linux/drivers/cpufreq/speedstep-smi.c
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   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 */
  33static int smi_port;
  34static int smi_cmd;
  35static unsigned int smi_sig;
  36
  37/* info about the processor */
  38static 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 */
  44static 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 */
  62static 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 */
 100static 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 */
 148static 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 */
 180static 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        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                        pr_debug("retry %u, previous result %u, waiting...\n",
 202                                        retry, result);
 203                        mdelay(retry * 50);
 204                }
 205                retry++;
 206                __asm__ __volatile__(
 207                        "push %%ebp\n"
 208                        "out %%al, (%%dx)\n"
 209                        "pop %%ebp"
 210                        : "=b" (new_state), "=D" (result),
 211                          "=c" (dummy), "=a" (dummy),
 212                          "=d" (dummy), "=S" (dummy)
 213                        : "a" (command), "b" (function), "c" (state),
 214                          "d" (smi_port), "S" (0), "D" (0)
 215                        );
 216        } while ((new_state != state) && (retry <= SMI_TRIES));
 217
 218        /* enable IRQs */
 219        local_irq_restore(flags);
 220
 221        if (new_state == state)
 222                pr_debug("change to %u MHz succeeded after %u tries "
 223                        "with result %u\n",
 224                        (speedstep_freqs[new_state].frequency / 1000),
 225                        retry, result);
 226        else
 227                printk(KERN_ERR "cpufreq: change to state %u "
 228                        "failed with new_state %u and result %u\n",
 229                        state, new_state, result);
 230
 231        return;
 232}
 233
 234
 235/**
 236 * speedstep_target - set a new CPUFreq policy
 237 * @policy: new policy
 238 * @target_freq: new freq
 239 * @relation:
 240 *
 241 * Sets a new CPUFreq policy/freq.
 242 */
 243static int speedstep_target(struct cpufreq_policy *policy,
 244                        unsigned int target_freq, unsigned int relation)
 245{
 246        unsigned int newstate = 0;
 247        struct cpufreq_freqs freqs;
 248
 249        if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
 250                                target_freq, relation, &newstate))
 251                return -EINVAL;
 252
 253        freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
 254        freqs.new = speedstep_freqs[newstate].frequency;
 255        freqs.cpu = 0; /* speedstep.c is UP only driver */
 256
 257        if (freqs.old == freqs.new)
 258                return 0;
 259
 260        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 261        speedstep_set_state(newstate);
 262        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 263
 264        return 0;
 265}
 266
 267
 268/**
 269 * speedstep_verify - verifies a new CPUFreq policy
 270 * @policy: new policy
 271 *
 272 * Limit must be within speedstep_low_freq and speedstep_high_freq, with
 273 * at least one border included.
 274 */
 275static int speedstep_verify(struct cpufreq_policy *policy)
 276{
 277        return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
 278}
 279
 280
 281static int speedstep_cpu_init(struct cpufreq_policy *policy)
 282{
 283        int result;
 284        unsigned int speed, state;
 285        unsigned int *low, *high;
 286
 287        /* capability check */
 288        if (policy->cpu != 0)
 289                return -ENODEV;
 290
 291        result = speedstep_smi_ownership();
 292        if (result) {
 293                pr_debug("fails in acquiring ownership of a SMI interface.\n");
 294                return -EINVAL;
 295        }
 296
 297        /* detect low and high frequency */
 298        low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
 299        high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
 300
 301        result = speedstep_smi_get_freqs(low, high);
 302        if (result) {
 303                /* fall back to speedstep_lib.c dection mechanism:
 304                 * try both states out */
 305                pr_debug("could not detect low and high frequencies "
 306                                "by SMI call.\n");
 307                result = speedstep_get_freqs(speedstep_processor,
 308                                low, high,
 309                                NULL,
 310                                &speedstep_set_state);
 311
 312                if (result) {
 313                        pr_debug("could not detect two different speeds"
 314                                        " -- aborting.\n");
 315                        return result;
 316                } else
 317                        pr_debug("workaround worked.\n");
 318        }
 319
 320        /* get current speed setting */
 321        state = speedstep_get_state();
 322        speed = speedstep_freqs[state].frequency;
 323
 324        pr_debug("currently at %s speed setting - %i MHz\n",
 325                (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
 326                ? "low" : "high",
 327                (speed / 1000));
 328
 329        /* cpuinfo and default policy values */
 330        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 331        policy->cur = speed;
 332
 333        result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
 334        if (result)
 335                return result;
 336
 337        cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
 338
 339        return 0;
 340}
 341
 342static int speedstep_cpu_exit(struct cpufreq_policy *policy)
 343{
 344        cpufreq_frequency_table_put_attr(policy->cpu);
 345        return 0;
 346}
 347
 348static unsigned int speedstep_get(unsigned int cpu)
 349{
 350        if (cpu)
 351                return -ENODEV;
 352        return speedstep_get_frequency(speedstep_processor);
 353}
 354
 355
 356static int speedstep_resume(struct cpufreq_policy *policy)
 357{
 358        int result = speedstep_smi_ownership();
 359
 360        if (result)
 361                pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
 362
 363        return result;
 364}
 365
 366static struct freq_attr *speedstep_attr[] = {
 367        &cpufreq_freq_attr_scaling_available_freqs,
 368        NULL,
 369};
 370
 371static struct cpufreq_driver speedstep_driver = {
 372        .name           = "speedstep-smi",
 373        .verify         = speedstep_verify,
 374        .target         = speedstep_target,
 375        .init           = speedstep_cpu_init,
 376        .exit           = speedstep_cpu_exit,
 377        .get            = speedstep_get,
 378        .resume         = speedstep_resume,
 379        .owner          = THIS_MODULE,
 380        .attr           = speedstep_attr,
 381};
 382
 383static const struct x86_cpu_id ss_smi_ids[] = {
 384        { X86_VENDOR_INTEL, 6, 0xb, },
 385        { X86_VENDOR_INTEL, 6, 0x8, },
 386        { X86_VENDOR_INTEL, 15, 2 },
 387        {}
 388};
 389#if 0
 390/* Not auto loaded currently */
 391MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
 392#endif
 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 */
 401static int __init speedstep_init(void)
 402{
 403        if (!x86_match_cpu(ss_smi_ids))
 404                return -ENODEV;
 405
 406        speedstep_processor = speedstep_detect_processor();
 407
 408        switch (speedstep_processor) {
 409        case SPEEDSTEP_CPU_PIII_T:
 410        case SPEEDSTEP_CPU_PIII_C:
 411        case SPEEDSTEP_CPU_PIII_C_EARLY:
 412                break;
 413        default:
 414                speedstep_processor = 0;
 415        }
 416
 417        if (!speedstep_processor) {
 418                pr_debug("No supported Intel CPU detected.\n");
 419                return -ENODEV;
 420        }
 421
 422        pr_debug("signature:0x%.8ulx, command:0x%.8ulx, "
 423                "event:0x%.8ulx, perf_level:0x%.8ulx.\n",
 424                ist_info.signature, ist_info.command,
 425                ist_info.event, ist_info.perf_level);
 426
 427        /* Error if no IST-SMI BIOS or no PARM
 428                 sig= 'ISGE' aka 'Intel Speedstep Gate E' */
 429        if ((ist_info.signature !=  0x47534943) && (
 430            (smi_port == 0) || (smi_cmd == 0)))
 431                return -ENODEV;
 432
 433        if (smi_sig == 1)
 434                smi_sig = 0x47534943;
 435        else
 436                smi_sig = ist_info.signature;
 437
 438        /* setup smi_port from MODLULE_PARM or BIOS */
 439        if ((smi_port > 0xff) || (smi_port < 0))
 440                return -EINVAL;
 441        else if (smi_port == 0)
 442                smi_port = ist_info.command & 0xff;
 443
 444        if ((smi_cmd > 0xff) || (smi_cmd < 0))
 445                return -EINVAL;
 446        else if (smi_cmd == 0)
 447                smi_cmd = (ist_info.command >> 16) & 0xff;
 448
 449        return cpufreq_register_driver(&speedstep_driver);
 450}
 451
 452
 453/**
 454 * speedstep_exit - unregisters SpeedStep support
 455 *
 456 *   Unregisters SpeedStep support.
 457 */
 458static void __exit speedstep_exit(void)
 459{
 460        cpufreq_unregister_driver(&speedstep_driver);
 461}
 462
 463module_param(smi_port, int, 0444);
 464module_param(smi_cmd,  int, 0444);
 465module_param(smi_sig, uint, 0444);
 466
 467MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
 468                "-- Intel's default setting is 0xb2");
 469MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
 470                "-- Intel's default setting is 0x82");
 471MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
 472                "SMI interface.");
 473
 474MODULE_AUTHOR("Hiroshi Miura");
 475MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
 476MODULE_LICENSE("GPL");
 477
 478module_init(speedstep_init);
 479module_exit(speedstep_exit);
 480
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