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