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, preferred_cpu;
 104
 105         if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 106                 return;
 107
 108         mutex_lock(&isolated_cpus_lock);
 109         cpumask_clear(tmp);
 110         for_each_cpu(cpu, pad_busy_cpus)
 111                 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
 112         cpumask_andnot(tmp, cpu_online_mask, tmp);
 113         /* avoid HT sibilings if possible */
 114         if (cpumask_empty(tmp))
 115                 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
 116         if (cpumask_empty(tmp)) {
 117                 mutex_unlock(&isolated_cpus_lock);
 118                 return;
 119         }
 120         for_each_cpu(cpu, tmp) {
 121                 if (cpu_weight[cpu] < min_weight) {
 122                         min_weight = cpu_weight[cpu];
 123                         preferred_cpu = cpu;
 124                 }
 125         }
 126
 127         if (tsk_in_cpu[tsk_index] != -1)
 128                 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 129         tsk_in_cpu[tsk_index] = preferred_cpu;
 130         cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
 131         cpu_weight[preferred_cpu]++;
 132         mutex_unlock(&isolated_cpus_lock);
 133
 134         set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
 135 }
 136
 137 static void exit_round_robin(unsigned int tsk_index)
 138 {
 139         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
 140         cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 141         tsk_in_cpu[tsk_index] = -1;
 142 }
 143
 144 static unsigned int idle_pct = 5; /* percentage */
 145 static unsigned int round_robin_time = 10; /* second */
 146 static int power_saving_thread(void *data)
 147 {
 148         struct sched_param param = {.sched_priority = 1};
 149         int do_sleep;
 150         unsigned int tsk_index = (unsigned long)data;
 151         u64 last_jiffies = 0;
 152
 153         sched_setscheduler(current, SCHED_RR, &param);
 154
 155         while (!kthread_should_stop()) {
 156                 int cpu;
 157                 u64 expire_time;
 158
 159                 try_to_freeze();
 160
 161                 /* round robin to cpus */
 162                 if (last_jiffies + round_robin_time * HZ < jiffies) {
 163                         last_jiffies = jiffies;
 164                         round_robin_cpu(tsk_index);
 165                 }
 166
 167                 do_sleep = 0;
 168
 169                 current_thread_info()->status &= ~TS_POLLING;
 170                 /*
 171                  * TS_POLLING-cleared state must be visible before we test
 172                  * NEED_RESCHED:
 173                  */
 174                 smp_mb();
 175
 176                 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
 177
 178                 while (!need_resched()) {
 179                         local_irq_disable();
 180                         cpu = smp_processor_id();
 181                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
 182                                 &cpu);
 183                         stop_critical_timings();
 184
 185                         __monitor((void *)&current_thread_info()->flags, 0, 0);
 186                         smp_mb();
 187                         if (!need_resched())
 188                                 __mwait(power_saving_mwait_eax, 1);
 189
 190                         start_critical_timings();
 191                         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
 192                                 &cpu);
 193                         local_irq_enable();
 194
 195                         if (jiffies > expire_time) {
 196                                 do_sleep = 1;
 197                                 break;
 198                         }
 199                 }
 200
 201                 current_thread_info()->status |= TS_POLLING;
 202
 203                 /*
 204                  * current sched_rt has threshold for rt task running time.
 205                  * When a rt task uses 95% CPU time, the rt thread will be
 206                  * scheduled out for 5% CPU time to not starve other tasks. But
 207                  * the mechanism only works when all CPUs have RT task running,
 208                  * as if one CPU hasn't RT task, RT task from other CPUs will
 209                  * borrow CPU time from this CPU and cause RT task use > 95%
 210                  * CPU time. To make 'avoid staration' work, takes a nap here.
 211                  */
 212                 if (do_sleep)
 213                         schedule_timeout_killable(HZ * idle_pct / 100);
 214         }
 215
 216         exit_round_robin(tsk_index);
 217         return 0;
 218 }
 219
 220 static struct task_struct *ps_tsks[NR_CPUS];
 221 static unsigned int ps_tsk_num;
 222 static int create_power_saving_task(void)
 223 {
 224         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
 225                 (void *)(unsigned long)ps_tsk_num,
 226                 "power_saving/%d", ps_tsk_num);
 227         if (ps_tsks[ps_tsk_num]) {
 228                 ps_tsk_num++;
 229                 return 0;
 230         }
 231         return -EINVAL;
 232 }
 233
 234 static void destroy_power_saving_task(void)
 235 {
 236         if (ps_tsk_num > 0) {
 237                 ps_tsk_num--;
 238                 kthread_stop(ps_tsks[ps_tsk_num]);
 239         }
 240 }
 241
 242 static void set_power_saving_task_num(unsigned int num)
 243 {
 244         if (num > ps_tsk_num) {
 245                 while (ps_tsk_num < num) {
 246                         if (create_power_saving_task())
 247                                 return;
 248                 }
 249         } else if (num < ps_tsk_num) {
 250                 while (ps_tsk_num > num)
 251                         destroy_power_saving_task();
 252         }
 253 }
 254
 255 static int acpi_pad_idle_cpus(unsigned int num_cpus)
 256 {
 257         get_online_cpus();
 258
 259         num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
 260         set_power_saving_task_num(num_cpus);
 261
 262         put_online_cpus();
 263         return 0;
 264 }
 265
 266 static uint32_t acpi_pad_idle_cpus_num(void)
 267 {
 268         return ps_tsk_num;
 269 }
 270
 271 static ssize_t acpi_pad_rrtime_store(struct device *dev,
 272         struct device_attribute *attr, const char *buf, size_t count)
 273 {
 274         unsigned long num;
 275         if (strict_strtoul(buf, 0, &num))
 276                 return -EINVAL;
 277         if (num < 1 || num >= 100)
 278                 return -EINVAL;
 279         mutex_lock(&isolated_cpus_lock);
 280         round_robin_time = num;
 281         mutex_unlock(&isolated_cpus_lock);
 282         return count;
 283 }
 284
 285 static ssize_t acpi_pad_rrtime_show(struct device *dev,
 286         struct device_attribute *attr, char *buf)
 287 {
 288         return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time);
 289 }
 290 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
 291         acpi_pad_rrtime_show,
 292         acpi_pad_rrtime_store);
 293
 294 static ssize_t acpi_pad_idlepct_store(struct device *dev,
 295         struct device_attribute *attr, const char *buf, size_t count)
 296 {
 297         unsigned long num;
 298         if (strict_strtoul(buf, 0, &num))
 299                 return -EINVAL;
 300         if (num < 1 || num >= 100)
 301                 return -EINVAL;
 302         mutex_lock(&isolated_cpus_lock);
 303         idle_pct = num;
 304         mutex_unlock(&isolated_cpus_lock);
 305         return count;
 306 }
 307
 308 static ssize_t acpi_pad_idlepct_show(struct device *dev,
 309         struct device_attribute *attr, char *buf)
 310 {
 311         return scnprintf(buf, PAGE_SIZE, "%d", idle_pct);
 312 }
 313 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
 314         acpi_pad_idlepct_show,
 315         acpi_pad_idlepct_store);
 316
 317 static ssize_t acpi_pad_idlecpus_store(struct device *dev,
 318         struct device_attribute *attr, const char *buf, size_t count)
 319 {
 320         unsigned long num;
 321         if (strict_strtoul(buf, 0, &num))
 322                 return -EINVAL;
 323         mutex_lock(&isolated_cpus_lock);
 324         acpi_pad_idle_cpus(num);
 325         mutex_unlock(&isolated_cpus_lock);
 326         return count;
 327 }
 328
 329 static ssize_t acpi_pad_idlecpus_show(struct device *dev,
 330         struct device_attribute *attr, char *buf)
 331 {
 332         return cpumask_scnprintf(buf, PAGE_SIZE,
 333                 to_cpumask(pad_busy_cpus_bits));
 334 }
 335 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
 336         acpi_pad_idlecpus_show,
 337         acpi_pad_idlecpus_store);
 338
 339 static int acpi_pad_add_sysfs(struct acpi_device *device)
 340 {
 341         int result;
 342
 343         result = device_create_file(&device->dev, &dev_attr_idlecpus);
 344         if (result)
 345                 return -ENODEV;
 346         result = device_create_file(&device->dev, &dev_attr_idlepct);
 347         if (result) {
 348                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 349                 return -ENODEV;
 350         }
 351         result = device_create_file(&device->dev, &dev_attr_rrtime);
 352         if (result) {
 353                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 354                 device_remove_file(&device->dev, &dev_attr_idlepct);
 355                 return -ENODEV;
 356         }
 357         return 0;
 358 }
 359
 360 static void acpi_pad_remove_sysfs(struct acpi_device *device)
 361 {
 362         device_remove_file(&device->dev, &dev_attr_idlecpus);
 363         device_remove_file(&device->dev, &dev_attr_idlepct);
 364         device_remove_file(&device->dev, &dev_attr_rrtime);
 365 }
 366
 367 /* Query firmware how many CPUs should be idle */
 368 static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
 369 {
 370         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 371         acpi_status status;
 372         union acpi_object *package;
 373         int rev, num, ret = -EINVAL;
 374
 375         status = acpi_evaluate_object(handle, "_PUR", NULL, &buffer);
 376         if (ACPI_FAILURE(status))
 377                 return -EINVAL;
 378         package = buffer.pointer;
 379         if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2)
 380                 goto out;
 381         rev = package->package.elements[0].integer.value;
 382         num = package->package.elements[1].integer.value;
 383         if (rev != 1)
 384                 goto out;
 385         *num_cpus = num;
 386         ret = 0;
 387 out:
 388         kfree(buffer.pointer);
 389         return ret;
 390 }
 391
 392 /* Notify firmware how many CPUs are idle */
 393 static void acpi_pad_ost(acpi_handle handle, int stat,
 394         uint32_t idle_cpus)
 395 {
 396         union acpi_object params[3] = {
 397                 {.type = ACPI_TYPE_INTEGER,},
 398                 {.type = ACPI_TYPE_INTEGER,},
 399                 {.type = ACPI_TYPE_BUFFER,},
 400         };
 401         struct acpi_object_list arg_list = {3, params};
 402
 403         params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
 404         params[1].integer.value =  stat;
 405         params[2].buffer.length = 4;
 406         params[2].buffer.pointer = (void *)&idle_cpus;
 407         acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 408 }
 409
 410 static void acpi_pad_handle_notify(acpi_handle handle)
 411 {
 412         int num_cpus, ret;
 413         uint32_t idle_cpus;
 414
 415         mutex_lock(&isolated_cpus_lock);
 416         if (acpi_pad_pur(handle, &num_cpus)) {
 417                 mutex_unlock(&isolated_cpus_lock);
 418                 return;
 419         }
 420         ret = acpi_pad_idle_cpus(num_cpus);
 421         idle_cpus = acpi_pad_idle_cpus_num();
 422         if (!ret)
 423                 acpi_pad_ost(handle, 0, idle_cpus);
 424         else
 425                 acpi_pad_ost(handle, 1, 0);
 426         mutex_unlock(&isolated_cpus_lock);
 427 }
 428
 429 static void acpi_pad_notify(acpi_handle handle, u32 event,
 430         void *data)
 431 {
 432         struct acpi_device *device = data;
 433
 434         switch (event) {
 435         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 436                 acpi_pad_handle_notify(handle);
 437                 acpi_bus_generate_proc_event(device, event, 0);
 438                 acpi_bus_generate_netlink_event(device->pnp.device_class,
 439                         dev_name(&device->dev), event, 0);
 440                 break;
 441         default:
 442                 printk(KERN_WARNING"Unsupported event [0x%x]\n", event);
 443                 break;
 444         }
 445 }
 446
 447 static int acpi_pad_add(struct acpi_device *device)
 448 {
 449         acpi_status status;
 450
 451         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 452         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 453
 454         if (acpi_pad_add_sysfs(device))
 455                 return -ENODEV;
 456
 457         status = acpi_install_notify_handler(device->handle,
 458                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
 459         if (ACPI_FAILURE(status)) {
 460                 acpi_pad_remove_sysfs(device);
 461                 return -ENODEV;
 462         }
 463
 464         return 0;
 465 }
 466
 467 static int acpi_pad_remove(struct acpi_device *device,
 468         int type)
 469 {
 470         mutex_lock(&isolated_cpus_lock);
 471         acpi_pad_idle_cpus(0);
 472         mutex_unlock(&isolated_cpus_lock);
 473
 474         acpi_remove_notify_handler(device->handle,
 475                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
 476         acpi_pad_remove_sysfs(device);
 477         return 0;
 478 }
 479
 480 static const struct acpi_device_id pad_device_ids[] = {
 481         {"ACPI000C", 0},
 482         {"", 0},
 483 };
 484 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
 485
 486 static struct acpi_driver acpi_pad_driver = {
 487         .name = "processor_aggregator",
 488         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
 489         .ids = pad_device_ids,
 490         .ops = {
 491                 .add = acpi_pad_add,
 492                 .remove = acpi_pad_remove,
 493         },
 494 };
 495
 496 static int __init acpi_pad_init(void)
 497 {
 498         power_saving_mwait_init();
 499         if (power_saving_mwait_eax == 0)
 500                 return -EINVAL;
 501
 502         return acpi_bus_register_driver(&acpi_pad_driver);
 503 }
 504
 505 static void __exit acpi_pad_exit(void)
 506 {
 507         acpi_bus_unregister_driver(&acpi_pad_driver);
 508 }
 509
 510 module_init(acpi_pad_init);
 511 module_exit(acpi_pad_exit);
 512 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
 513 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
 514 MODULE_LICENSE("GPL");