arch/arm/kernel/smp.c

   1 /*
   2  *  linux/arch/arm/kernel/smp.c
   3  *
   4  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/module.h>
  11 #include <linux/delay.h>
  12 #include <linux/init.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/cache.h>
  17 #include <linux/profile.h>
  18 #include <linux/errno.h>
  19 #include <linux/mm.h>
  20 #include <linux/err.h>
  21 #include <linux/cpu.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/irq.h>
  24 #include <linux/percpu.h>
  25 #include <linux/clockchips.h>
  26 #include <linux/completion.h>
  27 #include <linux/cpufreq.h>
  28 #include <linux/irq_work.h>
  29
  30 #include <linux/atomic.h>
  31 #include <asm/smp.h>
  32 #include <asm/cacheflush.h>
  33 #include <asm/cpu.h>
  34 #include <asm/cputype.h>
  35 #include <asm/exception.h>
  36 #include <asm/idmap.h>
  37 #include <asm/topology.h>
  38 #include <asm/mmu_context.h>
  39 #include <asm/pgtable.h>
  40 #include <asm/pgalloc.h>
  41 #include <asm/processor.h>
  42 #include <asm/sections.h>
  43 #include <asm/tlbflush.h>
  44 #include <asm/ptrace.h>
  45 #include <asm/smp_plat.h>
  46 #include <asm/virt.h>
  47 #include <asm/mach/arch.h>
  48 #include <asm/mpu.h>
  49
  50 #define CREATE_TRACE_POINTS
  51 #include <trace/events/ipi.h>
  52
  53 /*
  54  * as from 2.5, kernels no longer have an init_tasks structure
  55  * so we need some other way of telling a new secondary core
  56  * where to place its SVC stack
  57  */
  58 struct secondary_data secondary_data;
  59
  60 /*
  61  * control for which core is the next to come out of the secondary
  62  * boot "holding pen"
  63  */
  64 volatile int pen_release = -1;
  65
  66 enum ipi_msg_type {
  67         IPI_WAKEUP,
  68         IPI_TIMER,
  69         IPI_RESCHEDULE,
  70         IPI_CALL_FUNC,
  71         IPI_CALL_FUNC_SINGLE,
  72         IPI_CPU_STOP,
  73         IPI_IRQ_WORK,
  74         IPI_COMPLETION,
  75 };
  76
  77 static DECLARE_COMPLETION(cpu_running);
  78
  79 static struct smp_operations smp_ops;
  80
  81 void __init smp_set_ops(struct smp_operations *ops)
  82 {
  83         if (ops)
  84                 smp_ops = *ops;
  85 };
  86
  87 static unsigned long get_arch_pgd(pgd_t *pgd)
  88 {
  89 #ifdef CONFIG_ARM_LPAE
  90         return __phys_to_pfn(virt_to_phys(pgd));
  91 #else
  92         return virt_to_phys(pgd);
  93 #endif
  94 }
  95
  96 int __cpu_up(unsigned int cpu, struct task_struct *idle)
  97 {
  98         int ret;
  99
 100         if (!smp_ops.smp_boot_secondary)
 101                 return -ENOSYS;
 102
 103         /*
 104          * We need to tell the secondary core where to find
 105          * its stack and the page tables.
 106          */
 107         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 108 #ifdef CONFIG_ARM_MPU
 109         secondary_data.mpu_rgn_szr = mpu_rgn_info.rgns[MPU_RAM_REGION].drsr;
 110 #endif
 111
 112 #ifdef CONFIG_MMU
 113         secondary_data.pgdir = virt_to_phys(idmap_pgd);
 114         secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
 115 #endif
 116         sync_cache_w(&secondary_data);
 117
 118         /*
 119          * Now bring the CPU into our world.
 120          */
 121         ret = smp_ops.smp_boot_secondary(cpu, idle);
 122         if (ret == 0) {
 123                 /*
 124                  * CPU was successfully started, wait for it
 125                  * to come online or time out.
 126                  */
 127                 wait_for_completion_timeout(&cpu_running,
 128                                                  msecs_to_jiffies(1000));
 129
 130                 if (!cpu_online(cpu)) {
 131                         pr_crit("CPU%u: failed to come online\n", cpu);
 132                         ret = -EIO;
 133                 }
 134         } else {
 135                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
 136         }
 137
 138
 139         memset(&secondary_data, 0, sizeof(secondary_data));
 140         return ret;
 141 }
 142
 143 /* platform specific SMP operations */
 144 void __init smp_init_cpus(void)
 145 {
 146         if (smp_ops.smp_init_cpus)
 147                 smp_ops.smp_init_cpus();
 148 }
 149
 150 int platform_can_secondary_boot(void)
 151 {
 152         return !!smp_ops.smp_boot_secondary;
 153 }
 154
 155 int platform_can_cpu_hotplug(void)
 156 {
 157 #ifdef CONFIG_HOTPLUG_CPU
 158         if (smp_ops.cpu_kill)
 159                 return 1;
 160 #endif
 161
 162         return 0;
 163 }
 164
 165 #ifdef CONFIG_HOTPLUG_CPU
 166 static int platform_cpu_kill(unsigned int cpu)
 167 {
 168         if (smp_ops.cpu_kill)
 169                 return smp_ops.cpu_kill(cpu);
 170         return 1;
 171 }
 172
 173 static int platform_cpu_disable(unsigned int cpu)
 174 {
 175         if (smp_ops.cpu_disable)
 176                 return smp_ops.cpu_disable(cpu);
 177
 178         /*
 179          * By default, allow disabling all CPUs except the first one,
 180          * since this is special on a lot of platforms, e.g. because
 181          * of clock tick interrupts.
 182          */
 183         return cpu == 0 ? -EPERM : 0;
 184 }
 185 /*
 186  * __cpu_disable runs on the processor to be shutdown.
 187  */
 188 int __cpu_disable(void)
 189 {
 190         unsigned int cpu = smp_processor_id();
 191         int ret;
 192
 193         ret = platform_cpu_disable(cpu);
 194         if (ret)
 195                 return ret;
 196
 197         /*
 198          * Take this CPU offline.  Once we clear this, we can't return,
 199          * and we must not schedule until we're ready to give up the cpu.
 200          */
 201         set_cpu_online(cpu, false);
 202
 203         /*
 204          * OK - migrate IRQs away from this CPU
 205          */
 206         migrate_irqs();
 207
 208         /*
 209          * Flush user cache and TLB mappings, and then remove this CPU
 210          * from the vm mask set of all processes.
 211          *
 212          * Caches are flushed to the Level of Unification Inner Shareable
 213          * to write-back dirty lines to unified caches shared by all CPUs.
 214          */
 215         flush_cache_louis();
 216         local_flush_tlb_all();
 217
 218         clear_tasks_mm_cpumask(cpu);
 219
 220         return 0;
 221 }
 222
 223 static DECLARE_COMPLETION(cpu_died);
 224
 225 /*
 226  * called on the thread which is asking for a CPU to be shutdown -
 227  * waits until shutdown has completed, or it is timed out.
 228  */
 229 void __cpu_die(unsigned int cpu)
 230 {
 231         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 232                 pr_err("CPU%u: cpu didn't die\n", cpu);
 233                 return;
 234         }
 235         pr_notice("CPU%u: shutdown\n", cpu);
 236
 237         /*
 238          * platform_cpu_kill() is generally expected to do the powering off
 239          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 240          * be done by the CPU which is dying in preference to supporting
 241          * this call, but that means there is _no_ synchronisation between
 242          * the requesting CPU and the dying CPU actually losing power.
 243          */
 244         if (!platform_cpu_kill(cpu))
 245                 pr_err("CPU%u: unable to kill\n", cpu);
 246 }
 247
 248 /*
 249  * Called from the idle thread for the CPU which has been shutdown.
 250  *
 251  * Note that we disable IRQs here, but do not re-enable them
 252  * before returning to the caller. This is also the behaviour
 253  * of the other hotplug-cpu capable cores, so presumably coming
 254  * out of idle fixes this.
 255  */
 256 void __ref cpu_die(void)
 257 {
 258         unsigned int cpu = smp_processor_id();
 259
 260         idle_task_exit();
 261
 262         local_irq_disable();
 263
 264         /*
 265          * Flush the data out of the L1 cache for this CPU.  This must be
 266          * before the completion to ensure that data is safely written out
 267          * before platform_cpu_kill() gets called - which may disable
 268          * *this* CPU and power down its cache.
 269          */
 270         flush_cache_louis();
 271
 272         /*
 273          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 274          * this returns, power and/or clocks can be removed at any point
 275          * from this CPU and its cache by platform_cpu_kill().
 276          */
 277         complete(&cpu_died);
 278
 279         /*
 280          * Ensure that the cache lines associated with that completion are
 281          * written out.  This covers the case where _this_ CPU is doing the
 282          * powering down, to ensure that the completion is visible to the
 283          * CPU waiting for this one.
 284          */
 285         flush_cache_louis();
 286
 287         /*
 288          * The actual CPU shutdown procedure is at least platform (if not
 289          * CPU) specific.  This may remove power, or it may simply spin.
 290          *
 291          * Platforms are generally expected *NOT* to return from this call,
 292          * although there are some which do because they have no way to
 293          * power down the CPU.  These platforms are the _only_ reason we
 294          * have a return path which uses the fragment of assembly below.
 295          *
 296          * The return path should not be used for platforms which can
 297          * power off the CPU.
 298          */
 299         if (smp_ops.cpu_die)
 300                 smp_ops.cpu_die(cpu);
 301
 302         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 303                 cpu);
 304
 305         /*
 306          * Do not return to the idle loop - jump back to the secondary
 307          * cpu initialisation.  There's some initialisation which needs
 308          * to be repeated to undo the effects of taking the CPU offline.
 309          */
 310         __asm__("mov    sp, %0\n"
 311         "       mov     fp, #0\n"
 312         "       b       secondary_start_kernel"
 313                 :
 314                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 315 }
 316 #endif /* CONFIG_HOTPLUG_CPU */
 317
 318 /*
 319  * Called by both boot and secondaries to move global data into
 320  * per-processor storage.
 321  */
 322 static void smp_store_cpu_info(unsigned int cpuid)
 323 {
 324         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 325
 326         cpu_info->loops_per_jiffy = loops_per_jiffy;
 327         cpu_info->cpuid = read_cpuid_id();
 328
 329         store_cpu_topology(cpuid);
 330 }
 331
 332 /*
 333  * This is the secondary CPU boot entry.  We're using this CPUs
 334  * idle thread stack, but a set of temporary page tables.
 335  */
 336 asmlinkage void secondary_start_kernel(void)
 337 {
 338         struct mm_struct *mm = &init_mm;
 339         unsigned int cpu;
 340
 341         /*
 342          * The identity mapping is uncached (strongly ordered), so
 343          * switch away from it before attempting any exclusive accesses.
 344          */
 345         cpu_switch_mm(mm->pgd, mm);
 346         local_flush_bp_all();
 347         enter_lazy_tlb(mm, current);
 348         local_flush_tlb_all();
 349
 350         /*
 351          * All kernel threads share the same mm context; grab a
 352          * reference and switch to it.
 353          */
 354         cpu = smp_processor_id();
 355         atomic_inc(&mm->mm_count);
 356         current->active_mm = mm;
 357         cpumask_set_cpu(cpu, mm_cpumask(mm));
 358
 359         cpu_init();
 360
 361         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 362
 363         preempt_disable();
 364         trace_hardirqs_off();
 365
 366         /*
 367          * Give the platform a chance to do its own initialisation.
 368          */
 369         if (smp_ops.smp_secondary_init)
 370                 smp_ops.smp_secondary_init(cpu);
 371
 372         notify_cpu_starting(cpu);
 373
 374         calibrate_delay();
 375
 376         smp_store_cpu_info(cpu);
 377
 378         /*
 379          * OK, now it's safe to let the boot CPU continue.  Wait for
 380          * the CPU migration code to notice that the CPU is online
 381          * before we continue - which happens after __cpu_up returns.
 382          */
 383         set_cpu_online(cpu, true);
 384         complete(&cpu_running);
 385
 386         local_irq_enable();
 387         local_fiq_enable();
 388
 389         /*
 390          * OK, it's off to the idle thread for us
 391          */
 392         cpu_startup_entry(CPUHP_ONLINE);
 393 }
 394
 395 void __init smp_cpus_done(unsigned int max_cpus)
 396 {
 397         int cpu;
 398         unsigned long bogosum = 0;
 399
 400         for_each_online_cpu(cpu)
 401                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 402
 403         printk(KERN_INFO "SMP: Total of %d processors activated "
 404                "(%lu.%02lu BogoMIPS).\n",
 405                num_online_cpus(),
 406                bogosum / (500000/HZ),
 407                (bogosum / (5000/HZ)) % 100);
 408
 409         hyp_mode_check();
 410 }
 411
 412 void __init smp_prepare_boot_cpu(void)
 413 {
 414         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 415 }
 416
 417 void __init smp_prepare_cpus(unsigned int max_cpus)
 418 {
 419         unsigned int ncores = num_possible_cpus();
 420
 421         init_cpu_topology();
 422
 423         smp_store_cpu_info(smp_processor_id());
 424
 425         /*
 426          * are we trying to boot more cores than exist?
 427          */
 428         if (max_cpus > ncores)
 429                 max_cpus = ncores;
 430         if (ncores > 1 && max_cpus) {
 431                 /*
 432                  * Initialise the present map, which describes the set of CPUs
 433                  * actually populated at the present time. A platform should
 434                  * re-initialize the map in the platforms smp_prepare_cpus()
 435                  * if present != possible (e.g. physical hotplug).
 436                  */
 437                 init_cpu_present(cpu_possible_mask);
 438
 439                 /*
 440                  * Initialise the SCU if there are more than one CPU
 441                  * and let them know where to start.
 442                  */
 443                 if (smp_ops.smp_prepare_cpus)
 444                         smp_ops.smp_prepare_cpus(max_cpus);
 445         }
 446 }
 447
 448 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 449
 450 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 451 {
 452         if (!__smp_cross_call)
 453                 __smp_cross_call = fn;
 454 }
 455
 456 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 457 #define S(x,s)  [x] = s
 458         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 459         S(IPI_TIMER, "Timer broadcast interrupts"),
 460         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 461         S(IPI_CALL_FUNC, "Function call interrupts"),
 462         S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 463         S(IPI_CPU_STOP, "CPU stop interrupts"),
 464         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 465         S(IPI_COMPLETION, "completion interrupts"),
 466 };
 467
 468 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 469 {
 470         trace_ipi_raise(target, ipi_types[ipinr]);
 471         __smp_cross_call(target, ipinr);
 472 }
 473
 474 void show_ipi_list(struct seq_file *p, int prec)
 475 {
 476         unsigned int cpu, i;
 477
 478         for (i = 0; i < NR_IPI; i++) {
 479                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 480
 481                 for_each_online_cpu(cpu)
 482                         seq_printf(p, "%10u ",
 483                                    __get_irq_stat(cpu, ipi_irqs[i]));
 484
 485                 seq_printf(p, " %s\n", ipi_types[i]);
 486         }
 487 }
 488
 489 u64 smp_irq_stat_cpu(unsigned int cpu)
 490 {
 491         u64 sum = 0;
 492         int i;
 493
 494         for (i = 0; i < NR_IPI; i++)
 495                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 496
 497         return sum;
 498 }
 499
 500 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 501 {
 502         smp_cross_call(mask, IPI_CALL_FUNC);
 503 }
 504
 505 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 506 {
 507         smp_cross_call(mask, IPI_WAKEUP);
 508 }
 509
 510 void arch_send_call_function_single_ipi(int cpu)
 511 {
 512         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 513 }
 514
 515 #ifdef CONFIG_IRQ_WORK
 516 void arch_irq_work_raise(void)
 517 {
 518         if (arch_irq_work_has_interrupt())
 519                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 520 }
 521 #endif
 522
 523 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 524 void tick_broadcast(const struct cpumask *mask)
 525 {
 526         smp_cross_call(mask, IPI_TIMER);
 527 }
 528 #endif
 529
 530 static DEFINE_RAW_SPINLOCK(stop_lock);
 531
 532 /*
 533  * ipi_cpu_stop - handle IPI from smp_send_stop()
 534  */
 535 static void ipi_cpu_stop(unsigned int cpu)
 536 {
 537         if (system_state == SYSTEM_BOOTING ||
 538             system_state == SYSTEM_RUNNING) {
 539                 raw_spin_lock(&stop_lock);
 540                 pr_crit("CPU%u: stopping\n", cpu);
 541                 dump_stack();
 542                 raw_spin_unlock(&stop_lock);
 543         }
 544
 545         set_cpu_online(cpu, false);
 546
 547         local_fiq_disable();
 548         local_irq_disable();
 549
 550         while (1)
 551                 cpu_relax();
 552 }
 553
 554 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 555
 556 int register_ipi_completion(struct completion *completion, int cpu)
 557 {
 558         per_cpu(cpu_completion, cpu) = completion;
 559         return IPI_COMPLETION;
 560 }
 561
 562 static void ipi_complete(unsigned int cpu)
 563 {
 564         complete(per_cpu(cpu_completion, cpu));
 565 }
 566
 567 /*
 568  * Main handler for inter-processor interrupts
 569  */
 570 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 571 {
 572         handle_IPI(ipinr, regs);
 573 }
 574
 575 void handle_IPI(int ipinr, struct pt_regs *regs)
 576 {
 577         unsigned int cpu = smp_processor_id();
 578         struct pt_regs *old_regs = set_irq_regs(regs);
 579
 580         if ((unsigned)ipinr < NR_IPI) {
 581                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 582                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 583         }
 584
 585         switch (ipinr) {
 586         case IPI_WAKEUP:
 587                 break;
 588
 589 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 590         case IPI_TIMER:
 591                 irq_enter();
 592                 tick_receive_broadcast();
 593                 irq_exit();
 594                 break;
 595 #endif
 596
 597         case IPI_RESCHEDULE:
 598                 scheduler_ipi();
 599                 break;
 600
 601         case IPI_CALL_FUNC:
 602                 irq_enter();
 603                 generic_smp_call_function_interrupt();
 604                 irq_exit();
 605                 break;
 606
 607         case IPI_CALL_FUNC_SINGLE:
 608                 irq_enter();
 609                 generic_smp_call_function_single_interrupt();
 610                 irq_exit();
 611                 break;
 612
 613         case IPI_CPU_STOP:
 614                 irq_enter();
 615                 ipi_cpu_stop(cpu);
 616                 irq_exit();
 617                 break;
 618
 619 #ifdef CONFIG_IRQ_WORK
 620         case IPI_IRQ_WORK:
 621                 irq_enter();
 622                 irq_work_run();
 623                 irq_exit();
 624                 break;
 625 #endif
 626
 627         case IPI_COMPLETION:
 628                 irq_enter();
 629                 ipi_complete(cpu);
 630                 irq_exit();
 631                 break;
 632
 633         default:
 634                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 635                         cpu, ipinr);
 636                 break;
 637         }
 638
 639         if ((unsigned)ipinr < NR_IPI)
 640                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 641         set_irq_regs(old_regs);
 642 }
 643
 644 void smp_send_reschedule(int cpu)
 645 {
 646         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 647 }
 648
 649 void smp_send_stop(void)
 650 {
 651         unsigned long timeout;
 652         struct cpumask mask;
 653
 654         cpumask_copy(&mask, cpu_online_mask);
 655         cpumask_clear_cpu(smp_processor_id(), &mask);
 656         if (!cpumask_empty(&mask))
 657                 smp_cross_call(&mask, IPI_CPU_STOP);
 658
 659         /* Wait up to one second for other CPUs to stop */
 660         timeout = USEC_PER_SEC;
 661         while (num_online_cpus() > 1 && timeout--)
 662                 udelay(1);
 663
 664         if (num_online_cpus() > 1)
 665                 pr_warn("SMP: failed to stop secondary CPUs\n");
 666 }
 667
 668 /*
 669  * not supported here
 670  */
 671 int setup_profiling_timer(unsigned int multiplier)
 672 {
 673         return -EINVAL;
 674 }
 675
 676 #ifdef CONFIG_CPU_FREQ
 677
 678 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 679 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 680 static unsigned long global_l_p_j_ref;
 681 static unsigned long global_l_p_j_ref_freq;
 682
 683 static int cpufreq_callback(struct notifier_block *nb,
 684                                         unsigned long val, void *data)
 685 {
 686         struct cpufreq_freqs *freq = data;
 687         int cpu = freq->cpu;
 688
 689         if (freq->flags & CPUFREQ_CONST_LOOPS)
 690                 return NOTIFY_OK;
 691
 692         if (!per_cpu(l_p_j_ref, cpu)) {
 693                 per_cpu(l_p_j_ref, cpu) =
 694                         per_cpu(cpu_data, cpu).loops_per_jiffy;
 695                 per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 696                 if (!global_l_p_j_ref) {
 697                         global_l_p_j_ref = loops_per_jiffy;
 698                         global_l_p_j_ref_freq = freq->old;
 699                 }
 700         }
 701
 702         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 703             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 704                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 705                                                 global_l_p_j_ref_freq,
 706                                                 freq->new);
 707                 per_cpu(cpu_data, cpu).loops_per_jiffy =
 708                         cpufreq_scale(per_cpu(l_p_j_ref, cpu),
 709                                         per_cpu(l_p_j_ref_freq, cpu),
 710                                         freq->new);
 711         }
 712         return NOTIFY_OK;
 713 }
 714
 715 static struct notifier_block cpufreq_notifier = {
 716         .notifier_call  = cpufreq_callback,
 717 };
 718
 719 static int __init register_cpufreq_notifier(void)
 720 {
 721         return cpufreq_register_notifier(&cpufreq_notifier,
 722                                                 CPUFREQ_TRANSITION_NOTIFIER);
 723 }
 724 core_initcall(register_cpufreq_notifier);
 725
 726 #endif