| 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/interrupt.h> |
| 18 | #include <linux/percpu.h> |
| 19 | #include <linux/profile.h> |
| 20 | #include <linux/sched.h> |
| 21 | #include <linux/smp.h> |
| 22 | #include <linux/module.h> |
| 23 | |
| 24 | #include "tick-internal.h" |
| 25 | |
| 26 | /* |
| 27 | * Broadcast support for broken x86 hardware, where the local apic |
| 28 | * timer stops in C3 state. |
| 29 | */ |
| 30 | |
| 31 | static struct tick_device tick_broadcast_device; |
| 32 | static cpumask_var_t tick_broadcast_mask; |
| 33 | static cpumask_var_t tick_broadcast_on; |
| 34 | static cpumask_var_t tmpmask; |
| 35 | static DEFINE_RAW_SPINLOCK(tick_broadcast_lock); |
| 36 | static int tick_broadcast_force; |
| 37 | |
| 38 | #ifdef CONFIG_TICK_ONESHOT |
| 39 | static void tick_broadcast_clear_oneshot(int cpu); |
| 40 | #else |
| 41 | static inline void tick_broadcast_clear_oneshot(int cpu) { } |
| 42 | #endif |
| 43 | |
| 44 | /* |
| 45 | * Debugging: see timer_list.c |
| 46 | */ |
| 47 | struct tick_device *tick_get_broadcast_device(void) |
| 48 | { |
| 49 | return &tick_broadcast_device; |
| 50 | } |
| 51 | |
| 52 | struct cpumask *tick_get_broadcast_mask(void) |
| 53 | { |
| 54 | return tick_broadcast_mask; |
| 55 | } |
| 56 | |
| 57 | /* |
| 58 | * Start the device in periodic mode |
| 59 | */ |
| 60 | static void tick_broadcast_start_periodic(struct clock_event_device *bc) |
| 61 | { |
| 62 | if (bc) |
| 63 | tick_setup_periodic(bc, 1); |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * Check, if the device can be utilized as broadcast device: |
| 68 | */ |
| 69 | static bool tick_check_broadcast_device(struct clock_event_device *curdev, |
| 70 | struct clock_event_device *newdev) |
| 71 | { |
| 72 | if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) || |
| 73 | (newdev->features & CLOCK_EVT_FEAT_PERCPU) || |
| 74 | (newdev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 75 | return false; |
| 76 | |
| 77 | if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT && |
| 78 | !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) |
| 79 | return false; |
| 80 | |
| 81 | return !curdev || newdev->rating > curdev->rating; |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * Conditionally install/replace broadcast device |
| 86 | */ |
| 87 | void tick_install_broadcast_device(struct clock_event_device *dev) |
| 88 | { |
| 89 | struct clock_event_device *cur = tick_broadcast_device.evtdev; |
| 90 | |
| 91 | if (!tick_check_broadcast_device(cur, dev)) |
| 92 | return; |
| 93 | |
| 94 | if (!try_module_get(dev->owner)) |
| 95 | return; |
| 96 | |
| 97 | clockevents_exchange_device(cur, dev); |
| 98 | if (cur) |
| 99 | cur->event_handler = clockevents_handle_noop; |
| 100 | tick_broadcast_device.evtdev = dev; |
| 101 | if (!cpumask_empty(tick_broadcast_mask)) |
| 102 | tick_broadcast_start_periodic(dev); |
| 103 | /* |
| 104 | * Inform all cpus about this. We might be in a situation |
| 105 | * where we did not switch to oneshot mode because the per cpu |
| 106 | * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack |
| 107 | * of a oneshot capable broadcast device. Without that |
| 108 | * notification the systems stays stuck in periodic mode |
| 109 | * forever. |
| 110 | */ |
| 111 | if (dev->features & CLOCK_EVT_FEAT_ONESHOT) |
| 112 | tick_clock_notify(); |
| 113 | } |
| 114 | |
| 115 | /* |
| 116 | * Check, if the device is the broadcast device |
| 117 | */ |
| 118 | int tick_is_broadcast_device(struct clock_event_device *dev) |
| 119 | { |
| 120 | return (dev && tick_broadcast_device.evtdev == dev); |
| 121 | } |
| 122 | |
| 123 | int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq) |
| 124 | { |
| 125 | int ret = -ENODEV; |
| 126 | |
| 127 | if (tick_is_broadcast_device(dev)) { |
| 128 | raw_spin_lock(&tick_broadcast_lock); |
| 129 | ret = __clockevents_update_freq(dev, freq); |
| 130 | raw_spin_unlock(&tick_broadcast_lock); |
| 131 | } |
| 132 | return ret; |
| 133 | } |
| 134 | |
| 135 | |
| 136 | static void err_broadcast(const struct cpumask *mask) |
| 137 | { |
| 138 | pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n"); |
| 139 | } |
| 140 | |
| 141 | static void tick_device_setup_broadcast_func(struct clock_event_device *dev) |
| 142 | { |
| 143 | if (!dev->broadcast) |
| 144 | dev->broadcast = tick_broadcast; |
| 145 | if (!dev->broadcast) { |
| 146 | pr_warn_once("%s depends on broadcast, but no broadcast function available\n", |
| 147 | dev->name); |
| 148 | dev->broadcast = err_broadcast; |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | /* |
| 153 | * Check, if the device is disfunctional and a place holder, which |
| 154 | * needs to be handled by the broadcast device. |
| 155 | */ |
| 156 | int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) |
| 157 | { |
| 158 | struct clock_event_device *bc = tick_broadcast_device.evtdev; |
| 159 | unsigned long flags; |
| 160 | int ret; |
| 161 | |
| 162 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 163 | |
| 164 | /* |
| 165 | * Devices might be registered with both periodic and oneshot |
| 166 | * mode disabled. This signals, that the device needs to be |
| 167 | * operated from the broadcast device and is a placeholder for |
| 168 | * the cpu local device. |
| 169 | */ |
| 170 | if (!tick_device_is_functional(dev)) { |
| 171 | dev->event_handler = tick_handle_periodic; |
| 172 | tick_device_setup_broadcast_func(dev); |
| 173 | cpumask_set_cpu(cpu, tick_broadcast_mask); |
| 174 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) |
| 175 | tick_broadcast_start_periodic(bc); |
| 176 | else |
| 177 | tick_broadcast_setup_oneshot(bc); |
| 178 | ret = 1; |
| 179 | } else { |
| 180 | /* |
| 181 | * Clear the broadcast bit for this cpu if the |
| 182 | * device is not power state affected. |
| 183 | */ |
| 184 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 185 | cpumask_clear_cpu(cpu, tick_broadcast_mask); |
| 186 | else |
| 187 | tick_device_setup_broadcast_func(dev); |
| 188 | |
| 189 | /* |
| 190 | * Clear the broadcast bit if the CPU is not in |
| 191 | * periodic broadcast on state. |
| 192 | */ |
| 193 | if (!cpumask_test_cpu(cpu, tick_broadcast_on)) |
| 194 | cpumask_clear_cpu(cpu, tick_broadcast_mask); |
| 195 | |
| 196 | switch (tick_broadcast_device.mode) { |
| 197 | case TICKDEV_MODE_ONESHOT: |
| 198 | /* |
| 199 | * If the system is in oneshot mode we can |
| 200 | * unconditionally clear the oneshot mask bit, |
| 201 | * because the CPU is running and therefore |
| 202 | * not in an idle state which causes the power |
| 203 | * state affected device to stop. Let the |
| 204 | * caller initialize the device. |
| 205 | */ |
| 206 | tick_broadcast_clear_oneshot(cpu); |
| 207 | ret = 0; |
| 208 | break; |
| 209 | |
| 210 | case TICKDEV_MODE_PERIODIC: |
| 211 | /* |
| 212 | * If the system is in periodic mode, check |
| 213 | * whether the broadcast device can be |
| 214 | * switched off now. |
| 215 | */ |
| 216 | if (cpumask_empty(tick_broadcast_mask) && bc) |
| 217 | clockevents_shutdown(bc); |
| 218 | /* |
| 219 | * If we kept the cpu in the broadcast mask, |
| 220 | * tell the caller to leave the per cpu device |
| 221 | * in shutdown state. The periodic interrupt |
| 222 | * is delivered by the broadcast device. |
| 223 | */ |
| 224 | ret = cpumask_test_cpu(cpu, tick_broadcast_mask); |
| 225 | break; |
| 226 | default: |
| 227 | /* Nothing to do */ |
| 228 | ret = 0; |
| 229 | break; |
| 230 | } |
| 231 | } |
| 232 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 233 | return ret; |
| 234 | } |
| 235 | |
| 236 | #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST |
| 237 | int tick_receive_broadcast(void) |
| 238 | { |
| 239 | struct tick_device *td = this_cpu_ptr(&tick_cpu_device); |
| 240 | struct clock_event_device *evt = td->evtdev; |
| 241 | |
| 242 | if (!evt) |
| 243 | return -ENODEV; |
| 244 | |
| 245 | if (!evt->event_handler) |
| 246 | return -EINVAL; |
| 247 | |
| 248 | evt->event_handler(evt); |
| 249 | return 0; |
| 250 | } |
| 251 | #endif |
| 252 | |
| 253 | /* |
| 254 | * Broadcast the event to the cpus, which are set in the mask (mangled). |
| 255 | */ |
| 256 | static void tick_do_broadcast(struct cpumask *mask) |
| 257 | { |
| 258 | int cpu = smp_processor_id(); |
| 259 | struct tick_device *td; |
| 260 | |
| 261 | /* |
| 262 | * Check, if the current cpu is in the mask |
| 263 | */ |
| 264 | if (cpumask_test_cpu(cpu, mask)) { |
| 265 | cpumask_clear_cpu(cpu, mask); |
| 266 | td = &per_cpu(tick_cpu_device, cpu); |
| 267 | td->evtdev->event_handler(td->evtdev); |
| 268 | } |
| 269 | |
| 270 | if (!cpumask_empty(mask)) { |
| 271 | /* |
| 272 | * It might be necessary to actually check whether the devices |
| 273 | * have different broadcast functions. For now, just use the |
| 274 | * one of the first device. This works as long as we have this |
| 275 | * misfeature only on x86 (lapic) |
| 276 | */ |
| 277 | td = &per_cpu(tick_cpu_device, cpumask_first(mask)); |
| 278 | td->evtdev->broadcast(mask); |
| 279 | } |
| 280 | } |
| 281 | |
| 282 | /* |
| 283 | * Periodic broadcast: |
| 284 | * - invoke the broadcast handlers |
| 285 | */ |
| 286 | static void tick_do_periodic_broadcast(void) |
| 287 | { |
| 288 | cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask); |
| 289 | tick_do_broadcast(tmpmask); |
| 290 | } |
| 291 | |
| 292 | /* |
| 293 | * Event handler for periodic broadcast ticks |
| 294 | */ |
| 295 | static void tick_handle_periodic_broadcast(struct clock_event_device *dev) |
| 296 | { |
| 297 | ktime_t next; |
| 298 | |
| 299 | raw_spin_lock(&tick_broadcast_lock); |
| 300 | |
| 301 | tick_do_periodic_broadcast(); |
| 302 | |
| 303 | /* |
| 304 | * The device is in periodic mode. No reprogramming necessary: |
| 305 | */ |
| 306 | if (dev->mode == CLOCK_EVT_MODE_PERIODIC) |
| 307 | goto unlock; |
| 308 | |
| 309 | /* |
| 310 | * Setup the next period for devices, which do not have |
| 311 | * periodic mode. We read dev->next_event first and add to it |
| 312 | * when the event already expired. clockevents_program_event() |
| 313 | * sets dev->next_event only when the event is really |
| 314 | * programmed to the device. |
| 315 | */ |
| 316 | for (next = dev->next_event; ;) { |
| 317 | next = ktime_add(next, tick_period); |
| 318 | |
| 319 | if (!clockevents_program_event(dev, next, false)) |
| 320 | goto unlock; |
| 321 | tick_do_periodic_broadcast(); |
| 322 | } |
| 323 | unlock: |
| 324 | raw_spin_unlock(&tick_broadcast_lock); |
| 325 | } |
| 326 | |
| 327 | /* |
| 328 | * Powerstate information: The system enters/leaves a state, where |
| 329 | * affected devices might stop |
| 330 | */ |
| 331 | static void tick_do_broadcast_on_off(unsigned long *reason) |
| 332 | { |
| 333 | struct clock_event_device *bc, *dev; |
| 334 | struct tick_device *td; |
| 335 | unsigned long flags; |
| 336 | int cpu, bc_stopped; |
| 337 | |
| 338 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 339 | |
| 340 | cpu = smp_processor_id(); |
| 341 | td = &per_cpu(tick_cpu_device, cpu); |
| 342 | dev = td->evtdev; |
| 343 | bc = tick_broadcast_device.evtdev; |
| 344 | |
| 345 | /* |
| 346 | * Is the device not affected by the powerstate ? |
| 347 | */ |
| 348 | if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 349 | goto out; |
| 350 | |
| 351 | if (!tick_device_is_functional(dev)) |
| 352 | goto out; |
| 353 | |
| 354 | bc_stopped = cpumask_empty(tick_broadcast_mask); |
| 355 | |
| 356 | switch (*reason) { |
| 357 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
| 358 | case CLOCK_EVT_NOTIFY_BROADCAST_FORCE: |
| 359 | cpumask_set_cpu(cpu, tick_broadcast_on); |
| 360 | if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) { |
| 361 | if (tick_broadcast_device.mode == |
| 362 | TICKDEV_MODE_PERIODIC) |
| 363 | clockevents_shutdown(dev); |
| 364 | } |
| 365 | if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE) |
| 366 | tick_broadcast_force = 1; |
| 367 | break; |
| 368 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: |
| 369 | if (tick_broadcast_force) |
| 370 | break; |
| 371 | cpumask_clear_cpu(cpu, tick_broadcast_on); |
| 372 | if (!tick_device_is_functional(dev)) |
| 373 | break; |
| 374 | if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) { |
| 375 | if (tick_broadcast_device.mode == |
| 376 | TICKDEV_MODE_PERIODIC) |
| 377 | tick_setup_periodic(dev, 0); |
| 378 | } |
| 379 | break; |
| 380 | } |
| 381 | |
| 382 | if (cpumask_empty(tick_broadcast_mask)) { |
| 383 | if (!bc_stopped) |
| 384 | clockevents_shutdown(bc); |
| 385 | } else if (bc_stopped) { |
| 386 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) |
| 387 | tick_broadcast_start_periodic(bc); |
| 388 | else |
| 389 | tick_broadcast_setup_oneshot(bc); |
| 390 | } |
| 391 | out: |
| 392 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 393 | } |
| 394 | |
| 395 | /* |
| 396 | * Powerstate information: The system enters/leaves a state, where |
| 397 | * affected devices might stop. |
| 398 | */ |
| 399 | void tick_broadcast_on_off(unsigned long reason, int *oncpu) |
| 400 | { |
| 401 | if (!cpumask_test_cpu(*oncpu, cpu_online_mask)) |
| 402 | printk(KERN_ERR "tick-broadcast: ignoring broadcast for " |
| 403 | "offline CPU #%d\n", *oncpu); |
| 404 | else |
| 405 | tick_do_broadcast_on_off(&reason); |
| 406 | } |
| 407 | |
| 408 | /* |
| 409 | * Set the periodic handler depending on broadcast on/off |
| 410 | */ |
| 411 | void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast) |
| 412 | { |
| 413 | if (!broadcast) |
| 414 | dev->event_handler = tick_handle_periodic; |
| 415 | else |
| 416 | dev->event_handler = tick_handle_periodic_broadcast; |
| 417 | } |
| 418 | |
| 419 | /* |
| 420 | * Remove a CPU from broadcasting |
| 421 | */ |
| 422 | void tick_shutdown_broadcast(unsigned int *cpup) |
| 423 | { |
| 424 | struct clock_event_device *bc; |
| 425 | unsigned long flags; |
| 426 | unsigned int cpu = *cpup; |
| 427 | |
| 428 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 429 | |
| 430 | bc = tick_broadcast_device.evtdev; |
| 431 | cpumask_clear_cpu(cpu, tick_broadcast_mask); |
| 432 | cpumask_clear_cpu(cpu, tick_broadcast_on); |
| 433 | |
| 434 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) { |
| 435 | if (bc && cpumask_empty(tick_broadcast_mask)) |
| 436 | clockevents_shutdown(bc); |
| 437 | } |
| 438 | |
| 439 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 440 | } |
| 441 | |
| 442 | void tick_suspend_broadcast(void) |
| 443 | { |
| 444 | struct clock_event_device *bc; |
| 445 | unsigned long flags; |
| 446 | |
| 447 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 448 | |
| 449 | bc = tick_broadcast_device.evtdev; |
| 450 | if (bc) |
| 451 | clockevents_shutdown(bc); |
| 452 | |
| 453 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 454 | } |
| 455 | |
| 456 | int tick_resume_broadcast(void) |
| 457 | { |
| 458 | struct clock_event_device *bc; |
| 459 | unsigned long flags; |
| 460 | int broadcast = 0; |
| 461 | |
| 462 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 463 | |
| 464 | bc = tick_broadcast_device.evtdev; |
| 465 | |
| 466 | if (bc) { |
| 467 | clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME); |
| 468 | |
| 469 | switch (tick_broadcast_device.mode) { |
| 470 | case TICKDEV_MODE_PERIODIC: |
| 471 | if (!cpumask_empty(tick_broadcast_mask)) |
| 472 | tick_broadcast_start_periodic(bc); |
| 473 | broadcast = cpumask_test_cpu(smp_processor_id(), |
| 474 | tick_broadcast_mask); |
| 475 | break; |
| 476 | case TICKDEV_MODE_ONESHOT: |
| 477 | if (!cpumask_empty(tick_broadcast_mask)) |
| 478 | broadcast = tick_resume_broadcast_oneshot(bc); |
| 479 | break; |
| 480 | } |
| 481 | } |
| 482 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 483 | |
| 484 | return broadcast; |
| 485 | } |
| 486 | |
| 487 | |
| 488 | #ifdef CONFIG_TICK_ONESHOT |
| 489 | |
| 490 | static cpumask_var_t tick_broadcast_oneshot_mask; |
| 491 | static cpumask_var_t tick_broadcast_pending_mask; |
| 492 | static cpumask_var_t tick_broadcast_force_mask; |
| 493 | |
| 494 | /* |
| 495 | * Exposed for debugging: see timer_list.c |
| 496 | */ |
| 497 | struct cpumask *tick_get_broadcast_oneshot_mask(void) |
| 498 | { |
| 499 | return tick_broadcast_oneshot_mask; |
| 500 | } |
| 501 | |
| 502 | /* |
| 503 | * Called before going idle with interrupts disabled. Checks whether a |
| 504 | * broadcast event from the other core is about to happen. We detected |
| 505 | * that in tick_broadcast_oneshot_control(). The callsite can use this |
| 506 | * to avoid a deep idle transition as we are about to get the |
| 507 | * broadcast IPI right away. |
| 508 | */ |
| 509 | int tick_check_broadcast_expired(void) |
| 510 | { |
| 511 | return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask); |
| 512 | } |
| 513 | |
| 514 | /* |
| 515 | * Set broadcast interrupt affinity |
| 516 | */ |
| 517 | static void tick_broadcast_set_affinity(struct clock_event_device *bc, |
| 518 | const struct cpumask *cpumask) |
| 519 | { |
| 520 | if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ)) |
| 521 | return; |
| 522 | |
| 523 | if (cpumask_equal(bc->cpumask, cpumask)) |
| 524 | return; |
| 525 | |
| 526 | bc->cpumask = cpumask; |
| 527 | irq_set_affinity(bc->irq, bc->cpumask); |
| 528 | } |
| 529 | |
| 530 | static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu, |
| 531 | ktime_t expires, int force) |
| 532 | { |
| 533 | int ret; |
| 534 | |
| 535 | if (bc->mode != CLOCK_EVT_MODE_ONESHOT) |
| 536 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); |
| 537 | |
| 538 | ret = clockevents_program_event(bc, expires, force); |
| 539 | if (!ret) |
| 540 | tick_broadcast_set_affinity(bc, cpumask_of(cpu)); |
| 541 | return ret; |
| 542 | } |
| 543 | |
| 544 | int tick_resume_broadcast_oneshot(struct clock_event_device *bc) |
| 545 | { |
| 546 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); |
| 547 | return 0; |
| 548 | } |
| 549 | |
| 550 | /* |
| 551 | * Called from irq_enter() when idle was interrupted to reenable the |
| 552 | * per cpu device. |
| 553 | */ |
| 554 | void tick_check_oneshot_broadcast_this_cpu(void) |
| 555 | { |
| 556 | if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) { |
| 557 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); |
| 558 | |
| 559 | /* |
| 560 | * We might be in the middle of switching over from |
| 561 | * periodic to oneshot. If the CPU has not yet |
| 562 | * switched over, leave the device alone. |
| 563 | */ |
| 564 | if (td->mode == TICKDEV_MODE_ONESHOT) { |
| 565 | clockevents_set_mode(td->evtdev, |
| 566 | CLOCK_EVT_MODE_ONESHOT); |
| 567 | } |
| 568 | } |
| 569 | } |
| 570 | |
| 571 | /* |
| 572 | * Handle oneshot mode broadcasting |
| 573 | */ |
| 574 | static void tick_handle_oneshot_broadcast(struct clock_event_device *dev) |
| 575 | { |
| 576 | struct tick_device *td; |
| 577 | ktime_t now, next_event; |
| 578 | int cpu, next_cpu = 0; |
| 579 | |
| 580 | raw_spin_lock(&tick_broadcast_lock); |
| 581 | again: |
| 582 | dev->next_event.tv64 = KTIME_MAX; |
| 583 | next_event.tv64 = KTIME_MAX; |
| 584 | cpumask_clear(tmpmask); |
| 585 | now = ktime_get(); |
| 586 | /* Find all expired events */ |
| 587 | for_each_cpu(cpu, tick_broadcast_oneshot_mask) { |
| 588 | td = &per_cpu(tick_cpu_device, cpu); |
| 589 | if (td->evtdev->next_event.tv64 <= now.tv64) { |
| 590 | cpumask_set_cpu(cpu, tmpmask); |
| 591 | /* |
| 592 | * Mark the remote cpu in the pending mask, so |
| 593 | * it can avoid reprogramming the cpu local |
| 594 | * timer in tick_broadcast_oneshot_control(). |
| 595 | */ |
| 596 | cpumask_set_cpu(cpu, tick_broadcast_pending_mask); |
| 597 | } else if (td->evtdev->next_event.tv64 < next_event.tv64) { |
| 598 | next_event.tv64 = td->evtdev->next_event.tv64; |
| 599 | next_cpu = cpu; |
| 600 | } |
| 601 | } |
| 602 | |
| 603 | /* |
| 604 | * Remove the current cpu from the pending mask. The event is |
| 605 | * delivered immediately in tick_do_broadcast() ! |
| 606 | */ |
| 607 | cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask); |
| 608 | |
| 609 | /* Take care of enforced broadcast requests */ |
| 610 | cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask); |
| 611 | cpumask_clear(tick_broadcast_force_mask); |
| 612 | |
| 613 | /* |
| 614 | * Sanity check. Catch the case where we try to broadcast to |
| 615 | * offline cpus. |
| 616 | */ |
| 617 | if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask))) |
| 618 | cpumask_and(tmpmask, tmpmask, cpu_online_mask); |
| 619 | |
| 620 | /* |
| 621 | * Wakeup the cpus which have an expired event. |
| 622 | */ |
| 623 | tick_do_broadcast(tmpmask); |
| 624 | |
| 625 | /* |
| 626 | * Two reasons for reprogram: |
| 627 | * |
| 628 | * - The global event did not expire any CPU local |
| 629 | * events. This happens in dyntick mode, as the maximum PIT |
| 630 | * delta is quite small. |
| 631 | * |
| 632 | * - There are pending events on sleeping CPUs which were not |
| 633 | * in the event mask |
| 634 | */ |
| 635 | if (next_event.tv64 != KTIME_MAX) { |
| 636 | /* |
| 637 | * Rearm the broadcast device. If event expired, |
| 638 | * repeat the above |
| 639 | */ |
| 640 | if (tick_broadcast_set_event(dev, next_cpu, next_event, 0)) |
| 641 | goto again; |
| 642 | } |
| 643 | raw_spin_unlock(&tick_broadcast_lock); |
| 644 | } |
| 645 | |
| 646 | static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu) |
| 647 | { |
| 648 | if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER)) |
| 649 | return 0; |
| 650 | if (bc->next_event.tv64 == KTIME_MAX) |
| 651 | return 0; |
| 652 | return bc->bound_on == cpu ? -EBUSY : 0; |
| 653 | } |
| 654 | |
| 655 | static void broadcast_shutdown_local(struct clock_event_device *bc, |
| 656 | struct clock_event_device *dev) |
| 657 | { |
| 658 | /* |
| 659 | * For hrtimer based broadcasting we cannot shutdown the cpu |
| 660 | * local device if our own event is the first one to expire or |
| 661 | * if we own the broadcast timer. |
| 662 | */ |
| 663 | if (bc->features & CLOCK_EVT_FEAT_HRTIMER) { |
| 664 | if (broadcast_needs_cpu(bc, smp_processor_id())) |
| 665 | return; |
| 666 | if (dev->next_event.tv64 < bc->next_event.tv64) |
| 667 | return; |
| 668 | } |
| 669 | clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); |
| 670 | } |
| 671 | |
| 672 | static void broadcast_move_bc(int deadcpu) |
| 673 | { |
| 674 | struct clock_event_device *bc = tick_broadcast_device.evtdev; |
| 675 | |
| 676 | if (!bc || !broadcast_needs_cpu(bc, deadcpu)) |
| 677 | return; |
| 678 | /* This moves the broadcast assignment to this cpu */ |
| 679 | clockevents_program_event(bc, bc->next_event, 1); |
| 680 | } |
| 681 | |
| 682 | /* |
| 683 | * Powerstate information: The system enters/leaves a state, where |
| 684 | * affected devices might stop |
| 685 | * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups. |
| 686 | */ |
| 687 | int tick_broadcast_oneshot_control(unsigned long reason) |
| 688 | { |
| 689 | struct clock_event_device *bc, *dev; |
| 690 | struct tick_device *td; |
| 691 | unsigned long flags; |
| 692 | ktime_t now; |
| 693 | int cpu, ret = 0; |
| 694 | |
| 695 | /* |
| 696 | * Periodic mode does not care about the enter/exit of power |
| 697 | * states |
| 698 | */ |
| 699 | if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) |
| 700 | return 0; |
| 701 | |
| 702 | /* |
| 703 | * We are called with preemtion disabled from the depth of the |
| 704 | * idle code, so we can't be moved away. |
| 705 | */ |
| 706 | cpu = smp_processor_id(); |
| 707 | td = &per_cpu(tick_cpu_device, cpu); |
| 708 | dev = td->evtdev; |
| 709 | |
| 710 | if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) |
| 711 | return 0; |
| 712 | |
| 713 | bc = tick_broadcast_device.evtdev; |
| 714 | |
| 715 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 716 | if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) { |
| 717 | if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) { |
| 718 | WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask)); |
| 719 | broadcast_shutdown_local(bc, dev); |
| 720 | /* |
| 721 | * We only reprogram the broadcast timer if we |
| 722 | * did not mark ourself in the force mask and |
| 723 | * if the cpu local event is earlier than the |
| 724 | * broadcast event. If the current CPU is in |
| 725 | * the force mask, then we are going to be |
| 726 | * woken by the IPI right away. |
| 727 | */ |
| 728 | if (!cpumask_test_cpu(cpu, tick_broadcast_force_mask) && |
| 729 | dev->next_event.tv64 < bc->next_event.tv64) |
| 730 | tick_broadcast_set_event(bc, cpu, dev->next_event, 1); |
| 731 | } |
| 732 | /* |
| 733 | * If the current CPU owns the hrtimer broadcast |
| 734 | * mechanism, it cannot go deep idle and we remove the |
| 735 | * CPU from the broadcast mask. We don't have to go |
| 736 | * through the EXIT path as the local timer is not |
| 737 | * shutdown. |
| 738 | */ |
| 739 | ret = broadcast_needs_cpu(bc, cpu); |
| 740 | if (ret) |
| 741 | cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask); |
| 742 | } else { |
| 743 | if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) { |
| 744 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); |
| 745 | /* |
| 746 | * The cpu which was handling the broadcast |
| 747 | * timer marked this cpu in the broadcast |
| 748 | * pending mask and fired the broadcast |
| 749 | * IPI. So we are going to handle the expired |
| 750 | * event anyway via the broadcast IPI |
| 751 | * handler. No need to reprogram the timer |
| 752 | * with an already expired event. |
| 753 | */ |
| 754 | if (cpumask_test_and_clear_cpu(cpu, |
| 755 | tick_broadcast_pending_mask)) |
| 756 | goto out; |
| 757 | |
| 758 | /* |
| 759 | * Bail out if there is no next event. |
| 760 | */ |
| 761 | if (dev->next_event.tv64 == KTIME_MAX) |
| 762 | goto out; |
| 763 | /* |
| 764 | * If the pending bit is not set, then we are |
| 765 | * either the CPU handling the broadcast |
| 766 | * interrupt or we got woken by something else. |
| 767 | * |
| 768 | * We are not longer in the broadcast mask, so |
| 769 | * if the cpu local expiry time is already |
| 770 | * reached, we would reprogram the cpu local |
| 771 | * timer with an already expired event. |
| 772 | * |
| 773 | * This can lead to a ping-pong when we return |
| 774 | * to idle and therefor rearm the broadcast |
| 775 | * timer before the cpu local timer was able |
| 776 | * to fire. This happens because the forced |
| 777 | * reprogramming makes sure that the event |
| 778 | * will happen in the future and depending on |
| 779 | * the min_delta setting this might be far |
| 780 | * enough out that the ping-pong starts. |
| 781 | * |
| 782 | * If the cpu local next_event has expired |
| 783 | * then we know that the broadcast timer |
| 784 | * next_event has expired as well and |
| 785 | * broadcast is about to be handled. So we |
| 786 | * avoid reprogramming and enforce that the |
| 787 | * broadcast handler, which did not run yet, |
| 788 | * will invoke the cpu local handler. |
| 789 | * |
| 790 | * We cannot call the handler directly from |
| 791 | * here, because we might be in a NOHZ phase |
| 792 | * and we did not go through the irq_enter() |
| 793 | * nohz fixups. |
| 794 | */ |
| 795 | now = ktime_get(); |
| 796 | if (dev->next_event.tv64 <= now.tv64) { |
| 797 | cpumask_set_cpu(cpu, tick_broadcast_force_mask); |
| 798 | goto out; |
| 799 | } |
| 800 | /* |
| 801 | * We got woken by something else. Reprogram |
| 802 | * the cpu local timer device. |
| 803 | */ |
| 804 | tick_program_event(dev->next_event, 1); |
| 805 | } |
| 806 | } |
| 807 | out: |
| 808 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 809 | return ret; |
| 810 | } |
| 811 | |
| 812 | /* |
| 813 | * Reset the one shot broadcast for a cpu |
| 814 | * |
| 815 | * Called with tick_broadcast_lock held |
| 816 | */ |
| 817 | static void tick_broadcast_clear_oneshot(int cpu) |
| 818 | { |
| 819 | cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask); |
| 820 | cpumask_clear_cpu(cpu, tick_broadcast_pending_mask); |
| 821 | } |
| 822 | |
| 823 | static void tick_broadcast_init_next_event(struct cpumask *mask, |
| 824 | ktime_t expires) |
| 825 | { |
| 826 | struct tick_device *td; |
| 827 | int cpu; |
| 828 | |
| 829 | for_each_cpu(cpu, mask) { |
| 830 | td = &per_cpu(tick_cpu_device, cpu); |
| 831 | if (td->evtdev) |
| 832 | td->evtdev->next_event = expires; |
| 833 | } |
| 834 | } |
| 835 | |
| 836 | /** |
| 837 | * tick_broadcast_setup_oneshot - setup the broadcast device |
| 838 | */ |
| 839 | void tick_broadcast_setup_oneshot(struct clock_event_device *bc) |
| 840 | { |
| 841 | int cpu = smp_processor_id(); |
| 842 | |
| 843 | /* Set it up only once ! */ |
| 844 | if (bc->event_handler != tick_handle_oneshot_broadcast) { |
| 845 | int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC; |
| 846 | |
| 847 | bc->event_handler = tick_handle_oneshot_broadcast; |
| 848 | |
| 849 | /* |
| 850 | * We must be careful here. There might be other CPUs |
| 851 | * waiting for periodic broadcast. We need to set the |
| 852 | * oneshot_mask bits for those and program the |
| 853 | * broadcast device to fire. |
| 854 | */ |
| 855 | cpumask_copy(tmpmask, tick_broadcast_mask); |
| 856 | cpumask_clear_cpu(cpu, tmpmask); |
| 857 | cpumask_or(tick_broadcast_oneshot_mask, |
| 858 | tick_broadcast_oneshot_mask, tmpmask); |
| 859 | |
| 860 | if (was_periodic && !cpumask_empty(tmpmask)) { |
| 861 | clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT); |
| 862 | tick_broadcast_init_next_event(tmpmask, |
| 863 | tick_next_period); |
| 864 | tick_broadcast_set_event(bc, cpu, tick_next_period, 1); |
| 865 | } else |
| 866 | bc->next_event.tv64 = KTIME_MAX; |
| 867 | } else { |
| 868 | /* |
| 869 | * The first cpu which switches to oneshot mode sets |
| 870 | * the bit for all other cpus which are in the general |
| 871 | * (periodic) broadcast mask. So the bit is set and |
| 872 | * would prevent the first broadcast enter after this |
| 873 | * to program the bc device. |
| 874 | */ |
| 875 | tick_broadcast_clear_oneshot(cpu); |
| 876 | } |
| 877 | } |
| 878 | |
| 879 | /* |
| 880 | * Select oneshot operating mode for the broadcast device |
| 881 | */ |
| 882 | void tick_broadcast_switch_to_oneshot(void) |
| 883 | { |
| 884 | struct clock_event_device *bc; |
| 885 | unsigned long flags; |
| 886 | |
| 887 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 888 | |
| 889 | tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; |
| 890 | bc = tick_broadcast_device.evtdev; |
| 891 | if (bc) |
| 892 | tick_broadcast_setup_oneshot(bc); |
| 893 | |
| 894 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 895 | } |
| 896 | |
| 897 | |
| 898 | /* |
| 899 | * Remove a dead CPU from broadcasting |
| 900 | */ |
| 901 | void tick_shutdown_broadcast_oneshot(unsigned int *cpup) |
| 902 | { |
| 903 | unsigned long flags; |
| 904 | unsigned int cpu = *cpup; |
| 905 | |
| 906 | raw_spin_lock_irqsave(&tick_broadcast_lock, flags); |
| 907 | |
| 908 | /* |
| 909 | * Clear the broadcast masks for the dead cpu, but do not stop |
| 910 | * the broadcast device! |
| 911 | */ |
| 912 | cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask); |
| 913 | cpumask_clear_cpu(cpu, tick_broadcast_pending_mask); |
| 914 | cpumask_clear_cpu(cpu, tick_broadcast_force_mask); |
| 915 | |
| 916 | broadcast_move_bc(cpu); |
| 917 | |
| 918 | raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); |
| 919 | } |
| 920 | |
| 921 | /* |
| 922 | * Check, whether the broadcast device is in one shot mode |
| 923 | */ |
| 924 | int tick_broadcast_oneshot_active(void) |
| 925 | { |
| 926 | return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT; |
| 927 | } |
| 928 | |
| 929 | /* |
| 930 | * Check whether the broadcast device supports oneshot. |
| 931 | */ |
| 932 | bool tick_broadcast_oneshot_available(void) |
| 933 | { |
| 934 | struct clock_event_device *bc = tick_broadcast_device.evtdev; |
| 935 | |
| 936 | return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false; |
| 937 | } |
| 938 | |
| 939 | #endif |
| 940 | |
| 941 | void __init tick_broadcast_init(void) |
| 942 | { |
| 943 | zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT); |
| 944 | zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT); |
| 945 | zalloc_cpumask_var(&tmpmask, GFP_NOWAIT); |
| 946 | #ifdef CONFIG_TICK_ONESHOT |
| 947 | zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT); |
| 948 | zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT); |
| 949 | zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT); |
| 950 | #endif |
| 951 | } |