drivers/cpufreq/gx-suspmod.c

   1 /*
   2  *      Cyrix MediaGX and NatSemi Geode Suspend Modulation
   3  *      (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
   4  *      (C) 2002 Hiroshi Miura   <miura@da-cha.org>
   5  *      All Rights Reserved
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      version 2 as published by the Free Software Foundation
  10  *
  11  *      The author(s) of this software shall not be held liable for damages
  12  *      of any nature resulting due to the use of this software. This
  13  *      software is provided AS-IS with no warranties.
  14  *
  15  * Theoretical note:
  16  *
  17  *      (see Geode(tm) CS5530 manual (rev.4.1) page.56)
  18  *
  19  *      CPU frequency control on NatSemi Geode GX1/GXLV processor and CS55x0
  20  *      are based on Suspend Modulation.
  21  *
  22  *      Suspend Modulation works by asserting and de-asserting the SUSP# pin
  23  *      to CPU(GX1/GXLV) for configurable durations. When asserting SUSP#
  24  *      the CPU enters an idle state. GX1 stops its core clock when SUSP# is
  25  *      asserted then power consumption is reduced.
  26  *
  27  *      Suspend Modulation's OFF/ON duration are configurable
  28  *      with 'Suspend Modulation OFF Count Register'
  29  *      and 'Suspend Modulation ON Count Register'.
  30  *      These registers are 8bit counters that represent the number of
  31  *      32us intervals which the SUSP# pin is asserted(ON)/de-asserted(OFF)
  32  *      to the processor.
  33  *
  34  *      These counters define a ratio which is the effective frequency
  35  *      of operation of the system.
  36  *
  37  *                             OFF Count
  38  *      F_eff = Fgx * ----------------------
  39  *                      OFF Count + ON Count
  40  *
  41  *      0 <= On Count, Off Count <= 255
  42  *
  43  *      From these limits, we can get register values
  44  *
  45  *      off_duration + on_duration <= MAX_DURATION
  46  *      on_duration = off_duration * (stock_freq - freq) / freq
  47  *
  48  *      off_duration  =  (freq * DURATION) / stock_freq
  49  *      on_duration = DURATION - off_duration
  50  *
  51  *
  52  *---------------------------------------------------------------------------
  53  *
  54  * ChangeLog:
  55  *      Dec. 12, 2003   Hiroshi Miura <miura@da-cha.org>
  56  *              - fix on/off register mistake
  57  *              - fix cpu_khz calc when it stops cpu modulation.
  58  *
  59  *      Dec. 11, 2002   Hiroshi Miura <miura@da-cha.org>
  60  *              - rewrite for Cyrix MediaGX Cx5510/5520 and
  61  *                NatSemi Geode Cs5530(A).
  62  *
  63  *      Jul. ??, 2002  Zwane Mwaikambo <zwane@commfireservices.com>
  64  *              - cs5530_mod patch for 2.4.19-rc1.
  65  *
  66  *---------------------------------------------------------------------------
  67  *
  68  * Todo
  69  *      Test on machines with 5510, 5530, 5530A
  70  */
  71
  72 /************************************************************************
  73  *                      Suspend Modulation - Definitions                *
  74  ************************************************************************/
  75
  76 #include <linux/kernel.h>
  77 #include <linux/module.h>
  78 #include <linux/init.h>
  79 #include <linux/smp.h>
  80 #include <linux/cpufreq.h>
  81 #include <linux/pci.h>
  82 #include <linux/errno.h>
  83 #include <linux/slab.h>
  84
  85 #include <asm/cpu_device_id.h>
  86 #include <asm/processor-cyrix.h>
  87
  88 /* PCI config registers, all at F0 */
  89 #define PCI_PMER1       0x80    /* power management enable register 1 */
  90 #define PCI_PMER2       0x81    /* power management enable register 2 */
  91 #define PCI_PMER3       0x82    /* power management enable register 3 */
  92 #define PCI_IRQTC       0x8c    /* irq speedup timer counter register:typical 2 to 4ms */
  93 #define PCI_VIDTC       0x8d    /* video speedup timer counter register: typical 50 to 100ms */
  94 #define PCI_MODOFF      0x94    /* suspend modulation OFF counter register, 1 = 32us */
  95 #define PCI_MODON       0x95    /* suspend modulation ON counter register */
  96 #define PCI_SUSCFG      0x96    /* suspend configuration register */
  97
  98 /* PMER1 bits */
  99 #define GPM             (1<<0)  /* global power management */
 100 #define GIT             (1<<1)  /* globally enable PM device idle timers */
 101 #define GTR             (1<<2)  /* globally enable IO traps */
 102 #define IRQ_SPDUP       (1<<3)  /* disable clock throttle during interrupt handling */
 103 #define VID_SPDUP       (1<<4)  /* disable clock throttle during vga video handling */
 104
 105 /* SUSCFG bits */
 106 #define SUSMOD          (1<<0)  /* enable/disable suspend modulation */
 107 /* the below is supported only with cs5530 (after rev.1.2)/cs5530A */
 108 #define SMISPDUP        (1<<1)  /* select how SMI re-enable suspend modulation: */
 109                                 /* IRQTC timer or read SMI speedup disable reg.(F1BAR[08-09h]) */
 110 #define SUSCFG          (1<<2)  /* enable powering down a GXLV processor. "Special 3Volt Suspend" mode */
 111 /* the below is supported only with cs5530A */
 112 #define PWRSVE_ISA      (1<<3)  /* stop ISA clock  */
 113 #define PWRSVE          (1<<4)  /* active idle */
 114
 115 struct gxfreq_params {
 116         u8 on_duration;
 117         u8 off_duration;
 118         u8 pci_suscfg;
 119         u8 pci_pmer1;
 120         u8 pci_pmer2;
 121         struct pci_dev *cs55x0;
 122 };
 123
 124 static struct gxfreq_params *gx_params;
 125 static int stock_freq;
 126
 127 /* PCI bus clock - defaults to 30.000 if cpu_khz is not available */
 128 static int pci_busclk;
 129 module_param(pci_busclk, int, 0444);
 130
 131 /* maximum duration for which the cpu may be suspended
 132  * (32us * MAX_DURATION). If no parameter is given, this defaults
 133  * to 255.
 134  * Note that this leads to a maximum of 8 ms(!) where the CPU clock
 135  * is suspended -- processing power is just 0.39% of what it used to be,
 136  * though. 781.25 kHz(!) for a 200 MHz processor -- wow. */
 137 static int max_duration = 255;
 138 module_param(max_duration, int, 0444);
 139
 140 /* For the default policy, we want at least some processing power
 141  * - let's say 5%. (min = maxfreq / POLICY_MIN_DIV)
 142  */
 143 #define POLICY_MIN_DIV 20
 144
 145
 146 /**
 147  * we can detect a core multipiler from dir0_lsb
 148  * from GX1 datasheet p.56,
 149  *      MULT[3:0]:
 150  *      0000 = SYSCLK multiplied by 4 (test only)
 151  *      0001 = SYSCLK multiplied by 10
 152  *      0010 = SYSCLK multiplied by 4
 153  *      0011 = SYSCLK multiplied by 6
 154  *      0100 = SYSCLK multiplied by 9
 155  *      0101 = SYSCLK multiplied by 5
 156  *      0110 = SYSCLK multiplied by 7
 157  *      0111 = SYSCLK multiplied by 8
 158  *              of 33.3MHz
 159  **/
 160 static int gx_freq_mult[16] = {
 161                 4, 10, 4, 6, 9, 5, 7, 8,
 162                 0, 0, 0, 0, 0, 0, 0, 0
 163 };
 164
 165
 166 /****************************************************************
 167  *      Low Level chipset interface                             *
 168  ****************************************************************/
 169 static struct pci_device_id gx_chipset_tbl[] __initdata = {
 170         { PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY), },
 171         { PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5520), },
 172         { PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5510), },
 173         { 0, },
 174 };
 175 MODULE_DEVICE_TABLE(pci, gx_chipset_tbl);
 176
 177 static void gx_write_byte(int reg, int value)
 178 {
 179         pci_write_config_byte(gx_params->cs55x0, reg, value);
 180 }
 181
 182 /**
 183  * gx_detect_chipset:
 184  *
 185  **/
 186 static struct pci_dev * __init gx_detect_chipset(void)
 187 {
 188         struct pci_dev *gx_pci = NULL;
 189
 190         /* detect which companion chip is used */
 191         for_each_pci_dev(gx_pci) {
 192                 if ((pci_match_id(gx_chipset_tbl, gx_pci)) != NULL)
 193                         return gx_pci;
 194         }
 195
 196         pr_debug("error: no supported chipset found!\n");
 197         return NULL;
 198 }
 199
 200 /**
 201  * gx_get_cpuspeed:
 202  *
 203  * Finds out at which efficient frequency the Cyrix MediaGX/NatSemi
 204  * Geode CPU runs.
 205  */
 206 static unsigned int gx_get_cpuspeed(unsigned int cpu)
 207 {
 208         if ((gx_params->pci_suscfg & SUSMOD) == 0)
 209                 return stock_freq;
 210
 211         return (stock_freq * gx_params->off_duration)
 212                 / (gx_params->on_duration + gx_params->off_duration);
 213 }
 214
 215 /**
 216  *      gx_validate_speed:
 217  *      determine current cpu speed
 218  *
 219  **/
 220
 221 static unsigned int gx_validate_speed(unsigned int khz, u8 *on_duration,
 222                 u8 *off_duration)
 223 {
 224         unsigned int i;
 225         u8 tmp_on, tmp_off;
 226         int old_tmp_freq = stock_freq;
 227         int tmp_freq;
 228
 229         *off_duration = 1;
 230         *on_duration = 0;
 231
 232         for (i = max_duration; i > 0; i--) {
 233                 tmp_off = ((khz * i) / stock_freq) & 0xff;
 234                 tmp_on = i - tmp_off;
 235                 tmp_freq = (stock_freq * tmp_off) / i;
 236                 /* if this relation is closer to khz, use this. If it's equal,
 237                  * prefer it, too - lower latency */
 238                 if (abs(tmp_freq - khz) <= abs(old_tmp_freq - khz)) {
 239                         *on_duration = tmp_on;
 240                         *off_duration = tmp_off;
 241                         old_tmp_freq = tmp_freq;
 242                 }
 243         }
 244
 245         return old_tmp_freq;
 246 }
 247
 248
 249 /**
 250  * gx_set_cpuspeed:
 251  * set cpu speed in khz.
 252  **/
 253
 254 static void gx_set_cpuspeed(struct cpufreq_policy *policy, unsigned int khz)
 255 {
 256         u8 suscfg, pmer1;
 257         unsigned int new_khz;
 258         unsigned long flags;
 259         struct cpufreq_freqs freqs;
 260
 261         freqs.old = gx_get_cpuspeed(0);
 262
 263         new_khz = gx_validate_speed(khz, &gx_params->on_duration,
 264                         &gx_params->off_duration);
 265
 266         freqs.new = new_khz;
 267
 268         cpufreq_freq_transition_begin(policy, &freqs);
 269         local_irq_save(flags);
 270
 271         if (new_khz != stock_freq) {
 272                 /* if new khz == 100% of CPU speed, it is special case */
 273                 switch (gx_params->cs55x0->device) {
 274                 case PCI_DEVICE_ID_CYRIX_5530_LEGACY:
 275                         pmer1 = gx_params->pci_pmer1 | IRQ_SPDUP | VID_SPDUP;
 276                         /* FIXME: need to test other values -- Zwane,Miura */
 277                         /* typical 2 to 4ms */
 278                         gx_write_byte(PCI_IRQTC, 4);
 279                         /* typical 50 to 100ms */
 280                         gx_write_byte(PCI_VIDTC, 100);
 281                         gx_write_byte(PCI_PMER1, pmer1);
 282
 283                         if (gx_params->cs55x0->revision < 0x10) {
 284                                 /* CS5530(rev 1.2, 1.3) */
 285                                 suscfg = gx_params->pci_suscfg|SUSMOD;
 286                         } else {
 287                                 /* CS5530A,B.. */
 288                                 suscfg = gx_params->pci_suscfg|SUSMOD|PWRSVE;
 289                         }
 290                         break;
 291                 case PCI_DEVICE_ID_CYRIX_5520:
 292                 case PCI_DEVICE_ID_CYRIX_5510:
 293                         suscfg = gx_params->pci_suscfg | SUSMOD;
 294                         break;
 295                 default:
 296                         local_irq_restore(flags);
 297                         pr_debug("fatal: try to set unknown chipset.\n");
 298                         return;
 299                 }
 300         } else {
 301                 suscfg = gx_params->pci_suscfg & ~(SUSMOD);
 302                 gx_params->off_duration = 0;
 303                 gx_params->on_duration = 0;
 304                 pr_debug("suspend modulation disabled: cpu runs 100%% speed.\n");
 305         }
 306
 307         gx_write_byte(PCI_MODOFF, gx_params->off_duration);
 308         gx_write_byte(PCI_MODON, gx_params->on_duration);
 309
 310         gx_write_byte(PCI_SUSCFG, suscfg);
 311         pci_read_config_byte(gx_params->cs55x0, PCI_SUSCFG, &suscfg);
 312
 313         local_irq_restore(flags);
 314
 315         gx_params->pci_suscfg = suscfg;
 316
 317         cpufreq_freq_transition_end(policy, &freqs, 0);
 318
 319         pr_debug("suspend modulation w/ duration of ON:%d us, OFF:%d us\n",
 320                 gx_params->on_duration * 32, gx_params->off_duration * 32);
 321         pr_debug("suspend modulation w/ clock speed: %d kHz.\n", freqs.new);
 322 }
 323
 324 /****************************************************************
 325  *             High level functions                             *
 326  ****************************************************************/
 327
 328 /*
 329  *      cpufreq_gx_verify: test if frequency range is valid
 330  *
 331  *      This function checks if a given frequency range in kHz is valid
 332  *      for the hardware supported by the driver.
 333  */
 334
 335 static int cpufreq_gx_verify(struct cpufreq_policy *policy)
 336 {
 337         unsigned int tmp_freq = 0;
 338         u8 tmp1, tmp2;
 339
 340         if (!stock_freq || !policy)
 341                 return -EINVAL;
 342
 343         policy->cpu = 0;
 344         cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
 345                         stock_freq);
 346
 347         /* it needs to be assured that at least one supported frequency is
 348          * within policy->min and policy->max. If it is not, policy->max
 349          * needs to be increased until one freuqency is supported.
 350          * policy->min may not be decreased, though. This way we guarantee a
 351          * specific processing capacity.
 352          */
 353         tmp_freq = gx_validate_speed(policy->min, &tmp1, &tmp2);
 354         if (tmp_freq < policy->min)
 355                 tmp_freq += stock_freq / max_duration;
 356         policy->min = tmp_freq;
 357         if (policy->min > policy->max)
 358                 policy->max = tmp_freq;
 359         tmp_freq = gx_validate_speed(policy->max, &tmp1, &tmp2);
 360         if (tmp_freq > policy->max)
 361                 tmp_freq -= stock_freq / max_duration;
 362         policy->max = tmp_freq;
 363         if (policy->max < policy->min)
 364                 policy->max = policy->min;
 365         cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
 366                         stock_freq);
 367
 368         return 0;
 369 }
 370
 371 /*
 372  *      cpufreq_gx_target:
 373  *
 374  */
 375 static int cpufreq_gx_target(struct cpufreq_policy *policy,
 376                              unsigned int target_freq,
 377                              unsigned int relation)
 378 {
 379         u8 tmp1, tmp2;
 380         unsigned int tmp_freq;
 381
 382         if (!stock_freq || !policy)
 383                 return -EINVAL;
 384
 385         policy->cpu = 0;
 386
 387         tmp_freq = gx_validate_speed(target_freq, &tmp1, &tmp2);
 388         while (tmp_freq < policy->min) {
 389                 tmp_freq += stock_freq / max_duration;
 390                 tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
 391         }
 392         while (tmp_freq > policy->max) {
 393                 tmp_freq -= stock_freq / max_duration;
 394                 tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
 395         }
 396
 397         gx_set_cpuspeed(policy, tmp_freq);
 398
 399         return 0;
 400 }
 401
 402 static int cpufreq_gx_cpu_init(struct cpufreq_policy *policy)
 403 {
 404         unsigned int maxfreq;
 405
 406         if (!policy || policy->cpu != 0)
 407                 return -ENODEV;
 408
 409         /* determine maximum frequency */
 410         if (pci_busclk)
 411                 maxfreq = pci_busclk * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
 412         else if (cpu_khz)
 413                 maxfreq = cpu_khz;
 414         else
 415                 maxfreq = 30000 * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
 416
 417         stock_freq = maxfreq;
 418
 419         pr_debug("cpu max frequency is %d.\n", maxfreq);
 420
 421         /* setup basic struct for cpufreq API */
 422         policy->cpu = 0;
 423
 424         if (max_duration < POLICY_MIN_DIV)
 425                 policy->min = maxfreq / max_duration;
 426         else
 427                 policy->min = maxfreq / POLICY_MIN_DIV;
 428         policy->max = maxfreq;
 429         policy->cpuinfo.min_freq = maxfreq / max_duration;
 430         policy->cpuinfo.max_freq = maxfreq;
 431         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 432
 433         return 0;
 434 }
 435
 436 /*
 437  * cpufreq_gx_init:
 438  *   MediaGX/Geode GX initialize cpufreq driver
 439  */
 440 static struct cpufreq_driver gx_suspmod_driver = {
 441         .get            = gx_get_cpuspeed,
 442         .verify         = cpufreq_gx_verify,
 443         .target         = cpufreq_gx_target,
 444         .init           = cpufreq_gx_cpu_init,
 445         .name           = "gx-suspmod",
 446 };
 447
 448 static int __init cpufreq_gx_init(void)
 449 {
 450         int ret;
 451         struct gxfreq_params *params;
 452         struct pci_dev *gx_pci;
 453
 454         /* Test if we have the right hardware */
 455         gx_pci = gx_detect_chipset();
 456         if (gx_pci == NULL)
 457                 return -ENODEV;
 458
 459         /* check whether module parameters are sane */
 460         if (max_duration > 0xff)
 461                 max_duration = 0xff;
 462
 463         pr_debug("geode suspend modulation available.\n");
 464
 465         params = kzalloc(sizeof(*params), GFP_KERNEL);
 466         if (params == NULL)
 467                 return -ENOMEM;
 468
 469         params->cs55x0 = gx_pci;
 470         gx_params = params;
 471
 472         /* keep cs55x0 configurations */
 473         pci_read_config_byte(params->cs55x0, PCI_SUSCFG, &(params->pci_suscfg));
 474         pci_read_config_byte(params->cs55x0, PCI_PMER1, &(params->pci_pmer1));
 475         pci_read_config_byte(params->cs55x0, PCI_PMER2, &(params->pci_pmer2));
 476         pci_read_config_byte(params->cs55x0, PCI_MODON, &(params->on_duration));
 477         pci_read_config_byte(params->cs55x0, PCI_MODOFF,
 478                         &(params->off_duration));
 479
 480         ret = cpufreq_register_driver(&gx_suspmod_driver);
 481         if (ret) {
 482                 kfree(params);
 483                 return ret;                   /* register error! */
 484         }
 485
 486         return 0;
 487 }
 488
 489 static void __exit cpufreq_gx_exit(void)
 490 {
 491         cpufreq_unregister_driver(&gx_suspmod_driver);
 492         pci_dev_put(gx_params->cs55x0);
 493         kfree(gx_params);
 494 }
 495
 496 MODULE_AUTHOR("Hiroshi Miura <miura@da-cha.org>");
 497 MODULE_DESCRIPTION("Cpufreq driver for Cyrix MediaGX and NatSemi Geode");
 498 MODULE_LICENSE("GPL");
 499
 500 module_init(cpufreq_gx_init);
 501 module_exit(cpufreq_gx_exit);
 502