arch/x86/kernel/cpu/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/slab.h>
  21 #include <linux/delay.h>
  22 #include <linux/io.h>
  23 #include <asm/ist.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 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
  60                 "speedstep-smi", msg)
  61
  62 /**
  63  * speedstep_smi_ownership
  64  */
  65 static int speedstep_smi_ownership(void)
  66 {
  67         u32 command, result, magic, dummy;
  68         u32 function = GET_SPEEDSTEP_OWNER;
  69         unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
  70
  71         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
  72         magic = virt_to_phys(magic_data);
  73
  74         dprintk("trying to obtain ownership with command %x at port %x\n",
  75                         command, smi_port);
  76
  77         __asm__ __volatile__(
  78                 "push %%ebp\n"
  79                 "out %%al, (%%dx)\n"
  80                 "pop %%ebp\n"
  81                 : "=D" (result),
  82                   "=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
  83                   "=S" (dummy)
  84                 : "a" (command), "b" (function), "c" (0), "d" (smi_port),
  85                   "D" (0), "S" (magic)
  86                 : "memory"
  87         );
  88
  89         dprintk("result is %x\n", result);
  90
  91         return result;
  92 }
  93
  94 /**
  95  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
  96  * @low: the low frequency value is placed here
  97  * @high: the high frequency value is placed here
  98  *
  99  * Only available on later SpeedStep-enabled systems, returns false results or
 100  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
 101  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
 102  */
 103 static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
 104 {
 105         u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
 106         u32 state = 0;
 107         u32 function = GET_SPEEDSTEP_FREQS;
 108
 109         if (!(ist_info.event & 0xFFFF)) {
 110                 dprintk("bug #1422 -- can't read freqs from BIOS\n");
 111                 return -ENODEV;
 112         }
 113
 114         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 115
 116         dprintk("trying to determine frequencies with command %x at port %x\n",
 117                         command, smi_port);
 118
 119         __asm__ __volatile__(
 120                 "push %%ebp\n"
 121                 "out %%al, (%%dx)\n"
 122                 "pop %%ebp"
 123                 : "=a" (result),
 124                   "=b" (high_mhz),
 125                   "=c" (low_mhz),
 126                   "=d" (state), "=D" (edi), "=S" (dummy)
 127                 : "a" (command),
 128                   "b" (function),
 129                   "c" (state),
 130                   "d" (smi_port), "S" (0), "D" (0)
 131         );
 132
 133         dprintk("result %x, low_freq %u, high_freq %u\n",
 134                         result, low_mhz, high_mhz);
 135
 136         /* abort if results are obviously incorrect... */
 137         if ((high_mhz + low_mhz) < 600)
 138                 return -EINVAL;
 139
 140         *high = high_mhz * 1000;
 141         *low  = low_mhz  * 1000;
 142
 143         return result;
 144 }
 145
 146 /**
 147  * speedstep_get_state - set the SpeedStep state
 148  * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 149  *
 150  */
 151 static int speedstep_get_state(void)
 152 {
 153         u32 function = GET_SPEEDSTEP_STATE;
 154         u32 result, state, edi, command, dummy;
 155
 156         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 157
 158         dprintk("trying to determine current setting with command %x "
 159                 "at port %x\n", command, smi_port);
 160
 161         __asm__ __volatile__(
 162                 "push %%ebp\n"
 163                 "out %%al, (%%dx)\n"
 164                 "pop %%ebp\n"
 165                 : "=a" (result),
 166                   "=b" (state), "=D" (edi),
 167                   "=c" (dummy), "=d" (dummy), "=S" (dummy)
 168                 : "a" (command), "b" (function), "c" (0),
 169                   "d" (smi_port), "S" (0), "D" (0)
 170         );
 171
 172         dprintk("state is %x, result is %x\n", state, result);
 173
 174         return state & 1;
 175 }
 176
 177
 178 /**
 179  * speedstep_set_state - set the SpeedStep state
 180  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 181  *
 182  */
 183 static void speedstep_set_state(unsigned int state)
 184 {
 185         unsigned int result = 0, command, new_state, dummy;
 186         unsigned long flags;
 187         unsigned int function = SET_SPEEDSTEP_STATE;
 188         unsigned int retry = 0;
 189
 190         if (state > 0x1)
 191                 return;
 192
 193         /* Disable IRQs */
 194         local_irq_save(flags);
 195
 196         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 197
 198         dprintk("trying to set frequency to state %u "
 199                 "with command %x at port %x\n",
 200                 state, command, smi_port);
 201
 202         do {
 203                 if (retry) {
 204                         dprintk("retry %u, previous result %u, waiting...\n",
 205                                         retry, result);
 206                         mdelay(retry * 50);
 207                 }
 208                 retry++;
 209                 __asm__ __volatile__(
 210                         "push %%ebp\n"
 211                         "out %%al, (%%dx)\n"
 212                         "pop %%ebp"
 213                         : "=b" (new_state), "=D" (result),
 214                           "=c" (dummy), "=a" (dummy),
 215                           "=d" (dummy), "=S" (dummy)
 216                         : "a" (command), "b" (function), "c" (state),
 217                           "d" (smi_port), "S" (0), "D" (0)
 218                         );
 219         } while ((new_state != state) && (retry <= SMI_TRIES));
 220
 221         /* enable IRQs */
 222         local_irq_restore(flags);
 223
 224         if (new_state == state)
 225                 dprintk("change to %u MHz succeeded after %u tries "
 226                         "with result %u\n",
 227                         (speedstep_freqs[new_state].frequency / 1000),
 228                         retry, result);
 229         else
 230                 printk(KERN_ERR "cpufreq: change to state %u "
 231                         "failed with new_state %u and result %u\n",
 232                         state, new_state, result);
 233
 234         return;
 235 }
 236
 237
 238 /**
 239  * speedstep_target - set a new CPUFreq policy
 240  * @policy: new policy
 241  * @target_freq: new freq
 242  * @relation:
 243  *
 244  * Sets a new CPUFreq policy/freq.
 245  */
 246 static int speedstep_target(struct cpufreq_policy *policy,
 247                         unsigned int target_freq, unsigned int relation)
 248 {
 249         unsigned int newstate = 0;
 250         struct cpufreq_freqs freqs;
 251
 252         if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
 253                                 target_freq, relation, &newstate))
 254                 return -EINVAL;
 255
 256         freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
 257         freqs.new = speedstep_freqs[newstate].frequency;
 258         freqs.cpu = 0; /* speedstep.c is UP only driver */
 259
 260         if (freqs.old == freqs.new)
 261                 return 0;
 262
 263         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 264         speedstep_set_state(newstate);
 265         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 266
 267         return 0;
 268 }
 269
 270
 271 /**
 272  * speedstep_verify - verifies a new CPUFreq policy
 273  * @policy: new policy
 274  *
 275  * Limit must be within speedstep_low_freq and speedstep_high_freq, with
 276  * at least one border included.
 277  */
 278 static int speedstep_verify(struct cpufreq_policy *policy)
 279 {
 280         return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
 281 }
 282
 283
 284 static int speedstep_cpu_init(struct cpufreq_policy *policy)
 285 {
 286         int result;
 287         unsigned int speed, state;
 288         unsigned int *low, *high;
 289
 290         /* capability check */
 291         if (policy->cpu != 0)
 292                 return -ENODEV;
 293
 294         result = speedstep_smi_ownership();
 295         if (result) {
 296                 dprintk("fails in aquiring ownership of a SMI interface.\n");
 297                 return -EINVAL;
 298         }
 299
 300         /* detect low and high frequency */
 301         low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
 302         high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
 303
 304         result = speedstep_smi_get_freqs(low, high);
 305         if (result) {
 306                 /* fall back to speedstep_lib.c dection mechanism:
 307                  * try both states out */
 308                 dprintk("could not detect low and high frequencies "
 309                                 "by SMI call.\n");
 310                 result = speedstep_get_freqs(speedstep_processor,
 311                                 low, high,
 312                                 NULL,
 313                                 &speedstep_set_state);
 314
 315                 if (result) {
 316                         dprintk("could not detect two different speeds"
 317                                         " -- aborting.\n");
 318                         return result;
 319                 } else
 320                         dprintk("workaround worked.\n");
 321         }
 322
 323         /* get current speed setting */
 324         state = speedstep_get_state();
 325         speed = speedstep_freqs[state].frequency;
 326
 327         dprintk("currently at %s speed setting - %i MHz\n",
 328                 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
 329                 ? "low" : "high",
 330                 (speed / 1000));
 331
 332         /* cpuinfo and default policy values */
 333         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 334         policy->cur = speed;
 335
 336         result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
 337         if (result)
 338                 return result;
 339
 340         cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
 341
 342         return 0;
 343 }
 344
 345 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
 346 {
 347         cpufreq_frequency_table_put_attr(policy->cpu);
 348         return 0;
 349 }
 350
 351 static unsigned int speedstep_get(unsigned int cpu)
 352 {
 353         if (cpu)
 354                 return -ENODEV;
 355         return speedstep_get_frequency(speedstep_processor);
 356 }
 357
 358
 359 static int speedstep_resume(struct cpufreq_policy *policy)
 360 {
 361         int result = speedstep_smi_ownership();
 362
 363         if (result)
 364                 dprintk("fails in re-aquiring ownership of a SMI interface.\n");
 365
 366         return result;
 367 }
 368
 369 static struct freq_attr *speedstep_attr[] = {
 370         &cpufreq_freq_attr_scaling_available_freqs,
 371         NULL,
 372 };
 373
 374 static struct cpufreq_driver speedstep_driver = {
 375         .name           = "speedstep-smi",
 376         .verify         = speedstep_verify,
 377         .target         = speedstep_target,
 378         .init           = speedstep_cpu_init,
 379         .exit           = speedstep_cpu_exit,
 380         .get            = speedstep_get,
 381         .resume         = speedstep_resume,
 382         .owner          = THIS_MODULE,
 383         .attr           = speedstep_attr,
 384 };
 385
 386 /**
 387  * speedstep_init - initializes the SpeedStep CPUFreq driver
 388  *
 389  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 390  * BIOS, -EINVAL on problems during initiatization, and zero on
 391  * success.
 392  */
 393 static int __init speedstep_init(void)
 394 {
 395         speedstep_processor = speedstep_detect_processor();
 396
 397         switch (speedstep_processor) {
 398         case SPEEDSTEP_CPU_PIII_T:
 399         case SPEEDSTEP_CPU_PIII_C:
 400         case SPEEDSTEP_CPU_PIII_C_EARLY:
 401                 break;
 402         default:
 403                 speedstep_processor = 0;
 404         }
 405
 406         if (!speedstep_processor) {
 407                 dprintk("No supported Intel CPU detected.\n");
 408                 return -ENODEV;
 409         }
 410
 411         dprintk("signature:0x%.8lx, command:0x%.8lx, "
 412                 "event:0x%.8lx, perf_level:0x%.8lx.\n",
 413                 ist_info.signature, ist_info.command,
 414                 ist_info.event, ist_info.perf_level);
 415
 416         /* Error if no IST-SMI BIOS or no PARM
 417                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
 418         if ((ist_info.signature !=  0x47534943) && (
 419             (smi_port == 0) || (smi_cmd == 0)))
 420                 return -ENODEV;
 421
 422         if (smi_sig == 1)
 423                 smi_sig = 0x47534943;
 424         else
 425                 smi_sig = ist_info.signature;
 426
 427         /* setup smi_port from MODLULE_PARM or BIOS */
 428         if ((smi_port > 0xff) || (smi_port < 0))
 429                 return -EINVAL;
 430         else if (smi_port == 0)
 431                 smi_port = ist_info.command & 0xff;
 432
 433         if ((smi_cmd > 0xff) || (smi_cmd < 0))
 434                 return -EINVAL;
 435         else if (smi_cmd == 0)
 436                 smi_cmd = (ist_info.command >> 16) & 0xff;
 437
 438         return cpufreq_register_driver(&speedstep_driver);
 439 }
 440
 441
 442 /**
 443  * speedstep_exit - unregisters SpeedStep support
 444  *
 445  *   Unregisters SpeedStep support.
 446  */
 447 static void __exit speedstep_exit(void)
 448 {
 449         cpufreq_unregister_driver(&speedstep_driver);
 450 }
 451
 452 module_param(smi_port, int, 0444);
 453 module_param(smi_cmd,  int, 0444);
 454 module_param(smi_sig, uint, 0444);
 455
 456 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
 457                 "-- Intel's default setting is 0xb2");
 458 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
 459                 "-- Intel's default setting is 0x82");
 460 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
 461                 "SMI interface.");
 462
 463 MODULE_AUTHOR("Hiroshi Miura");
 464 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
 465 MODULE_LICENSE("GPL");
 466
 467 module_init(speedstep_init);
 468 module_exit(speedstep_exit);