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
 108 unsigned long profile_pc(struct pt_regs *regs)
 109 {
 110         unsigned long pc = instruction_pointer(regs);
 111
 112         if (regs->gr[0] & PSW_N)
 113                 pc -= 4;
 114
 115 #ifdef CONFIG_SMP
 116         if (in_lock_functions(pc))
 117                 pc = regs->gr[2];
 118 #endif
 119
 120         return pc;
 121 }
 122 EXPORT_SYMBOL(profile_pc);
 123
 124
 125 /*** converted from ia64 ***/
 126 /*
 127  * Return the number of micro-seconds that elapsed since the last
 128  * update to wall time (aka xtime aka wall_jiffies).  The xtime_lock
 129  * must be at least read-locked when calling this routine.
 130  */
 131 static inline unsigned long
 132 gettimeoffset (void)
 133 {
 134 #ifndef CONFIG_SMP
 135         /*
 136          * FIXME: This won't work on smp because jiffies are updated by cpu 0.
 137          *    Once parisc-linux learns the cr16 difference between processors,
 138          *    this could be made to work.
 139          */
 140         long last_tick;
 141         long elapsed_cycles;
 142
 143         /* it_value is the intended time of the next tick */
 144         last_tick = cpu_data[smp_processor_id()].it_value;
 145
 146         /* Subtract one tick and account for possible difference between
 147          * when we expected the tick and when it actually arrived.
 148          * (aka wall vs real)
 149          */
 150         last_tick -= clocktick * (jiffies - wall_jiffies + 1);
 151         elapsed_cycles = mfctl(16) - last_tick;
 152
 153         /* the precision of this math could be improved */
 154         return elapsed_cycles / (PAGE0->mem_10msec / 10000);
 155 #else
 156         return 0;
 157 #endif
 158 }
 159
 160 void
 161 do_gettimeofday (struct timeval *tv)
 162 {
 163         unsigned long flags, seq, usec, sec;
 164
 165         do {
 166                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 167                 usec = gettimeoffset();
 168                 sec = xtime.tv_sec;
 169                 usec += (xtime.tv_nsec / 1000);
 170         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 171
 172         while (usec >= 1000000) {
 173                 usec -= 1000000;
 174                 ++sec;
 175         }
 176
 177         tv->tv_sec = sec;
 178         tv->tv_usec = usec;
 179 }
 180
 181 EXPORT_SYMBOL(do_gettimeofday);
 182
 183 int
 184 do_settimeofday (struct timespec *tv)
 185 {
 186         time_t wtm_sec, sec = tv->tv_sec;
 187         long wtm_nsec, nsec = tv->tv_nsec;
 188
 189         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 190                 return -EINVAL;
 191
 192         write_seqlock_irq(&xtime_lock);
 193         {
 194                 /*
 195                  * This is revolting. We need to set "xtime"
 196                  * correctly. However, the value in this location is
 197                  * the value at the most recent update of wall time.
 198                  * Discover what correction gettimeofday would have
 199                  * done, and then undo it!
 200                  */
 201                 nsec -= gettimeoffset() * 1000;
 202
 203                 wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 204                 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 205
 206                 set_normalized_timespec(&xtime, sec, nsec);
 207                 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 208
 209                 ntp_clear();
 210         }
 211         write_sequnlock_irq(&xtime_lock);
 212         clock_was_set();
 213         return 0;
 214 }
 215 EXPORT_SYMBOL(do_settimeofday);
 216
 217 /*
 218  * XXX: We can do better than this.
 219  * Returns nanoseconds
 220  */
 221
 222 unsigned long long sched_clock(void)
 223 {
 224         return (unsigned long long)jiffies * (1000000000 / HZ);
 225 }
 226
 227
 228 void __init time_init(void)
 229 {
 230         unsigned long next_tick;
 231         static struct pdc_tod tod_data;
 232
 233         clocktick = (100 * PAGE0->mem_10msec) / HZ;
 234         halftick = clocktick / 2;
 235
 236         /* Setup clock interrupt timing */
 237
 238         next_tick = mfctl(16);
 239         next_tick += clocktick;
 240         cpu_data[smp_processor_id()].it_value = next_tick;
 241
 242         /* kick off Itimer (CR16) */
 243         mtctl(next_tick, 16);
 244
 245         if(pdc_tod_read(&tod_data) == 0) {
 246                 write_seqlock_irq(&xtime_lock);
 247                 xtime.tv_sec = tod_data.tod_sec;
 248                 xtime.tv_nsec = tod_data.tod_usec * 1000;
 249                 set_normalized_timespec(&wall_to_monotonic,
 250                                         -xtime.tv_sec, -xtime.tv_nsec);
 251                 write_sequnlock_irq(&xtime_lock);
 252         } else {
 253                 printk(KERN_ERR "Error reading tod clock\n");
 254                 xtime.tv_sec = 0;
 255                 xtime.tv_nsec = 0;
 256         }
 257 }
 258