drivers/cpufreq/speedstep-lib.c

   1 /*
   2  * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
   3  *
   4  *  Licensed under the terms of the GNU GPL License version 2.
   5  *
   6  *  Library for common functions for Intel SpeedStep v.1 and v.2 support
   7  *
   8  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/init.h>
  17 #include <linux/cpufreq.h>
  18
  19 #include <asm/msr.h>
  20 #include <asm/tsc.h>
  21 #include "speedstep-lib.h"
  22
  23 #define PFX "speedstep-lib: "
  24
  25 #ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK
  26 static int relaxed_check;
  27 #else
  28 #define relaxed_check 0
  29 #endif
  30
  31 /*********************************************************************
  32  *                   GET PROCESSOR CORE SPEED IN KHZ                 *
  33  *********************************************************************/
  34
  35 static unsigned int pentium3_get_frequency(enum speedstep_processor processor)
  36 {
  37         /* See table 14 of p3_ds.pdf and table 22 of 29834003.pdf */
  38         static const struct {
  39                 unsigned int ratio;     /* Frequency Multiplier (x10) */
  40                 u8 bitmap;              /* power on configuration bits
  41                                         [27, 25:22] (in MSR 0x2a) */
  42         } msr_decode_mult[] = {
  43                 { 30, 0x01 },
  44                 { 35, 0x05 },
  45                 { 40, 0x02 },
  46                 { 45, 0x06 },
  47                 { 50, 0x00 },
  48                 { 55, 0x04 },
  49                 { 60, 0x0b },
  50                 { 65, 0x0f },
  51                 { 70, 0x09 },
  52                 { 75, 0x0d },
  53                 { 80, 0x0a },
  54                 { 85, 0x26 },
  55                 { 90, 0x20 },
  56                 { 100, 0x2b },
  57                 { 0, 0xff }     /* error or unknown value */
  58         };
  59
  60         /* PIII(-M) FSB settings: see table b1-b of 24547206.pdf */
  61         static const struct {
  62                 unsigned int value;     /* Front Side Bus speed in MHz */
  63                 u8 bitmap;              /* power on configuration bits [18: 19]
  64                                         (in MSR 0x2a) */
  65         } msr_decode_fsb[] = {
  66                 {  66, 0x0 },
  67                 { 100, 0x2 },
  68                 { 133, 0x1 },
  69                 {   0, 0xff}
  70         };
  71
  72         u32 msr_lo, msr_tmp;
  73         int i = 0, j = 0;
  74
  75         /* read MSR 0x2a - we only need the low 32 bits */
  76         rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
  77         pr_debug("P3 - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
  78         msr_tmp = msr_lo;
  79
  80         /* decode the FSB */
  81         msr_tmp &= 0x00c0000;
  82         msr_tmp >>= 18;
  83         while (msr_tmp != msr_decode_fsb[i].bitmap) {
  84                 if (msr_decode_fsb[i].bitmap == 0xff)
  85                         return 0;
  86                 i++;
  87         }
  88
  89         /* decode the multiplier */
  90         if (processor == SPEEDSTEP_CPU_PIII_C_EARLY) {
  91                 pr_debug("workaround for early PIIIs\n");
  92                 msr_lo &= 0x03c00000;
  93         } else
  94                 msr_lo &= 0x0bc00000;
  95         msr_lo >>= 22;
  96         while (msr_lo != msr_decode_mult[j].bitmap) {
  97                 if (msr_decode_mult[j].bitmap == 0xff)
  98                         return 0;
  99                 j++;
 100         }
 101
 102         pr_debug("speed is %u\n",
 103                 (msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100));
 104
 105         return msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100;
 106 }
 107
 108
 109 static unsigned int pentiumM_get_frequency(void)
 110 {
 111         u32 msr_lo, msr_tmp;
 112
 113         rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
 114         pr_debug("PM - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
 115
 116         /* see table B-2 of 24547212.pdf */
 117         if (msr_lo & 0x00040000) {
 118                 printk(KERN_DEBUG PFX "PM - invalid FSB: 0x%x 0x%x\n",
 119                                 msr_lo, msr_tmp);
 120                 return 0;
 121         }
 122
 123         msr_tmp = (msr_lo >> 22) & 0x1f;
 124         pr_debug("bits 22-26 are 0x%x, speed is %u\n",
 125                         msr_tmp, (msr_tmp * 100 * 1000));
 126
 127         return msr_tmp * 100 * 1000;
 128 }
 129
 130 static unsigned int pentium_core_get_frequency(void)
 131 {
 132         u32 fsb = 0;
 133         u32 msr_lo, msr_tmp;
 134         int ret;
 135
 136         rdmsr(MSR_FSB_FREQ, msr_lo, msr_tmp);
 137         /* see table B-2 of 25366920.pdf */
 138         switch (msr_lo & 0x07) {
 139         case 5:
 140                 fsb = 100000;
 141                 break;
 142         case 1:
 143                 fsb = 133333;
 144                 break;
 145         case 3:
 146                 fsb = 166667;
 147                 break;
 148         case 2:
 149                 fsb = 200000;
 150                 break;
 151         case 0:
 152                 fsb = 266667;
 153                 break;
 154         case 4:
 155                 fsb = 333333;
 156                 break;
 157         default:
 158                 pr_err("PCORE - MSR_FSB_FREQ undefined value\n");
 159         }
 160
 161         rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
 162         pr_debug("PCORE - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n",
 163                         msr_lo, msr_tmp);
 164
 165         msr_tmp = (msr_lo >> 22) & 0x1f;
 166         pr_debug("bits 22-26 are 0x%x, speed is %u\n",
 167                         msr_tmp, (msr_tmp * fsb));
 168
 169         ret = (msr_tmp * fsb);
 170         return ret;
 171 }
 172
 173
 174 static unsigned int pentium4_get_frequency(void)
 175 {
 176         struct cpuinfo_x86 *c = &boot_cpu_data;
 177         u32 msr_lo, msr_hi, mult;
 178         unsigned int fsb = 0;
 179         unsigned int ret;
 180         u8 fsb_code;
 181
 182         /* Pentium 4 Model 0 and 1 do not have the Core Clock Frequency
 183          * to System Bus Frequency Ratio Field in the Processor Frequency
 184          * Configuration Register of the MSR. Therefore the current
 185          * frequency cannot be calculated and has to be measured.
 186          */
 187         if (c->x86_model < 2)
 188                 return cpu_khz;
 189
 190         rdmsr(0x2c, msr_lo, msr_hi);
 191
 192         pr_debug("P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi);
 193
 194         /* decode the FSB: see IA-32 Intel (C) Architecture Software
 195          * Developer's Manual, Volume 3: System Prgramming Guide,
 196          * revision #12 in Table B-1: MSRs in the Pentium 4 and
 197          * Intel Xeon Processors, on page B-4 and B-5.
 198          */
 199         fsb_code = (msr_lo >> 16) & 0x7;
 200         switch (fsb_code) {
 201         case 0:
 202                 fsb = 100 * 1000;
 203                 break;
 204         case 1:
 205                 fsb = 13333 * 10;
 206                 break;
 207         case 2:
 208                 fsb = 200 * 1000;
 209                 break;
 210         }
 211
 212         if (!fsb)
 213                 printk(KERN_DEBUG PFX "couldn't detect FSB speed. "
 214                                 "Please send an e-mail to <linux@brodo.de>\n");
 215
 216         /* Multiplier. */
 217         mult = msr_lo >> 24;
 218
 219         pr_debug("P4 - FSB %u kHz; Multiplier %u; Speed %u kHz\n",
 220                         fsb, mult, (fsb * mult));
 221
 222         ret = (fsb * mult);
 223         return ret;
 224 }
 225
 226
 227 /* Warning: may get called from smp_call_function_single. */
 228 unsigned int speedstep_get_frequency(enum speedstep_processor processor)
 229 {
 230         switch (processor) {
 231         case SPEEDSTEP_CPU_PCORE:
 232                 return pentium_core_get_frequency();
 233         case SPEEDSTEP_CPU_PM:
 234                 return pentiumM_get_frequency();
 235         case SPEEDSTEP_CPU_P4D:
 236         case SPEEDSTEP_CPU_P4M:
 237                 return pentium4_get_frequency();
 238         case SPEEDSTEP_CPU_PIII_T:
 239         case SPEEDSTEP_CPU_PIII_C:
 240         case SPEEDSTEP_CPU_PIII_C_EARLY:
 241                 return pentium3_get_frequency(processor);
 242         default:
 243                 return 0;
 244         };
 245         return 0;
 246 }
 247 EXPORT_SYMBOL_GPL(speedstep_get_frequency);
 248
 249
 250 /*********************************************************************
 251  *                 DETECT SPEEDSTEP-CAPABLE PROCESSOR                *
 252  *********************************************************************/
 253
 254 /* Keep in sync with the x86_cpu_id tables in the different modules */
 255 unsigned int speedstep_detect_processor(void)
 256 {
 257         struct cpuinfo_x86 *c = &cpu_data(0);
 258         u32 ebx, msr_lo, msr_hi;
 259
 260         pr_debug("x86: %x, model: %x\n", c->x86, c->x86_model);
 261
 262         if ((c->x86_vendor != X86_VENDOR_INTEL) ||
 263             ((c->x86 != 6) && (c->x86 != 0xF)))
 264                 return 0;
 265
 266         if (c->x86 == 0xF) {
 267                 /* Intel Mobile Pentium 4-M
 268                  * or Intel Mobile Pentium 4 with 533 MHz FSB */
 269                 if (c->x86_model != 2)
 270                         return 0;
 271
 272                 ebx = cpuid_ebx(0x00000001);
 273                 ebx &= 0x000000FF;
 274
 275                 pr_debug("ebx value is %x, x86_stepping is %x\n", ebx, c->x86_stepping);
 276
 277                 switch (c->x86_stepping) {
 278                 case 4:
 279                         /*
 280                          * B-stepping [M-P4-M]
 281                          * sample has ebx = 0x0f, production has 0x0e.
 282                          */
 283                         if ((ebx == 0x0e) || (ebx == 0x0f))
 284                                 return SPEEDSTEP_CPU_P4M;
 285                         break;
 286                 case 7:
 287                         /*
 288                          * C-stepping [M-P4-M]
 289                          * needs to have ebx=0x0e, else it's a celeron:
 290                          * cf. 25130917.pdf / page 7, footnote 5 even
 291                          * though 25072120.pdf / page 7 doesn't say
 292                          * samples are only of B-stepping...
 293                          */
 294                         if (ebx == 0x0e)
 295                                 return SPEEDSTEP_CPU_P4M;
 296                         break;
 297                 case 9:
 298                         /*
 299                          * D-stepping [M-P4-M or M-P4/533]
 300                          *
 301                          * this is totally strange: CPUID 0x0F29 is
 302                          * used by M-P4-M, M-P4/533 and(!) Celeron CPUs.
 303                          * The latter need to be sorted out as they don't
 304                          * support speedstep.
 305                          * Celerons with CPUID 0x0F29 may have either
 306                          * ebx=0x8 or 0xf -- 25130917.pdf doesn't say anything
 307                          * specific.
 308                          * M-P4-Ms may have either ebx=0xe or 0xf [see above]
 309                          * M-P4/533 have either ebx=0xe or 0xf. [25317607.pdf]
 310                          * also, M-P4M HTs have ebx=0x8, too
 311                          * For now, they are distinguished by the model_id
 312                          * string
 313                          */
 314                         if ((ebx == 0x0e) ||
 315                                 (strstr(c->x86_model_id,
 316                                     "Mobile Intel(R) Pentium(R) 4") != NULL))
 317                                 return SPEEDSTEP_CPU_P4M;
 318                         break;
 319                 default:
 320                         break;
 321                 }
 322                 return 0;
 323         }
 324
 325         switch (c->x86_model) {
 326         case 0x0B: /* Intel PIII [Tualatin] */
 327                 /* cpuid_ebx(1) is 0x04 for desktop PIII,
 328                  * 0x06 for mobile PIII-M */
 329                 ebx = cpuid_ebx(0x00000001);
 330                 pr_debug("ebx is %x\n", ebx);
 331
 332                 ebx &= 0x000000FF;
 333
 334                 if (ebx != 0x06)
 335                         return 0;
 336
 337                 /* So far all PIII-M processors support SpeedStep. See
 338                  * Intel's 24540640.pdf of June 2003
 339                  */
 340                 return SPEEDSTEP_CPU_PIII_T;
 341
 342         case 0x08: /* Intel PIII [Coppermine] */
 343
 344                 /* all mobile PIII Coppermines have FSB 100 MHz
 345                  * ==> sort out a few desktop PIIIs. */
 346                 rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_hi);
 347                 pr_debug("Coppermine: MSR_IA32_EBL_CR_POWERON is 0x%x, 0x%x\n",
 348                                 msr_lo, msr_hi);
 349                 msr_lo &= 0x00c0000;
 350                 if (msr_lo != 0x0080000)
 351                         return 0;
 352
 353                 /*
 354                  * If the processor is a mobile version,
 355                  * platform ID has bit 50 set
 356                  * it has SpeedStep technology if either
 357                  * bit 56 or 57 is set
 358                  */
 359                 rdmsr(MSR_IA32_PLATFORM_ID, msr_lo, msr_hi);
 360                 pr_debug("Coppermine: MSR_IA32_PLATFORM ID is 0x%x, 0x%x\n",
 361                                 msr_lo, msr_hi);
 362                 if ((msr_hi & (1<<18)) &&
 363                     (relaxed_check ? 1 : (msr_hi & (3<<24)))) {
 364                         if (c->x86_stepping == 0x01) {
 365                                 pr_debug("early PIII version\n");
 366                                 return SPEEDSTEP_CPU_PIII_C_EARLY;
 367                         } else
 368                                 return SPEEDSTEP_CPU_PIII_C;
 369                 }
 370                 /* fall through */
 371         default:
 372                 return 0;
 373         }
 374 }
 375 EXPORT_SYMBOL_GPL(speedstep_detect_processor);
 376
 377
 378 /*********************************************************************
 379  *                     DETECT SPEEDSTEP SPEEDS                       *
 380  *********************************************************************/
 381
 382 unsigned int speedstep_get_freqs(enum speedstep_processor processor,
 383                                   unsigned int *low_speed,
 384                                   unsigned int *high_speed,
 385                                   unsigned int *transition_latency,
 386                                   void (*set_state) (unsigned int state))
 387 {
 388         unsigned int prev_speed;
 389         unsigned int ret = 0;
 390         unsigned long flags;
 391         ktime_t tv1, tv2;
 392
 393         if ((!processor) || (!low_speed) || (!high_speed) || (!set_state))
 394                 return -EINVAL;
 395
 396         pr_debug("trying to determine both speeds\n");
 397
 398         /* get current speed */
 399         prev_speed = speedstep_get_frequency(processor);
 400         if (!prev_speed)
 401                 return -EIO;
 402
 403         pr_debug("previous speed is %u\n", prev_speed);
 404
 405         preempt_disable();
 406         local_irq_save(flags);
 407
 408         /* switch to low state */
 409         set_state(SPEEDSTEP_LOW);
 410         *low_speed = speedstep_get_frequency(processor);
 411         if (!*low_speed) {
 412                 ret = -EIO;
 413                 goto out;
 414         }
 415
 416         pr_debug("low speed is %u\n", *low_speed);
 417
 418         /* start latency measurement */
 419         if (transition_latency)
 420                 tv1 = ktime_get();
 421
 422         /* switch to high state */
 423         set_state(SPEEDSTEP_HIGH);
 424
 425         /* end latency measurement */
 426         if (transition_latency)
 427                 tv2 = ktime_get();
 428
 429         *high_speed = speedstep_get_frequency(processor);
 430         if (!*high_speed) {
 431                 ret = -EIO;
 432                 goto out;
 433         }
 434
 435         pr_debug("high speed is %u\n", *high_speed);
 436
 437         if (*low_speed == *high_speed) {
 438                 ret = -ENODEV;
 439                 goto out;
 440         }
 441
 442         /* switch to previous state, if necessary */
 443         if (*high_speed != prev_speed)
 444                 set_state(SPEEDSTEP_LOW);
 445
 446         if (transition_latency) {
 447                 *transition_latency = ktime_to_us(ktime_sub(tv2, tv1));
 448                 pr_debug("transition latency is %u uSec\n", *transition_latency);
 449
 450                 /* convert uSec to nSec and add 20% for safety reasons */
 451                 *transition_latency *= 1200;
 452
 453                 /* check if the latency measurement is too high or too low
 454                  * and set it to a safe value (500uSec) in that case
 455                  */
 456                 if (*transition_latency > 10000000 ||
 457                     *transition_latency < 50000) {
 458                         pr_warn("frequency transition measured seems out of range (%u nSec), falling back to a safe one of %u nSec\n",
 459                                 *transition_latency, 500000);
 460                         *transition_latency = 500000;
 461                 }
 462         }
 463
 464 out:
 465         local_irq_restore(flags);
 466         preempt_enable();
 467
 468         return ret;
 469 }
 470 EXPORT_SYMBOL_GPL(speedstep_get_freqs);
 471
 472 #ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK
 473 module_param(relaxed_check, int, 0444);
 474 MODULE_PARM_DESC(relaxed_check,
 475                 "Don't do all checks for speedstep capability.");
 476 #endif
 477
 478 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
 479 MODULE_DESCRIPTION("Library for Intel SpeedStep 1 or 2 cpufreq drivers.");
 480 MODULE_LICENSE("GPL");