drivers/xen/xen-acpi-processor.c

   1 /*
   2  * Copyright 2012 by Oracle Inc
   3  * Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
   4  *
   5  * This code borrows ideas from https://lkml.org/lkml/2011/11/30/249
   6  * so many thanks go to Kevin Tian <kevin.tian@intel.com>
   7  * and Yu Ke <ke.yu@intel.com>.
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms and conditions of the GNU General Public License,
  11  * version 2, as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope it will be useful, but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16  * more details.
  17  *
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/cpumask.h>
  23 #include <linux/cpufreq.h>
  24 #include <linux/freezer.h>
  25 #include <linux/kernel.h>
  26 #include <linux/kthread.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/types.h>
  30 #include <linux/syscore_ops.h>
  31 #include <linux/acpi.h>
  32 #include <acpi/processor.h>
  33 #include <xen/xen.h>
  34 #include <xen/interface/platform.h>
  35 #include <asm/xen/hypercall.h>
  36
  37 static int no_hypercall;
  38 MODULE_PARM_DESC(off, "Inhibit the hypercall.");
  39 module_param_named(off, no_hypercall, int, 0400);
  40
  41 /*
  42  * Note: Do not convert the acpi_id* below to cpumask_var_t or use cpumask_bit
  43  * - as those shrink to nr_cpu_bits (which is dependent on possible_cpu), which
  44  * can be less than what we want to put in. Instead use the 'nr_acpi_bits'
  45  * which is dynamically computed based on the MADT or x2APIC table.
  46  */
  47 static unsigned int nr_acpi_bits;
  48 /* Mutex to protect the acpi_ids_done - for CPU hotplug use. */
  49 static DEFINE_MUTEX(acpi_ids_mutex);
  50 /* Which ACPI ID we have processed from 'struct acpi_processor'. */
  51 static unsigned long *acpi_ids_done;
  52 /* Which ACPI ID exist in the SSDT/DSDT processor definitions. */
  53 static unsigned long *acpi_id_present;
  54 /* And if there is an _CST definition (or a PBLK) for the ACPI IDs */
  55 static unsigned long *acpi_id_cst_present;
  56
  57 static int push_cxx_to_hypervisor(struct acpi_processor *_pr)
  58 {
  59         struct xen_platform_op op = {
  60                 .cmd                    = XENPF_set_processor_pminfo,
  61                 .interface_version      = XENPF_INTERFACE_VERSION,
  62                 .u.set_pminfo.id        = _pr->acpi_id,
  63                 .u.set_pminfo.type      = XEN_PM_CX,
  64         };
  65         struct xen_processor_cx *dst_cx, *dst_cx_states = NULL;
  66         struct acpi_processor_cx *cx;
  67         unsigned int i, ok;
  68         int ret = 0;
  69
  70         dst_cx_states = kcalloc(_pr->power.count,
  71                                 sizeof(struct xen_processor_cx), GFP_KERNEL);
  72         if (!dst_cx_states)
  73                 return -ENOMEM;
  74
  75         for (ok = 0, i = 1; i <= _pr->power.count; i++) {
  76                 cx = &_pr->power.states[i];
  77                 if (!cx->valid)
  78                         continue;
  79
  80                 dst_cx = &(dst_cx_states[ok++]);
  81
  82                 dst_cx->reg.space_id = ACPI_ADR_SPACE_SYSTEM_IO;
  83                 if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
  84                         dst_cx->reg.bit_width = 8;
  85                         dst_cx->reg.bit_offset = 0;
  86                         dst_cx->reg.access_size = 1;
  87                 } else {
  88                         dst_cx->reg.space_id = ACPI_ADR_SPACE_FIXED_HARDWARE;
  89                         if (cx->entry_method == ACPI_CSTATE_FFH) {
  90                                 /* NATIVE_CSTATE_BEYOND_HALT */
  91                                 dst_cx->reg.bit_offset = 2;
  92                                 dst_cx->reg.bit_width = 1; /* VENDOR_INTEL */
  93                         }
  94                         dst_cx->reg.access_size = 0;
  95                 }
  96                 dst_cx->reg.address = cx->address;
  97
  98                 dst_cx->type = cx->type;
  99                 dst_cx->latency = cx->latency;
 100
 101                 dst_cx->dpcnt = 0;
 102                 set_xen_guest_handle(dst_cx->dp, NULL);
 103         }
 104         if (!ok) {
 105                 pr_debug("No _Cx for ACPI CPU %u\n", _pr->acpi_id);
 106                 kfree(dst_cx_states);
 107                 return -EINVAL;
 108         }
 109         op.u.set_pminfo.power.count = ok;
 110         op.u.set_pminfo.power.flags.bm_control = _pr->flags.bm_control;
 111         op.u.set_pminfo.power.flags.bm_check = _pr->flags.bm_check;
 112         op.u.set_pminfo.power.flags.has_cst = _pr->flags.has_cst;
 113         op.u.set_pminfo.power.flags.power_setup_done =
 114                 _pr->flags.power_setup_done;
 115
 116         set_xen_guest_handle(op.u.set_pminfo.power.states, dst_cx_states);
 117
 118         if (!no_hypercall)
 119                 ret = HYPERVISOR_platform_op(&op);
 120
 121         if (!ret) {
 122                 pr_debug("ACPI CPU%u - C-states uploaded.\n", _pr->acpi_id);
 123                 for (i = 1; i <= _pr->power.count; i++) {
 124                         cx = &_pr->power.states[i];
 125                         if (!cx->valid)
 126                                 continue;
 127                         pr_debug("     C%d: %s %d uS\n",
 128                                  cx->type, cx->desc, (u32)cx->latency);
 129                 }
 130         } else if ((ret != -EINVAL) && (ret != -ENOSYS))
 131                 /* EINVAL means the ACPI ID is incorrect - meaning the ACPI
 132                  * table is referencing a non-existing CPU - which can happen
 133                  * with broken ACPI tables. */
 134                 pr_err("(CX): Hypervisor error (%d) for ACPI CPU%u\n",
 135                        ret, _pr->acpi_id);
 136
 137         kfree(dst_cx_states);
 138
 139         return ret;
 140 }
 141 static struct xen_processor_px *
 142 xen_copy_pss_data(struct acpi_processor *_pr,
 143                   struct xen_processor_performance *dst_perf)
 144 {
 145         struct xen_processor_px *dst_states = NULL;
 146         unsigned int i;
 147
 148         BUILD_BUG_ON(sizeof(struct xen_processor_px) !=
 149                      sizeof(struct acpi_processor_px));
 150
 151         dst_states = kcalloc(_pr->performance->state_count,
 152                              sizeof(struct xen_processor_px), GFP_KERNEL);
 153         if (!dst_states)
 154                 return ERR_PTR(-ENOMEM);
 155
 156         dst_perf->state_count = _pr->performance->state_count;
 157         for (i = 0; i < _pr->performance->state_count; i++) {
 158                 /* Fortunatly for us, they are both the same size */
 159                 memcpy(&(dst_states[i]), &(_pr->performance->states[i]),
 160                        sizeof(struct acpi_processor_px));
 161         }
 162         return dst_states;
 163 }
 164 static int xen_copy_psd_data(struct acpi_processor *_pr,
 165                              struct xen_processor_performance *dst)
 166 {
 167         struct acpi_psd_package *pdomain;
 168
 169         BUILD_BUG_ON(sizeof(struct xen_psd_package) !=
 170                      sizeof(struct acpi_psd_package));
 171
 172         /* This information is enumerated only if acpi_processor_preregister_performance
 173          * has been called.
 174          */
 175         dst->shared_type = _pr->performance->shared_type;
 176
 177         pdomain = &(_pr->performance->domain_info);
 178
 179         /* 'acpi_processor_preregister_performance' does not parse if the
 180          * num_processors <= 1, but Xen still requires it. Do it manually here.
 181          */
 182         if (pdomain->num_processors <= 1) {
 183                 if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ALL)
 184                         dst->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 185                 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_HW_ALL)
 186                         dst->shared_type = CPUFREQ_SHARED_TYPE_HW;
 187                 else if (pdomain->coord_type == DOMAIN_COORD_TYPE_SW_ANY)
 188                         dst->shared_type = CPUFREQ_SHARED_TYPE_ANY;
 189
 190         }
 191         memcpy(&(dst->domain_info), pdomain, sizeof(struct acpi_psd_package));
 192         return 0;
 193 }
 194 static int xen_copy_pct_data(struct acpi_pct_register *pct,
 195                              struct xen_pct_register *dst_pct)
 196 {
 197         /* It would be nice if you could just do 'memcpy(pct, dst_pct') but
 198          * sadly the Xen structure did not have the proper padding so the
 199          * descriptor field takes two (dst_pct) bytes instead of one (pct).
 200          */
 201         dst_pct->descriptor = pct->descriptor;
 202         dst_pct->length = pct->length;
 203         dst_pct->space_id = pct->space_id;
 204         dst_pct->bit_width = pct->bit_width;
 205         dst_pct->bit_offset = pct->bit_offset;
 206         dst_pct->reserved = pct->reserved;
 207         dst_pct->address = pct->address;
 208         return 0;
 209 }
 210 static int push_pxx_to_hypervisor(struct acpi_processor *_pr)
 211 {
 212         int ret = 0;
 213         struct xen_platform_op op = {
 214                 .cmd                    = XENPF_set_processor_pminfo,
 215                 .interface_version      = XENPF_INTERFACE_VERSION,
 216                 .u.set_pminfo.id        = _pr->acpi_id,
 217                 .u.set_pminfo.type      = XEN_PM_PX,
 218         };
 219         struct xen_processor_performance *dst_perf;
 220         struct xen_processor_px *dst_states = NULL;
 221
 222         dst_perf = &op.u.set_pminfo.perf;
 223
 224         dst_perf->platform_limit = _pr->performance_platform_limit;
 225         dst_perf->flags |= XEN_PX_PPC;
 226         xen_copy_pct_data(&(_pr->performance->control_register),
 227                           &dst_perf->control_register);
 228         xen_copy_pct_data(&(_pr->performance->status_register),
 229                           &dst_perf->status_register);
 230         dst_perf->flags |= XEN_PX_PCT;
 231         dst_states = xen_copy_pss_data(_pr, dst_perf);
 232         if (!IS_ERR_OR_NULL(dst_states)) {
 233                 set_xen_guest_handle(dst_perf->states, dst_states);
 234                 dst_perf->flags |= XEN_PX_PSS;
 235         }
 236         if (!xen_copy_psd_data(_pr, dst_perf))
 237                 dst_perf->flags |= XEN_PX_PSD;
 238
 239         if (dst_perf->flags != (XEN_PX_PSD | XEN_PX_PSS | XEN_PX_PCT | XEN_PX_PPC)) {
 240                 pr_warn("ACPI CPU%u missing some P-state data (%x), skipping\n",
 241                         _pr->acpi_id, dst_perf->flags);
 242                 ret = -ENODEV;
 243                 goto err_free;
 244         }
 245
 246         if (!no_hypercall)
 247                 ret = HYPERVISOR_platform_op(&op);
 248
 249         if (!ret) {
 250                 struct acpi_processor_performance *perf;
 251                 unsigned int i;
 252
 253                 perf = _pr->performance;
 254                 pr_debug("ACPI CPU%u - P-states uploaded.\n", _pr->acpi_id);
 255                 for (i = 0; i < perf->state_count; i++) {
 256                         pr_debug("     %cP%d: %d MHz, %d mW, %d uS\n",
 257                         (i == perf->state ? '*' : ' '), i,
 258                         (u32) perf->states[i].core_frequency,
 259                         (u32) perf->states[i].power,
 260                         (u32) perf->states[i].transition_latency);
 261                 }
 262         } else if ((ret != -EINVAL) && (ret != -ENOSYS))
 263                 /* EINVAL means the ACPI ID is incorrect - meaning the ACPI
 264                  * table is referencing a non-existing CPU - which can happen
 265                  * with broken ACPI tables. */
 266                 pr_warn("(_PXX): Hypervisor error (%d) for ACPI CPU%u\n",
 267                         ret, _pr->acpi_id);
 268 err_free:
 269         if (!IS_ERR_OR_NULL(dst_states))
 270                 kfree(dst_states);
 271
 272         return ret;
 273 }
 274 static int upload_pm_data(struct acpi_processor *_pr)
 275 {
 276         int err = 0;
 277
 278         mutex_lock(&acpi_ids_mutex);
 279         if (__test_and_set_bit(_pr->acpi_id, acpi_ids_done)) {
 280                 mutex_unlock(&acpi_ids_mutex);
 281                 return -EBUSY;
 282         }
 283         if (_pr->flags.power)
 284                 err = push_cxx_to_hypervisor(_pr);
 285
 286         if (_pr->performance && _pr->performance->states)
 287                 err |= push_pxx_to_hypervisor(_pr);
 288
 289         mutex_unlock(&acpi_ids_mutex);
 290         return err;
 291 }
 292 static unsigned int __init get_max_acpi_id(void)
 293 {
 294         struct xenpf_pcpuinfo *info;
 295         struct xen_platform_op op = {
 296                 .cmd = XENPF_get_cpuinfo,
 297                 .interface_version = XENPF_INTERFACE_VERSION,
 298         };
 299         int ret = 0;
 300         unsigned int i, last_cpu, max_acpi_id = 0;
 301
 302         info = &op.u.pcpu_info;
 303         info->xen_cpuid = 0;
 304
 305         ret = HYPERVISOR_platform_op(&op);
 306         if (ret)
 307                 return NR_CPUS;
 308
 309         /* The max_present is the same irregardless of the xen_cpuid */
 310         last_cpu = op.u.pcpu_info.max_present;
 311         for (i = 0; i <= last_cpu; i++) {
 312                 info->xen_cpuid = i;
 313                 ret = HYPERVISOR_platform_op(&op);
 314                 if (ret)
 315                         continue;
 316                 max_acpi_id = max(info->acpi_id, max_acpi_id);
 317         }
 318         max_acpi_id *= 2; /* Slack for CPU hotplug support. */
 319         pr_debug("Max ACPI ID: %u\n", max_acpi_id);
 320         return max_acpi_id;
 321 }
 322 /*
 323  * The read_acpi_id and check_acpi_ids are there to support the Xen
 324  * oddity of virtual CPUs != physical CPUs in the initial domain.
 325  * The user can supply 'xen_max_vcpus=X' on the Xen hypervisor line
 326  * which will band the amount of CPUs the initial domain can see.
 327  * In general that is OK, except it plays havoc with any of the
 328  * for_each_[present|online]_cpu macros which are banded to the virtual
 329  * CPU amount.
 330  */
 331 static acpi_status
 332 read_acpi_id(acpi_handle handle, u32 lvl, void *context, void **rv)
 333 {
 334         u32 acpi_id;
 335         acpi_status status;
 336         acpi_object_type acpi_type;
 337         unsigned long long tmp;
 338         union acpi_object object = { 0 };
 339         struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
 340         acpi_io_address pblk = 0;
 341
 342         status = acpi_get_type(handle, &acpi_type);
 343         if (ACPI_FAILURE(status))
 344                 return AE_OK;
 345
 346         switch (acpi_type) {
 347         case ACPI_TYPE_PROCESSOR:
 348                 status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
 349                 if (ACPI_FAILURE(status))
 350                         return AE_OK;
 351                 acpi_id = object.processor.proc_id;
 352                 pblk = object.processor.pblk_address;
 353                 break;
 354         case ACPI_TYPE_DEVICE:
 355                 status = acpi_evaluate_integer(handle, "_UID", NULL, &tmp);
 356                 if (ACPI_FAILURE(status))
 357                         return AE_OK;
 358                 acpi_id = tmp;
 359                 break;
 360         default:
 361                 return AE_OK;
 362         }
 363         /* There are more ACPI Processor objects than in x2APIC or MADT.
 364          * This can happen with incorrect ACPI SSDT declerations. */
 365         if (acpi_id > nr_acpi_bits) {
 366                 pr_debug("We only have %u, trying to set %u\n",
 367                          nr_acpi_bits, acpi_id);
 368                 return AE_OK;
 369         }
 370         /* OK, There is a ACPI Processor object */
 371         __set_bit(acpi_id, acpi_id_present);
 372
 373         pr_debug("ACPI CPU%u w/ PBLK:0x%lx\n", acpi_id, (unsigned long)pblk);
 374
 375         status = acpi_evaluate_object(handle, "_CST", NULL, &buffer);
 376         if (ACPI_FAILURE(status)) {
 377                 if (!pblk)
 378                         return AE_OK;
 379         }
 380         /* .. and it has a C-state */
 381         __set_bit(acpi_id, acpi_id_cst_present);
 382
 383         return AE_OK;
 384 }
 385 static int check_acpi_ids(struct acpi_processor *pr_backup)
 386 {
 387
 388         if (!pr_backup)
 389                 return -ENODEV;
 390
 391         if (acpi_id_present && acpi_id_cst_present)
 392                 /* OK, done this once .. skip to uploading */
 393                 goto upload;
 394
 395         /* All online CPUs have been processed at this stage. Now verify
 396          * whether in fact "online CPUs" == physical CPUs.
 397          */
 398         acpi_id_present = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
 399         if (!acpi_id_present)
 400                 return -ENOMEM;
 401
 402         acpi_id_cst_present = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
 403         if (!acpi_id_cst_present) {
 404                 kfree(acpi_id_present);
 405                 return -ENOMEM;
 406         }
 407
 408         acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
 409                             ACPI_UINT32_MAX,
 410                             read_acpi_id, NULL, NULL, NULL);
 411         acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, read_acpi_id, NULL, NULL);
 412
 413 upload:
 414         if (!bitmap_equal(acpi_id_present, acpi_ids_done, nr_acpi_bits)) {
 415                 unsigned int i;
 416                 for_each_set_bit(i, acpi_id_present, nr_acpi_bits) {
 417                         pr_backup->acpi_id = i;
 418                         /* Mask out C-states if there are no _CST or PBLK */
 419                         pr_backup->flags.power = test_bit(i, acpi_id_cst_present);
 420                         (void)upload_pm_data(pr_backup);
 421                 }
 422         }
 423
 424         return 0;
 425 }
 426
 427 /* acpi_perf_data is a pointer to percpu data. */
 428 static struct acpi_processor_performance __percpu *acpi_perf_data;
 429
 430 static void free_acpi_perf_data(void)
 431 {
 432         unsigned int i;
 433
 434         /* Freeing a NULL pointer is OK, and alloc_percpu zeroes. */
 435         for_each_possible_cpu(i)
 436                 free_cpumask_var(per_cpu_ptr(acpi_perf_data, i)
 437                                  ->shared_cpu_map);
 438         free_percpu(acpi_perf_data);
 439 }
 440
 441 static int xen_upload_processor_pm_data(void)
 442 {
 443         struct acpi_processor *pr_backup = NULL;
 444         unsigned int i;
 445         int rc = 0;
 446
 447         pr_info("Uploading Xen processor PM info\n");
 448
 449         for_each_possible_cpu(i) {
 450                 struct acpi_processor *_pr;
 451                 _pr = per_cpu(processors, i /* APIC ID */);
 452                 if (!_pr)
 453                         continue;
 454
 455                 if (!pr_backup) {
 456                         pr_backup = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
 457                         if (pr_backup)
 458                                 memcpy(pr_backup, _pr, sizeof(struct acpi_processor));
 459                 }
 460                 (void)upload_pm_data(_pr);
 461         }
 462
 463         rc = check_acpi_ids(pr_backup);
 464         kfree(pr_backup);
 465
 466         return rc;
 467 }
 468
 469 static void xen_acpi_processor_resume_worker(struct work_struct *dummy)
 470 {
 471         int rc;
 472
 473         bitmap_zero(acpi_ids_done, nr_acpi_bits);
 474
 475         rc = xen_upload_processor_pm_data();
 476         if (rc != 0)
 477                 pr_info("ACPI data upload failed, error = %d\n", rc);
 478 }
 479
 480 static void xen_acpi_processor_resume(void)
 481 {
 482         static DECLARE_WORK(wq, xen_acpi_processor_resume_worker);
 483
 484         /*
 485          * xen_upload_processor_pm_data() calls non-atomic code.
 486          * However, the context for xen_acpi_processor_resume is syscore
 487          * with only the boot CPU online and in an atomic context.
 488          *
 489          * So defer the upload for some point safer.
 490          */
 491         schedule_work(&wq);
 492 }
 493
 494 static struct syscore_ops xap_syscore_ops = {
 495         .resume = xen_acpi_processor_resume,
 496 };
 497
 498 static int __init xen_acpi_processor_init(void)
 499 {
 500         unsigned int i;
 501         int rc;
 502
 503         if (!xen_initial_domain())
 504                 return -ENODEV;
 505
 506         nr_acpi_bits = get_max_acpi_id() + 1;
 507         acpi_ids_done = kcalloc(BITS_TO_LONGS(nr_acpi_bits), sizeof(unsigned long), GFP_KERNEL);
 508         if (!acpi_ids_done)
 509                 return -ENOMEM;
 510
 511         acpi_perf_data = alloc_percpu(struct acpi_processor_performance);
 512         if (!acpi_perf_data) {
 513                 pr_debug("Memory allocation error for acpi_perf_data\n");
 514                 kfree(acpi_ids_done);
 515                 return -ENOMEM;
 516         }
 517         for_each_possible_cpu(i) {
 518                 if (!zalloc_cpumask_var_node(
 519                         &per_cpu_ptr(acpi_perf_data, i)->shared_cpu_map,
 520                         GFP_KERNEL, cpu_to_node(i))) {
 521                         rc = -ENOMEM;
 522                         goto err_out;
 523                 }
 524         }
 525
 526         /* Do initialization in ACPI core. It is OK to fail here. */
 527         (void)acpi_processor_preregister_performance(acpi_perf_data);
 528
 529         for_each_possible_cpu(i) {
 530                 struct acpi_processor *pr;
 531                 struct acpi_processor_performance *perf;
 532
 533                 pr = per_cpu(processors, i);
 534                 perf = per_cpu_ptr(acpi_perf_data, i);
 535                 if (!pr)
 536                         continue;
 537
 538                 pr->performance = perf;
 539                 rc = acpi_processor_get_performance_info(pr);
 540                 if (rc)
 541                         goto err_out;
 542         }
 543
 544         rc = xen_upload_processor_pm_data();
 545         if (rc)
 546                 goto err_unregister;
 547
 548         register_syscore_ops(&xap_syscore_ops);
 549
 550         return 0;
 551 err_unregister:
 552         for_each_possible_cpu(i)
 553                 acpi_processor_unregister_performance(i);
 554
 555 err_out:
 556         /* Freeing a NULL pointer is OK: alloc_percpu zeroes. */
 557         free_acpi_perf_data();
 558         kfree(acpi_ids_done);
 559         return rc;
 560 }
 561 static void __exit xen_acpi_processor_exit(void)
 562 {
 563         int i;
 564
 565         unregister_syscore_ops(&xap_syscore_ops);
 566         kfree(acpi_ids_done);
 567         kfree(acpi_id_present);
 568         kfree(acpi_id_cst_present);
 569         for_each_possible_cpu(i)
 570                 acpi_processor_unregister_performance(i);
 571
 572         free_acpi_perf_data();
 573 }
 574
 575 MODULE_AUTHOR("Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>");
 576 MODULE_DESCRIPTION("Xen ACPI Processor P-states (and Cx) driver which uploads PM data to Xen hypervisor");
 577 MODULE_LICENSE("GPL");
 578
 579 /* We want to be loaded before the CPU freq scaling drivers are loaded.
 580  * They are loaded in late_initcall. */
 581 device_initcall(xen_acpi_processor_init);
 582 module_exit(xen_acpi_processor_exit);