arch/s390/kernel/time.c

   1 /*
   2  *  arch/s390/kernel/time.c
   3  *    Time of day based timer functions.
   4  *
   5  *  S390 version
   6  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *    Author(s): Hartmut Penner (hp@de.ibm.com),
   8  *               Martin Schwidefsky (schwidefsky@de.ibm.com),
   9  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
  10  *
  11  *  Derived from "arch/i386/kernel/time.c"
  12  *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
  13  */
  14
  15 #include <linux/errno.h>
  16 #include <linux/module.h>
  17 #include <linux/sched.h>
  18 #include <linux/kernel.h>
  19 #include <linux/param.h>
  20 #include <linux/string.h>
  21 #include <linux/mm.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/time.h>
  24 #include <linux/delay.h>
  25 #include <linux/init.h>
  26 #include <linux/smp.h>
  27 #include <linux/types.h>
  28 #include <linux/profile.h>
  29 #include <linux/timex.h>
  30 #include <linux/notifier.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/delay.h>
  34 #include <asm/s390_ext.h>
  35 #include <asm/div64.h>
  36 #include <asm/irq.h>
  37 #include <asm/timer.h>
  38
  39 /* change this if you have some constant time drift */
  40 #define USECS_PER_JIFFY     ((unsigned long) 1000000/HZ)
  41 #define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
  42
  43 /*
  44  * Create a small time difference between the timer interrupts
  45  * on the different cpus to avoid lock contention.
  46  */
  47 #define CPU_DEVIATION       (smp_processor_id() << 12)
  48
  49 #define TICK_SIZE tick
  50
  51 static ext_int_info_t ext_int_info_cc;
  52 static u64 init_timer_cc;
  53 static u64 jiffies_timer_cc;
  54 static u64 xtime_cc;
  55
  56 extern unsigned long wall_jiffies;
  57
  58 /*
  59  * Scheduler clock - returns current time in nanosec units.
  60  */
  61 unsigned long long sched_clock(void)
  62 {
  63         return ((get_clock() - jiffies_timer_cc) * 125) >> 9;
  64 }
  65
  66 /*
  67  * Monotonic_clock - returns # of nanoseconds passed since time_init()
  68  */
  69 unsigned long long monotonic_clock(void)
  70 {
  71         return sched_clock();
  72 }
  73 EXPORT_SYMBOL(monotonic_clock);
  74
  75 void tod_to_timeval(__u64 todval, struct timespec *xtime)
  76 {
  77         unsigned long long sec;
  78
  79         sec = todval >> 12;
  80         do_div(sec, 1000000);
  81         xtime->tv_sec = sec;
  82         todval -= (sec * 1000000) << 12;
  83         xtime->tv_nsec = ((todval * 1000) >> 12);
  84 }
  85
  86 static inline unsigned long do_gettimeoffset(void)
  87 {
  88         __u64 now;
  89
  90         now = (get_clock() - jiffies_timer_cc) >> 12;
  91         /* We require the offset from the latest update of xtime */
  92         now -= (__u64) wall_jiffies*USECS_PER_JIFFY;
  93         return (unsigned long) now;
  94 }
  95
  96 /*
  97  * This version of gettimeofday has microsecond resolution.
  98  */
  99 void do_gettimeofday(struct timeval *tv)
 100 {
 101         unsigned long flags;
 102         unsigned long seq;
 103         unsigned long usec, sec;
 104
 105         do {
 106                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 107
 108                 sec = xtime.tv_sec;
 109                 usec = xtime.tv_nsec / 1000 + do_gettimeoffset();
 110         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 111
 112         while (usec >= 1000000) {
 113                 usec -= 1000000;
 114                 sec++;
 115         }
 116
 117         tv->tv_sec = sec;
 118         tv->tv_usec = usec;
 119 }
 120
 121 EXPORT_SYMBOL(do_gettimeofday);
 122
 123 int do_settimeofday(struct timespec *tv)
 124 {
 125         time_t wtm_sec, sec = tv->tv_sec;
 126         long wtm_nsec, nsec = tv->tv_nsec;
 127
 128         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 129                 return -EINVAL;
 130
 131         write_seqlock_irq(&xtime_lock);
 132         /* This is revolting. We need to set the xtime.tv_nsec
 133          * correctly. However, the value in this location is
 134          * is value at the last tick.
 135          * Discover what correction gettimeofday
 136          * would have done, and then undo it!
 137          */
 138         nsec -= do_gettimeoffset() * 1000;
 139
 140         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 141         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 142
 143         set_normalized_timespec(&xtime, sec, nsec);
 144         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 145
 146         ntp_clear();
 147         write_sequnlock_irq(&xtime_lock);
 148         clock_was_set();
 149         return 0;
 150 }
 151
 152 EXPORT_SYMBOL(do_settimeofday);
 153
 154
 155 #ifdef CONFIG_PROFILING
 156 #define s390_do_profile(regs)   profile_tick(CPU_PROFILING, regs)
 157 #else
 158 #define s390_do_profile(regs)  do { ; } while(0)
 159 #endif /* CONFIG_PROFILING */
 160
 161
 162 /*
 163  * timer_interrupt() needs to keep up the real-time clock,
 164  * as well as call the "do_timer()" routine every clocktick
 165  */
 166 void account_ticks(struct pt_regs *regs)
 167 {
 168         __u64 tmp;
 169         __u32 ticks, xticks;
 170
 171         /* Calculate how many ticks have passed. */
 172         if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) {
 173                 /*
 174                  * We have to program the clock comparator even if
 175                  * no tick has passed. That happens if e.g. an i/o
 176                  * interrupt wakes up an idle processor that has
 177                  * switched off its hz timer.
 178                  */
 179                 tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
 180                 asm volatile ("SCKC %0" : : "m" (tmp));
 181                 return;
 182         }
 183         tmp = S390_lowcore.int_clock - S390_lowcore.jiffy_timer;
 184         if (tmp >= 2*CLK_TICKS_PER_JIFFY) {  /* more than two ticks ? */
 185                 ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1;
 186                 S390_lowcore.jiffy_timer +=
 187                         CLK_TICKS_PER_JIFFY * (__u64) ticks;
 188         } else if (tmp >= CLK_TICKS_PER_JIFFY) {
 189                 ticks = 2;
 190                 S390_lowcore.jiffy_timer += 2*CLK_TICKS_PER_JIFFY;
 191         } else {
 192                 ticks = 1;
 193                 S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
 194         }
 195
 196         /* set clock comparator for next tick */
 197         tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
 198         asm volatile ("SCKC %0" : : "m" (tmp));
 199
 200 #ifdef CONFIG_SMP
 201         /*
 202          * Do not rely on the boot cpu to do the calls to do_timer.
 203          * Spread it over all cpus instead.
 204          */
 205         write_seqlock(&xtime_lock);
 206         if (S390_lowcore.jiffy_timer > xtime_cc) {
 207                 tmp = S390_lowcore.jiffy_timer - xtime_cc;
 208                 if (tmp >= 2*CLK_TICKS_PER_JIFFY) {
 209                         xticks = __div(tmp, CLK_TICKS_PER_JIFFY);
 210                         xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY;
 211                 } else {
 212                         xticks = 1;
 213                         xtime_cc += CLK_TICKS_PER_JIFFY;
 214                 }
 215                 while (xticks--)
 216                         do_timer(regs);
 217         }
 218         write_sequnlock(&xtime_lock);
 219 #else
 220         for (xticks = ticks; xticks > 0; xticks--)
 221                 do_timer(regs);
 222 #endif
 223
 224 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 225         account_tick_vtime(current);
 226 #else
 227         while (ticks--)
 228                 update_process_times(user_mode(regs));
 229 #endif
 230
 231         s390_do_profile(regs);
 232 }
 233
 234 #ifdef CONFIG_NO_IDLE_HZ
 235
 236 #ifdef CONFIG_NO_IDLE_HZ_INIT
 237 int sysctl_hz_timer = 0;
 238 #else
 239 int sysctl_hz_timer = 1;
 240 #endif
 241
 242 /*
 243  * Stop the HZ tick on the current CPU.
 244  * Only cpu_idle may call this function.
 245  */
 246 static inline void stop_hz_timer(void)
 247 {
 248         unsigned long flags;
 249         unsigned long seq, next;
 250         __u64 timer, todval;
 251         int cpu = smp_processor_id();
 252
 253         if (sysctl_hz_timer != 0)
 254                 return;
 255
 256         cpu_set(cpu, nohz_cpu_mask);
 257
 258         /*
 259          * Leave the clock comparator set up for the next timer
 260          * tick if either rcu or a softirq is pending.
 261          */
 262         if (rcu_needs_cpu(cpu) || local_softirq_pending()) {
 263                 cpu_clear(cpu, nohz_cpu_mask);
 264                 return;
 265         }
 266
 267         /*
 268          * This cpu is going really idle. Set up the clock comparator
 269          * for the next event.
 270          */
 271         next = next_timer_interrupt();
 272         do {
 273                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 274                 timer = ((__u64) next) - ((__u64) jiffies) + jiffies_64;
 275         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 276         todval = -1ULL;
 277         /* Be careful about overflows. */
 278         if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
 279                 timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
 280                 if (timer >= jiffies_timer_cc)
 281                         todval = timer;
 282         }
 283         asm volatile ("SCKC %0" : : "m" (todval));
 284 }
 285
 286 /*
 287  * Start the HZ tick on the current CPU.
 288  * Only cpu_idle may call this function.
 289  */
 290 static inline void start_hz_timer(void)
 291 {
 292         if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
 293                 return;
 294         account_ticks(task_pt_regs(current));
 295         cpu_clear(smp_processor_id(), nohz_cpu_mask);
 296 }
 297
 298 static int nohz_idle_notify(struct notifier_block *self,
 299                             unsigned long action, void *hcpu)
 300 {
 301         switch (action) {
 302         case CPU_IDLE:
 303                 stop_hz_timer();
 304                 break;
 305         case CPU_NOT_IDLE:
 306                 start_hz_timer();
 307                 break;
 308         }
 309         return NOTIFY_OK;
 310 }
 311
 312 static struct notifier_block nohz_idle_nb = {
 313         .notifier_call = nohz_idle_notify,
 314 };
 315
 316 void __init nohz_init(void)
 317 {
 318         if (register_idle_notifier(&nohz_idle_nb))
 319                 panic("Couldn't register idle notifier");
 320 }
 321
 322 #endif
 323
 324 /*
 325  * Start the clock comparator on the current CPU.
 326  */
 327 void init_cpu_timer(void)
 328 {
 329         unsigned long cr0;
 330         __u64 timer;
 331
 332         timer = jiffies_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY;
 333         S390_lowcore.jiffy_timer = timer + CLK_TICKS_PER_JIFFY;
 334         timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
 335         asm volatile ("SCKC %0" : : "m" (timer));
 336         /* allow clock comparator timer interrupt */
 337         __ctl_store(cr0, 0, 0);
 338         cr0 |= 0x800;
 339         __ctl_load(cr0, 0, 0);
 340 }
 341
 342 extern void vtime_init(void);
 343
 344 /*
 345  * Initialize the TOD clock and the CPU timer of
 346  * the boot cpu.
 347  */
 348 void __init time_init(void)
 349 {
 350         __u64 set_time_cc;
 351         int cc;
 352
 353         /* kick the TOD clock */
 354         asm volatile ("STCK 0(%1)\n\t"
 355                       "IPM  %0\n\t"
 356                       "SRL  %0,28" : "=r" (cc) : "a" (&init_timer_cc)
 357                                    : "memory", "cc");
 358         switch (cc) {
 359         case 0: /* clock in set state: all is fine */
 360                 break;
 361         case 1: /* clock in non-set state: FIXME */
 362                 printk("time_init: TOD clock in non-set state\n");
 363                 break;
 364         case 2: /* clock in error state: FIXME */
 365                 printk("time_init: TOD clock in error state\n");
 366                 break;
 367         case 3: /* clock in stopped or not-operational state: FIXME */
 368                 printk("time_init: TOD clock stopped/non-operational\n");
 369                 break;
 370         }
 371         jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY;
 372
 373         /* set xtime */
 374         xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY;
 375         set_time_cc = init_timer_cc - 0x8126d60e46000000LL +
 376                 (0x3c26700LL*1000000*4096);
 377         tod_to_timeval(set_time_cc, &xtime);
 378         set_normalized_timespec(&wall_to_monotonic,
 379                                 -xtime.tv_sec, -xtime.tv_nsec);
 380
 381         /* request the clock comparator external interrupt */
 382         if (register_early_external_interrupt(0x1004, NULL,
 383                                               &ext_int_info_cc) != 0)
 384                 panic("Couldn't request external interrupt 0x1004");
 385
 386         init_cpu_timer();
 387
 388 #ifdef CONFIG_NO_IDLE_HZ
 389         nohz_init();
 390 #endif
 391
 392 #ifdef CONFIG_VIRT_TIMER
 393         vtime_init();
 394 #endif
 395 }
 396