drivers/cpufreq/speedstep-smi.c

   1 /*
   2  * Intel SpeedStep SMI driver.
   3  *
   4  * (C) 2003  Hiroshi Miura <miura@da-cha.org>
   5  *
   6  *  Licensed under the terms of the GNU GPL License version 2.
   7  *
   8  */
   9
  10
  11 /*********************************************************************
  12  *                        SPEEDSTEP - DEFINITIONS                    *
  13  *********************************************************************/
  14
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/init.h>
  19 #include <linux/cpufreq.h>
  20 #include <linux/delay.h>
  21 #include <linux/io.h>
  22 #include <asm/ist.h>
  23 #include <asm/cpu_device_id.h>
  24
  25 #include "speedstep-lib.h"
  26
  27 /* speedstep system management interface port/command.
  28  *
  29  * These parameters are got from IST-SMI BIOS call.
  30  * If user gives it, these are used.
  31  *
  32  */
  33 static int smi_port;
  34 static int smi_cmd;
  35 static unsigned int smi_sig;
  36
  37 /* info about the processor */
  38 static enum speedstep_processor speedstep_processor;
  39
  40 /*
  41  * There are only two frequency states for each processor. Values
  42  * are in kHz for the time being.
  43  */
  44 static struct cpufreq_frequency_table speedstep_freqs[] = {
  45         {SPEEDSTEP_HIGH,        0},
  46         {SPEEDSTEP_LOW,         0},
  47         {0,                     CPUFREQ_TABLE_END},
  48 };
  49
  50 #define GET_SPEEDSTEP_OWNER 0
  51 #define GET_SPEEDSTEP_STATE 1
  52 #define SET_SPEEDSTEP_STATE 2
  53 #define GET_SPEEDSTEP_FREQS 4
  54
  55 /* how often shall the SMI call be tried if it failed, e.g. because
  56  * of DMA activity going on? */
  57 #define SMI_TRIES 5
  58
  59 /**
  60  * speedstep_smi_ownership
  61  */
  62 static int speedstep_smi_ownership(void)
  63 {
  64         u32 command, result, magic, dummy;
  65         u32 function = GET_SPEEDSTEP_OWNER;
  66         unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
  67
  68         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
  69         magic = virt_to_phys(magic_data);
  70
  71         pr_debug("trying to obtain ownership with command %x at port %x\n",
  72                         command, smi_port);
  73
  74         __asm__ __volatile__(
  75                 "push %%ebp\n"
  76                 "out %%al, (%%dx)\n"
  77                 "pop %%ebp\n"
  78                 : "=D" (result),
  79                   "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
  80                   "=S" (dummy)
  81                 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
  82                   "D" (0), "S" (magic)
  83                 : "memory"
  84         );
  85
  86         pr_debug("result is %x\n", result);
  87
  88         return result;
  89 }
  90
  91 /**
  92  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
  93  * @low: the low frequency value is placed here
  94  * @high: the high frequency value is placed here
  95  *
  96  * Only available on later SpeedStep-enabled systems, returns false results or
  97  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
  98  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
  99  */
 100 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
 101 {
 102         u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
 103         u32 state = 0;
 104         u32 function = GET_SPEEDSTEP_FREQS;
 105
 106         if (!(ist_info.event & 0xFFFF)) {
 107                 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
 108                 return -ENODEV;
 109         }
 110
 111         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 112
 113         pr_debug("trying to determine frequencies with command %x at port %x\n",
 114                         command, smi_port);
 115
 116         __asm__ __volatile__(
 117                 "push %%ebp\n"
 118                 "out %%al, (%%dx)\n"
 119                 "pop %%ebp"
 120                 : "=a" (result),
 121                   "=b" (high_mhz),
 122                   "=c" (low_mhz),
 123                   "=d" (state), "=D" (edi), "=S" (dummy)
 124                 : "a" (command),
 125                   "b" (function),
 126                   "c" (state),
 127                   "d" (smi_port), "S" (0), "D" (0)
 128         );
 129
 130         pr_debug("result %x, low_freq %u, high_freq %u\n",
 131                         result, low_mhz, high_mhz);
 132
 133         /* abort if results are obviously incorrect... */
 134         if ((high_mhz + low_mhz) < 600)
 135                 return -EINVAL;
 136
 137         *high = high_mhz * 1000;
 138         *low  = low_mhz  * 1000;
 139
 140         return result;
 141 }
 142
 143 /**
 144  * speedstep_get_state - set the SpeedStep state
 145  * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 146  *
 147  */
 148 static int speedstep_get_state(void)
 149 {
 150         u32 function = GET_SPEEDSTEP_STATE;
 151         u32 result, state, edi, command, dummy;
 152
 153         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 154
 155         pr_debug("trying to determine current setting with command %x "
 156                 "at port %x\n", command, smi_port);
 157
 158         __asm__ __volatile__(
 159                 "push %%ebp\n"
 160                 "out %%al, (%%dx)\n"
 161                 "pop %%ebp\n"
 162                 : "=a" (result),
 163                   "=b" (state), "=D" (edi),
 164                   "=c" (dummy), "=d" (dummy), "=S" (dummy)
 165                 : "a" (command), "b" (function), "c" (0),
 166                   "d" (smi_port), "S" (0), "D" (0)
 167         );
 168
 169         pr_debug("state is %x, result is %x\n", state, result);
 170
 171         return state & 1;
 172 }
 173
 174
 175 /**
 176  * speedstep_set_state - set the SpeedStep state
 177  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 178  *
 179  */
 180 static void speedstep_set_state(unsigned int state)
 181 {
 182         unsigned int result = 0, command, new_state, dummy;
 183         unsigned long flags;
 184         unsigned int function = SET_SPEEDSTEP_STATE;
 185         unsigned int retry = 0;
 186
 187         if (state > 0x1)
 188                 return;
 189
 190         /* Disable IRQs */
 191         preempt_disable();
 192         local_irq_save(flags);
 193
 194         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 195
 196         pr_debug("trying to set frequency to state %u "
 197                 "with command %x at port %x\n",
 198                 state, command, smi_port);
 199
 200         do {
 201                 if (retry) {
 202                         /*
 203                          * We need to enable interrupts, otherwise the blockage
 204                          * won't resolve.
 205                          *
 206                          * We disable preemption so that other processes don't
 207                          * run. If other processes were running, they could
 208                          * submit more DMA requests, making the blockage worse.
 209                          */
 210                         pr_debug("retry %u, previous result %u, waiting...\n",
 211                                         retry, result);
 212                         local_irq_enable();
 213                         mdelay(retry * 50);
 214                         local_irq_disable();
 215                 }
 216                 retry++;
 217                 __asm__ __volatile__(
 218                         "push %%ebp\n"
 219                         "out %%al, (%%dx)\n"
 220                         "pop %%ebp"
 221                         : "=b" (new_state), "=D" (result),
 222                           "=c" (dummy), "=a" (dummy),
 223                           "=d" (dummy), "=S" (dummy)
 224                         : "a" (command), "b" (function), "c" (state),
 225                           "d" (smi_port), "S" (0), "D" (0)
 226                         );
 227         } while ((new_state != state) && (retry <= SMI_TRIES));
 228
 229         /* enable IRQs */
 230         local_irq_restore(flags);
 231         preempt_enable();
 232
 233         if (new_state == state)
 234                 pr_debug("change to %u MHz succeeded after %u tries "
 235                         "with result %u\n",
 236                         (speedstep_freqs[new_state].frequency / 1000),
 237                         retry, result);
 238         else
 239                 printk(KERN_ERR "cpufreq: change to state %u "
 240                         "failed with new_state %u and result %u\n",
 241                         state, new_state, result);
 242
 243         return;
 244 }
 245
 246
 247 /**
 248  * speedstep_target - set a new CPUFreq policy
 249  * @policy: new policy
 250  * @target_freq: new freq
 251  * @relation:
 252  *
 253  * Sets a new CPUFreq policy/freq.
 254  */
 255 static int speedstep_target(struct cpufreq_policy *policy,
 256                         unsigned int target_freq, unsigned int relation)
 257 {
 258         unsigned int newstate = 0;
 259         struct cpufreq_freqs freqs;
 260
 261         if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
 262                                 target_freq, relation, &newstate))
 263                 return -EINVAL;
 264
 265         freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
 266         freqs.new = speedstep_freqs[newstate].frequency;
 267
 268         if (freqs.old == freqs.new)
 269                 return 0;
 270
 271         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 272         speedstep_set_state(newstate);
 273         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 274
 275         return 0;
 276 }
 277
 278
 279 /**
 280  * speedstep_verify - verifies a new CPUFreq policy
 281  * @policy: new policy
 282  *
 283  * Limit must be within speedstep_low_freq and speedstep_high_freq, with
 284  * at least one border included.
 285  */
 286 static int speedstep_verify(struct cpufreq_policy *policy)
 287 {
 288         return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
 289 }
 290
 291
 292 static int speedstep_cpu_init(struct cpufreq_policy *policy)
 293 {
 294         int result;
 295         unsigned int speed, state;
 296         unsigned int *low, *high;
 297
 298         /* capability check */
 299         if (policy->cpu != 0)
 300                 return -ENODEV;
 301
 302         result = speedstep_smi_ownership();
 303         if (result) {
 304                 pr_debug("fails in acquiring ownership of a SMI interface.\n");
 305                 return -EINVAL;
 306         }
 307
 308         /* detect low and high frequency */
 309         low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
 310         high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
 311
 312         result = speedstep_smi_get_freqs(low, high);
 313         if (result) {
 314                 /* fall back to speedstep_lib.c dection mechanism:
 315                  * try both states out */
 316                 pr_debug("could not detect low and high frequencies "
 317                                 "by SMI call.\n");
 318                 result = speedstep_get_freqs(speedstep_processor,
 319                                 low, high,
 320                                 NULL,
 321                                 &speedstep_set_state);
 322
 323                 if (result) {
 324                         pr_debug("could not detect two different speeds"
 325                                         " -- aborting.\n");
 326                         return result;
 327                 } else
 328                         pr_debug("workaround worked.\n");
 329         }
 330
 331         /* get current speed setting */
 332         state = speedstep_get_state();
 333         speed = speedstep_freqs[state].frequency;
 334
 335         pr_debug("currently at %s speed setting - %i MHz\n",
 336                 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
 337                 ? "low" : "high",
 338                 (speed / 1000));
 339
 340         /* cpuinfo and default policy values */
 341         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 342         policy->cur = speed;
 343
 344         result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
 345         if (result)
 346                 return result;
 347
 348         cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
 349
 350         return 0;
 351 }
 352
 353 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
 354 {
 355         cpufreq_frequency_table_put_attr(policy->cpu);
 356         return 0;
 357 }
 358
 359 static unsigned int speedstep_get(unsigned int cpu)
 360 {
 361         if (cpu)
 362                 return -ENODEV;
 363         return speedstep_get_frequency(speedstep_processor);
 364 }
 365
 366
 367 static int speedstep_resume(struct cpufreq_policy *policy)
 368 {
 369         int result = speedstep_smi_ownership();
 370
 371         if (result)
 372                 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
 373
 374         return result;
 375 }
 376
 377 static struct freq_attr *speedstep_attr[] = {
 378         &cpufreq_freq_attr_scaling_available_freqs,
 379         NULL,
 380 };
 381
 382 static struct cpufreq_driver speedstep_driver = {
 383         .name           = "speedstep-smi",
 384         .verify         = speedstep_verify,
 385         .target         = speedstep_target,
 386         .init           = speedstep_cpu_init,
 387         .exit           = speedstep_cpu_exit,
 388         .get            = speedstep_get,
 389         .resume         = speedstep_resume,
 390         .owner          = THIS_MODULE,
 391         .attr           = speedstep_attr,
 392 };
 393
 394 static const struct x86_cpu_id ss_smi_ids[] = {
 395         { X86_VENDOR_INTEL, 6, 0xb, },
 396         { X86_VENDOR_INTEL, 6, 0x8, },
 397         { X86_VENDOR_INTEL, 15, 2 },
 398         {}
 399 };
 400 #if 0
 401 /* Not auto loaded currently */
 402 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
 403 #endif
 404
 405 /**
 406  * speedstep_init - initializes the SpeedStep CPUFreq driver
 407  *
 408  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 409  * BIOS, -EINVAL on problems during initiatization, and zero on
 410  * success.
 411  */
 412 static int __init speedstep_init(void)
 413 {
 414         if (!x86_match_cpu(ss_smi_ids))
 415                 return -ENODEV;
 416
 417         speedstep_processor = speedstep_detect_processor();
 418
 419         switch (speedstep_processor) {
 420         case SPEEDSTEP_CPU_PIII_T:
 421         case SPEEDSTEP_CPU_PIII_C:
 422         case SPEEDSTEP_CPU_PIII_C_EARLY:
 423                 break;
 424         default:
 425                 speedstep_processor = 0;
 426         }
 427
 428         if (!speedstep_processor) {
 429                 pr_debug("No supported Intel CPU detected.\n");
 430                 return -ENODEV;
 431         }
 432
 433         pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
 434                 "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
 435                 ist_info.signature, ist_info.command,
 436                 ist_info.event, ist_info.perf_level);
 437
 438         /* Error if no IST-SMI BIOS or no PARM
 439                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
 440         if ((ist_info.signature !=  0x47534943) && (
 441             (smi_port == 0) || (smi_cmd == 0)))
 442                 return -ENODEV;
 443
 444         if (smi_sig == 1)
 445                 smi_sig = 0x47534943;
 446         else
 447                 smi_sig = ist_info.signature;
 448
 449         /* setup smi_port from MODLULE_PARM or BIOS */
 450         if ((smi_port > 0xff) || (smi_port < 0))
 451                 return -EINVAL;
 452         else if (smi_port == 0)
 453                 smi_port = ist_info.command & 0xff;
 454
 455         if ((smi_cmd > 0xff) || (smi_cmd < 0))
 456                 return -EINVAL;
 457         else if (smi_cmd == 0)
 458                 smi_cmd = (ist_info.command >> 16) & 0xff;
 459
 460         return cpufreq_register_driver(&speedstep_driver);
 461 }
 462
 463
 464 /**
 465  * speedstep_exit - unregisters SpeedStep support
 466  *
 467  *   Unregisters SpeedStep support.
 468  */
 469 static void __exit speedstep_exit(void)
 470 {
 471         cpufreq_unregister_driver(&speedstep_driver);
 472 }
 473
 474 module_param(smi_port, int, 0444);
 475 module_param(smi_cmd,  int, 0444);
 476 module_param(smi_sig, uint, 0444);
 477
 478 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
 479                 "-- Intel's default setting is 0xb2");
 480 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
 481                 "-- Intel's default setting is 0x82");
 482 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
 483                 "SMI interface.");
 484
 485 MODULE_AUTHOR("Hiroshi Miura");
 486 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
 487 MODULE_LICENSE("GPL");
 488
 489 module_init(speedstep_init);
 490 module_exit(speedstep_exit);