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