drivers/acpi/acpi_pad.c

   1 /*
   2  * acpi_pad.c ACPI Processor Aggregator Driver
   3  *
   4  * Copyright (c) 2009, Intel Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/cpumask.h>
  23 #include <linux/module.h>
  24 #include <linux/init.h>
  25 #include <linux/types.h>
  26 #include <linux/kthread.h>
  27 #include <linux/freezer.h>
  28 #include <linux/cpu.h>
  29 #include <linux/clockchips.h>
  30 #include <acpi/acpi_bus.h>
  31 #include <acpi/acpi_drivers.h>
  32
  33 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "processor_aggregator"
  34 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
  35 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
  36 static DEFINE_MUTEX(isolated_cpus_lock);
  37
  38 #define MWAIT_SUBSTATE_MASK     (0xf)
  39 #define MWAIT_CSTATE_MASK       (0xf)
  40 #define MWAIT_SUBSTATE_SIZE     (4)
  41 #define CPUID_MWAIT_LEAF (5)
  42 #define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
  43 #define CPUID5_ECX_INTERRUPT_BREAK      (0x2)
  44 static unsigned long power_saving_mwait_eax;
  45 static void power_saving_mwait_init(void)
  46 {
  47         unsigned int eax, ebx, ecx, edx;
  48         unsigned int highest_cstate = 0;
  49         unsigned int highest_subcstate = 0;
  50         int i;
  51
  52         if (!boot_cpu_has(X86_FEATURE_MWAIT))
  53                 return;
  54         if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
  55                 return;
  56
  57         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
  58
  59         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
  60             !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
  61                 return;
  62
  63         edx >>= MWAIT_SUBSTATE_SIZE;
  64         for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
  65                 if (edx & MWAIT_SUBSTATE_MASK) {
  66                         highest_cstate = i;
  67                         highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
  68                 }
  69         }
  70         power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
  71                 (highest_subcstate - 1);
  72
  73         for_each_online_cpu(i)
  74                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &i);
  75
  76 #if defined(CONFIG_GENERIC_TIME) && defined(CONFIG_X86)
  77         switch (boot_cpu_data.x86_vendor) {
  78         case X86_VENDOR_AMD:
  79         case X86_VENDOR_INTEL:
  80                 /*
  81                  * AMD Fam10h TSC will tick in all
  82                  * C/P/S0/S1 states when this bit is set.
  83                  */
  84                 if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
  85                         return;
  86
  87                 /*FALL THROUGH*/
  88         default:
  89                 /* TSC could halt in idle, so notify users */
  90                 mark_tsc_unstable("TSC halts in idle");
  91         }
  92 #endif
  93 }
  94
  95 static unsigned long cpu_weight[NR_CPUS];
  96 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
  97 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
  98 static void round_robin_cpu(unsigned int tsk_index)
  99 {
 100         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
 101         cpumask_var_t tmp;
 102         int cpu;
 103         unsigned long min_weight = -1;
 104         unsigned long uninitialized_var(preferred_cpu);
 105
 106         if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 107                 return;
 108
 109         mutex_lock(&isolated_cpus_lock);
 110         cpumask_clear(tmp);
 111         for_each_cpu(cpu, pad_busy_cpus)
 112                 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
 113         cpumask_andnot(tmp, cpu_online_mask, tmp);
 114         /* avoid HT sibilings if possible */
 115         if (cpumask_empty(tmp))
 116                 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
 117         if (cpumask_empty(tmp)) {
 118                 mutex_unlock(&isolated_cpus_lock);
 119                 return;
 120         }
 121         for_each_cpu(cpu, tmp) {
 122                 if (cpu_weight[cpu] < min_weight) {
 123                         min_weight = cpu_weight[cpu];
 124                         preferred_cpu = cpu;
 125                 }
 126         }
 127
 128         if (tsk_in_cpu[tsk_index] != -1)
 129                 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 130         tsk_in_cpu[tsk_index] = preferred_cpu;
 131         cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
 132         cpu_weight[preferred_cpu]++;
 133         mutex_unlock(&isolated_cpus_lock);
 134
 135         set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
 136 }
 137
 138 static void exit_round_robin(unsigned int tsk_index)
 139 {
 140         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
 141         cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 142         tsk_in_cpu[tsk_index] = -1;
 143 }
 144
 145 static unsigned int idle_pct = 5; /* percentage */
 146 static unsigned int round_robin_time = 10; /* second */
 147 static int power_saving_thread(void *data)
 148 {
 149         struct sched_param param = {.sched_priority = 1};
 150         int do_sleep;
 151         unsigned int tsk_index = (unsigned long)data;
 152         u64 last_jiffies = 0;
 153
 154         sched_setscheduler(current, SCHED_RR, &param);
 155
 156         while (!kthread_should_stop()) {
 157                 int cpu;
 158                 u64 expire_time;
 159
 160                 try_to_freeze();
 161
 162                 /* round robin to cpus */
 163                 if (last_jiffies + round_robin_time * HZ < jiffies) {
 164                         last_jiffies = jiffies;
 165                         round_robin_cpu(tsk_index);
 166                 }
 167
 168                 do_sleep = 0;
 169
 170                 current_thread_info()->status &= ~TS_POLLING;
 171                 /*
 172                  * TS_POLLING-cleared state must be visible before we test
 173                  * NEED_RESCHED:
 174                  */
 175                 smp_mb();
 176
 177                 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
 178
 179                 while (!need_resched()) {
 180                         local_irq_disable();
 181                         cpu = smp_processor_id();
 182                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
 183                                 &cpu);
 184                         stop_critical_timings();
 185
 186                         __monitor((void *)&current_thread_info()->flags, 0, 0);
 187                         smp_mb();
 188                         if (!need_resched())
 189                                 __mwait(power_saving_mwait_eax, 1);
 190
 191                         start_critical_timings();
 192                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
 193                                 &cpu);
 194                         local_irq_enable();
 195
 196                         if (jiffies > expire_time) {
 197                                 do_sleep = 1;
 198                                 break;
 199                         }
 200                 }
 201
 202                 current_thread_info()->status |= TS_POLLING;
 203
 204                 /*
 205                  * current sched_rt has threshold for rt task running time.
 206                  * When a rt task uses 95% CPU time, the rt thread will be
 207                  * scheduled out for 5% CPU time to not starve other tasks. But
 208                  * the mechanism only works when all CPUs have RT task running,
 209                  * as if one CPU hasn't RT task, RT task from other CPUs will
 210                  * borrow CPU time from this CPU and cause RT task use > 95%
 211                  * CPU time. To make 'avoid starvation' work, takes a nap here.
 212                  */
 213                 if (do_sleep)
 214                         schedule_timeout_killable(HZ * idle_pct / 100);
 215         }
 216
 217         exit_round_robin(tsk_index);
 218         return 0;
 219 }
 220
 221 static struct task_struct *ps_tsks[NR_CPUS];
 222 static unsigned int ps_tsk_num;
 223 static int create_power_saving_task(void)
 224 {
 225         int rc = -ENOMEM;
 226
 227         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
 228                 (void *)(unsigned long)ps_tsk_num,
 229                 "power_saving/%d", ps_tsk_num);
 230         rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
 231         if (!rc)
 232                 ps_tsk_num++;
 233         else
 234                 ps_tsks[ps_tsk_num] = NULL;
 235
 236         return rc;
 237 }
 238
 239 static void destroy_power_saving_task(void)
 240 {
 241         if (ps_tsk_num > 0) {
 242                 ps_tsk_num--;
 243                 kthread_stop(ps_tsks[ps_tsk_num]);
 244                 ps_tsks[ps_tsk_num] = NULL;
 245         }
 246 }
 247
 248 static void set_power_saving_task_num(unsigned int num)
 249 {
 250         if (num > ps_tsk_num) {
 251                 while (ps_tsk_num < num) {
 252                         if (create_power_saving_task())
 253                                 return;
 254                 }
 255         } else if (num < ps_tsk_num) {
 256                 while (ps_tsk_num > num)
 257                         destroy_power_saving_task();
 258         }
 259 }
 260
 261 static void acpi_pad_idle_cpus(unsigned int num_cpus)
 262 {
 263         get_online_cpus();
 264
 265         num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
 266         set_power_saving_task_num(num_cpus);
 267
 268         put_online_cpus();
 269 }
 270
 271 static uint32_t acpi_pad_idle_cpus_num(void)
 272 {
 273         return ps_tsk_num;
 274 }
 275
 276 static ssize_t acpi_pad_rrtime_store(struct device *dev,
 277         struct device_attribute *attr, const char *buf, size_t count)
 278 {
 279         unsigned long num;
 280         if (strict_strtoul(buf, 0, &num))
 281                 return -EINVAL;
 282         if (num < 1 || num >= 100)
 283                 return -EINVAL;
 284         mutex_lock(&isolated_cpus_lock);
 285         round_robin_time = num;
 286         mutex_unlock(&isolated_cpus_lock);
 287         return count;
 288 }
 289
 290 static ssize_t acpi_pad_rrtime_show(struct device *dev,
 291         struct device_attribute *attr, char *buf)
 292 {
 293         return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time);
 294 }
 295 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
 296         acpi_pad_rrtime_show,
 297         acpi_pad_rrtime_store);
 298
 299 static ssize_t acpi_pad_idlepct_store(struct device *dev,
 300         struct device_attribute *attr, const char *buf, size_t count)
 301 {
 302         unsigned long num;
 303         if (strict_strtoul(buf, 0, &num))
 304                 return -EINVAL;
 305         if (num < 1 || num >= 100)
 306                 return -EINVAL;
 307         mutex_lock(&isolated_cpus_lock);
 308         idle_pct = num;
 309         mutex_unlock(&isolated_cpus_lock);
 310         return count;
 311 }
 312
 313 static ssize_t acpi_pad_idlepct_show(struct device *dev,
 314         struct device_attribute *attr, char *buf)
 315 {
 316         return scnprintf(buf, PAGE_SIZE, "%d", idle_pct);
 317 }
 318 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
 319         acpi_pad_idlepct_show,
 320         acpi_pad_idlepct_store);
 321
 322 static ssize_t acpi_pad_idlecpus_store(struct device *dev,
 323         struct device_attribute *attr, const char *buf, size_t count)
 324 {
 325         unsigned long num;
 326         if (strict_strtoul(buf, 0, &num))
 327                 return -EINVAL;
 328         mutex_lock(&isolated_cpus_lock);
 329         acpi_pad_idle_cpus(num);
 330         mutex_unlock(&isolated_cpus_lock);
 331         return count;
 332 }
 333
 334 static ssize_t acpi_pad_idlecpus_show(struct device *dev,
 335         struct device_attribute *attr, char *buf)
 336 {
 337         return cpumask_scnprintf(buf, PAGE_SIZE,
 338                 to_cpumask(pad_busy_cpus_bits));
 339 }
 340 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
 341         acpi_pad_idlecpus_show,
 342         acpi_pad_idlecpus_store);
 343
 344 static int acpi_pad_add_sysfs(struct acpi_device *device)
 345 {
 346         int result;
 347
 348         result = device_create_file(&device->dev, &dev_attr_idlecpus);
 349         if (result)
 350                 return -ENODEV;
 351         result = device_create_file(&device->dev, &dev_attr_idlepct);
 352         if (result) {
 353                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 354                 return -ENODEV;
 355         }
 356         result = device_create_file(&device->dev, &dev_attr_rrtime);
 357         if (result) {
 358                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 359                 device_remove_file(&device->dev, &dev_attr_idlepct);
 360                 return -ENODEV;
 361         }
 362         return 0;
 363 }
 364
 365 static void acpi_pad_remove_sysfs(struct acpi_device *device)
 366 {
 367         device_remove_file(&device->dev, &dev_attr_idlecpus);
 368         device_remove_file(&device->dev, &dev_attr_idlepct);
 369         device_remove_file(&device->dev, &dev_attr_rrtime);
 370 }
 371
 372 /* Query firmware how many CPUs should be idle */
 373 static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
 374 {
 375         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 376         union acpi_object *package;
 377         int rev, num, ret = -EINVAL;
 378
 379         if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
 380                 return -EINVAL;
 381
 382         if (!buffer.length || !buffer.pointer)
 383                 return -EINVAL;
 384
 385         package = buffer.pointer;
 386         if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2)
 387                 goto out;
 388         rev = package->package.elements[0].integer.value;
 389         num = package->package.elements[1].integer.value;
 390         if (rev != 1 || num < 0)
 391                 goto out;
 392         *num_cpus = num;
 393         ret = 0;
 394 out:
 395         kfree(buffer.pointer);
 396         return ret;
 397 }
 398
 399 /* Notify firmware how many CPUs are idle */
 400 static void acpi_pad_ost(acpi_handle handle, int stat,
 401         uint32_t idle_cpus)
 402 {
 403         union acpi_object params[3] = {
 404                 {.type = ACPI_TYPE_INTEGER,},
 405                 {.type = ACPI_TYPE_INTEGER,},
 406                 {.type = ACPI_TYPE_BUFFER,},
 407         };
 408         struct acpi_object_list arg_list = {3, params};
 409
 410         params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
 411         params[1].integer.value =  stat;
 412         params[2].buffer.length = 4;
 413         params[2].buffer.pointer = (void *)&idle_cpus;
 414         acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 415 }
 416
 417 static void acpi_pad_handle_notify(acpi_handle handle)
 418 {
 419         int num_cpus;
 420         uint32_t idle_cpus;
 421
 422         mutex_lock(&isolated_cpus_lock);
 423         if (acpi_pad_pur(handle, &num_cpus)) {
 424                 mutex_unlock(&isolated_cpus_lock);
 425                 return;
 426         }
 427         acpi_pad_idle_cpus(num_cpus);
 428         idle_cpus = acpi_pad_idle_cpus_num();
 429         acpi_pad_ost(handle, 0, idle_cpus);
 430         mutex_unlock(&isolated_cpus_lock);
 431 }
 432
 433 static void acpi_pad_notify(acpi_handle handle, u32 event,
 434         void *data)
 435 {
 436         struct acpi_device *device = data;
 437
 438         switch (event) {
 439         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 440                 acpi_pad_handle_notify(handle);
 441                 acpi_bus_generate_proc_event(device, event, 0);
 442                 acpi_bus_generate_netlink_event(device->pnp.device_class,
 443                         dev_name(&device->dev), event, 0);
 444                 break;
 445         default:
 446                 printk(KERN_WARNING"Unsupported event [0x%x]\n", event);
 447                 break;
 448         }
 449 }
 450
 451 static int acpi_pad_add(struct acpi_device *device)
 452 {
 453         acpi_status status;
 454
 455         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 456         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 457
 458         if (acpi_pad_add_sysfs(device))
 459                 return -ENODEV;
 460
 461         status = acpi_install_notify_handler(device->handle,
 462                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
 463         if (ACPI_FAILURE(status)) {
 464                 acpi_pad_remove_sysfs(device);
 465                 return -ENODEV;
 466         }
 467
 468         return 0;
 469 }
 470
 471 static int acpi_pad_remove(struct acpi_device *device,
 472         int type)
 473 {
 474         mutex_lock(&isolated_cpus_lock);
 475         acpi_pad_idle_cpus(0);
 476         mutex_unlock(&isolated_cpus_lock);
 477
 478         acpi_remove_notify_handler(device->handle,
 479                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
 480         acpi_pad_remove_sysfs(device);
 481         return 0;
 482 }
 483
 484 static const struct acpi_device_id pad_device_ids[] = {
 485         {"ACPI000C", 0},
 486         {"", 0},
 487 };
 488 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
 489
 490 static struct acpi_driver acpi_pad_driver = {
 491         .name = "processor_aggregator",
 492         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
 493         .ids = pad_device_ids,
 494         .ops = {
 495                 .add = acpi_pad_add,
 496                 .remove = acpi_pad_remove,
 497         },
 498 };
 499
 500 static int __init acpi_pad_init(void)
 501 {
 502         power_saving_mwait_init();
 503         if (power_saving_mwait_eax == 0)
 504                 return -EINVAL;
 505
 506         return acpi_bus_register_driver(&acpi_pad_driver);
 507 }
 508
 509 static void __exit acpi_pad_exit(void)
 510 {
 511         acpi_bus_unregister_driver(&acpi_pad_driver);
 512 }
 513
 514 module_init(acpi_pad_init);
 515 module_exit(acpi_pad_exit);
 516 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
 517 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
 518 MODULE_LICENSE("GPL");