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 #define pr_fmt(fmt) "cpufreq: " fmt
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/init.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/delay.h>
  23 #include <linux/io.h>
  24 #include <asm/ist.h>
  25 #include <asm/cpu_device_id.h>
  26
  27 #include "speedstep-lib.h"
  28
  29 /* speedstep system management interface port/command.
  30  *
  31  * These parameters are got from IST-SMI BIOS call.
  32  * If user gives it, these are used.
  33  *
  34  */
  35 static int smi_port;
  36 static int smi_cmd;
  37 static unsigned int smi_sig;
  38
  39 /* info about the processor */
  40 static enum speedstep_processor speedstep_processor;
  41
  42 /*
  43  * There are only two frequency states for each processor. Values
  44  * are in kHz for the time being.
  45  */
  46 static struct cpufreq_frequency_table speedstep_freqs[] = {
  47         {0, SPEEDSTEP_HIGH,     0},
  48         {0, SPEEDSTEP_LOW,      0},
  49         {0, 0,                  CPUFREQ_TABLE_END},
  50 };
  51
  52 #define GET_SPEEDSTEP_OWNER 0
  53 #define GET_SPEEDSTEP_STATE 1
  54 #define SET_SPEEDSTEP_STATE 2
  55 #define GET_SPEEDSTEP_FREQS 4
  56
  57 /* how often shall the SMI call be tried if it failed, e.g. because
  58  * of DMA activity going on? */
  59 #define SMI_TRIES 5
  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         pr_debug("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         pr_debug("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                 pr_debug("bug #1422 -- can't read freqs from BIOS\n");
 110                 return -ENODEV;
 111         }
 112
 113         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 114
 115         pr_debug("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         pr_debug("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_set_state - set the SpeedStep state
 147  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
 148  *
 149  */
 150 static void speedstep_set_state(unsigned int state)
 151 {
 152         unsigned int result = 0, command, new_state, dummy;
 153         unsigned long flags;
 154         unsigned int function = SET_SPEEDSTEP_STATE;
 155         unsigned int retry = 0;
 156
 157         if (state > 0x1)
 158                 return;
 159
 160         /* Disable IRQs */
 161         preempt_disable();
 162         local_irq_save(flags);
 163
 164         command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
 165
 166         pr_debug("trying to set frequency to state %u "
 167                 "with command %x at port %x\n",
 168                 state, command, smi_port);
 169
 170         do {
 171                 if (retry) {
 172                         /*
 173                          * We need to enable interrupts, otherwise the blockage
 174                          * won't resolve.
 175                          *
 176                          * We disable preemption so that other processes don't
 177                          * run. If other processes were running, they could
 178                          * submit more DMA requests, making the blockage worse.
 179                          */
 180                         pr_debug("retry %u, previous result %u, waiting...\n",
 181                                         retry, result);
 182                         local_irq_enable();
 183                         mdelay(retry * 50);
 184                         local_irq_disable();
 185                 }
 186                 retry++;
 187                 __asm__ __volatile__(
 188                         "push %%ebp\n"
 189                         "out %%al, (%%dx)\n"
 190                         "pop %%ebp"
 191                         : "=b" (new_state), "=D" (result),
 192                           "=c" (dummy), "=a" (dummy),
 193                           "=d" (dummy), "=S" (dummy)
 194                         : "a" (command), "b" (function), "c" (state),
 195                           "d" (smi_port), "S" (0), "D" (0)
 196                         );
 197         } while ((new_state != state) && (retry <= SMI_TRIES));
 198
 199         /* enable IRQs */
 200         local_irq_restore(flags);
 201         preempt_enable();
 202
 203         if (new_state == state)
 204                 pr_debug("change to %u MHz succeeded after %u tries "
 205                         "with result %u\n",
 206                         (speedstep_freqs[new_state].frequency / 1000),
 207                         retry, result);
 208         else
 209                 pr_err("change to state %u failed with new_state %u and result %u\n",
 210                        state, new_state, result);
 211
 212         return;
 213 }
 214
 215
 216 /**
 217  * speedstep_target - set a new CPUFreq policy
 218  * @policy: new policy
 219  * @index: index of new freq
 220  *
 221  * Sets a new CPUFreq policy/freq.
 222  */
 223 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
 224 {
 225         speedstep_set_state(index);
 226
 227         return 0;
 228 }
 229
 230
 231 static int speedstep_cpu_init(struct cpufreq_policy *policy)
 232 {
 233         int result;
 234         unsigned int *low, *high;
 235
 236         /* capability check */
 237         if (policy->cpu != 0)
 238                 return -ENODEV;
 239
 240         result = speedstep_smi_ownership();
 241         if (result) {
 242                 pr_debug("fails in acquiring ownership of a SMI interface.\n");
 243                 return -EINVAL;
 244         }
 245
 246         /* detect low and high frequency */
 247         low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
 248         high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
 249
 250         result = speedstep_smi_get_freqs(low, high);
 251         if (result) {
 252                 /* fall back to speedstep_lib.c dection mechanism:
 253                  * try both states out */
 254                 pr_debug("could not detect low and high frequencies "
 255                                 "by SMI call.\n");
 256                 result = speedstep_get_freqs(speedstep_processor,
 257                                 low, high,
 258                                 NULL,
 259                                 &speedstep_set_state);
 260
 261                 if (result) {
 262                         pr_debug("could not detect two different speeds"
 263                                         " -- aborting.\n");
 264                         return result;
 265                 } else
 266                         pr_debug("workaround worked.\n");
 267         }
 268
 269         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 270         return cpufreq_table_validate_and_show(policy, speedstep_freqs);
 271 }
 272
 273 static unsigned int speedstep_get(unsigned int cpu)
 274 {
 275         if (cpu)
 276                 return -ENODEV;
 277         return speedstep_get_frequency(speedstep_processor);
 278 }
 279
 280
 281 static int speedstep_resume(struct cpufreq_policy *policy)
 282 {
 283         int result = speedstep_smi_ownership();
 284
 285         if (result)
 286                 pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
 287
 288         return result;
 289 }
 290
 291 static struct cpufreq_driver speedstep_driver = {
 292         .name           = "speedstep-smi",
 293         .verify         = cpufreq_generic_frequency_table_verify,
 294         .target_index   = speedstep_target,
 295         .init           = speedstep_cpu_init,
 296         .get            = speedstep_get,
 297         .resume         = speedstep_resume,
 298         .attr           = cpufreq_generic_attr,
 299 };
 300
 301 static const struct x86_cpu_id ss_smi_ids[] = {
 302         { X86_VENDOR_INTEL, 6, 0xb, },
 303         { X86_VENDOR_INTEL, 6, 0x8, },
 304         { X86_VENDOR_INTEL, 15, 2 },
 305         {}
 306 };
 307 #if 0
 308 /* Not auto loaded currently */
 309 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
 310 #endif
 311
 312 /**
 313  * speedstep_init - initializes the SpeedStep CPUFreq driver
 314  *
 315  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
 316  * BIOS, -EINVAL on problems during initiatization, and zero on
 317  * success.
 318  */
 319 static int __init speedstep_init(void)
 320 {
 321         if (!x86_match_cpu(ss_smi_ids))
 322                 return -ENODEV;
 323
 324         speedstep_processor = speedstep_detect_processor();
 325
 326         switch (speedstep_processor) {
 327         case SPEEDSTEP_CPU_PIII_T:
 328         case SPEEDSTEP_CPU_PIII_C:
 329         case SPEEDSTEP_CPU_PIII_C_EARLY:
 330                 break;
 331         default:
 332                 speedstep_processor = 0;
 333         }
 334
 335         if (!speedstep_processor) {
 336                 pr_debug("No supported Intel CPU detected.\n");
 337                 return -ENODEV;
 338         }
 339
 340         pr_debug("signature:0x%.8x, command:0x%.8x, "
 341                 "event:0x%.8x, perf_level:0x%.8x.\n",
 342                 ist_info.signature, ist_info.command,
 343                 ist_info.event, ist_info.perf_level);
 344
 345         /* Error if no IST-SMI BIOS or no PARM
 346                  sig= 'ISGE' aka 'Intel Speedstep Gate E' */
 347         if ((ist_info.signature !=  0x47534943) && (
 348             (smi_port == 0) || (smi_cmd == 0)))
 349                 return -ENODEV;
 350
 351         if (smi_sig == 1)
 352                 smi_sig = 0x47534943;
 353         else
 354                 smi_sig = ist_info.signature;
 355
 356         /* setup smi_port from MODLULE_PARM or BIOS */
 357         if ((smi_port > 0xff) || (smi_port < 0))
 358                 return -EINVAL;
 359         else if (smi_port == 0)
 360                 smi_port = ist_info.command & 0xff;
 361
 362         if ((smi_cmd > 0xff) || (smi_cmd < 0))
 363                 return -EINVAL;
 364         else if (smi_cmd == 0)
 365                 smi_cmd = (ist_info.command >> 16) & 0xff;
 366
 367         return cpufreq_register_driver(&speedstep_driver);
 368 }
 369
 370
 371 /**
 372  * speedstep_exit - unregisters SpeedStep support
 373  *
 374  *   Unregisters SpeedStep support.
 375  */
 376 static void __exit speedstep_exit(void)
 377 {
 378         cpufreq_unregister_driver(&speedstep_driver);
 379 }
 380
 381 module_param(smi_port, int, 0444);
 382 module_param(smi_cmd,  int, 0444);
 383 module_param(smi_sig, uint, 0444);
 384
 385 MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
 386                 "-- Intel's default setting is 0xb2");
 387 MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
 388                 "-- Intel's default setting is 0x82");
 389 MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
 390                 "SMI interface.");
 391
 392 MODULE_AUTHOR("Hiroshi Miura");
 393 MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
 394 MODULE_LICENSE("GPL");
 395
 396 module_init(speedstep_init);
 397 module_exit(speedstep_exit);