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 /* xtime and wall_jiffies keep wall-clock time */
  37 extern unsigned long wall_jiffies;
  38
  39 static long clocktick;  /* timer cycles per tick */
  40 static long halftick;
  41
  42 #ifdef CONFIG_SMP
  43 extern void smp_do_timer(struct pt_regs *regs);
  44 #endif
  45
  46 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  47 {
  48         long now;
  49         long next_tick;
  50         int nticks;
  51         int cpu = smp_processor_id();
  52
  53         profile_tick(CPU_PROFILING, regs);
  54
  55         now = mfctl(16);
  56         /* initialize next_tick to time at last clocktick */
  57         next_tick = cpu_data[cpu].it_value;
  58
  59         /* since time passes between the interrupt and the mfctl()
  60          * above, it is never true that last_tick + clocktick == now.  If we
  61          * never miss a clocktick, we could set next_tick = last_tick + clocktick
  62          * but maybe we'll miss ticks, hence the loop.
  63          *
  64          * Variables are *signed*.
  65          */
  66
  67         nticks = 0;
  68         while((next_tick - now) < halftick) {
  69                 next_tick += clocktick;
  70                 nticks++;
  71         }
  72         mtctl(next_tick, 16);
  73         cpu_data[cpu].it_value = next_tick;
  74
  75         while (nticks--) {
  76 #ifdef CONFIG_SMP
  77                 smp_do_timer(regs);
  78 #else
  79                 update_process_times(user_mode(regs));
  80 #endif
  81                 if (cpu == 0) {
  82                         write_seqlock(&xtime_lock);
  83                         do_timer(regs);
  84                         write_sequnlock(&xtime_lock);
  85                 }
  86         }
  87
  88         /* check soft power switch status */
  89         if (cpu == 0 && !atomic_read(&power_tasklet.count))
  90                 tasklet_schedule(&power_tasklet);
  91
  92         return IRQ_HANDLED;
  93 }
  94
  95
  96 unsigned long profile_pc(struct pt_regs *regs)
  97 {
  98         unsigned long pc = instruction_pointer(regs);
  99
 100         if (regs->gr[0] & PSW_N)
 101                 pc -= 4;
 102
 103 #ifdef CONFIG_SMP
 104         if (in_lock_functions(pc))
 105                 pc = regs->gr[2];
 106 #endif
 107
 108         return pc;
 109 }
 110 EXPORT_SYMBOL(profile_pc);
 111
 112
 113 /*** converted from ia64 ***/
 114 /*
 115  * Return the number of micro-seconds that elapsed since the last
 116  * update to wall time (aka xtime aka wall_jiffies).  The xtime_lock
 117  * must be at least read-locked when calling this routine.
 118  */
 119 static inline unsigned long
 120 gettimeoffset (void)
 121 {
 122 #ifndef CONFIG_SMP
 123         /*
 124          * FIXME: This won't work on smp because jiffies are updated by cpu 0.
 125          *    Once parisc-linux learns the cr16 difference between processors,
 126          *    this could be made to work.
 127          */
 128         long last_tick;
 129         long elapsed_cycles;
 130
 131         /* it_value is the intended time of the next tick */
 132         last_tick = cpu_data[smp_processor_id()].it_value;
 133
 134         /* Subtract one tick and account for possible difference between
 135          * when we expected the tick and when it actually arrived.
 136          * (aka wall vs real)
 137          */
 138         last_tick -= clocktick * (jiffies - wall_jiffies + 1);
 139         elapsed_cycles = mfctl(16) - last_tick;
 140
 141         /* the precision of this math could be improved */
 142         return elapsed_cycles / (PAGE0->mem_10msec / 10000);
 143 #else
 144         return 0;
 145 #endif
 146 }
 147
 148 void
 149 do_gettimeofday (struct timeval *tv)
 150 {
 151         unsigned long flags, seq, usec, sec;
 152
 153         do {
 154                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 155                 usec = gettimeoffset();
 156                 sec = xtime.tv_sec;
 157                 usec += (xtime.tv_nsec / 1000);
 158         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 159
 160         while (usec >= 1000000) {
 161                 usec -= 1000000;
 162                 ++sec;
 163         }
 164
 165         tv->tv_sec = sec;
 166         tv->tv_usec = usec;
 167 }
 168
 169 EXPORT_SYMBOL(do_gettimeofday);
 170
 171 int
 172 do_settimeofday (struct timespec *tv)
 173 {
 174         time_t wtm_sec, sec = tv->tv_sec;
 175         long wtm_nsec, nsec = tv->tv_nsec;
 176
 177         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 178                 return -EINVAL;
 179
 180         write_seqlock_irq(&xtime_lock);
 181         {
 182                 /*
 183                  * This is revolting. We need to set "xtime"
 184                  * correctly. However, the value in this location is
 185                  * the value at the most recent update of wall time.
 186                  * Discover what correction gettimeofday would have
 187                  * done, and then undo it!
 188                  */
 189                 nsec -= gettimeoffset() * 1000;
 190
 191                 wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 192                 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 193
 194                 set_normalized_timespec(&xtime, sec, nsec);
 195                 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 196
 197                 ntp_clear();
 198         }
 199         write_sequnlock_irq(&xtime_lock);
 200         clock_was_set();
 201         return 0;
 202 }
 203 EXPORT_SYMBOL(do_settimeofday);
 204
 205 /*
 206  * XXX: We can do better than this.
 207  * Returns nanoseconds
 208  */
 209
 210 unsigned long long sched_clock(void)
 211 {
 212         return (unsigned long long)jiffies * (1000000000 / HZ);
 213 }
 214
 215
 216 void __init time_init(void)
 217 {
 218         unsigned long next_tick;
 219         static struct pdc_tod tod_data;
 220
 221         clocktick = (100 * PAGE0->mem_10msec) / HZ;
 222         halftick = clocktick / 2;
 223
 224         /* Setup clock interrupt timing */
 225
 226         next_tick = mfctl(16);
 227         next_tick += clocktick;
 228         cpu_data[smp_processor_id()].it_value = next_tick;
 229
 230         /* kick off Itimer (CR16) */
 231         mtctl(next_tick, 16);
 232
 233         if(pdc_tod_read(&tod_data) == 0) {
 234                 write_seqlock_irq(&xtime_lock);
 235                 xtime.tv_sec = tod_data.tod_sec;
 236                 xtime.tv_nsec = tod_data.tod_usec * 1000;
 237                 set_normalized_timespec(&wall_to_monotonic,
 238                                         -xtime.tv_sec, -xtime.tv_nsec);
 239                 write_sequnlock_irq(&xtime_lock);
 240         } else {
 241                 printk(KERN_ERR "Error reading tod clock\n");
 242                 xtime.tv_sec = 0;
 243                 xtime.tv_nsec = 0;
 244         }
 245 }
 246