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 static ext_int_info_t ext_int_info_cc; 53 static u64 init_timer_cc; 54 static u64 jiffies_timer_cc; 55 static u64 xtime_cc; 56 57 extern unsigned long wall_jiffies; 58 59 /* 60 * Scheduler clock - returns current time in nanosec units. 61 */ 62 unsigned long long sched_clock(void) 63 { 64 return ((get_clock() - jiffies_timer_cc) * 125) >> 9; 65 } 66 67 /* 68 * Monotonic_clock - returns # of nanoseconds passed since time_init() 69 */ 70 unsigned long long monotonic_clock(void) 71 { 72 return sched_clock(); 73 } 74 EXPORT_SYMBOL(monotonic_clock); 75 76 void tod_to_timeval(__u64 todval, struct timespec *xtime) 77 { 78 unsigned long long sec; 79 80 sec = todval >> 12; 81 do_div(sec, 1000000); 82 xtime->tv_sec = sec; 83 todval -= (sec * 1000000) << 12; 84 xtime->tv_nsec = ((todval * 1000) >> 12); 85 } 86 87 static inline unsigned long do_gettimeoffset(void) 88 { 89 __u64 now; 90 91 now = (get_clock() - jiffies_timer_cc) >> 12; 92 /* We require the offset from the latest update of xtime */ 93 now -= (__u64) wall_jiffies*USECS_PER_JIFFY; 94 return (unsigned long) now; 95 } 96 97 /* 98 * This version of gettimeofday has microsecond resolution. 99 */ 100 void do_gettimeofday(struct timeval *tv) 101 { 102 unsigned long flags; 103 unsigned long seq; 104 unsigned long usec, sec; 105 106 do { 107 seq = read_seqbegin_irqsave(&xtime_lock, flags); 108 109 sec = xtime.tv_sec; 110 usec = xtime.tv_nsec / 1000 + do_gettimeoffset(); 111 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 112 113 while (usec >= 1000000) { 114 usec -= 1000000; 115 sec++; 116 } 117 118 tv->tv_sec = sec; 119 tv->tv_usec = usec; 120 } 121 122 EXPORT_SYMBOL(do_gettimeofday); 123 124 int do_settimeofday(struct timespec *tv) 125 { 126 time_t wtm_sec, sec = tv->tv_sec; 127 long wtm_nsec, nsec = tv->tv_nsec; 128 129 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) 130 return -EINVAL; 131 132 write_seqlock_irq(&xtime_lock); 133 /* This is revolting. We need to set the xtime.tv_nsec 134 * correctly. However, the value in this location is 135 * is value at the last tick. 136 * Discover what correction gettimeofday 137 * would have done, and then undo it! 138 */ 139 nsec -= do_gettimeoffset() * 1000; 140 141 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); 142 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); 143 144 set_normalized_timespec(&xtime, sec, nsec); 145 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); 146 147 ntp_clear(); 148 write_sequnlock_irq(&xtime_lock); 149 clock_was_set(); 150 return 0; 151 } 152 153 EXPORT_SYMBOL(do_settimeofday); 154 155 156 #ifdef CONFIG_PROFILING 157 #define s390_do_profile(regs) profile_tick(CPU_PROFILING, regs) 158 #else 159 #define s390_do_profile(regs) do { ; } while(0) 160 #endif /* CONFIG_PROFILING */ 161 162 163 /* 164 * timer_interrupt() needs to keep up the real-time clock, 165 * as well as call the "do_timer()" routine every clocktick 166 */ 167 void account_ticks(struct pt_regs *regs) 168 { 169 __u64 tmp; 170 __u32 ticks, xticks; 171 172 /* Calculate how many ticks have passed. */ 173 if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) { 174 /* 175 * We have to program the clock comparator even if 176 * no tick has passed. That happens if e.g. an i/o 177 * interrupt wakes up an idle processor that has 178 * switched off its hz timer. 179 */ 180 tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION; 181 asm volatile ("SCKC %0" : : "m" (tmp)); 182 return; 183 } 184 tmp = S390_lowcore.int_clock - S390_lowcore.jiffy_timer; 185 if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than two ticks ? */ 186 ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1; 187 S390_lowcore.jiffy_timer += 188 CLK_TICKS_PER_JIFFY * (__u64) ticks; 189 } else if (tmp >= CLK_TICKS_PER_JIFFY) { 190 ticks = 2; 191 S390_lowcore.jiffy_timer += 2*CLK_TICKS_PER_JIFFY; 192 } else { 193 ticks = 1; 194 S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY; 195 } 196 197 /* set clock comparator for next tick */ 198 tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION; 199 asm volatile ("SCKC %0" : : "m" (tmp)); 200 201 #ifdef CONFIG_SMP 202 /* 203 * Do not rely on the boot cpu to do the calls to do_timer. 204 * Spread it over all cpus instead. 205 */ 206 write_seqlock(&xtime_lock); 207 if (S390_lowcore.jiffy_timer > xtime_cc) { 208 tmp = S390_lowcore.jiffy_timer - xtime_cc; 209 if (tmp >= 2*CLK_TICKS_PER_JIFFY) { 210 xticks = __div(tmp, CLK_TICKS_PER_JIFFY); 211 xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY; 212 } else { 213 xticks = 1; 214 xtime_cc += CLK_TICKS_PER_JIFFY; 215 } 216 while (xticks--) 217 do_timer(regs); 218 } 219 write_sequnlock(&xtime_lock); 220 #else 221 for (xticks = ticks; xticks > 0; xticks--) 222 do_timer(regs); 223 #endif 224 225 #ifdef CONFIG_VIRT_CPU_ACCOUNTING 226 account_tick_vtime(current); 227 #else 228 while (ticks--) 229 update_process_times(user_mode(regs)); 230 #endif 231 232 s390_do_profile(regs); 233 } 234 235 #ifdef CONFIG_NO_IDLE_HZ 236 237 #ifdef CONFIG_NO_IDLE_HZ_INIT 238 int sysctl_hz_timer = 0; 239 #else 240 int sysctl_hz_timer = 1; 241 #endif 242 243 /* 244 * Stop the HZ tick on the current CPU. 245 * Only cpu_idle may call this function. 246 */ 247 static inline void stop_hz_timer(void) 248 { 249 unsigned long flags; 250 unsigned long seq, next; 251 __u64 timer, todval; 252 253 if (sysctl_hz_timer != 0) 254 return; 255 256 cpu_set(smp_processor_id(), 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_pending(smp_processor_id()) || local_softirq_pending()) { 263 cpu_clear(smp_processor_id(), 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 - 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, 0, 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 } 396 397