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
  24 #include "speedstep-lib.h"
  25
  26 /* speedstep system management interface port/command.
  27  *
  28  * These parameters are got from IST-SMI BIOS call.
  29  * If user gives it, these are used.
  30  *
  31  */
  32 static int smi_port;
  33 static int smi_cmd;
  34 static unsigned int smi_sig;
  35
  36 /* info about the processor */
  37 static enum speedstep_processor speedstep_processor;
  38
  39 /*
  40  * There are only two frequency states for each processor. Values
  41  * are in kHz for the time being.
  42  */
  43 static struct cpufreq_frequency_table speedstep_freqs[] = {
  44         {SPEEDSTEP_HIGH,        0},
  45         {SPEEDSTEP_LOW,         0},
  46         {0,                     CPUFREQ_TABLE_END},
  47 };
  48
  49 #define GET_SPEEDSTEP_OWNER 0
  50 #define GET_SPEEDSTEP_STATE 1
  51 #define SET_SPEEDSTEP_STATE 2
  52 #define GET_SPEEDSTEP_FREQS 4
  53
  54 /* how often shall the SMI call be tried if it failed, e.g. because
  55  * of DMA activity going on? */
  56 #define SMI_TRIES 5
  57
  58 /**
  59  * speedstep_smi_ownership
  60  */
  61 static int speedstep_smi_ownership(void)
  62 {
  63         u32 command, result, magic, dummy;
  64         u32 function = GET_SPEEDSTEP_OWNER;
  65         unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
  66
  67         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
  68         magic = virt_to_phys(magic_data);
  69
  70         pr_debug("trying to obtain ownership with command %x at port %x\n",
  71                         command, smi_port);
  72
  73         __asm__ __volatile__(
  74                 "push %%ebp\n"
  75                 "out %%al, (%%dx)\n"
  76                 "pop %%ebp\n"
  77                 : "=D" (result),
  78                   "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
  79                   "=S" (dummy)
  80                 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
  81                   "D" (0), "S" (magic)
  82                 : "memory"
  83         );
  84
  85         pr_debug("result is %x\n", result);
  86
  87         return result;
  88 }
  89
  90 /**
  91  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
  92  * @low: the low frequency value is placed here
  93  * @high: the high frequency value is placed here
  94  *
  95  * Only available on later SpeedStep-enabled systems, returns false results or
  96  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
  97  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
  98  */
  99 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
 100 {
 101         u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
 102         u32 state = 0;
 103         u32 function = GET_SPEEDSTEP_FREQS;
 104
 105         if (!(ist_info.event & 0xFFFF)) {
 106                 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
 107                 return -ENODEV;
 108         }
 109
 110         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 111
 112         pr_debug("trying to determine frequencies with command %x at port %x\n",
 113                         command, smi_port);
 114
 115         __asm__ __volatile__(
 116                 "push %%ebp\n"
 117                 "out %%al, (%%dx)\n"
 118                 "pop %%ebp"
 119                 : "=a" (result),
 120                   "=b" (high_mhz),
 121                   "=c" (low_mhz),
 122                   "=d" (state), "=D" (edi), "=S" (dummy)
 123                 : "a" (command),
 124                   "b" (function),
 125                   "c" (state),
 126                   "d" (smi_port), "S" (0), "D" (0)
 127         );
 128
 129         pr_debug("result %x, low_freq %u, high_freq %u\n",
 130                         result, low_mhz, high_mhz);
 131
 132         /* abort if results are obviously incorrect... */
 133         if ((high_mhz + low_mhz) < 600)
 134                 return -EINVAL;
 135
 136         *high = high_mhz * 1000;
 137         *low  = low_mhz  * 1000;
 138
 139         return result;
 140 }
 141
 142 /**
 143  * speedstep_get_state - set the SpeedStep state
 144  * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 145  *
 146  */
 147 static int speedstep_get_state(void)
 148 {
 149         u32 function = GET_SPEEDSTEP_STATE;
 150         u32 result, state, edi, command, dummy;
 151
 152         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 153
 154         pr_debug("trying to determine current setting with command %x "
 155                 "at port %x\n", command, smi_port);
 156
 157         __asm__ __volatile__(
 158                 "push %%ebp\n"
 159                 "out %%al, (%%dx)\n"
 160                 "pop %%ebp\n"
 161                 : "=a" (result),
 162                   "=b" (state), "=D" (edi),
 163                   "=c" (dummy), "=d" (dummy), "=S" (dummy)
 164                 : "a" (command), "b" (function), "c" (0),
 165                   "d" (smi_port), "S" (0), "D" (0)
 166         );
 167
 168         pr_debug("state is %x, result is %x\n", state, result);
 169
 170         return state & 1;
 171 }
 172
 173
 174 /**
 175  * speedstep_set_state - set the SpeedStep state
 176  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 177  *
 178  */
 179 static void speedstep_set_state(unsigned int state)
 180 {
 181         unsigned int result = 0, command, new_state, dummy;
 182         unsigned long flags;
 183         unsigned int function = SET_SPEEDSTEP_STATE;
 184         unsigned int retry = 0;
 185
 186         if (state > 0x1)
 187                 return;
 188
 189         /* Disable IRQs */
 190         preempt_disable();
 191         local_irq_save(flags);
 192
 193         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 194
 195         pr_debug("trying to set frequency to state %u "
 196                 "with command %x at port %x\n",
 197                 state, command, smi_port);
 198
 199         do {
 200                 if (retry) {
 201                         /*
 202                          * We need to enable interrupts, otherwise the blockage
 203                          * won't resolve.
 204                          *
 205                          * We disable preemption so that other processes don't
 206                          * run. If other processes were running, they could
 207                          * submit more DMA requests, making the blockage worse.
 208                          */
 209                         pr_debug("retry %u, previous result %u, waiting...\n",
 210                                         retry, result);
 211                         local_irq_enable();
 212                         mdelay(retry * 50);
 213                         local_irq_disable();
 214                 }
 215                 retry++;
 216                 __asm__ __volatile__(
 217                         "push %%ebp\n"
 218                         "out %%al, (%%dx)\n"
 219                         "pop %%ebp"
 220                         : "=b" (new_state), "=D" (result),
 221                           "=c" (dummy), "=a" (dummy),
 222                           "=d" (dummy), "=S" (dummy)
 223                         : "a" (command), "b" (function), "c" (state),
 224                           "d" (smi_port), "S" (0), "D" (0)
 225                         );
 226         } while ((new_state != state) && (retry <= SMI_TRIES));
 227
 228         /* enable IRQs */
 229         local_irq_restore(flags);
 230         preempt_enable();
 231
 232         if (new_state == state)
 233                 pr_debug("change to %u MHz succeeded after %u tries "
 234                         "with result %u\n",
 235                         (speedstep_freqs[new_state].frequency / 1000),
 236                         retry, result);
 237         else
 238                 printk(KERN_ERR "cpufreq: change to state %u "
 239                         "failed with new_state %u and result %u\n",
 240                         state, new_state, result);
 241
 242         return;
 243 }
 244
 245
 246 /**
 247  * speedstep_target - set a new CPUFreq policy
 248  * @policy: new policy
 249  * @target_freq: new freq
 250  * @relation:
 251  *
 252  * Sets a new CPUFreq policy/freq.
 253  */
 254 static int speedstep_target(struct cpufreq_policy *policy,
 255                         unsigned int target_freq, unsigned int relation)
 256 {
 257         unsigned int newstate = 0;
 258         struct cpufreq_freqs freqs;
 259
 260         if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
 261                                 target_freq, relation, &newstate))
 262                 return -EINVAL;
 263
 264         freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
 265         freqs.new = speedstep_freqs[newstate].frequency;
 266         freqs.cpu = 0; /* speedstep.c is UP only driver */
 267
 268         if (freqs.old == freqs.new)
 269                 return 0;
 270
 271         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 272         speedstep_set_state(newstate);
 273         cpufreq_notify_transition(&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 /**
 395  * speedstep_init - initializes the SpeedStep CPUFreq driver
 396  *
 397  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 398  * BIOS, -EINVAL on problems during initiatization, and zero on
 399  * success.
 400  */
 401 static int __init speedstep_init(void)
 402 {
 403         speedstep_processor = speedstep_detect_processor();
 404
 405         switch (speedstep_processor) {
 406         case SPEEDSTEP_CPU_PIII_T:
 407         case SPEEDSTEP_CPU_PIII_C:
 408         case SPEEDSTEP_CPU_PIII_C_EARLY:
 409                 break;
 410         default:
 411                 speedstep_processor = 0;
 412         }
 413
 414         if (!speedstep_processor) {
 415                 pr_debug("No supported Intel CPU detected.\n");
 416                 return -ENODEV;
 417         }
 418
 419         pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
 420                 "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
 421                 ist_info.signature, ist_info.command,
 422                 ist_info.event, ist_info.perf_level);
 423
 424         /* Error if no IST-SMI BIOS or no PARM
 425                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
 426         if ((ist_info.signature !=  0x47534943) && (
 427             (smi_port == 0) || (smi_cmd == 0)))
 428                 return -ENODEV;
 429
 430         if (smi_sig == 1)
 431                 smi_sig = 0x47534943;
 432         else
 433                 smi_sig = ist_info.signature;
 434
 435         /* setup smi_port from MODLULE_PARM or BIOS */
 436         if ((smi_port > 0xff) || (smi_port < 0))
 437                 return -EINVAL;
 438         else if (smi_port == 0)
 439                 smi_port = ist_info.command & 0xff;
 440
 441         if ((smi_cmd > 0xff) || (smi_cmd < 0))
 442                 return -EINVAL;
 443         else if (smi_cmd == 0)
 444                 smi_cmd = (ist_info.command >> 16) & 0xff;
 445
 446         return cpufreq_register_driver(&speedstep_driver);
 447 }
 448
 449
 450 /**
 451  * speedstep_exit - unregisters SpeedStep support
 452  *
 453  *   Unregisters SpeedStep support.
 454  */
 455 static void __exit speedstep_exit(void)
 456 {
 457         cpufreq_unregister_driver(&speedstep_driver);
 458 }
 459
 460 module_param(smi_port, int, 0444);
 461 module_param(smi_cmd,  int, 0444);
 462 module_param(smi_sig, uint, 0444);
 463
 464 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
 465                 "-- Intel's default setting is 0xb2");
 466 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
 467                 "-- Intel's default setting is 0x82");
 468 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
 469                 "SMI interface.");
 470
 471 MODULE_AUTHOR("Hiroshi Miura");
 472 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
 473 MODULE_LICENSE("GPL");
 474
 475 module_init(speedstep_init);
 476 module_exit(speedstep_exit);