git.oblomov.eu Git - linux-2.6/blob - kernel/time/tick-broadcast.c

   1 /*
   2  * linux/kernel/time/tick-broadcast.c
   3  *
   4  * This file contains functions which emulate a local clock-event
   5  * device via a broadcast event source.
   6  *
   7  * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   8  * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   9  * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
  10  *
  11  * This code is licenced under the GPL version 2. For details see
  12  * kernel-base/COPYING.
  13  */
  14 #include <linux/cpu.h>
  15 #include <linux/err.h>
  16 #include <linux/hrtimer.h>
  17 #include <linux/irq.h>
  18 #include <linux/percpu.h>
  19 #include <linux/profile.h>
  20 #include <linux/sched.h>
  21 #include <linux/tick.h>
  22
  23 #include "tick-internal.h"
  24
  25 /*
  26  * Broadcast support for broken x86 hardware, where the local apic
  27  * timer stops in C3 state.
  28  */
  29
  30 struct tick_device tick_broadcast_device;
  31 static cpumask_t tick_broadcast_mask;
  32 static DEFINE_SPINLOCK(tick_broadcast_lock);
  33
  34 #ifdef CONFIG_TICK_ONESHOT
  35 static void tick_broadcast_clear_oneshot(int cpu);
  36 #else
  37 static inline void tick_broadcast_clear_oneshot(int cpu) { }
  38 #endif
  39
  40 /*
  41  * Debugging: see timer_list.c
  42  */
  43 struct tick_device *tick_get_broadcast_device(void)
  44 {
  45         return &tick_broadcast_device;
  46 }
  47
  48 cpumask_t *tick_get_broadcast_mask(void)
  49 {
  50         return &tick_broadcast_mask;
  51 }
  52
  53 /*
  54  * Start the device in periodic mode
  55  */
  56 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
  57 {
  58         if (bc)
  59                 tick_setup_periodic(bc, 1);
  60 }
  61
  62 /*
  63  * Check, if the device can be utilized as broadcast device:
  64  */
  65 int tick_check_broadcast_device(struct clock_event_device *dev)
  66 {
  67         if ((tick_broadcast_device.evtdev &&
  68              tick_broadcast_device.evtdev->rating >= dev->rating) ||
  69              (dev->features & CLOCK_EVT_FEAT_C3STOP))
  70                 return 0;
  71
  72         clockevents_exchange_device(NULL, dev);
  73         tick_broadcast_device.evtdev = dev;
  74         if (!cpus_empty(tick_broadcast_mask))
  75                 tick_broadcast_start_periodic(dev);
  76         return 1;
  77 }
  78
  79 /*
  80  * Check, if the device is the broadcast device
  81  */
  82 int tick_is_broadcast_device(struct clock_event_device *dev)
  83 {
  84         return (dev && tick_broadcast_device.evtdev == dev);
  85 }
  86
  87 /*
  88  * Check, if the device is disfunctional and a place holder, which
  89  * needs to be handled by the broadcast device.
  90  */
  91 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
  92 {
  93         unsigned long flags;
  94         int ret = 0;
  95
  96         spin_lock_irqsave(&tick_broadcast_lock, flags);
  97
  98         /*
  99          * Devices might be registered with both periodic and oneshot
 100          * mode disabled. This signals, that the device needs to be
 101          * operated from the broadcast device and is a placeholder for
 102          * the cpu local device.
 103          */
 104         if (!tick_device_is_functional(dev)) {
 105                 dev->event_handler = tick_handle_periodic;
 106                 cpu_set(cpu, tick_broadcast_mask);
 107                 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
 108                 ret = 1;
 109         } else {
 110                 /*
 111                  * When the new device is not affected by the stop
 112                  * feature and the cpu is marked in the broadcast mask
 113                  * then clear the broadcast bit.
 114                  */
 115                 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
 116                         int cpu = smp_processor_id();
 117
 118                         cpu_clear(cpu, tick_broadcast_mask);
 119                         tick_broadcast_clear_oneshot(cpu);
 120                 }
 121         }
 122         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 123         return ret;
 124 }
 125
 126 /*
 127  * Broadcast the event to the cpus, which are set in the mask
 128  */
 129 int tick_do_broadcast(cpumask_t mask)
 130 {
 131         int ret = 0, cpu = smp_processor_id();
 132         struct tick_device *td;
 133
 134         /*
 135          * Check, if the current cpu is in the mask
 136          */
 137         if (cpu_isset(cpu, mask)) {
 138                 cpu_clear(cpu, mask);
 139                 td = &per_cpu(tick_cpu_device, cpu);
 140                 td->evtdev->event_handler(td->evtdev);
 141                 ret = 1;
 142         }
 143
 144         if (!cpus_empty(mask)) {
 145                 /*
 146                  * It might be necessary to actually check whether the devices
 147                  * have different broadcast functions. For now, just use the
 148                  * one of the first device. This works as long as we have this
 149                  * misfeature only on x86 (lapic)
 150                  */
 151                 cpu = first_cpu(mask);
 152                 td = &per_cpu(tick_cpu_device, cpu);
 153                 td->evtdev->broadcast(mask);
 154                 ret = 1;
 155         }
 156         return ret;
 157 }
 158
 159 /*
 160  * Periodic broadcast:
 161  * - invoke the broadcast handlers
 162  */
 163 static void tick_do_periodic_broadcast(void)
 164 {
 165         cpumask_t mask;
 166
 167         spin_lock(&tick_broadcast_lock);
 168
 169         cpus_and(mask, cpu_online_map, tick_broadcast_mask);
 170         tick_do_broadcast(mask);
 171
 172         spin_unlock(&tick_broadcast_lock);
 173 }
 174
 175 /*
 176  * Event handler for periodic broadcast ticks
 177  */
 178 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
 179 {
 180         tick_do_periodic_broadcast();
 181
 182         /*
 183          * The device is in periodic mode. No reprogramming necessary:
 184          */
 185         if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
 186                 return;
 187
 188         /*
 189          * Setup the next period for devices, which do not have
 190          * periodic mode:
 191          */
 192         for (;;) {
 193                 ktime_t next = ktime_add(dev->next_event, tick_period);
 194
 195                 if (!clockevents_program_event(dev, next, ktime_get()))
 196                         return;
 197                 tick_do_periodic_broadcast();
 198         }
 199 }
 200
 201 /*
 202  * Powerstate information: The system enters/leaves a state, where
 203  * affected devices might stop
 204  */
 205 static void tick_do_broadcast_on_off(void *why)
 206 {
 207         struct clock_event_device *bc, *dev;
 208         struct tick_device *td;
 209         unsigned long flags, *reason = why;
 210         int cpu;
 211
 212         spin_lock_irqsave(&tick_broadcast_lock, flags);
 213
 214         cpu = smp_processor_id();
 215         td = &per_cpu(tick_cpu_device, cpu);
 216         dev = td->evtdev;
 217         bc = tick_broadcast_device.evtdev;
 218
 219         /*
 220          * Is the device not affected by the powerstate ?
 221          */
 222         if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
 223                 goto out;
 224
 225         /*
 226          * Defect device ?
 227          */
 228         if (!tick_device_is_functional(dev)) {
 229                 /*
 230                  * AMD C1E wreckage fixup:
 231                  *
 232                  * Device was registered functional in the first
 233                  * place. Now the secondary CPU detected the C1E
 234                  * misfeature and notifies us to fix it up
 235                  */
 236                 if (*reason != CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
 237                         goto out;
 238         }
 239
 240         switch (*reason) {
 241         case CLOCK_EVT_NOTIFY_BROADCAST_ON:
 242         case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
 243                 if (!cpu_isset(cpu, tick_broadcast_mask)) {
 244                         cpu_set(cpu, tick_broadcast_mask);
 245                         if (td->mode == TICKDEV_MODE_PERIODIC)
 246                                 clockevents_set_mode(dev,
 247                                                      CLOCK_EVT_MODE_SHUTDOWN);
 248                 }
 249                 break;
 250         case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
 251                 if (cpu_isset(cpu, tick_broadcast_mask)) {
 252                         cpu_clear(cpu, tick_broadcast_mask);
 253                         if (td->mode == TICKDEV_MODE_PERIODIC)
 254                                 tick_setup_periodic(dev, 0);
 255                 }
 256                 break;
 257         }
 258
 259         if (cpus_empty(tick_broadcast_mask))
 260                 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
 261         else {
 262                 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
 263                         tick_broadcast_start_periodic(bc);
 264                 else
 265                         tick_broadcast_setup_oneshot(bc);
 266         }
 267 out:
 268         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 269 }
 270
 271 /*
 272  * Powerstate information: The system enters/leaves a state, where
 273  * affected devices might stop.
 274  */
 275 void tick_broadcast_on_off(unsigned long reason, int *oncpu)
 276 {
 277         if (!cpu_isset(*oncpu, cpu_online_map))
 278                 printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
 279                        "offline CPU #%d\n", *oncpu);
 280         else
 281                 smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
 282                                          &reason, 1, 1);
 283 }
 284
 285 /*
 286  * Set the periodic handler depending on broadcast on/off
 287  */
 288 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
 289 {
 290         if (!broadcast)
 291                 dev->event_handler = tick_handle_periodic;
 292         else
 293                 dev->event_handler = tick_handle_periodic_broadcast;
 294 }
 295
 296 /*
 297  * Remove a CPU from broadcasting
 298  */
 299 void tick_shutdown_broadcast(unsigned int *cpup)
 300 {
 301         struct clock_event_device *bc;
 302         unsigned long flags;
 303         unsigned int cpu = *cpup;
 304
 305         spin_lock_irqsave(&tick_broadcast_lock, flags);
 306
 307         bc = tick_broadcast_device.evtdev;
 308         cpu_clear(cpu, tick_broadcast_mask);
 309
 310         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
 311                 if (bc && cpus_empty(tick_broadcast_mask))
 312                         clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
 313         }
 314
 315         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 316 }
 317
 318 void tick_suspend_broadcast(void)
 319 {
 320         struct clock_event_device *bc;
 321         unsigned long flags;
 322
 323         spin_lock_irqsave(&tick_broadcast_lock, flags);
 324
 325         bc = tick_broadcast_device.evtdev;
 326         if (bc)
 327                 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
 328
 329         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 330 }
 331
 332 int tick_resume_broadcast(void)
 333 {
 334         struct clock_event_device *bc;
 335         unsigned long flags;
 336         int broadcast = 0;
 337
 338         spin_lock_irqsave(&tick_broadcast_lock, flags);
 339
 340         bc = tick_broadcast_device.evtdev;
 341
 342         if (bc) {
 343                 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
 344
 345                 switch (tick_broadcast_device.mode) {
 346                 case TICKDEV_MODE_PERIODIC:
 347                         if(!cpus_empty(tick_broadcast_mask))
 348                                 tick_broadcast_start_periodic(bc);
 349                         broadcast = cpu_isset(smp_processor_id(),
 350                                               tick_broadcast_mask);
 351                         break;
 352                 case TICKDEV_MODE_ONESHOT:
 353                         broadcast = tick_resume_broadcast_oneshot(bc);
 354                         break;
 355                 }
 356         }
 357         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 358
 359         return broadcast;
 360 }
 361
 362
 363 #ifdef CONFIG_TICK_ONESHOT
 364
 365 static cpumask_t tick_broadcast_oneshot_mask;
 366
 367 /*
 368  * Debugging: see timer_list.c
 369  */
 370 cpumask_t *tick_get_broadcast_oneshot_mask(void)
 371 {
 372         return &tick_broadcast_oneshot_mask;
 373 }
 374
 375 static int tick_broadcast_set_event(ktime_t expires, int force)
 376 {
 377         struct clock_event_device *bc = tick_broadcast_device.evtdev;
 378         ktime_t now = ktime_get();
 379         int res;
 380
 381         for(;;) {
 382                 res = clockevents_program_event(bc, expires, now);
 383                 if (!res || !force)
 384                         return res;
 385                 now = ktime_get();
 386                 expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
 387         }
 388 }
 389
 390 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
 391 {
 392         clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
 393         return 0;
 394 }
 395
 396 /*
 397  * Reprogram the broadcast device:
 398  *
 399  * Called with tick_broadcast_lock held and interrupts disabled.
 400  */
 401 static int tick_broadcast_reprogram(void)
 402 {
 403         ktime_t expires = { .tv64 = KTIME_MAX };
 404         struct tick_device *td;
 405         int cpu;
 406
 407         /*
 408          * Find the event which expires next:
 409          */
 410         for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
 411              cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
 412                 td = &per_cpu(tick_cpu_device, cpu);
 413                 if (td->evtdev->next_event.tv64 < expires.tv64)
 414                         expires = td->evtdev->next_event;
 415         }
 416
 417         if (expires.tv64 == KTIME_MAX)
 418                 return 0;
 419
 420         return tick_broadcast_set_event(expires, 0);
 421 }
 422
 423 /*
 424  * Handle oneshot mode broadcasting
 425  */
 426 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
 427 {
 428         struct tick_device *td;
 429         cpumask_t mask;
 430         ktime_t now;
 431         int cpu;
 432
 433         spin_lock(&tick_broadcast_lock);
 434 again:
 435         dev->next_event.tv64 = KTIME_MAX;
 436         mask = CPU_MASK_NONE;
 437         now = ktime_get();
 438         /* Find all expired events */
 439         for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
 440              cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
 441                 td = &per_cpu(tick_cpu_device, cpu);
 442                 if (td->evtdev->next_event.tv64 <= now.tv64)
 443                         cpu_set(cpu, mask);
 444         }
 445
 446         /*
 447          * Wakeup the cpus which have an expired event. The broadcast
 448          * device is reprogrammed in the return from idle code.
 449          */
 450         if (!tick_do_broadcast(mask)) {
 451                 /*
 452                  * The global event did not expire any CPU local
 453                  * events. This happens in dyntick mode, as the
 454                  * maximum PIT delta is quite small.
 455                  */
 456                 if (tick_broadcast_reprogram())
 457                         goto again;
 458         }
 459         spin_unlock(&tick_broadcast_lock);
 460 }
 461
 462 /*
 463  * Powerstate information: The system enters/leaves a state, where
 464  * affected devices might stop
 465  */
 466 void tick_broadcast_oneshot_control(unsigned long reason)
 467 {
 468         struct clock_event_device *bc, *dev;
 469         struct tick_device *td;
 470         unsigned long flags;
 471         int cpu;
 472
 473         spin_lock_irqsave(&tick_broadcast_lock, flags);
 474
 475         /*
 476          * Periodic mode does not care about the enter/exit of power
 477          * states
 478          */
 479         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
 480                 goto out;
 481
 482         bc = tick_broadcast_device.evtdev;
 483         cpu = smp_processor_id();
 484         td = &per_cpu(tick_cpu_device, cpu);
 485         dev = td->evtdev;
 486
 487         if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
 488                 goto out;
 489
 490         if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
 491                 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
 492                         cpu_set(cpu, tick_broadcast_oneshot_mask);
 493                         clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
 494                         if (dev->next_event.tv64 < bc->next_event.tv64)
 495                                 tick_broadcast_set_event(dev->next_event, 1);
 496                 }
 497         } else {
 498                 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
 499                         cpu_clear(cpu, tick_broadcast_oneshot_mask);
 500                         clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
 501                         if (dev->next_event.tv64 != KTIME_MAX)
 502                                 tick_program_event(dev->next_event, 1);
 503                 }
 504         }
 505
 506 out:
 507         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 508 }
 509
 510 /*
 511  * Reset the one shot broadcast for a cpu
 512  *
 513  * Called with tick_broadcast_lock held
 514  */
 515 static void tick_broadcast_clear_oneshot(int cpu)
 516 {
 517         cpu_clear(cpu, tick_broadcast_oneshot_mask);
 518 }
 519
 520 /**
 521  * tick_broadcast_setup_highres - setup the broadcast device for highres
 522  */
 523 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
 524 {
 525         bc->event_handler = tick_handle_oneshot_broadcast;
 526         clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
 527         bc->next_event.tv64 = KTIME_MAX;
 528 }
 529
 530 /*
 531  * Select oneshot operating mode for the broadcast device
 532  */
 533 void tick_broadcast_switch_to_oneshot(void)
 534 {
 535         struct clock_event_device *bc;
 536         unsigned long flags;
 537
 538         spin_lock_irqsave(&tick_broadcast_lock, flags);
 539
 540         tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
 541         bc = tick_broadcast_device.evtdev;
 542         if (bc)
 543                 tick_broadcast_setup_oneshot(bc);
 544         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 545 }
 546
 547
 548 /*
 549  * Remove a dead CPU from broadcasting
 550  */
 551 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
 552 {
 553         unsigned long flags;
 554         unsigned int cpu = *cpup;
 555
 556         spin_lock_irqsave(&tick_broadcast_lock, flags);
 557
 558         /*
 559          * Clear the broadcast mask flag for the dead cpu, but do not
 560          * stop the broadcast device!
 561          */
 562         cpu_clear(cpu, tick_broadcast_oneshot_mask);
 563
 564         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 565 }
 566
 567 #endif