arch/i386/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/pci.h>
  21 #include <linux/slab.h>
  22 #include <linux/delay.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 = 0;
  34 static int smi_cmd = 0;
  35 static unsigned int smi_sig = 0;
  36
  37 /* info about the processor */
  38 static unsigned int speedstep_processor = 0;
  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, "speedstep-smi", msg)
  60
  61 /**
  62  * speedstep_smi_ownership
  63  */
  64 static int speedstep_smi_ownership (void)
  65 {
  66         u32 command, result, magic;
  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", command, smi_port);
  74
  75         __asm__ __volatile__(
  76                 "out %%al, (%%dx)\n"
  77                 : "=D" (result)
  78                 : "a" (command), "b" (function), "c" (0), "d" (smi_port), "D" (0), "S" (magic)
  79         );
  80
  81         dprintk("result is %x\n", result);
  82
  83         return result;
  84 }
  85
  86 /**
  87  * speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
  88  * @low: the low frequency value is placed here
  89  * @high: the high frequency value is placed here
  90  *
  91  * Only available on later SpeedStep-enabled systems, returns false results or
  92  * even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
  93  * shows that the latter occurs if !(ist_info.event & 0xFFFF).
  94  */
  95 static int speedstep_smi_get_freqs (unsigned int *low, unsigned int *high)
  96 {
  97         u32 command, result = 0, edi, high_mhz, low_mhz;
  98         u32 state=0;
  99         u32 function = GET_SPEEDSTEP_FREQS;
 100
 101         if (!(ist_info.event & 0xFFFF)) {
 102                 dprintk("bug #1422 -- can't read freqs from BIOS\n");
 103                 return -ENODEV;
 104         }
 105
 106         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 107
 108         dprintk("trying to determine frequencies with command %x at port %x\n", command, smi_port);
 109
 110         __asm__ __volatile__("movl $0, %%edi\n"
 111                 "out %%al, (%%dx)\n"
 112                 : "=a" (result), "=b" (high_mhz), "=c" (low_mhz), "=d" (state), "=D" (edi)
 113                 : "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
 114         );
 115
 116         dprintk("result %x, low_freq %u, high_freq %u\n", result, low_mhz, high_mhz);
 117
 118         /* abort if results are obviously incorrect... */
 119         if ((high_mhz + low_mhz) < 600)
 120                 return -EINVAL;
 121
 122         *high = high_mhz * 1000;
 123         *low  = low_mhz  * 1000;
 124
 125         return result;
 126 }
 127
 128 /**
 129  * speedstep_get_state - set the SpeedStep state
 130  * @state: processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 131  *
 132  */
 133 static int speedstep_get_state (void)
 134 {
 135         u32 function=GET_SPEEDSTEP_STATE;
 136         u32 result, state, edi, command;
 137
 138         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 139
 140         dprintk("trying to determine current setting with command %x at port %x\n", command, smi_port);
 141
 142         __asm__ __volatile__("movl $0, %%edi\n"
 143                 "out %%al, (%%dx)\n"
 144                 : "=a" (result), "=b" (state), "=D" (edi)
 145                 : "a" (command), "b" (function), "c" (0), "d" (smi_port), "S" (0)
 146         );
 147
 148         dprintk("state is %x, result is %x\n", state, result);
 149
 150         return (state & 1);
 151 }
 152
 153
 154 /**
 155  * speedstep_set_state - set the SpeedStep state
 156  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 157  *
 158  */
 159 static void speedstep_set_state (unsigned int state)
 160 {
 161         unsigned int result = 0, command, new_state;
 162         unsigned long flags;
 163         unsigned int function=SET_SPEEDSTEP_STATE;
 164         unsigned int retry = 0;
 165
 166         if (state > 0x1)
 167                 return;
 168
 169         /* Disable IRQs */
 170         local_irq_save(flags);
 171
 172         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 173
 174         dprintk("trying to set frequency to state %u with command %x at port %x\n", state, command, smi_port);
 175
 176         do {
 177                 if (retry) {
 178                         dprintk("retry %u, previous result %u, waiting...\n", retry, result);
 179                         mdelay(retry * 50);
 180                 }
 181                 retry++;
 182                 __asm__ __volatile__(
 183                         "movl $0, %%edi\n"
 184                         "out %%al, (%%dx)\n"
 185                         : "=b" (new_state), "=D" (result)
 186                         : "a" (command), "b" (function), "c" (state), "d" (smi_port), "S" (0)
 187                         );
 188         } while ((new_state != state) && (retry <= SMI_TRIES));
 189
 190         /* enable IRQs */
 191         local_irq_restore(flags);
 192
 193         if (new_state == state) {
 194                 dprintk("change to %u MHz succeeded after %u tries with result %u\n", (speedstep_freqs[new_state].frequency / 1000), retry, result);
 195         } else {
 196                 printk(KERN_ERR "cpufreq: change failed with new_state %u and result %u\n", new_state, result);
 197         }
 198
 199         return;
 200 }
 201
 202
 203 /**
 204  * speedstep_target - set a new CPUFreq policy
 205  * @policy: new policy
 206  * @target_freq: new freq
 207  * @relation:
 208  *
 209  * Sets a new CPUFreq policy/freq.
 210  */
 211 static int speedstep_target (struct cpufreq_policy *policy,
 212                         unsigned int target_freq, unsigned int relation)
 213 {
 214         unsigned int newstate = 0;
 215         struct cpufreq_freqs freqs;
 216
 217         if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0], target_freq, relation, &newstate))
 218                 return -EINVAL;
 219
 220         freqs.old = speedstep_freqs[speedstep_get_state()].frequency;
 221         freqs.new = speedstep_freqs[newstate].frequency;
 222         freqs.cpu = 0; /* speedstep.c is UP only driver */
 223
 224         if (freqs.old == freqs.new)
 225                 return 0;
 226
 227         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 228         speedstep_set_state(newstate);
 229         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 230
 231         return 0;
 232 }
 233
 234
 235 /**
 236  * speedstep_verify - verifies a new CPUFreq policy
 237  * @policy: new policy
 238  *
 239  * Limit must be within speedstep_low_freq and speedstep_high_freq, with
 240  * at least one border included.
 241  */
 242 static int speedstep_verify (struct cpufreq_policy *policy)
 243 {
 244         return cpufreq_frequency_table_verify(policy, &speedstep_freqs[0]);
 245 }
 246
 247
 248 static int speedstep_cpu_init(struct cpufreq_policy *policy)
 249 {
 250         int result;
 251         unsigned int speed,state;
 252
 253         /* capability check */
 254         if (policy->cpu != 0)
 255                 return -ENODEV;
 256
 257         result = speedstep_smi_ownership();
 258         if (result) {
 259                 dprintk("fails in aquiring ownership of a SMI interface.\n");
 260                 return -EINVAL;
 261         }
 262
 263         /* detect low and high frequency */
 264         result = speedstep_smi_get_freqs(&speedstep_freqs[SPEEDSTEP_LOW].frequency,
 265                                 &speedstep_freqs[SPEEDSTEP_HIGH].frequency);
 266         if (result) {
 267                 /* fall back to speedstep_lib.c dection mechanism: try both states out */
 268                 dprintk("could not detect low and high frequencies by SMI call.\n");
 269                 result = speedstep_get_freqs(speedstep_processor,
 270                                 &speedstep_freqs[SPEEDSTEP_LOW].frequency,
 271                                 &speedstep_freqs[SPEEDSTEP_HIGH].frequency,
 272                                 NULL,
 273                                 &speedstep_set_state);
 274
 275                 if (result) {
 276                         dprintk("could not detect two different speeds -- aborting.\n");
 277                         return result;
 278                 } else
 279                         dprintk("workaround worked.\n");
 280         }
 281
 282         /* get current speed setting */
 283         state = speedstep_get_state();
 284         speed = speedstep_freqs[state].frequency;
 285
 286         dprintk("currently at %s speed setting - %i MHz\n",
 287                 (speed == speedstep_freqs[SPEEDSTEP_LOW].frequency) ? "low" : "high",
 288                 (speed / 1000));
 289
 290         /* cpuinfo and default policy values */
 291         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 292         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 293         policy->cur = speed;
 294
 295         result = cpufreq_frequency_table_cpuinfo(policy, speedstep_freqs);
 296         if (result)
 297                 return (result);
 298
 299         cpufreq_frequency_table_get_attr(speedstep_freqs, policy->cpu);
 300
 301         return 0;
 302 }
 303
 304 static int speedstep_cpu_exit(struct cpufreq_policy *policy)
 305 {
 306         cpufreq_frequency_table_put_attr(policy->cpu);
 307         return 0;
 308 }
 309
 310 static unsigned int speedstep_get(unsigned int cpu)
 311 {
 312         if (cpu)
 313                 return -ENODEV;
 314         return speedstep_get_processor_frequency(speedstep_processor);
 315 }
 316
 317
 318 static int speedstep_resume(struct cpufreq_policy *policy)
 319 {
 320         int result = speedstep_smi_ownership();
 321
 322         if (result)
 323                 dprintk("fails in re-aquiring ownership of a SMI interface.\n");
 324
 325         return result;
 326 }
 327
 328 static struct freq_attr* speedstep_attr[] = {
 329         &cpufreq_freq_attr_scaling_available_freqs,
 330         NULL,
 331 };
 332
 333 static struct cpufreq_driver speedstep_driver = {
 334         .name           = "speedstep-smi",
 335         .verify         = speedstep_verify,
 336         .target         = speedstep_target,
 337         .init           = speedstep_cpu_init,
 338         .exit           = speedstep_cpu_exit,
 339         .get            = speedstep_get,
 340         .resume         = speedstep_resume,
 341         .owner          = THIS_MODULE,
 342         .attr           = speedstep_attr,
 343 };
 344
 345 /**
 346  * speedstep_init - initializes the SpeedStep CPUFreq driver
 347  *
 348  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 349  * BIOS, -EINVAL on problems during initiatization, and zero on
 350  * success.
 351  */
 352 static int __init speedstep_init(void)
 353 {
 354         speedstep_processor = speedstep_detect_processor();
 355
 356         switch (speedstep_processor) {
 357         case SPEEDSTEP_PROCESSOR_PIII_T:
 358         case SPEEDSTEP_PROCESSOR_PIII_C:
 359         case SPEEDSTEP_PROCESSOR_PIII_C_EARLY:
 360                 break;
 361         case SPEEDSTEP_PROCESSOR_P4M:
 362                 printk(KERN_INFO "speedstep-smi: you're trying to use this cpufreq driver on a Pentium 4-based CPU. Most likely it will not work.\n");
 363                 break;
 364         default:
 365                 speedstep_processor = 0;
 366         }
 367
 368         if (!speedstep_processor) {
 369                 dprintk ("No supported Intel CPU detected.\n");
 370                 return -ENODEV;
 371         }
 372
 373         dprintk("signature:0x%.8lx, command:0x%.8lx, event:0x%.8lx, perf_level:0x%.8lx.\n",
 374                 ist_info.signature, ist_info.command, ist_info.event, ist_info.perf_level);
 375
 376         /* Error if no IST-SMI BIOS or no PARM
 377                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
 378         if ((ist_info.signature !=  0x47534943) && (
 379             (smi_port == 0) || (smi_cmd == 0)))
 380                 return -ENODEV;
 381
 382         if (smi_sig == 1)
 383                 smi_sig = 0x47534943;
 384         else
 385                 smi_sig = ist_info.signature;
 386
 387         /* setup smi_port from MODLULE_PARM or BIOS */
 388         if ((smi_port > 0xff) || (smi_port < 0))
 389                 return -EINVAL;
 390         else if (smi_port == 0)
 391                 smi_port = ist_info.command & 0xff;
 392
 393         if ((smi_cmd > 0xff) || (smi_cmd < 0))
 394                 return -EINVAL;
 395         else if (smi_cmd == 0)
 396                 smi_cmd = (ist_info.command >> 16) & 0xff;
 397
 398         return cpufreq_register_driver(&speedstep_driver);
 399 }
 400
 401
 402 /**
 403  * speedstep_exit - unregisters SpeedStep support
 404  *
 405  *   Unregisters SpeedStep support.
 406  */
 407 static void __exit speedstep_exit(void)
 408 {
 409         cpufreq_unregister_driver(&speedstep_driver);
 410 }
 411
 412 module_param(smi_port,  int, 0444);
 413 module_param(smi_cmd,   int, 0444);
 414 module_param(smi_sig,  uint, 0444);
 415
 416 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value -- Intel's default setting is 0xb2");
 417 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value -- Intel's default setting is 0x82");
 418 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the SMI interface.");
 419
 420 MODULE_AUTHOR ("Hiroshi Miura");
 421 MODULE_DESCRIPTION ("Speedstep driver for IST applet SMI interface.");
 422 MODULE_LICENSE ("GPL");
 423
 424 module_init(speedstep_init);
 425 module_exit(speedstep_exit);