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         return 0;
 179 }
 180
 181 int platform_can_hotplug_cpu(unsigned int cpu)
 182 {
 183         /* cpu_die must be specified to support hotplug */
 184         if (!smp_ops.cpu_die)
 185                 return 0;
 186
 187         if (smp_ops.cpu_can_disable)
 188                 return smp_ops.cpu_can_disable(cpu);
 189
 190         /*
 191          * By default, allow disabling all CPUs except the first one,
 192          * since this is special on a lot of platforms, e.g. because
 193          * of clock tick interrupts.
 194          */
 195         return cpu != 0;
 196 }
 197
 198 /*
 199  * __cpu_disable runs on the processor to be shutdown.
 200  */
 201 int __cpu_disable(void)
 202 {
 203         unsigned int cpu = smp_processor_id();
 204         int ret;
 205
 206         ret = platform_cpu_disable(cpu);
 207         if (ret)
 208                 return ret;
 209
 210         /*
 211          * Take this CPU offline.  Once we clear this, we can't return,
 212          * and we must not schedule until we're ready to give up the cpu.
 213          */
 214         set_cpu_online(cpu, false);
 215
 216         /*
 217          * OK - migrate IRQs away from this CPU
 218          */
 219         migrate_irqs();
 220
 221         /*
 222          * Flush user cache and TLB mappings, and then remove this CPU
 223          * from the vm mask set of all processes.
 224          *
 225          * Caches are flushed to the Level of Unification Inner Shareable
 226          * to write-back dirty lines to unified caches shared by all CPUs.
 227          */
 228         flush_cache_louis();
 229         local_flush_tlb_all();
 230
 231         clear_tasks_mm_cpumask(cpu);
 232
 233         return 0;
 234 }
 235
 236 static DECLARE_COMPLETION(cpu_died);
 237
 238 /*
 239  * called on the thread which is asking for a CPU to be shutdown -
 240  * waits until shutdown has completed, or it is timed out.
 241  */
 242 void __cpu_die(unsigned int cpu)
 243 {
 244         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
 245                 pr_err("CPU%u: cpu didn't die\n", cpu);
 246                 return;
 247         }
 248         pr_notice("CPU%u: shutdown\n", cpu);
 249
 250         /*
 251          * platform_cpu_kill() is generally expected to do the powering off
 252          * and/or cutting of clocks to the dying CPU.  Optionally, this may
 253          * be done by the CPU which is dying in preference to supporting
 254          * this call, but that means there is _no_ synchronisation between
 255          * the requesting CPU and the dying CPU actually losing power.
 256          */
 257         if (!platform_cpu_kill(cpu))
 258                 pr_err("CPU%u: unable to kill\n", cpu);
 259 }
 260
 261 /*
 262  * Called from the idle thread for the CPU which has been shutdown.
 263  *
 264  * Note that we disable IRQs here, but do not re-enable them
 265  * before returning to the caller. This is also the behaviour
 266  * of the other hotplug-cpu capable cores, so presumably coming
 267  * out of idle fixes this.
 268  */
 269 void arch_cpu_idle_dead(void)
 270 {
 271         unsigned int cpu = smp_processor_id();
 272
 273         idle_task_exit();
 274
 275         local_irq_disable();
 276
 277         /*
 278          * Flush the data out of the L1 cache for this CPU.  This must be
 279          * before the completion to ensure that data is safely written out
 280          * before platform_cpu_kill() gets called - which may disable
 281          * *this* CPU and power down its cache.
 282          */
 283         flush_cache_louis();
 284
 285         /*
 286          * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
 287          * this returns, power and/or clocks can be removed at any point
 288          * from this CPU and its cache by platform_cpu_kill().
 289          */
 290         complete(&cpu_died);
 291
 292         /*
 293          * Ensure that the cache lines associated with that completion are
 294          * written out.  This covers the case where _this_ CPU is doing the
 295          * powering down, to ensure that the completion is visible to the
 296          * CPU waiting for this one.
 297          */
 298         flush_cache_louis();
 299
 300         /*
 301          * The actual CPU shutdown procedure is at least platform (if not
 302          * CPU) specific.  This may remove power, or it may simply spin.
 303          *
 304          * Platforms are generally expected *NOT* to return from this call,
 305          * although there are some which do because they have no way to
 306          * power down the CPU.  These platforms are the _only_ reason we
 307          * have a return path which uses the fragment of assembly below.
 308          *
 309          * The return path should not be used for platforms which can
 310          * power off the CPU.
 311          */
 312         if (smp_ops.cpu_die)
 313                 smp_ops.cpu_die(cpu);
 314
 315         pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
 316                 cpu);
 317
 318         /*
 319          * Do not return to the idle loop - jump back to the secondary
 320          * cpu initialisation.  There's some initialisation which needs
 321          * to be repeated to undo the effects of taking the CPU offline.
 322          */
 323         __asm__("mov    sp, %0\n"
 324         "       mov     fp, #0\n"
 325         "       b       secondary_start_kernel"
 326                 :
 327                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
 328 }
 329 #endif /* CONFIG_HOTPLUG_CPU */
 330
 331 /*
 332  * Called by both boot and secondaries to move global data into
 333  * per-processor storage.
 334  */
 335 static void smp_store_cpu_info(unsigned int cpuid)
 336 {
 337         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 338
 339         cpu_info->loops_per_jiffy = loops_per_jiffy;
 340         cpu_info->cpuid = read_cpuid_id();
 341
 342         store_cpu_topology(cpuid);
 343 }
 344
 345 /*
 346  * This is the secondary CPU boot entry.  We're using this CPUs
 347  * idle thread stack, but a set of temporary page tables.
 348  */
 349 asmlinkage void secondary_start_kernel(void)
 350 {
 351         struct mm_struct *mm = &init_mm;
 352         unsigned int cpu;
 353
 354         /*
 355          * The identity mapping is uncached (strongly ordered), so
 356          * switch away from it before attempting any exclusive accesses.
 357          */
 358         cpu_switch_mm(mm->pgd, mm);
 359         local_flush_bp_all();
 360         enter_lazy_tlb(mm, current);
 361         local_flush_tlb_all();
 362
 363         /*
 364          * All kernel threads share the same mm context; grab a
 365          * reference and switch to it.
 366          */
 367         cpu = smp_processor_id();
 368         atomic_inc(&mm->mm_count);
 369         current->active_mm = mm;
 370         cpumask_set_cpu(cpu, mm_cpumask(mm));
 371
 372         cpu_init();
 373
 374         pr_debug("CPU%u: Booted secondary processor\n", cpu);
 375
 376         preempt_disable();
 377         trace_hardirqs_off();
 378
 379         /*
 380          * Give the platform a chance to do its own initialisation.
 381          */
 382         if (smp_ops.smp_secondary_init)
 383                 smp_ops.smp_secondary_init(cpu);
 384
 385         notify_cpu_starting(cpu);
 386
 387         calibrate_delay();
 388
 389         smp_store_cpu_info(cpu);
 390
 391         /*
 392          * OK, now it's safe to let the boot CPU continue.  Wait for
 393          * the CPU migration code to notice that the CPU is online
 394          * before we continue - which happens after __cpu_up returns.
 395          */
 396         set_cpu_online(cpu, true);
 397         complete(&cpu_running);
 398
 399         local_irq_enable();
 400         local_fiq_enable();
 401
 402         /*
 403          * OK, it's off to the idle thread for us
 404          */
 405         cpu_startup_entry(CPUHP_ONLINE);
 406 }
 407
 408 void __init smp_cpus_done(unsigned int max_cpus)
 409 {
 410         int cpu;
 411         unsigned long bogosum = 0;
 412
 413         for_each_online_cpu(cpu)
 414                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 415
 416         printk(KERN_INFO "SMP: Total of %d processors activated "
 417                "(%lu.%02lu BogoMIPS).\n",
 418                num_online_cpus(),
 419                bogosum / (500000/HZ),
 420                (bogosum / (5000/HZ)) % 100);
 421
 422         hyp_mode_check();
 423 }
 424
 425 void __init smp_prepare_boot_cpu(void)
 426 {
 427         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
 428 }
 429
 430 void __init smp_prepare_cpus(unsigned int max_cpus)
 431 {
 432         unsigned int ncores = num_possible_cpus();
 433
 434         init_cpu_topology();
 435
 436         smp_store_cpu_info(smp_processor_id());
 437
 438         /*
 439          * are we trying to boot more cores than exist?
 440          */
 441         if (max_cpus > ncores)
 442                 max_cpus = ncores;
 443         if (ncores > 1 && max_cpus) {
 444                 /*
 445                  * Initialise the present map, which describes the set of CPUs
 446                  * actually populated at the present time. A platform should
 447                  * re-initialize the map in the platforms smp_prepare_cpus()
 448                  * if present != possible (e.g. physical hotplug).
 449                  */
 450                 init_cpu_present(cpu_possible_mask);
 451
 452                 /*
 453                  * Initialise the SCU if there are more than one CPU
 454                  * and let them know where to start.
 455                  */
 456                 if (smp_ops.smp_prepare_cpus)
 457                         smp_ops.smp_prepare_cpus(max_cpus);
 458         }
 459 }
 460
 461 static void (*__smp_cross_call)(const struct cpumask *, unsigned int);
 462
 463 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
 464 {
 465         if (!__smp_cross_call)
 466                 __smp_cross_call = fn;
 467 }
 468
 469 static const char *ipi_types[NR_IPI] __tracepoint_string = {
 470 #define S(x,s)  [x] = s
 471         S(IPI_WAKEUP, "CPU wakeup interrupts"),
 472         S(IPI_TIMER, "Timer broadcast interrupts"),
 473         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
 474         S(IPI_CALL_FUNC, "Function call interrupts"),
 475         S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 476         S(IPI_CPU_STOP, "CPU stop interrupts"),
 477         S(IPI_IRQ_WORK, "IRQ work interrupts"),
 478         S(IPI_COMPLETION, "completion interrupts"),
 479 };
 480
 481 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
 482 {
 483         trace_ipi_raise(target, ipi_types[ipinr]);
 484         __smp_cross_call(target, ipinr);
 485 }
 486
 487 void show_ipi_list(struct seq_file *p, int prec)
 488 {
 489         unsigned int cpu, i;
 490
 491         for (i = 0; i < NR_IPI; i++) {
 492                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
 493
 494                 for_each_online_cpu(cpu)
 495                         seq_printf(p, "%10u ",
 496                                    __get_irq_stat(cpu, ipi_irqs[i]));
 497
 498                 seq_printf(p, " %s\n", ipi_types[i]);
 499         }
 500 }
 501
 502 u64 smp_irq_stat_cpu(unsigned int cpu)
 503 {
 504         u64 sum = 0;
 505         int i;
 506
 507         for (i = 0; i < NR_IPI; i++)
 508                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
 509
 510         return sum;
 511 }
 512
 513 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 514 {
 515         smp_cross_call(mask, IPI_CALL_FUNC);
 516 }
 517
 518 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
 519 {
 520         smp_cross_call(mask, IPI_WAKEUP);
 521 }
 522
 523 void arch_send_call_function_single_ipi(int cpu)
 524 {
 525         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 526 }
 527
 528 #ifdef CONFIG_IRQ_WORK
 529 void arch_irq_work_raise(void)
 530 {
 531         if (arch_irq_work_has_interrupt())
 532                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 533 }
 534 #endif
 535
 536 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 537 void tick_broadcast(const struct cpumask *mask)
 538 {
 539         smp_cross_call(mask, IPI_TIMER);
 540 }
 541 #endif
 542
 543 static DEFINE_RAW_SPINLOCK(stop_lock);
 544
 545 /*
 546  * ipi_cpu_stop - handle IPI from smp_send_stop()
 547  */
 548 static void ipi_cpu_stop(unsigned int cpu)
 549 {
 550         if (system_state == SYSTEM_BOOTING ||
 551             system_state == SYSTEM_RUNNING) {
 552                 raw_spin_lock(&stop_lock);
 553                 pr_crit("CPU%u: stopping\n", cpu);
 554                 dump_stack();
 555                 raw_spin_unlock(&stop_lock);
 556         }
 557
 558         set_cpu_online(cpu, false);
 559
 560         local_fiq_disable();
 561         local_irq_disable();
 562
 563         while (1)
 564                 cpu_relax();
 565 }
 566
 567 static DEFINE_PER_CPU(struct completion *, cpu_completion);
 568
 569 int register_ipi_completion(struct completion *completion, int cpu)
 570 {
 571         per_cpu(cpu_completion, cpu) = completion;
 572         return IPI_COMPLETION;
 573 }
 574
 575 static void ipi_complete(unsigned int cpu)
 576 {
 577         complete(per_cpu(cpu_completion, cpu));
 578 }
 579
 580 /*
 581  * Main handler for inter-processor interrupts
 582  */
 583 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 584 {
 585         handle_IPI(ipinr, regs);
 586 }
 587
 588 void handle_IPI(int ipinr, struct pt_regs *regs)
 589 {
 590         unsigned int cpu = smp_processor_id();
 591         struct pt_regs *old_regs = set_irq_regs(regs);
 592
 593         if ((unsigned)ipinr < NR_IPI) {
 594                 trace_ipi_entry_rcuidle(ipi_types[ipinr]);
 595                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
 596         }
 597
 598         switch (ipinr) {
 599         case IPI_WAKEUP:
 600                 break;
 601
 602 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 603         case IPI_TIMER:
 604                 irq_enter();
 605                 tick_receive_broadcast();
 606                 irq_exit();
 607                 break;
 608 #endif
 609
 610         case IPI_RESCHEDULE:
 611                 scheduler_ipi();
 612                 break;
 613
 614         case IPI_CALL_FUNC:
 615                 irq_enter();
 616                 generic_smp_call_function_interrupt();
 617                 irq_exit();
 618                 break;
 619
 620         case IPI_CALL_FUNC_SINGLE:
 621                 irq_enter();
 622                 generic_smp_call_function_single_interrupt();
 623                 irq_exit();
 624                 break;
 625
 626         case IPI_CPU_STOP:
 627                 irq_enter();
 628                 ipi_cpu_stop(cpu);
 629                 irq_exit();
 630                 break;
 631
 632 #ifdef CONFIG_IRQ_WORK
 633         case IPI_IRQ_WORK:
 634                 irq_enter();
 635                 irq_work_run();
 636                 irq_exit();
 637                 break;
 638 #endif
 639
 640         case IPI_COMPLETION:
 641                 irq_enter();
 642                 ipi_complete(cpu);
 643                 irq_exit();
 644                 break;
 645
 646         default:
 647                 pr_crit("CPU%u: Unknown IPI message 0x%x\n",
 648                         cpu, ipinr);
 649                 break;
 650         }
 651
 652         if ((unsigned)ipinr < NR_IPI)
 653                 trace_ipi_exit_rcuidle(ipi_types[ipinr]);
 654         set_irq_regs(old_regs);
 655 }
 656
 657 void smp_send_reschedule(int cpu)
 658 {
 659         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
 660 }
 661
 662 void smp_send_stop(void)
 663 {
 664         unsigned long timeout;
 665         struct cpumask mask;
 666
 667         cpumask_copy(&mask, cpu_online_mask);
 668         cpumask_clear_cpu(smp_processor_id(), &mask);
 669         if (!cpumask_empty(&mask))
 670                 smp_cross_call(&mask, IPI_CPU_STOP);
 671
 672         /* Wait up to one second for other CPUs to stop */
 673         timeout = USEC_PER_SEC;
 674         while (num_online_cpus() > 1 && timeout--)
 675                 udelay(1);
 676
 677         if (num_online_cpus() > 1)
 678                 pr_warn("SMP: failed to stop secondary CPUs\n");
 679 }
 680
 681 /*
 682  * not supported here
 683  */
 684 int setup_profiling_timer(unsigned int multiplier)
 685 {
 686         return -EINVAL;
 687 }
 688
 689 #ifdef CONFIG_CPU_FREQ
 690
 691 static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
 692 static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
 693 static unsigned long global_l_p_j_ref;
 694 static unsigned long global_l_p_j_ref_freq;
 695
 696 static int cpufreq_callback(struct notifier_block *nb,
 697                                         unsigned long val, void *data)
 698 {
 699         struct cpufreq_freqs *freq = data;
 700         int cpu = freq->cpu;
 701
 702         if (freq->flags & CPUFREQ_CONST_LOOPS)
 703                 return NOTIFY_OK;
 704
 705         if (!per_cpu(l_p_j_ref, cpu)) {
 706                 per_cpu(l_p_j_ref, cpu) =
 707                         per_cpu(cpu_data, cpu).loops_per_jiffy;
 708                 per_cpu(l_p_j_ref_freq, cpu) = freq->old;
 709                 if (!global_l_p_j_ref) {
 710                         global_l_p_j_ref = loops_per_jiffy;
 711                         global_l_p_j_ref_freq = freq->old;
 712                 }
 713         }
 714
 715         if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
 716             (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
 717                 loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
 718                                                 global_l_p_j_ref_freq,
 719                                                 freq->new);
 720                 per_cpu(cpu_data, cpu).loops_per_jiffy =
 721                         cpufreq_scale(per_cpu(l_p_j_ref, cpu),
 722                                         per_cpu(l_p_j_ref_freq, cpu),
 723                                         freq->new);
 724         }
 725         return NOTIFY_OK;
 726 }
 727
 728 static struct notifier_block cpufreq_notifier = {
 729         .notifier_call  = cpufreq_callback,
 730 };
 731
 732 static int __init register_cpufreq_notifier(void)
 733 {
 734         return cpufreq_register_notifier(&cpufreq_notifier,
 735                                                 CPUFREQ_TRANSITION_NOTIFIER);
 736 }
 737 core_initcall(register_cpufreq_notifier);
 738
 739 #endif