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