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 staration' 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         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
 226                 (void *)(unsigned long)ps_tsk_num,
 227                 "power_saving/%d", ps_tsk_num);
 228         if (ps_tsks[ps_tsk_num]) {
 229                 ps_tsk_num++;
 230                 return 0;
 231         }
 232         return -EINVAL;
 233 }
 234
 235 static void destroy_power_saving_task(void)
 236 {
 237         if (ps_tsk_num > 0) {
 238                 ps_tsk_num--;
 239                 kthread_stop(ps_tsks[ps_tsk_num]);
 240         }
 241 }
 242
 243 static void set_power_saving_task_num(unsigned int num)
 244 {
 245         if (num > ps_tsk_num) {
 246                 while (ps_tsk_num < num) {
 247                         if (create_power_saving_task())
 248                                 return;
 249                 }
 250         } else if (num < ps_tsk_num) {
 251                 while (ps_tsk_num > num)
 252                         destroy_power_saving_task();
 253         }
 254 }
 255
 256 static int acpi_pad_idle_cpus(unsigned int num_cpus)
 257 {
 258         get_online_cpus();
 259
 260         num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
 261         set_power_saving_task_num(num_cpus);
 262
 263         put_online_cpus();
 264         return 0;
 265 }
 266
 267 static uint32_t acpi_pad_idle_cpus_num(void)
 268 {
 269         return ps_tsk_num;
 270 }
 271
 272 static ssize_t acpi_pad_rrtime_store(struct device *dev,
 273         struct device_attribute *attr, const char *buf, size_t count)
 274 {
 275         unsigned long num;
 276         if (strict_strtoul(buf, 0, &num))
 277                 return -EINVAL;
 278         if (num < 1 || num >= 100)
 279                 return -EINVAL;
 280         mutex_lock(&isolated_cpus_lock);
 281         round_robin_time = num;
 282         mutex_unlock(&isolated_cpus_lock);
 283         return count;
 284 }
 285
 286 static ssize_t acpi_pad_rrtime_show(struct device *dev,
 287         struct device_attribute *attr, char *buf)
 288 {
 289         return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time);
 290 }
 291 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
 292         acpi_pad_rrtime_show,
 293         acpi_pad_rrtime_store);
 294
 295 static ssize_t acpi_pad_idlepct_store(struct device *dev,
 296         struct device_attribute *attr, const char *buf, size_t count)
 297 {
 298         unsigned long num;
 299         if (strict_strtoul(buf, 0, &num))
 300                 return -EINVAL;
 301         if (num < 1 || num >= 100)
 302                 return -EINVAL;
 303         mutex_lock(&isolated_cpus_lock);
 304         idle_pct = num;
 305         mutex_unlock(&isolated_cpus_lock);
 306         return count;
 307 }
 308
 309 static ssize_t acpi_pad_idlepct_show(struct device *dev,
 310         struct device_attribute *attr, char *buf)
 311 {
 312         return scnprintf(buf, PAGE_SIZE, "%d", idle_pct);
 313 }
 314 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
 315         acpi_pad_idlepct_show,
 316         acpi_pad_idlepct_store);
 317
 318 static ssize_t acpi_pad_idlecpus_store(struct device *dev,
 319         struct device_attribute *attr, const char *buf, size_t count)
 320 {
 321         unsigned long num;
 322         if (strict_strtoul(buf, 0, &num))
 323                 return -EINVAL;
 324         mutex_lock(&isolated_cpus_lock);
 325         acpi_pad_idle_cpus(num);
 326         mutex_unlock(&isolated_cpus_lock);
 327         return count;
 328 }
 329
 330 static ssize_t acpi_pad_idlecpus_show(struct device *dev,
 331         struct device_attribute *attr, char *buf)
 332 {
 333         return cpumask_scnprintf(buf, PAGE_SIZE,
 334                 to_cpumask(pad_busy_cpus_bits));
 335 }
 336 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
 337         acpi_pad_idlecpus_show,
 338         acpi_pad_idlecpus_store);
 339
 340 static int acpi_pad_add_sysfs(struct acpi_device *device)
 341 {
 342         int result;
 343
 344         result = device_create_file(&device->dev, &dev_attr_idlecpus);
 345         if (result)
 346                 return -ENODEV;
 347         result = device_create_file(&device->dev, &dev_attr_idlepct);
 348         if (result) {
 349                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 350                 return -ENODEV;
 351         }
 352         result = device_create_file(&device->dev, &dev_attr_rrtime);
 353         if (result) {
 354                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 355                 device_remove_file(&device->dev, &dev_attr_idlepct);
 356                 return -ENODEV;
 357         }
 358         return 0;
 359 }
 360
 361 static void acpi_pad_remove_sysfs(struct acpi_device *device)
 362 {
 363         device_remove_file(&device->dev, &dev_attr_idlecpus);
 364         device_remove_file(&device->dev, &dev_attr_idlepct);
 365         device_remove_file(&device->dev, &dev_attr_rrtime);
 366 }
 367
 368 /* Query firmware how many CPUs should be idle */
 369 static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
 370 {
 371         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 372         acpi_status status;
 373         union acpi_object *package;
 374         int rev, num, ret = -EINVAL;
 375
 376         status = acpi_evaluate_object(handle, "_PUR", NULL, &buffer);
 377         if (ACPI_FAILURE(status))
 378                 return -EINVAL;
 379         package = buffer.pointer;
 380         if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2)
 381                 goto out;
 382         rev = package->package.elements[0].integer.value;
 383         num = package->package.elements[1].integer.value;
 384         if (rev != 1)
 385                 goto out;
 386         *num_cpus = num;
 387         ret = 0;
 388 out:
 389         kfree(buffer.pointer);
 390         return ret;
 391 }
 392
 393 /* Notify firmware how many CPUs are idle */
 394 static void acpi_pad_ost(acpi_handle handle, int stat,
 395         uint32_t idle_cpus)
 396 {
 397         union acpi_object params[3] = {
 398                 {.type = ACPI_TYPE_INTEGER,},
 399                 {.type = ACPI_TYPE_INTEGER,},
 400                 {.type = ACPI_TYPE_BUFFER,},
 401         };
 402         struct acpi_object_list arg_list = {3, params};
 403
 404         params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
 405         params[1].integer.value =  stat;
 406         params[2].buffer.length = 4;
 407         params[2].buffer.pointer = (void *)&idle_cpus;
 408         acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 409 }
 410
 411 static void acpi_pad_handle_notify(acpi_handle handle)
 412 {
 413         int num_cpus, ret;
 414         uint32_t idle_cpus;
 415
 416         mutex_lock(&isolated_cpus_lock);
 417         if (acpi_pad_pur(handle, &num_cpus)) {
 418                 mutex_unlock(&isolated_cpus_lock);
 419                 return;
 420         }
 421         ret = acpi_pad_idle_cpus(num_cpus);
 422         idle_cpus = acpi_pad_idle_cpus_num();
 423         if (!ret)
 424                 acpi_pad_ost(handle, 0, idle_cpus);
 425         else
 426                 acpi_pad_ost(handle, 1, 0);
 427         mutex_unlock(&isolated_cpus_lock);
 428 }
 429
 430 static void acpi_pad_notify(acpi_handle handle, u32 event,
 431         void *data)
 432 {
 433         struct acpi_device *device = data;
 434
 435         switch (event) {
 436         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 437                 acpi_pad_handle_notify(handle);
 438                 acpi_bus_generate_proc_event(device, event, 0);
 439                 acpi_bus_generate_netlink_event(device->pnp.device_class,
 440                         dev_name(&device->dev), event, 0);
 441                 break;
 442         default:
 443                 printk(KERN_WARNING"Unsupported event [0x%x]\n", event);
 444                 break;
 445         }
 446 }
 447
 448 static int acpi_pad_add(struct acpi_device *device)
 449 {
 450         acpi_status status;
 451
 452         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 453         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 454
 455         if (acpi_pad_add_sysfs(device))
 456                 return -ENODEV;
 457
 458         status = acpi_install_notify_handler(device->handle,
 459                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
 460         if (ACPI_FAILURE(status)) {
 461                 acpi_pad_remove_sysfs(device);
 462                 return -ENODEV;
 463         }
 464
 465         return 0;
 466 }
 467
 468 static int acpi_pad_remove(struct acpi_device *device,
 469         int type)
 470 {
 471         mutex_lock(&isolated_cpus_lock);
 472         acpi_pad_idle_cpus(0);
 473         mutex_unlock(&isolated_cpus_lock);
 474
 475         acpi_remove_notify_handler(device->handle,
 476                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
 477         acpi_pad_remove_sysfs(device);
 478         return 0;
 479 }
 480
 481 static const struct acpi_device_id pad_device_ids[] = {
 482         {"ACPI000C", 0},
 483         {"", 0},
 484 };
 485 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
 486
 487 static struct acpi_driver acpi_pad_driver = {
 488         .name = "processor_aggregator",
 489         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
 490         .ids = pad_device_ids,
 491         .ops = {
 492                 .add = acpi_pad_add,
 493                 .remove = acpi_pad_remove,
 494         },
 495 };
 496
 497 static int __init acpi_pad_init(void)
 498 {
 499         power_saving_mwait_init();
 500         if (power_saving_mwait_eax == 0)
 501                 return -EINVAL;
 502
 503         return acpi_bus_register_driver(&acpi_pad_driver);
 504 }
 505
 506 static void __exit acpi_pad_exit(void)
 507 {
 508         acpi_bus_unregister_driver(&acpi_pad_driver);
 509 }
 510
 511 module_init(acpi_pad_init);
 512 module_exit(acpi_pad_exit);
 513 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
 514 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
 515 MODULE_LICENSE("GPL");