drivers/cpufreq/powernow-k7.c

   1 /*
   2  *  AMD K7 Powernow driver.
   3  *  (C) 2003 Dave Jones on behalf of SuSE Labs.
   4  *  (C) 2003-2004 Dave Jones <[email protected]>
   5  *
   6  *  Licensed under the terms of the GNU GPL License version 2.
   7  *  Based upon datasheets & sample CPUs kindly provided by AMD.
   8  *
   9  * Errata 5:
  10  *  CPU may fail to execute a FID/VID change in presence of interrupt.
  11  *  - We cli/sti on stepping A0 CPUs around the FID/VID transition.
  12  * Errata 15:
  13  *  CPU with half frequency multipliers may hang upon wakeup from disconnect.
  14  *  - We disable half multipliers if ACPI is used on A0 stepping CPUs.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/init.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/slab.h>
  23 #include <linux/string.h>
  24 #include <linux/dmi.h>
  25 #include <linux/timex.h>
  26 #include <linux/io.h>
  27
  28 #include <asm/timer.h>          /* Needed for recalibrate_cpu_khz() */
  29 #include <asm/msr.h>
  30 #include <asm/cpu_device_id.h>
  31
  32 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
  33 #include <linux/acpi.h>
  34 #include <acpi/processor.h>
  35 #endif
  36
  37 #include "powernow-k7.h"
  38
  39 #define PFX "powernow: "
  40
  41
  42 struct psb_s {
  43         u8 signature[10];
  44         u8 tableversion;
  45         u8 flags;
  46         u16 settlingtime;
  47         u8 reserved1;
  48         u8 numpst;
  49 };
  50
  51 struct pst_s {
  52         u32 cpuid;
  53         u8 fsbspeed;
  54         u8 maxfid;
  55         u8 startvid;
  56         u8 numpstates;
  57 };
  58
  59 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
  60 union powernow_acpi_control_t {
  61         struct {
  62                 unsigned long fid:5,
  63                         vid:5,
  64                         sgtc:20,
  65                         res1:2;
  66         } bits;
  67         unsigned long val;
  68 };
  69 #endif
  70
  71 /* divide by 1000 to get VCore voltage in V. */
  72 static const int mobile_vid_table[32] = {
  73     2000, 1950, 1900, 1850, 1800, 1750, 1700, 1650,
  74     1600, 1550, 1500, 1450, 1400, 1350, 1300, 0,
  75     1275, 1250, 1225, 1200, 1175, 1150, 1125, 1100,
  76     1075, 1050, 1025, 1000, 975, 950, 925, 0,
  77 };
  78
  79 /* divide by 10 to get FID. */
  80 static const int fid_codes[32] = {
  81     110, 115, 120, 125, 50, 55, 60, 65,
  82     70, 75, 80, 85, 90, 95, 100, 105,
  83     30, 190, 40, 200, 130, 135, 140, 210,
  84     150, 225, 160, 165, 170, 180, -1, -1,
  85 };
  86
  87 /* This parameter is used in order to force ACPI instead of legacy method for
  88  * configuration purpose.
  89  */
  90
  91 static int acpi_force;
  92
  93 static struct cpufreq_frequency_table *powernow_table;
  94
  95 static unsigned int can_scale_bus;
  96 static unsigned int can_scale_vid;
  97 static unsigned int minimum_speed = -1;
  98 static unsigned int maximum_speed;
  99 static unsigned int number_scales;
 100 static unsigned int fsb;
 101 static unsigned int latency;
 102 static char have_a0;
 103
 104 static int check_fsb(unsigned int fsbspeed)
 105 {
 106         int delta;
 107         unsigned int f = fsb / 1000;
 108
 109         delta = (fsbspeed > f) ? fsbspeed - f : f - fsbspeed;
 110         return delta < 5;
 111 }
 112
 113 static const struct x86_cpu_id powernow_k7_cpuids[] = {
 114         { X86_VENDOR_AMD, 6, },
 115         {}
 116 };
 117 MODULE_DEVICE_TABLE(x86cpu, powernow_k7_cpuids);
 118
 119 static int check_powernow(void)
 120 {
 121         struct cpuinfo_x86 *c = &cpu_data(0);
 122         unsigned int maxei, eax, ebx, ecx, edx;
 123
 124         if (!x86_match_cpu(powernow_k7_cpuids))
 125                 return 0;
 126
 127         /* Get maximum capabilities */
 128         maxei = cpuid_eax(0x80000000);
 129         if (maxei < 0x80000007) {       /* Any powernow info ? */
 130 #ifdef MODULE
 131                 printk(KERN_INFO PFX "No powernow capabilities detected\n");
 132 #endif
 133                 return 0;
 134         }
 135
 136         if ((c->x86_model == 6) && (c->x86_mask == 0)) {
 137                 printk(KERN_INFO PFX "K7 660[A0] core detected, "
 138                                 "enabling errata workarounds\n");
 139                 have_a0 = 1;
 140         }
 141
 142         cpuid(0x80000007, &eax, &ebx, &ecx, &edx);
 143
 144         /* Check we can actually do something before we say anything.*/
 145         if (!(edx & (1 << 1 | 1 << 2)))
 146                 return 0;
 147
 148         printk(KERN_INFO PFX "PowerNOW! Technology present. Can scale: ");
 149
 150         if (edx & 1 << 1) {
 151                 printk("frequency");
 152                 can_scale_bus = 1;
 153         }
 154
 155         if ((edx & (1 << 1 | 1 << 2)) == 0x6)
 156                 printk(" and ");
 157
 158         if (edx & 1 << 2) {
 159                 printk("voltage");
 160                 can_scale_vid = 1;
 161         }
 162
 163         printk(".\n");
 164         return 1;
 165 }
 166
 167 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
 168 static void invalidate_entry(unsigned int entry)
 169 {
 170         powernow_table[entry].frequency = CPUFREQ_ENTRY_INVALID;
 171 }
 172 #endif
 173
 174 static int get_ranges(unsigned char *pst)
 175 {
 176         unsigned int j;
 177         unsigned int speed;
 178         u8 fid, vid;
 179
 180         powernow_table = kzalloc((sizeof(*powernow_table) *
 181                                 (number_scales + 1)), GFP_KERNEL);
 182         if (!powernow_table)
 183                 return -ENOMEM;
 184
 185         for (j = 0 ; j < number_scales; j++) {
 186                 fid = *pst++;
 187
 188                 powernow_table[j].frequency = (fsb * fid_codes[fid]) / 10;
 189                 powernow_table[j].driver_data = fid; /* lower 8 bits */
 190
 191                 speed = powernow_table[j].frequency;
 192
 193                 if ((fid_codes[fid] % 10) == 5) {
 194 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
 195                         if (have_a0 == 1)
 196                                 invalidate_entry(j);
 197 #endif
 198                 }
 199
 200                 if (speed < minimum_speed)
 201                         minimum_speed = speed;
 202                 if (speed > maximum_speed)
 203                         maximum_speed = speed;
 204
 205                 vid = *pst++;
 206                 powernow_table[j].driver_data |= (vid << 8); /* upper 8 bits */
 207
 208                 pr_debug("   FID: 0x%x (%d.%dx [%dMHz])  "
 209                          "VID: 0x%x (%d.%03dV)\n", fid, fid_codes[fid] / 10,
 210                          fid_codes[fid] % 10, speed/1000, vid,
 211                          mobile_vid_table[vid]/1000,
 212                          mobile_vid_table[vid]%1000);
 213         }
 214         powernow_table[number_scales].frequency = CPUFREQ_TABLE_END;
 215         powernow_table[number_scales].driver_data = 0;
 216
 217         return 0;
 218 }
 219
 220
 221 static void change_FID(int fid)
 222 {
 223         union msr_fidvidctl fidvidctl;
 224
 225         rdmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
 226         if (fidvidctl.bits.FID != fid) {
 227                 fidvidctl.bits.SGTC = latency;
 228                 fidvidctl.bits.FID = fid;
 229                 fidvidctl.bits.VIDC = 0;
 230                 fidvidctl.bits.FIDC = 1;
 231                 wrmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
 232         }
 233 }
 234
 235
 236 static void change_VID(int vid)
 237 {
 238         union msr_fidvidctl fidvidctl;
 239
 240         rdmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
 241         if (fidvidctl.bits.VID != vid) {
 242                 fidvidctl.bits.SGTC = latency;
 243                 fidvidctl.bits.VID = vid;
 244                 fidvidctl.bits.FIDC = 0;
 245                 fidvidctl.bits.VIDC = 1;
 246                 wrmsrl(MSR_K7_FID_VID_CTL, fidvidctl.val);
 247         }
 248 }
 249
 250
 251 static int powernow_target(struct cpufreq_policy *policy, unsigned int index)
 252 {
 253         u8 fid, vid;
 254         struct cpufreq_freqs freqs;
 255         union msr_fidvidstatus fidvidstatus;
 256         int cfid;
 257
 258         /* fid are the lower 8 bits of the index we stored into
 259          * the cpufreq frequency table in powernow_decode_bios,
 260          * vid are the upper 8 bits.
 261          */
 262
 263         fid = powernow_table[index].driver_data & 0xFF;
 264         vid = (powernow_table[index].driver_data & 0xFF00) >> 8;
 265
 266         rdmsrl(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
 267         cfid = fidvidstatus.bits.CFID;
 268         freqs.old = fsb * fid_codes[cfid] / 10;
 269
 270         freqs.new = powernow_table[index].frequency;
 271
 272         /* Now do the magic poking into the MSRs.  */
 273
 274         if (have_a0 == 1)       /* A0 errata 5 */
 275                 local_irq_disable();
 276
 277         if (freqs.old > freqs.new) {
 278                 /* Going down, so change FID first */
 279                 change_FID(fid);
 280                 change_VID(vid);
 281         } else {
 282                 /* Going up, so change VID first */
 283                 change_VID(vid);
 284                 change_FID(fid);
 285         }
 286
 287
 288         if (have_a0 == 1)
 289                 local_irq_enable();
 290
 291         return 0;
 292 }
 293
 294
 295 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
 296
 297 static struct acpi_processor_performance *acpi_processor_perf;
 298
 299 static int powernow_acpi_init(void)
 300 {
 301         int i;
 302         int retval = 0;
 303         union powernow_acpi_control_t pc;
 304
 305         if (acpi_processor_perf != NULL && powernow_table != NULL) {
 306                 retval = -EINVAL;
 307                 goto err0;
 308         }
 309
 310         acpi_processor_perf = kzalloc(sizeof(*acpi_processor_perf), GFP_KERNEL);
 311         if (!acpi_processor_perf) {
 312                 retval = -ENOMEM;
 313                 goto err0;
 314         }
 315
 316         if (!zalloc_cpumask_var(&acpi_processor_perf->shared_cpu_map,
 317                                                                 GFP_KERNEL)) {
 318                 retval = -ENOMEM;
 319                 goto err05;
 320         }
 321
 322         if (acpi_processor_register_performance(acpi_processor_perf, 0)) {
 323                 retval = -EIO;
 324                 goto err1;
 325         }
 326
 327         if (acpi_processor_perf->control_register.space_id !=
 328                         ACPI_ADR_SPACE_FIXED_HARDWARE) {
 329                 retval = -ENODEV;
 330                 goto err2;
 331         }
 332
 333         if (acpi_processor_perf->status_register.space_id !=
 334                         ACPI_ADR_SPACE_FIXED_HARDWARE) {
 335                 retval = -ENODEV;
 336                 goto err2;
 337         }
 338
 339         number_scales = acpi_processor_perf->state_count;
 340
 341         if (number_scales < 2) {
 342                 retval = -ENODEV;
 343                 goto err2;
 344         }
 345
 346         powernow_table = kzalloc((sizeof(*powernow_table) *
 347                                 (number_scales + 1)), GFP_KERNEL);
 348         if (!powernow_table) {
 349                 retval = -ENOMEM;
 350                 goto err2;
 351         }
 352
 353         pc.val = (unsigned long) acpi_processor_perf->states[0].control;
 354         for (i = 0; i < number_scales; i++) {
 355                 u8 fid, vid;
 356                 struct acpi_processor_px *state =
 357                         &acpi_processor_perf->states[i];
 358                 unsigned int speed, speed_mhz;
 359
 360                 pc.val = (unsigned long) state->control;
 361                 pr_debug("acpi:  P%d: %d MHz %d mW %d uS control %08x SGTC %d\n",
 362                          i,
 363                          (u32) state->core_frequency,
 364                          (u32) state->power,
 365                          (u32) state->transition_latency,
 366                          (u32) state->control,
 367                          pc.bits.sgtc);
 368
 369                 vid = pc.bits.vid;
 370                 fid = pc.bits.fid;
 371
 372                 powernow_table[i].frequency = fsb * fid_codes[fid] / 10;
 373                 powernow_table[i].driver_data = fid; /* lower 8 bits */
 374                 powernow_table[i].driver_data |= (vid << 8); /* upper 8 bits */
 375
 376                 speed = powernow_table[i].frequency;
 377                 speed_mhz = speed / 1000;
 378
 379                 /* processor_perflib will multiply the MHz value by 1000 to
 380                  * get a KHz value (e.g. 1266000). However, powernow-k7 works
 381                  * with true KHz values (e.g. 1266768). To ensure that all
 382                  * powernow frequencies are available, we must ensure that
 383                  * ACPI doesn't restrict them, so we round up the MHz value
 384                  * to ensure that perflib's computed KHz value is greater than
 385                  * or equal to powernow's KHz value.
 386                  */
 387                 if (speed % 1000 > 0)
 388                         speed_mhz++;
 389
 390                 if ((fid_codes[fid] % 10) == 5) {
 391                         if (have_a0 == 1)
 392                                 invalidate_entry(i);
 393                 }
 394
 395                 pr_debug("   FID: 0x%x (%d.%dx [%dMHz])  "
 396                          "VID: 0x%x (%d.%03dV)\n", fid, fid_codes[fid] / 10,
 397                          fid_codes[fid] % 10, speed_mhz, vid,
 398                          mobile_vid_table[vid]/1000,
 399                          mobile_vid_table[vid]%1000);
 400
 401                 if (state->core_frequency != speed_mhz) {
 402                         state->core_frequency = speed_mhz;
 403                         pr_debug("   Corrected ACPI frequency to %d\n",
 404                                 speed_mhz);
 405                 }
 406
 407                 if (latency < pc.bits.sgtc)
 408                         latency = pc.bits.sgtc;
 409
 410                 if (speed < minimum_speed)
 411                         minimum_speed = speed;
 412                 if (speed > maximum_speed)
 413                         maximum_speed = speed;
 414         }
 415
 416         powernow_table[i].frequency = CPUFREQ_TABLE_END;
 417         powernow_table[i].driver_data = 0;
 418
 419         /* notify BIOS that we exist */
 420         acpi_processor_notify_smm(THIS_MODULE);
 421
 422         return 0;
 423
 424 err2:
 425         acpi_processor_unregister_performance(acpi_processor_perf, 0);
 426 err1:
 427         free_cpumask_var(acpi_processor_perf->shared_cpu_map);
 428 err05:
 429         kfree(acpi_processor_perf);
 430 err0:
 431         printk(KERN_WARNING PFX "ACPI perflib can not be used on "
 432                         "this platform\n");
 433         acpi_processor_perf = NULL;
 434         return retval;
 435 }
 436 #else
 437 static int powernow_acpi_init(void)
 438 {
 439         printk(KERN_INFO PFX "no support for ACPI processor found."
 440                "  Please recompile your kernel with ACPI processor\n");
 441         return -EINVAL;
 442 }
 443 #endif
 444
 445 static void print_pst_entry(struct pst_s *pst, unsigned int j)
 446 {
 447         pr_debug("PST:%d (@%p)\n", j, pst);
 448         pr_debug(" cpuid: 0x%x  fsb: %d  maxFID: 0x%x  startvid: 0x%x\n",
 449                 pst->cpuid, pst->fsbspeed, pst->maxfid, pst->startvid);
 450 }
 451
 452 static int powernow_decode_bios(int maxfid, int startvid)
 453 {
 454         struct psb_s *psb;
 455         struct pst_s *pst;
 456         unsigned int i, j;
 457         unsigned char *p;
 458         unsigned int etuple;
 459         unsigned int ret;
 460
 461         etuple = cpuid_eax(0x80000001);
 462
 463         for (i = 0xC0000; i < 0xffff0 ; i += 16) {
 464
 465                 p = phys_to_virt(i);
 466
 467                 if (memcmp(p, "AMDK7PNOW!",  10) == 0) {
 468                         pr_debug("Found PSB header at %p\n", p);
 469                         psb = (struct psb_s *) p;
 470                         pr_debug("Table version: 0x%x\n", psb->tableversion);
 471                         if (psb->tableversion != 0x12) {
 472                                 printk(KERN_INFO PFX "Sorry, only v1.2 tables"
 473                                                 " supported right now\n");
 474                                 return -ENODEV;
 475                         }
 476
 477                         pr_debug("Flags: 0x%x\n", psb->flags);
 478                         if ((psb->flags & 1) == 0)
 479                                 pr_debug("Mobile voltage regulator\n");
 480                         else
 481                                 pr_debug("Desktop voltage regulator\n");
 482
 483                         latency = psb->settlingtime;
 484                         if (latency < 100) {
 485                                 printk(KERN_INFO PFX "BIOS set settling time "
 486                                                 "to %d microseconds. "
 487                                                 "Should be at least 100. "
 488                                                 "Correcting.\n", latency);
 489                                 latency = 100;
 490                         }
 491                         pr_debug("Settling Time: %d microseconds.\n",
 492                                         psb->settlingtime);
 493                         pr_debug("Has %d PST tables. (Only dumping ones "
 494                                         "relevant to this CPU).\n",
 495                                         psb->numpst);
 496
 497                         p += sizeof(*psb);
 498
 499                         pst = (struct pst_s *) p;
 500
 501                         for (j = 0; j < psb->numpst; j++) {
 502                                 pst = (struct pst_s *) p;
 503                                 number_scales = pst->numpstates;
 504
 505                                 if ((etuple == pst->cpuid) &&
 506                                     check_fsb(pst->fsbspeed) &&
 507                                     (maxfid == pst->maxfid) &&
 508                                     (startvid == pst->startvid)) {
 509                                         print_pst_entry(pst, j);
 510                                         p = (char *)pst + sizeof(*pst);
 511                                         ret = get_ranges(p);
 512                                         return ret;
 513                                 } else {
 514                                         unsigned int k;
 515                                         p = (char *)pst + sizeof(*pst);
 516                                         for (k = 0; k < number_scales; k++)
 517                                                 p += 2;
 518                                 }
 519                         }
 520                         printk(KERN_INFO PFX "No PST tables match this cpuid "
 521                                         "(0x%x)\n", etuple);
 522                         printk(KERN_INFO PFX "This is indicative of a broken "
 523                                         "BIOS.\n");
 524
 525                         return -EINVAL;
 526                 }
 527                 p++;
 528         }
 529
 530         return -ENODEV;
 531 }
 532
 533
 534 /*
 535  * We use the fact that the bus frequency is somehow
 536  * a multiple of 100000/3 khz, then we compute sgtc according
 537  * to this multiple.
 538  * That way, we match more how AMD thinks all of that work.
 539  * We will then get the same kind of behaviour already tested under
 540  * the "well-known" other OS.
 541  */
 542 static int fixup_sgtc(void)
 543 {
 544         unsigned int sgtc;
 545         unsigned int m;
 546
 547         m = fsb / 3333;
 548         if ((m % 10) >= 5)
 549                 m += 5;
 550
 551         m /= 10;
 552
 553         sgtc = 100 * m * latency;
 554         sgtc = sgtc / 3;
 555         if (sgtc > 0xfffff) {
 556                 printk(KERN_WARNING PFX "SGTC too large %d\n", sgtc);
 557                 sgtc = 0xfffff;
 558         }
 559         return sgtc;
 560 }
 561
 562 static unsigned int powernow_get(unsigned int cpu)
 563 {
 564         union msr_fidvidstatus fidvidstatus;
 565         unsigned int cfid;
 566
 567         if (cpu)
 568                 return 0;
 569         rdmsrl(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
 570         cfid = fidvidstatus.bits.CFID;
 571
 572         return fsb * fid_codes[cfid] / 10;
 573 }
 574
 575
 576 static int acer_cpufreq_pst(const struct dmi_system_id *d)
 577 {
 578         printk(KERN_WARNING PFX
 579                 "%s laptop with broken PST tables in BIOS detected.\n",
 580                 d->ident);
 581         printk(KERN_WARNING PFX
 582                 "You need to downgrade to 3A21 (09/09/2002), or try a newer "
 583                 "BIOS than 3A71 (01/20/2003)\n");
 584         printk(KERN_WARNING PFX
 585                 "cpufreq scaling has been disabled as a result of this.\n");
 586         return 0;
 587 }
 588
 589 /*
 590  * Some Athlon laptops have really fucked PST tables.
 591  * A BIOS update is all that can save them.
 592  * Mention this, and disable cpufreq.
 593  */
 594 static struct dmi_system_id powernow_dmi_table[] = {
 595         {
 596                 .callback = acer_cpufreq_pst,
 597                 .ident = "Acer Aspire",
 598                 .matches = {
 599                         DMI_MATCH(DMI_SYS_VENDOR, "Insyde Software"),
 600                         DMI_MATCH(DMI_BIOS_VERSION, "3A71"),
 601                 },
 602         },
 603         { }
 604 };
 605
 606 static int powernow_cpu_init(struct cpufreq_policy *policy)
 607 {
 608         union msr_fidvidstatus fidvidstatus;
 609         int result;
 610
 611         if (policy->cpu != 0)
 612                 return -ENODEV;
 613
 614         rdmsrl(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
 615
 616         recalibrate_cpu_khz();
 617
 618         fsb = (10 * cpu_khz) / fid_codes[fidvidstatus.bits.CFID];
 619         if (!fsb) {
 620                 printk(KERN_WARNING PFX "can not determine bus frequency\n");
 621                 return -EINVAL;
 622         }
 623         pr_debug("FSB: %3dMHz\n", fsb/1000);
 624
 625         if (dmi_check_system(powernow_dmi_table) || acpi_force) {
 626                 printk(KERN_INFO PFX "PSB/PST known to be broken.  "
 627                                 "Trying ACPI instead\n");
 628                 result = powernow_acpi_init();
 629         } else {
 630                 result = powernow_decode_bios(fidvidstatus.bits.MFID,
 631                                 fidvidstatus.bits.SVID);
 632                 if (result) {
 633                         printk(KERN_INFO PFX "Trying ACPI perflib\n");
 634                         maximum_speed = 0;
 635                         minimum_speed = -1;
 636                         latency = 0;
 637                         result = powernow_acpi_init();
 638                         if (result) {
 639                                 printk(KERN_INFO PFX
 640                                         "ACPI and legacy methods failed\n");
 641                         }
 642                 } else {
 643                         /* SGTC use the bus clock as timer */
 644                         latency = fixup_sgtc();
 645                         printk(KERN_INFO PFX "SGTC: %d\n", latency);
 646                 }
 647         }
 648
 649         if (result)
 650                 return result;
 651
 652         printk(KERN_INFO PFX "Minimum speed %d MHz. Maximum speed %d MHz.\n",
 653                                 minimum_speed/1000, maximum_speed/1000);
 654
 655         policy->cpuinfo.transition_latency =
 656                 cpufreq_scale(2000000UL, fsb, latency);
 657
 658         return cpufreq_table_validate_and_show(policy, powernow_table);
 659 }
 660
 661 static int powernow_cpu_exit(struct cpufreq_policy *policy)
 662 {
 663 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
 664         if (acpi_processor_perf) {
 665                 acpi_processor_unregister_performance(acpi_processor_perf, 0);
 666                 free_cpumask_var(acpi_processor_perf->shared_cpu_map);
 667                 kfree(acpi_processor_perf);
 668         }
 669 #endif
 670
 671         kfree(powernow_table);
 672         return 0;
 673 }
 674
 675 static struct cpufreq_driver powernow_driver = {
 676         .verify         = cpufreq_generic_frequency_table_verify,
 677         .target_index   = powernow_target,
 678         .get            = powernow_get,
 679 #ifdef CONFIG_X86_POWERNOW_K7_ACPI
 680         .bios_limit     = acpi_processor_get_bios_limit,
 681 #endif
 682         .init           = powernow_cpu_init,
 683         .exit           = powernow_cpu_exit,
 684         .name           = "powernow-k7",
 685         .attr           = cpufreq_generic_attr,
 686 };
 687
 688 static int __init powernow_init(void)
 689 {
 690         if (check_powernow() == 0)
 691                 return -ENODEV;
 692         return cpufreq_register_driver(&powernow_driver);
 693 }
 694
 695
 696 static void __exit powernow_exit(void)
 697 {
 698         cpufreq_unregister_driver(&powernow_driver);
 699 }
 700
 701 module_param(acpi_force,  int, 0444);
 702 MODULE_PARM_DESC(acpi_force, "Force ACPI to be used.");
 703
 704 MODULE_AUTHOR("Dave Jones <[email protected]>");
 705 MODULE_DESCRIPTION("Powernow driver for AMD K7 processors.");
 706 MODULE_LICENSE("GPL");
 707
 708 late_initcall(powernow_init);
 709 module_exit(powernow_exit);
 710