158
 159         if (unlikely(usec > LONG_MAX)) {
 160                 /* This can happen if the gettimeoffset adjustment is
 161                  * negative and xtime.tv_nsec is smaller than the
 162                  * adjustment */
 163                 printk(KERN_ERR "do_gettimeofday() spurious xtime.tv_nsec of %ld\n", usec);
 164                 usec += USEC_PER_SEC;
 165                 --sec;
 166                 /* This should never happen, it means the negative
 167                  * time adjustment was more than a second, so there's
 168                  * something seriously wrong */
 169                 BUG_ON(usec > LONG_MAX);
 170         }
 171
 172
 173         while (usec >= USEC_PER_SEC) {
 174                 usec -= USEC_PER_SEC;
 175                 ++sec;
 176         }
 177
 178         tv->tv_sec = sec;
 179         tv->tv_usec = usec;
 180 }
 181
 182 EXPORT_SYMBOL(do_gettimeofday);
 183
 184 int
 185 do_settimeofday (struct timespec *tv)
 186 {
 187         time_t wtm_sec, sec = tv->tv_sec;
 188         long wtm_nsec, nsec = tv->tv_nsec;
 189
 190         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 191                 return -EINVAL;
 192
 193         write_seqlock_irq(&xtime_lock);
 194         {
 195                 /*
 196                  * This is revolting. We need to set "xtime"
 197                  * correctly. However, the value in this location is
 198                  * the value at the most recent update of wall time.
 199                  * Discover what correction gettimeofday would have
 200                  * done, and then undo it!
 201                  */
 202                 nsec -= gettimeoffset() * 1000;
 203
 204                 wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 205                 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 206
 207                 set_normalized_timespec(&xtime, sec, nsec);
 208                 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 209
 210                 ntp_clear();
 211         }
 212         write_sequnlock_irq(&xtime_lock);
 213         clock_was_set();
 214         return 0;
 215 }
 216 EXPORT_SYMBOL(do_settimeofday);
 217
 218 /*
 219  * XXX: We can do better than this.
 220  * Returns nanoseconds
 221  */
 222
 223 unsigned long long sched_clock(void)
 224 {
 225         return (unsigned long long)jiffies * (1000000000 / HZ);
 226 }
 227
 228
 229 void __init time_init(void)
 230 {
 231         unsigned long next_tick;
 232         static struct pdc_tod tod_data;
 233
 234         clocktick = (100 * PAGE0->mem_10msec) / HZ;
 235         halftick = clocktick / 2;
 236
 237         /* Setup clock interrupt timing */
 238
 239         next_tick = mfctl(16);
 240         next_tick += clocktick;
 241         cpu_data[smp_processor_id()].it_value = next_tick;
 242
 243         /* kick off Itimer (CR16) */
 244         mtctl(next_tick, 16);
 245
 246         if(pdc_tod_read(&tod_data) == 0) {
 247                 write_seqlock_irq(&xtime_lock);
 248                 xtime.tv_sec = tod_data.tod_sec;
 249                 xtime.tv_nsec = tod_data.tod_usec * 1000;
 250                 set_normalized_timespec(&wall_to_monotonic,
 251                                         -xtime.tv_sec, -xtime.tv_nsec);
 252                 write_sequnlock_irq(&xtime_lock);
 253         } else {
 254                 printk(KERN_ERR "Error reading tod clock\n");
 255                 xtime.tv_sec = 0;
 256                 xtime.tv_nsec = 0;
 257         }
 258 }
 259