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  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/cpumask.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/types.h>
  22 #include <linux/kthread.h>
  23 #include <uapi/linux/sched/types.h>
  24 #include <linux/freezer.h>
  25 #include <linux/cpu.h>
  26 #include <linux/tick.h>
  27 #include <linux/slab.h>
  28 #include <linux/acpi.h>
  29 #include <asm/mwait.h>
  30 #include <xen/xen.h>
  31
  32 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
  33 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
  34 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
  35 static DEFINE_MUTEX(isolated_cpus_lock);
  36 static DEFINE_MUTEX(round_robin_lock);
  37
  38 static unsigned long power_saving_mwait_eax;
  39
  40 static unsigned char tsc_detected_unstable;
  41 static unsigned char tsc_marked_unstable;
  42
  43 static void power_saving_mwait_init(void)
  44 {
  45         unsigned int eax, ebx, ecx, edx;
  46         unsigned int highest_cstate = 0;
  47         unsigned int highest_subcstate = 0;
  48         int i;
  49
  50         if (!boot_cpu_has(X86_FEATURE_MWAIT))
  51                 return;
  52         if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
  53                 return;
  54
  55         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
  56
  57         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
  58             !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
  59                 return;
  60
  61         edx >>= MWAIT_SUBSTATE_SIZE;
  62         for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
  63                 if (edx & MWAIT_SUBSTATE_MASK) {
  64                         highest_cstate = i;
  65                         highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
  66                 }
  67         }
  68         power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
  69                 (highest_subcstate - 1);
  70
  71 #if defined(CONFIG_X86)
  72         switch (boot_cpu_data.x86_vendor) {
  73         case X86_VENDOR_AMD:
  74         case X86_VENDOR_INTEL:
  75                 /*
  76                  * AMD Fam10h TSC will tick in all
  77                  * C/P/S0/S1 states when this bit is set.
  78                  */
  79                 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
  80                         tsc_detected_unstable = 1;
  81                 break;
  82         default:
  83                 /* TSC could halt in idle */
  84                 tsc_detected_unstable = 1;
  85         }
  86 #endif
  87 }
  88
  89 static unsigned long cpu_weight[NR_CPUS];
  90 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
  91 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
  92 static void round_robin_cpu(unsigned int tsk_index)
  93 {
  94         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
  95         cpumask_var_t tmp;
  96         int cpu;
  97         unsigned long min_weight = -1;
  98         unsigned long uninitialized_var(preferred_cpu);
  99
 100         if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
 101                 return;
 102
 103         mutex_lock(&round_robin_lock);
 104         cpumask_clear(tmp);
 105         for_each_cpu(cpu, pad_busy_cpus)
 106                 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
 107         cpumask_andnot(tmp, cpu_online_mask, tmp);
 108         /* avoid HT sibilings if possible */
 109         if (cpumask_empty(tmp))
 110                 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
 111         if (cpumask_empty(tmp)) {
 112                 mutex_unlock(&round_robin_lock);
 113                 free_cpumask_var(tmp);
 114                 return;
 115         }
 116         for_each_cpu(cpu, tmp) {
 117                 if (cpu_weight[cpu] < min_weight) {
 118                         min_weight = cpu_weight[cpu];
 119                         preferred_cpu = cpu;
 120                 }
 121         }
 122
 123         if (tsk_in_cpu[tsk_index] != -1)
 124                 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 125         tsk_in_cpu[tsk_index] = preferred_cpu;
 126         cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
 127         cpu_weight[preferred_cpu]++;
 128         mutex_unlock(&round_robin_lock);
 129
 130         set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
 131
 132         free_cpumask_var(tmp);
 133 }
 134
 135 static void exit_round_robin(unsigned int tsk_index)
 136 {
 137         struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
 138         cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
 139         tsk_in_cpu[tsk_index] = -1;
 140 }
 141
 142 static unsigned int idle_pct = 5; /* percentage */
 143 static unsigned int round_robin_time = 1; /* second */
 144 static int power_saving_thread(void *data)
 145 {
 146         struct sched_param param = {.sched_priority = 1};
 147         int do_sleep;
 148         unsigned int tsk_index = (unsigned long)data;
 149         u64 last_jiffies = 0;
 150
 151         sched_setscheduler(current, SCHED_RR, &param);
 152
 153         while (!kthread_should_stop()) {
 154                 unsigned long expire_time;
 155
 156                 /* round robin to cpus */
 157                 expire_time = last_jiffies + round_robin_time * HZ;
 158                 if (time_before(expire_time, jiffies)) {
 159                         last_jiffies = jiffies;
 160                         round_robin_cpu(tsk_index);
 161                 }
 162
 163                 do_sleep = 0;
 164
 165                 expire_time = jiffies + HZ * (100 - idle_pct) / 100;
 166
 167                 while (!need_resched()) {
 168                         if (tsc_detected_unstable && !tsc_marked_unstable) {
 169                                 /* TSC could halt in idle, so notify users */
 170                                 mark_tsc_unstable("TSC halts in idle");
 171                                 tsc_marked_unstable = 1;
 172                         }
 173                         local_irq_disable();
 174                         tick_broadcast_enable();
 175                         tick_broadcast_enter();
 176                         stop_critical_timings();
 177
 178                         mwait_idle_with_hints(power_saving_mwait_eax, 1);
 179
 180                         start_critical_timings();
 181                         tick_broadcast_exit();
 182                         local_irq_enable();
 183
 184                         if (time_before(expire_time, jiffies)) {
 185                                 do_sleep = 1;
 186                                 break;
 187                         }
 188                 }
 189
 190                 /*
 191                  * current sched_rt has threshold for rt task running time.
 192                  * When a rt task uses 95% CPU time, the rt thread will be
 193                  * scheduled out for 5% CPU time to not starve other tasks. But
 194                  * the mechanism only works when all CPUs have RT task running,
 195                  * as if one CPU hasn't RT task, RT task from other CPUs will
 196                  * borrow CPU time from this CPU and cause RT task use > 95%
 197                  * CPU time. To make 'avoid starvation' work, takes a nap here.
 198                  */
 199                 if (unlikely(do_sleep))
 200                         schedule_timeout_killable(HZ * idle_pct / 100);
 201
 202                 /* If an external event has set the need_resched flag, then
 203                  * we need to deal with it, or this loop will continue to
 204                  * spin without calling __mwait().
 205                  */
 206                 if (unlikely(need_resched()))
 207                         schedule();
 208         }
 209
 210         exit_round_robin(tsk_index);
 211         return 0;
 212 }
 213
 214 static struct task_struct *ps_tsks[NR_CPUS];
 215 static unsigned int ps_tsk_num;
 216 static int create_power_saving_task(void)
 217 {
 218         int rc;
 219
 220         ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
 221                 (void *)(unsigned long)ps_tsk_num,
 222                 "acpi_pad/%d", ps_tsk_num);
 223
 224         if (IS_ERR(ps_tsks[ps_tsk_num])) {
 225                 rc = PTR_ERR(ps_tsks[ps_tsk_num]);
 226                 ps_tsks[ps_tsk_num] = NULL;
 227         } else {
 228                 rc = 0;
 229                 ps_tsk_num++;
 230         }
 231
 232         return rc;
 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                 ps_tsks[ps_tsk_num] = NULL;
 241         }
 242 }
 243
 244 static void set_power_saving_task_num(unsigned int num)
 245 {
 246         if (num > ps_tsk_num) {
 247                 while (ps_tsk_num < num) {
 248                         if (create_power_saving_task())
 249                                 return;
 250                 }
 251         } else if (num < ps_tsk_num) {
 252                 while (ps_tsk_num > num)
 253                         destroy_power_saving_task();
 254         }
 255 }
 256
 257 static void acpi_pad_idle_cpus(unsigned int num_cpus)
 258 {
 259         get_online_cpus();
 260
 261         num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
 262         set_power_saving_task_num(num_cpus);
 263
 264         put_online_cpus();
 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 (kstrtoul(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\n", 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 (kstrtoul(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\n", 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 (kstrtoul(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 cpumap_print_to_pagebuf(false, buf,
 334                                        to_cpumask(pad_busy_cpus_bits));
 335 }
 336
 337 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
 338         acpi_pad_idlecpus_show,
 339         acpi_pad_idlecpus_store);
 340
 341 static int acpi_pad_add_sysfs(struct acpi_device *device)
 342 {
 343         int result;
 344
 345         result = device_create_file(&device->dev, &dev_attr_idlecpus);
 346         if (result)
 347                 return -ENODEV;
 348         result = device_create_file(&device->dev, &dev_attr_idlepct);
 349         if (result) {
 350                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 351                 return -ENODEV;
 352         }
 353         result = device_create_file(&device->dev, &dev_attr_rrtime);
 354         if (result) {
 355                 device_remove_file(&device->dev, &dev_attr_idlecpus);
 356                 device_remove_file(&device->dev, &dev_attr_idlepct);
 357                 return -ENODEV;
 358         }
 359         return 0;
 360 }
 361
 362 static void acpi_pad_remove_sysfs(struct acpi_device *device)
 363 {
 364         device_remove_file(&device->dev, &dev_attr_idlecpus);
 365         device_remove_file(&device->dev, &dev_attr_idlepct);
 366         device_remove_file(&device->dev, &dev_attr_rrtime);
 367 }
 368
 369 /*
 370  * Query firmware how many CPUs should be idle
 371  * return -1 on failure
 372  */
 373 static int acpi_pad_pur(acpi_handle handle)
 374 {
 375         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 376         union acpi_object *package;
 377         int num = -1;
 378
 379         if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
 380                 return num;
 381
 382         if (!buffer.length || !buffer.pointer)
 383                 return num;
 384
 385         package = buffer.pointer;
 386
 387         if (package->type == ACPI_TYPE_PACKAGE &&
 388                 package->package.count == 2 &&
 389                 package->package.elements[0].integer.value == 1) /* rev 1 */
 390
 391                 num = package->package.elements[1].integer.value;
 392
 393         kfree(buffer.pointer);
 394         return num;
 395 }
 396
 397 static void acpi_pad_handle_notify(acpi_handle handle)
 398 {
 399         int num_cpus;
 400         uint32_t idle_cpus;
 401         struct acpi_buffer param = {
 402                 .length = 4,
 403                 .pointer = (void *)&idle_cpus,
 404         };
 405
 406         mutex_lock(&isolated_cpus_lock);
 407         num_cpus = acpi_pad_pur(handle);
 408         if (num_cpus < 0) {
 409                 mutex_unlock(&isolated_cpus_lock);
 410                 return;
 411         }
 412         acpi_pad_idle_cpus(num_cpus);
 413         idle_cpus = acpi_pad_idle_cpus_num();
 414         acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, &param);
 415         mutex_unlock(&isolated_cpus_lock);
 416 }
 417
 418 static void acpi_pad_notify(acpi_handle handle, u32 event,
 419         void *data)
 420 {
 421         struct acpi_device *device = data;
 422
 423         switch (event) {
 424         case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
 425                 acpi_pad_handle_notify(handle);
 426                 acpi_bus_generate_netlink_event(device->pnp.device_class,
 427                         dev_name(&device->dev), event, 0);
 428                 break;
 429         default:
 430                 pr_warn("Unsupported event [0x%x]\n", event);
 431                 break;
 432         }
 433 }
 434
 435 static int acpi_pad_add(struct acpi_device *device)
 436 {
 437         acpi_status status;
 438
 439         strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
 440         strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
 441
 442         if (acpi_pad_add_sysfs(device))
 443                 return -ENODEV;
 444
 445         status = acpi_install_notify_handler(device->handle,
 446                 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
 447         if (ACPI_FAILURE(status)) {
 448                 acpi_pad_remove_sysfs(device);
 449                 return -ENODEV;
 450         }
 451
 452         return 0;
 453 }
 454
 455 static int acpi_pad_remove(struct acpi_device *device)
 456 {
 457         mutex_lock(&isolated_cpus_lock);
 458         acpi_pad_idle_cpus(0);
 459         mutex_unlock(&isolated_cpus_lock);
 460
 461         acpi_remove_notify_handler(device->handle,
 462                 ACPI_DEVICE_NOTIFY, acpi_pad_notify);
 463         acpi_pad_remove_sysfs(device);
 464         return 0;
 465 }
 466
 467 static const struct acpi_device_id pad_device_ids[] = {
 468         {"ACPI000C", 0},
 469         {"", 0},
 470 };
 471 MODULE_DEVICE_TABLE(acpi, pad_device_ids);
 472
 473 static struct acpi_driver acpi_pad_driver = {
 474         .name = "processor_aggregator",
 475         .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
 476         .ids = pad_device_ids,
 477         .ops = {
 478                 .add = acpi_pad_add,
 479                 .remove = acpi_pad_remove,
 480         },
 481 };
 482
 483 static int __init acpi_pad_init(void)
 484 {
 485         /* Xen ACPI PAD is used when running as Xen Dom0. */
 486         if (xen_initial_domain())
 487                 return -ENODEV;
 488
 489         power_saving_mwait_init();
 490         if (power_saving_mwait_eax == 0)
 491                 return -EINVAL;
 492
 493         return acpi_bus_register_driver(&acpi_pad_driver);
 494 }
 495
 496 static void __exit acpi_pad_exit(void)
 497 {
 498         acpi_bus_unregister_driver(&acpi_pad_driver);
 499 }
 500
 501 module_init(acpi_pad_init);
 502 module_exit(acpi_pad_exit);
 503 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
 504 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
 505 MODULE_LICENSE("GPL");