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