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         int cpu = get_cpu();
 278
 279         if (!cpu_isset(*oncpu, cpu_online_map)) {
 280                 printk(KERN_ERR "tick-braodcast: ignoring broadcast for "
 281                        "offline CPU #%d\n", *oncpu);
 282         } else {
 283
 284                 if (cpu == *oncpu)
 285                         tick_do_broadcast_on_off(&reason);
 286                 else
 287                         smp_call_function_single(*oncpu,
 288                                                  tick_do_broadcast_on_off,
 289                                                  &reason, 1, 1);
 290         }
 291         put_cpu();
 292 }
 293
 294 /*
 295  * Set the periodic handler depending on broadcast on/off
 296  */
 297 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
 298 {
 299         if (!broadcast)
 300                 dev->event_handler = tick_handle_periodic;
 301         else
 302                 dev->event_handler = tick_handle_periodic_broadcast;
 303 }
 304
 305 /*
 306  * Remove a CPU from broadcasting
 307  */
 308 void tick_shutdown_broadcast(unsigned int *cpup)
 309 {
 310         struct clock_event_device *bc;
 311         unsigned long flags;
 312         unsigned int cpu = *cpup;
 313
 314         spin_lock_irqsave(&tick_broadcast_lock, flags);
 315
 316         bc = tick_broadcast_device.evtdev;
 317         cpu_clear(cpu, tick_broadcast_mask);
 318
 319         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
 320                 if (bc && cpus_empty(tick_broadcast_mask))
 321                         clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
 322         }
 323
 324         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 325 }
 326
 327 void tick_suspend_broadcast(void)
 328 {
 329         struct clock_event_device *bc;
 330         unsigned long flags;
 331
 332         spin_lock_irqsave(&tick_broadcast_lock, flags);
 333
 334         bc = tick_broadcast_device.evtdev;
 335         if (bc)
 336                 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
 337
 338         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 339 }
 340
 341 int tick_resume_broadcast(void)
 342 {
 343         struct clock_event_device *bc;
 344         unsigned long flags;
 345         int broadcast = 0;
 346
 347         spin_lock_irqsave(&tick_broadcast_lock, flags);
 348
 349         bc = tick_broadcast_device.evtdev;
 350
 351         if (bc) {
 352                 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
 353
 354                 switch (tick_broadcast_device.mode) {
 355                 case TICKDEV_MODE_PERIODIC:
 356                         if(!cpus_empty(tick_broadcast_mask))
 357                                 tick_broadcast_start_periodic(bc);
 358                         broadcast = cpu_isset(smp_processor_id(),
 359                                               tick_broadcast_mask);
 360                         break;
 361                 case TICKDEV_MODE_ONESHOT:
 362                         broadcast = tick_resume_broadcast_oneshot(bc);
 363                         break;
 364                 }
 365         }
 366         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 367
 368         return broadcast;
 369 }
 370
 371
 372 #ifdef CONFIG_TICK_ONESHOT
 373
 374 static cpumask_t tick_broadcast_oneshot_mask;
 375
 376 /*
 377  * Debugging: see timer_list.c
 378  */
 379 cpumask_t *tick_get_broadcast_oneshot_mask(void)
 380 {
 381         return &tick_broadcast_oneshot_mask;
 382 }
 383
 384 static int tick_broadcast_set_event(ktime_t expires, int force)
 385 {
 386         struct clock_event_device *bc = tick_broadcast_device.evtdev;
 387         ktime_t now = ktime_get();
 388         int res;
 389
 390         for(;;) {
 391                 res = clockevents_program_event(bc, expires, now);
 392                 if (!res || !force)
 393                         return res;
 394                 now = ktime_get();
 395                 expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
 396         }
 397 }
 398
 399 int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
 400 {
 401         clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
 402         return 0;
 403 }
 404
 405 /*
 406  * Reprogram the broadcast device:
 407  *
 408  * Called with tick_broadcast_lock held and interrupts disabled.
 409  */
 410 static int tick_broadcast_reprogram(void)
 411 {
 412         ktime_t expires = { .tv64 = KTIME_MAX };
 413         struct tick_device *td;
 414         int cpu;
 415
 416         /*
 417          * Find the event which expires next:
 418          */
 419         for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
 420              cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
 421                 td = &per_cpu(tick_cpu_device, cpu);
 422                 if (td->evtdev->next_event.tv64 < expires.tv64)
 423                         expires = td->evtdev->next_event;
 424         }
 425
 426         if (expires.tv64 == KTIME_MAX)
 427                 return 0;
 428
 429         return tick_broadcast_set_event(expires, 0);
 430 }
 431
 432 /*
 433  * Handle oneshot mode broadcasting
 434  */
 435 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
 436 {
 437         struct tick_device *td;
 438         cpumask_t mask;
 439         ktime_t now;
 440         int cpu;
 441
 442         spin_lock(&tick_broadcast_lock);
 443 again:
 444         dev->next_event.tv64 = KTIME_MAX;
 445         mask = CPU_MASK_NONE;
 446         now = ktime_get();
 447         /* Find all expired events */
 448         for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
 449              cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
 450                 td = &per_cpu(tick_cpu_device, cpu);
 451                 if (td->evtdev->next_event.tv64 <= now.tv64)
 452                         cpu_set(cpu, mask);
 453         }
 454
 455         /*
 456          * Wakeup the cpus which have an expired event. The broadcast
 457          * device is reprogrammed in the return from idle code.
 458          */
 459         if (!tick_do_broadcast(mask)) {
 460                 /*
 461                  * The global event did not expire any CPU local
 462                  * events. This happens in dyntick mode, as the
 463                  * maximum PIT delta is quite small.
 464                  */
 465                 if (tick_broadcast_reprogram())
 466                         goto again;
 467         }
 468         spin_unlock(&tick_broadcast_lock);
 469 }
 470
 471 /*
 472  * Powerstate information: The system enters/leaves a state, where
 473  * affected devices might stop
 474  */
 475 void tick_broadcast_oneshot_control(unsigned long reason)
 476 {
 477         struct clock_event_device *bc, *dev;
 478         struct tick_device *td;
 479         unsigned long flags;
 480         int cpu;
 481
 482         spin_lock_irqsave(&tick_broadcast_lock, flags);
 483
 484         /*
 485          * Periodic mode does not care about the enter/exit of power
 486          * states
 487          */
 488         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
 489                 goto out;
 490
 491         bc = tick_broadcast_device.evtdev;
 492         cpu = smp_processor_id();
 493         td = &per_cpu(tick_cpu_device, cpu);
 494         dev = td->evtdev;
 495
 496         if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
 497                 goto out;
 498
 499         if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
 500                 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
 501                         cpu_set(cpu, tick_broadcast_oneshot_mask);
 502                         clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
 503                         if (dev->next_event.tv64 < bc->next_event.tv64)
 504                                 tick_broadcast_set_event(dev->next_event, 1);
 505                 }
 506         } else {
 507                 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
 508                         cpu_clear(cpu, tick_broadcast_oneshot_mask);
 509                         clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
 510                         if (dev->next_event.tv64 != KTIME_MAX)
 511                                 tick_program_event(dev->next_event, 1);
 512                 }
 513         }
 514
 515 out:
 516         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 517 }
 518
 519 /*
 520  * Reset the one shot broadcast for a cpu
 521  *
 522  * Called with tick_broadcast_lock held
 523  */
 524 static void tick_broadcast_clear_oneshot(int cpu)
 525 {
 526         cpu_clear(cpu, tick_broadcast_oneshot_mask);
 527 }
 528
 529 /**
 530  * tick_broadcast_setup_highres - setup the broadcast device for highres
 531  */
 532 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
 533 {
 534         bc->event_handler = tick_handle_oneshot_broadcast;
 535         clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
 536         bc->next_event.tv64 = KTIME_MAX;
 537 }
 538
 539 /*
 540  * Select oneshot operating mode for the broadcast device
 541  */
 542 void tick_broadcast_switch_to_oneshot(void)
 543 {
 544         struct clock_event_device *bc;
 545         unsigned long flags;
 546
 547         spin_lock_irqsave(&tick_broadcast_lock, flags);
 548
 549         tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
 550         bc = tick_broadcast_device.evtdev;
 551         if (bc)
 552                 tick_broadcast_setup_oneshot(bc);
 553         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 554 }
 555
 556
 557 /*
 558  * Remove a dead CPU from broadcasting
 559  */
 560 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
 561 {
 562         unsigned long flags;
 563         unsigned int cpu = *cpup;
 564
 565         spin_lock_irqsave(&tick_broadcast_lock, flags);
 566
 567         /*
 568          * Clear the broadcast mask flag for the dead cpu, but do not
 569          * stop the broadcast device!
 570          */
 571         cpu_clear(cpu, tick_broadcast_oneshot_mask);
 572
 573         spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 574 }
 575
 576 #endif