Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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; |
| 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 | timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY; |
| 269 | asm volatile ("SCKC %0" : : "m" (timer)); |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Start the HZ tick on the current CPU. |
| 274 | * Only cpu_idle may call this function. |
| 275 | */ |
| 276 | static inline void start_hz_timer(void) |
| 277 | { |
| 278 | if (!cpu_isset(smp_processor_id(), nohz_cpu_mask)) |
| 279 | return; |
| 280 | account_ticks(__KSTK_PTREGS(current)); |
| 281 | cpu_clear(smp_processor_id(), nohz_cpu_mask); |
| 282 | } |
| 283 | |
| 284 | static int nohz_idle_notify(struct notifier_block *self, |
| 285 | unsigned long action, void *hcpu) |
| 286 | { |
| 287 | switch (action) { |
| 288 | case CPU_IDLE: |
| 289 | stop_hz_timer(); |
| 290 | break; |
| 291 | case CPU_NOT_IDLE: |
| 292 | start_hz_timer(); |
| 293 | break; |
| 294 | } |
| 295 | return NOTIFY_OK; |
| 296 | } |
| 297 | |
| 298 | static struct notifier_block nohz_idle_nb = { |
| 299 | .notifier_call = nohz_idle_notify, |
| 300 | }; |
| 301 | |
| 302 | void __init nohz_init(void) |
| 303 | { |
| 304 | if (register_idle_notifier(&nohz_idle_nb)) |
| 305 | panic("Couldn't register idle notifier"); |
| 306 | } |
| 307 | |
| 308 | #endif |
| 309 | |
| 310 | /* |
| 311 | * Start the clock comparator on the current CPU. |
| 312 | */ |
| 313 | void init_cpu_timer(void) |
| 314 | { |
| 315 | unsigned long cr0; |
| 316 | __u64 timer; |
| 317 | |
| 318 | timer = jiffies_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY; |
| 319 | S390_lowcore.jiffy_timer = timer + CLK_TICKS_PER_JIFFY; |
| 320 | timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION; |
| 321 | asm volatile ("SCKC %0" : : "m" (timer)); |
| 322 | /* allow clock comparator timer interrupt */ |
| 323 | __ctl_store(cr0, 0, 0); |
| 324 | cr0 |= 0x800; |
| 325 | __ctl_load(cr0, 0, 0); |
| 326 | } |
| 327 | |
| 328 | extern void vtime_init(void); |
| 329 | |
| 330 | /* |
| 331 | * Initialize the TOD clock and the CPU timer of |
| 332 | * the boot cpu. |
| 333 | */ |
| 334 | void __init time_init(void) |
| 335 | { |
| 336 | __u64 set_time_cc; |
| 337 | int cc; |
| 338 | |
| 339 | /* kick the TOD clock */ |
| 340 | asm volatile ("STCK 0(%1)\n\t" |
| 341 | "IPM %0\n\t" |
| 342 | "SRL %0,28" : "=r" (cc) : "a" (&init_timer_cc) |
| 343 | : "memory", "cc"); |
| 344 | switch (cc) { |
| 345 | case 0: /* clock in set state: all is fine */ |
| 346 | break; |
| 347 | case 1: /* clock in non-set state: FIXME */ |
| 348 | printk("time_init: TOD clock in non-set state\n"); |
| 349 | break; |
| 350 | case 2: /* clock in error state: FIXME */ |
| 351 | printk("time_init: TOD clock in error state\n"); |
| 352 | break; |
| 353 | case 3: /* clock in stopped or not-operational state: FIXME */ |
| 354 | printk("time_init: TOD clock stopped/non-operational\n"); |
| 355 | break; |
| 356 | } |
| 357 | jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY; |
| 358 | |
| 359 | /* set xtime */ |
| 360 | xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY; |
| 361 | set_time_cc = init_timer_cc - 0x8126d60e46000000LL + |
| 362 | (0x3c26700LL*1000000*4096); |
| 363 | tod_to_timeval(set_time_cc, &xtime); |
| 364 | set_normalized_timespec(&wall_to_monotonic, |
| 365 | -xtime.tv_sec, -xtime.tv_nsec); |
| 366 | |
| 367 | /* request the clock comparator external interrupt */ |
| 368 | if (register_early_external_interrupt(0x1004, 0, |
| 369 | &ext_int_info_cc) != 0) |
| 370 | panic("Couldn't request external interrupt 0x1004"); |
| 371 | |
| 372 | init_cpu_timer(); |
| 373 | |
| 374 | #ifdef CONFIG_NO_IDLE_HZ |
| 375 | nohz_init(); |
| 376 | #endif |
| 377 | |
| 378 | #ifdef CONFIG_VIRT_TIMER |
| 379 | vtime_init(); |
| 380 | #endif |
| 381 | } |
| 382 | |