drivers/cpufreq/pcc-cpufreq.c

   1 /*
   2  *  pcc-cpufreq.c - Processor Clocking Control firmware cpufreq interface
   3  *
   4  *  Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
   5  *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
   6  *      Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
   7  *
   8  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; version 2 of the License.
  13  *
  14  *  This program is distributed in the hope that it will be useful, but
  15  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or NON
  17  *  INFRINGEMENT. See the GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License along
  20  *  with this program; if not, write to the Free Software Foundation, Inc.,
  21  *  675 Mass Ave, Cambridge, MA 02139, USA.
  22  *
  23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/init.h>
  29 #include <linux/smp.h>
  30 #include <linux/sched.h>
  31 #include <linux/cpufreq.h>
  32 #include <linux/compiler.h>
  33 #include <linux/slab.h>
  34 #include <linux/platform_device.h>
  35
  36 #include <linux/acpi.h>
  37 #include <linux/io.h>
  38 #include <linux/spinlock.h>
  39 #include <linux/uaccess.h>
  40
  41 #include <acpi/processor.h>
  42
  43 #define PCC_VERSION     "1.10.00"
  44 #define POLL_LOOPS      300
  45
  46 #define CMD_COMPLETE    0x1
  47 #define CMD_GET_FREQ    0x0
  48 #define CMD_SET_FREQ    0x1
  49
  50 #define BUF_SZ          4
  51
  52 struct pcc_register_resource {
  53         u8 descriptor;
  54         u16 length;
  55         u8 space_id;
  56         u8 bit_width;
  57         u8 bit_offset;
  58         u8 access_size;
  59         u64 address;
  60 } __attribute__ ((packed));
  61
  62 struct pcc_memory_resource {
  63         u8 descriptor;
  64         u16 length;
  65         u8 space_id;
  66         u8 resource_usage;
  67         u8 type_specific;
  68         u64 granularity;
  69         u64 minimum;
  70         u64 maximum;
  71         u64 translation_offset;
  72         u64 address_length;
  73 } __attribute__ ((packed));
  74
  75 static struct cpufreq_driver pcc_cpufreq_driver;
  76
  77 struct pcc_header {
  78         u32 signature;
  79         u16 length;
  80         u8 major;
  81         u8 minor;
  82         u32 features;
  83         u16 command;
  84         u16 status;
  85         u32 latency;
  86         u32 minimum_time;
  87         u32 maximum_time;
  88         u32 nominal;
  89         u32 throttled_frequency;
  90         u32 minimum_frequency;
  91 };
  92
  93 static void __iomem *pcch_virt_addr;
  94 static struct pcc_header __iomem *pcch_hdr;
  95
  96 static DEFINE_SPINLOCK(pcc_lock);
  97
  98 static struct acpi_generic_address doorbell;
  99
 100 static u64 doorbell_preserve;
 101 static u64 doorbell_write;
 102
 103 static u8 OSC_UUID[16] = {0x9F, 0x2C, 0x9B, 0x63, 0x91, 0x70, 0x1f, 0x49,
 104                           0xBB, 0x4F, 0xA5, 0x98, 0x2F, 0xA1, 0xB5, 0x46};
 105
 106 struct pcc_cpu {
 107         u32 input_offset;
 108         u32 output_offset;
 109 };
 110
 111 static struct pcc_cpu __percpu *pcc_cpu_info;
 112
 113 static int pcc_cpufreq_verify(struct cpufreq_policy_data *policy)
 114 {
 115         cpufreq_verify_within_cpu_limits(policy);
 116         return 0;
 117 }
 118
 119 static inline void pcc_cmd(void)
 120 {
 121         u64 doorbell_value;
 122         int i;
 123
 124         acpi_read(&doorbell_value, &doorbell);
 125         acpi_write((doorbell_value & doorbell_preserve) | doorbell_write,
 126                    &doorbell);
 127
 128         for (i = 0; i < POLL_LOOPS; i++) {
 129                 if (ioread16(&pcch_hdr->status) & CMD_COMPLETE)
 130                         break;
 131         }
 132 }
 133
 134 static inline void pcc_clear_mapping(void)
 135 {
 136         if (pcch_virt_addr)
 137                 iounmap(pcch_virt_addr);
 138         pcch_virt_addr = NULL;
 139 }
 140
 141 static unsigned int pcc_get_freq(unsigned int cpu)
 142 {
 143         struct pcc_cpu *pcc_cpu_data;
 144         unsigned int curr_freq;
 145         unsigned int freq_limit;
 146         u16 status;
 147         u32 input_buffer;
 148         u32 output_buffer;
 149
 150         spin_lock(&pcc_lock);
 151
 152         pr_debug("get: get_freq for CPU %d\n", cpu);
 153         pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 154
 155         input_buffer = 0x1;
 156         iowrite32(input_buffer,
 157                         (pcch_virt_addr + pcc_cpu_data->input_offset));
 158         iowrite16(CMD_GET_FREQ, &pcch_hdr->command);
 159
 160         pcc_cmd();
 161
 162         output_buffer =
 163                 ioread32(pcch_virt_addr + pcc_cpu_data->output_offset);
 164
 165         /* Clear the input buffer - we are done with the current command */
 166         memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 167
 168         status = ioread16(&pcch_hdr->status);
 169         if (status != CMD_COMPLETE) {
 170                 pr_debug("get: FAILED: for CPU %d, status is %d\n",
 171                         cpu, status);
 172                 goto cmd_incomplete;
 173         }
 174         iowrite16(0, &pcch_hdr->status);
 175         curr_freq = (((ioread32(&pcch_hdr->nominal) * (output_buffer & 0xff))
 176                         / 100) * 1000);
 177
 178         pr_debug("get: SUCCESS: (virtual) output_offset for cpu %d is "
 179                 "0x%p, contains a value of: 0x%x. Speed is: %d MHz\n",
 180                 cpu, (pcch_virt_addr + pcc_cpu_data->output_offset),
 181                 output_buffer, curr_freq);
 182
 183         freq_limit = (output_buffer >> 8) & 0xff;
 184         if (freq_limit != 0xff) {
 185                 pr_debug("get: frequency for cpu %d is being temporarily"
 186                         " capped at %d\n", cpu, curr_freq);
 187         }
 188
 189         spin_unlock(&pcc_lock);
 190         return curr_freq;
 191
 192 cmd_incomplete:
 193         iowrite16(0, &pcch_hdr->status);
 194         spin_unlock(&pcc_lock);
 195         return 0;
 196 }
 197
 198 static int pcc_cpufreq_target(struct cpufreq_policy *policy,
 199                               unsigned int target_freq,
 200                               unsigned int relation)
 201 {
 202         struct pcc_cpu *pcc_cpu_data;
 203         struct cpufreq_freqs freqs;
 204         u16 status;
 205         u32 input_buffer;
 206         int cpu;
 207
 208         cpu = policy->cpu;
 209         pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 210
 211         pr_debug("target: CPU %d should go to target freq: %d "
 212                 "(virtual) input_offset is 0x%p\n",
 213                 cpu, target_freq,
 214                 (pcch_virt_addr + pcc_cpu_data->input_offset));
 215
 216         freqs.old = policy->cur;
 217         freqs.new = target_freq;
 218         cpufreq_freq_transition_begin(policy, &freqs);
 219         spin_lock(&pcc_lock);
 220
 221         input_buffer = 0x1 | (((target_freq * 100)
 222                                / (ioread32(&pcch_hdr->nominal) * 1000)) << 8);
 223         iowrite32(input_buffer,
 224                         (pcch_virt_addr + pcc_cpu_data->input_offset));
 225         iowrite16(CMD_SET_FREQ, &pcch_hdr->command);
 226
 227         pcc_cmd();
 228
 229         /* Clear the input buffer - we are done with the current command */
 230         memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 231
 232         status = ioread16(&pcch_hdr->status);
 233         iowrite16(0, &pcch_hdr->status);
 234
 235         spin_unlock(&pcc_lock);
 236         cpufreq_freq_transition_end(policy, &freqs, status != CMD_COMPLETE);
 237
 238         if (status != CMD_COMPLETE) {
 239                 pr_debug("target: FAILED for cpu %d, with status: 0x%x\n",
 240                         cpu, status);
 241                 return -EINVAL;
 242         }
 243
 244         pr_debug("target: was SUCCESSFUL for cpu %d\n", cpu);
 245
 246         return 0;
 247 }
 248
 249 static int pcc_get_offset(int cpu)
 250 {
 251         acpi_status status;
 252         struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
 253         union acpi_object *pccp, *offset;
 254         struct pcc_cpu *pcc_cpu_data;
 255         struct acpi_processor *pr;
 256         int ret = 0;
 257
 258         pr = per_cpu(processors, cpu);
 259         pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
 260
 261         if (!pr)
 262                 return -ENODEV;
 263
 264         status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
 265         if (ACPI_FAILURE(status))
 266                 return -ENODEV;
 267
 268         pccp = buffer.pointer;
 269         if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
 270                 ret = -ENODEV;
 271                 goto out_free;
 272         }
 273
 274         offset = &(pccp->package.elements[0]);
 275         if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 276                 ret = -ENODEV;
 277                 goto out_free;
 278         }
 279
 280         pcc_cpu_data->input_offset = offset->integer.value;
 281
 282         offset = &(pccp->package.elements[1]);
 283         if (!offset || offset->type != ACPI_TYPE_INTEGER) {
 284                 ret = -ENODEV;
 285                 goto out_free;
 286         }
 287
 288         pcc_cpu_data->output_offset = offset->integer.value;
 289
 290         memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
 291         memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);
 292
 293         pr_debug("pcc_get_offset: for CPU %d: pcc_cpu_data "
 294                 "input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x\n",
 295                 cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
 296 out_free:
 297         kfree(buffer.pointer);
 298         return ret;
 299 }
 300
 301 static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
 302 {
 303         acpi_status status;
 304         struct acpi_object_list input;
 305         struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 306         union acpi_object in_params[4];
 307         union acpi_object *out_obj;
 308         u32 capabilities[2];
 309         u32 errors;
 310         u32 supported;
 311         int ret = 0;
 312
 313         input.count = 4;
 314         input.pointer = in_params;
 315         in_params[0].type               = ACPI_TYPE_BUFFER;
 316         in_params[0].buffer.length      = 16;
 317         in_params[0].buffer.pointer     = OSC_UUID;
 318         in_params[1].type               = ACPI_TYPE_INTEGER;
 319         in_params[1].integer.value      = 1;
 320         in_params[2].type               = ACPI_TYPE_INTEGER;
 321         in_params[2].integer.value      = 2;
 322         in_params[3].type               = ACPI_TYPE_BUFFER;
 323         in_params[3].buffer.length      = 8;
 324         in_params[3].buffer.pointer     = (u8 *)&capabilities;
 325
 326         capabilities[0] = OSC_QUERY_ENABLE;
 327         capabilities[1] = 0x1;
 328
 329         status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 330         if (ACPI_FAILURE(status))
 331                 return -ENODEV;
 332
 333         if (!output.length)
 334                 return -ENODEV;
 335
 336         out_obj = output.pointer;
 337         if (out_obj->type != ACPI_TYPE_BUFFER) {
 338                 ret = -ENODEV;
 339                 goto out_free;
 340         }
 341
 342         errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 343         if (errors) {
 344                 ret = -ENODEV;
 345                 goto out_free;
 346         }
 347
 348         supported = *((u32 *)(out_obj->buffer.pointer + 4));
 349         if (!(supported & 0x1)) {
 350                 ret = -ENODEV;
 351                 goto out_free;
 352         }
 353
 354         kfree(output.pointer);
 355         capabilities[0] = 0x0;
 356         capabilities[1] = 0x1;
 357
 358         status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
 359         if (ACPI_FAILURE(status))
 360                 return -ENODEV;
 361
 362         if (!output.length)
 363                 return -ENODEV;
 364
 365         out_obj = output.pointer;
 366         if (out_obj->type != ACPI_TYPE_BUFFER) {
 367                 ret = -ENODEV;
 368                 goto out_free;
 369         }
 370
 371         errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
 372         if (errors) {
 373                 ret = -ENODEV;
 374                 goto out_free;
 375         }
 376
 377         supported = *((u32 *)(out_obj->buffer.pointer + 4));
 378         if (!(supported & 0x1)) {
 379                 ret = -ENODEV;
 380                 goto out_free;
 381         }
 382
 383 out_free:
 384         kfree(output.pointer);
 385         return ret;
 386 }
 387
 388 static int __init pcc_cpufreq_evaluate(void)
 389 {
 390         acpi_status status;
 391         struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 392         struct pcc_memory_resource *mem_resource;
 393         struct pcc_register_resource *reg_resource;
 394         union acpi_object *out_obj, *member;
 395         acpi_handle handle, osc_handle;
 396         int ret = 0;
 397
 398         status = acpi_get_handle(NULL, "\\_SB", &handle);
 399         if (ACPI_FAILURE(status))
 400                 return -ENODEV;
 401
 402         if (!acpi_has_method(handle, "PCCH"))
 403                 return -ENODEV;
 404
 405         status = acpi_get_handle(handle, "_OSC", &osc_handle);
 406         if (ACPI_SUCCESS(status)) {
 407                 ret = pcc_cpufreq_do_osc(&osc_handle);
 408                 if (ret)
 409                         pr_debug("probe: _OSC evaluation did not succeed\n");
 410                 /* Firmware's use of _OSC is optional */
 411                 ret = 0;
 412         }
 413
 414         status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
 415         if (ACPI_FAILURE(status))
 416                 return -ENODEV;
 417
 418         out_obj = output.pointer;
 419         if (out_obj->type != ACPI_TYPE_PACKAGE) {
 420                 ret = -ENODEV;
 421                 goto out_free;
 422         }
 423
 424         member = &out_obj->package.elements[0];
 425         if (member->type != ACPI_TYPE_BUFFER) {
 426                 ret = -ENODEV;
 427                 goto out_free;
 428         }
 429
 430         mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;
 431
 432         pr_debug("probe: mem_resource descriptor: 0x%x,"
 433                 " length: %d, space_id: %d, resource_usage: %d,"
 434                 " type_specific: %d, granularity: 0x%llx,"
 435                 " minimum: 0x%llx, maximum: 0x%llx,"
 436                 " translation_offset: 0x%llx, address_length: 0x%llx\n",
 437                 mem_resource->descriptor, mem_resource->length,
 438                 mem_resource->space_id, mem_resource->resource_usage,
 439                 mem_resource->type_specific, mem_resource->granularity,
 440                 mem_resource->minimum, mem_resource->maximum,
 441                 mem_resource->translation_offset,
 442                 mem_resource->address_length);
 443
 444         if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 445                 ret = -ENODEV;
 446                 goto out_free;
 447         }
 448
 449         pcch_virt_addr = ioremap(mem_resource->minimum,
 450                                         mem_resource->address_length);
 451         if (pcch_virt_addr == NULL) {
 452                 pr_debug("probe: could not map shared mem region\n");
 453                 ret = -ENOMEM;
 454                 goto out_free;
 455         }
 456         pcch_hdr = pcch_virt_addr;
 457
 458         pr_debug("probe: PCCH header (virtual) addr: 0x%p\n", pcch_hdr);
 459         pr_debug("probe: PCCH header is at physical address: 0x%llx,"
 460                 " signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
 461                 " supported features: 0x%x, command field: 0x%x,"
 462                 " status field: 0x%x, nominal latency: %d us\n",
 463                 mem_resource->minimum, ioread32(&pcch_hdr->signature),
 464                 ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
 465                 ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
 466                 ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
 467                 ioread32(&pcch_hdr->latency));
 468
 469         pr_debug("probe: min time between commands: %d us,"
 470                 " max time between commands: %d us,"
 471                 " nominal CPU frequency: %d MHz,"
 472                 " minimum CPU frequency: %d MHz,"
 473                 " minimum CPU frequency without throttling: %d MHz\n",
 474                 ioread32(&pcch_hdr->minimum_time),
 475                 ioread32(&pcch_hdr->maximum_time),
 476                 ioread32(&pcch_hdr->nominal),
 477                 ioread32(&pcch_hdr->throttled_frequency),
 478                 ioread32(&pcch_hdr->minimum_frequency));
 479
 480         member = &out_obj->package.elements[1];
 481         if (member->type != ACPI_TYPE_BUFFER) {
 482                 ret = -ENODEV;
 483                 goto pcch_free;
 484         }
 485
 486         reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
 487
 488         doorbell.space_id = reg_resource->space_id;
 489         doorbell.bit_width = reg_resource->bit_width;
 490         doorbell.bit_offset = reg_resource->bit_offset;
 491         doorbell.access_width = 4;
 492         doorbell.address = reg_resource->address;
 493
 494         pr_debug("probe: doorbell: space_id is %d, bit_width is %d, "
 495                 "bit_offset is %d, access_width is %d, address is 0x%llx\n",
 496                 doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
 497                 doorbell.access_width, reg_resource->address);
 498
 499         member = &out_obj->package.elements[2];
 500         if (member->type != ACPI_TYPE_INTEGER) {
 501                 ret = -ENODEV;
 502                 goto pcch_free;
 503         }
 504
 505         doorbell_preserve = member->integer.value;
 506
 507         member = &out_obj->package.elements[3];
 508         if (member->type != ACPI_TYPE_INTEGER) {
 509                 ret = -ENODEV;
 510                 goto pcch_free;
 511         }
 512
 513         doorbell_write = member->integer.value;
 514
 515         pr_debug("probe: doorbell_preserve: 0x%llx,"
 516                 " doorbell_write: 0x%llx\n",
 517                 doorbell_preserve, doorbell_write);
 518
 519         pcc_cpu_info = alloc_percpu(struct pcc_cpu);
 520         if (!pcc_cpu_info) {
 521                 ret = -ENOMEM;
 522                 goto pcch_free;
 523         }
 524
 525         printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
 526                " limits: %d MHz, %d MHz\n", PCC_VERSION,
 527                ioread32(&pcch_hdr->minimum_frequency),
 528                ioread32(&pcch_hdr->nominal));
 529         kfree(output.pointer);
 530         return ret;
 531 pcch_free:
 532         pcc_clear_mapping();
 533 out_free:
 534         kfree(output.pointer);
 535         return ret;
 536 }
 537
 538 static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 539 {
 540         unsigned int cpu = policy->cpu;
 541         unsigned int result = 0;
 542
 543         if (!pcch_virt_addr) {
 544                 result = -1;
 545                 goto out;
 546         }
 547
 548         result = pcc_get_offset(cpu);
 549         if (result) {
 550                 pr_debug("init: PCCP evaluation failed\n");
 551                 goto out;
 552         }
 553
 554         policy->max = policy->cpuinfo.max_freq =
 555                 ioread32(&pcch_hdr->nominal) * 1000;
 556         policy->min = policy->cpuinfo.min_freq =
 557                 ioread32(&pcch_hdr->minimum_frequency) * 1000;
 558
 559         pr_debug("init: policy->max is %d, policy->min is %d\n",
 560                 policy->max, policy->min);
 561 out:
 562         return result;
 563 }
 564
 565 static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 566 {
 567         return 0;
 568 }
 569
 570 static struct cpufreq_driver pcc_cpufreq_driver = {
 571         .flags = CPUFREQ_CONST_LOOPS,
 572         .get = pcc_get_freq,
 573         .verify = pcc_cpufreq_verify,
 574         .target = pcc_cpufreq_target,
 575         .init = pcc_cpufreq_cpu_init,
 576         .exit = pcc_cpufreq_cpu_exit,
 577         .name = "pcc-cpufreq",
 578 };
 579
 580 static int __init pcc_cpufreq_probe(struct platform_device *pdev)
 581 {
 582         int ret;
 583
 584         /* Skip initialization if another cpufreq driver is there. */
 585         if (cpufreq_get_current_driver())
 586                 return -ENODEV;
 587
 588         if (acpi_disabled)
 589                 return -ENODEV;
 590
 591         ret = pcc_cpufreq_evaluate();
 592         if (ret) {
 593                 pr_debug("pcc_cpufreq_probe: PCCH evaluation failed\n");
 594                 return ret;
 595         }
 596
 597         if (num_present_cpus() > 4) {
 598                 pcc_cpufreq_driver.flags |= CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING;
 599                 pr_err("%s: Too many CPUs, dynamic performance scaling disabled\n",
 600                        __func__);
 601                 pr_err("%s: Try to enable another scaling driver through BIOS settings\n",
 602                        __func__);
 603                 pr_err("%s: and complain to the system vendor\n", __func__);
 604         }
 605
 606         ret = cpufreq_register_driver(&pcc_cpufreq_driver);
 607
 608         return ret;
 609 }
 610
 611 static void pcc_cpufreq_remove(struct platform_device *pdev)
 612 {
 613         cpufreq_unregister_driver(&pcc_cpufreq_driver);
 614
 615         pcc_clear_mapping();
 616
 617         free_percpu(pcc_cpu_info);
 618 }
 619
 620 static struct platform_driver pcc_cpufreq_platdrv = {
 621         .driver = {
 622                 .name   = "pcc-cpufreq",
 623         },
 624         .remove_new     = pcc_cpufreq_remove,
 625 };
 626
 627 static int __init pcc_cpufreq_init(void)
 628 {
 629         return platform_driver_probe(&pcc_cpufreq_platdrv, pcc_cpufreq_probe);
 630 }
 631
 632 static void __exit pcc_cpufreq_exit(void)
 633 {
 634         platform_driver_unregister(&pcc_cpufreq_platdrv);
 635 }
 636
 637 MODULE_ALIAS("platform:pcc-cpufreq");
 638
 639 MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
 640 MODULE_VERSION(PCC_VERSION);
 641 MODULE_DESCRIPTION("Processor Clocking Control interface driver");
 642 MODULE_LICENSE("GPL");
 643
 644 late_initcall(pcc_cpufreq_init);
 645 module_exit(pcc_cpufreq_exit);