drivers/cpufreq/e_powersaver.c

   1 /*
   2  *  Based on documentation provided by Dave Jones. Thanks!
   3  *
   4  *  Licensed under the terms of the GNU GPL License version 2.
   5  *
   6  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/cpufreq.h>
  15 #include <linux/ioport.h>
  16 #include <linux/slab.h>
  17 #include <linux/timex.h>
  18 #include <linux/io.h>
  19 #include <linux/delay.h>
  20
  21 #include <asm/cpu_device_id.h>
  22 #include <asm/msr.h>
  23 #include <asm/tsc.h>
  24
  25 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
  26 #include <linux/acpi.h>
  27 #include <acpi/processor.h>
  28 #endif
  29
  30 #define EPS_BRAND_C7M   0
  31 #define EPS_BRAND_C7    1
  32 #define EPS_BRAND_EDEN  2
  33 #define EPS_BRAND_C3    3
  34 #define EPS_BRAND_C7D   4
  35
  36 struct eps_cpu_data {
  37         u32 fsb;
  38 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
  39         u32 bios_limit;
  40 #endif
  41         struct cpufreq_frequency_table freq_table[];
  42 };
  43
  44 static struct eps_cpu_data *eps_cpu[NR_CPUS];
  45
  46 /* Module parameters */
  47 static int freq_failsafe_off;
  48 static int voltage_failsafe_off;
  49 static int set_max_voltage;
  50
  51 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
  52 static int ignore_acpi_limit;
  53
  54 static struct acpi_processor_performance *eps_acpi_cpu_perf;
  55
  56 /* Minimum necessary to get acpi_processor_get_bios_limit() working */
  57 static int eps_acpi_init(void)
  58 {
  59         eps_acpi_cpu_perf = kzalloc(sizeof(*eps_acpi_cpu_perf),
  60                                       GFP_KERNEL);
  61         if (!eps_acpi_cpu_perf)
  62                 return -ENOMEM;
  63
  64         if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
  65                                                                 GFP_KERNEL)) {
  66                 kfree(eps_acpi_cpu_perf);
  67                 eps_acpi_cpu_perf = NULL;
  68                 return -ENOMEM;
  69         }
  70
  71         if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
  72                 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
  73                 kfree(eps_acpi_cpu_perf);
  74                 eps_acpi_cpu_perf = NULL;
  75                 return -EIO;
  76         }
  77         return 0;
  78 }
  79
  80 static int eps_acpi_exit(struct cpufreq_policy *policy)
  81 {
  82         if (eps_acpi_cpu_perf) {
  83                 acpi_processor_unregister_performance(0);
  84                 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
  85                 kfree(eps_acpi_cpu_perf);
  86                 eps_acpi_cpu_perf = NULL;
  87         }
  88         return 0;
  89 }
  90 #endif
  91
  92 static unsigned int eps_get(unsigned int cpu)
  93 {
  94         struct eps_cpu_data *centaur;
  95         u32 lo, hi;
  96
  97         if (cpu)
  98                 return 0;
  99         centaur = eps_cpu[cpu];
 100         if (centaur == NULL)
 101                 return 0;
 102
 103         /* Return current frequency */
 104         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 105         return centaur->fsb * ((lo >> 8) & 0xff);
 106 }
 107
 108 static int eps_set_state(struct eps_cpu_data *centaur,
 109                          struct cpufreq_policy *policy,
 110                          u32 dest_state)
 111 {
 112         u32 lo, hi;
 113         int i;
 114
 115         /* Wait while CPU is busy */
 116         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 117         i = 0;
 118         while (lo & ((1 << 16) | (1 << 17))) {
 119                 udelay(16);
 120                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 121                 i++;
 122                 if (unlikely(i > 64)) {
 123                         return -ENODEV;
 124                 }
 125         }
 126         /* Set new multiplier and voltage */
 127         wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
 128         /* Wait until transition end */
 129         i = 0;
 130         do {
 131                 udelay(16);
 132                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 133                 i++;
 134                 if (unlikely(i > 64)) {
 135                         return -ENODEV;
 136                 }
 137         } while (lo & ((1 << 16) | (1 << 17)));
 138
 139 #ifdef DEBUG
 140         {
 141         u8 current_multiplier, current_voltage;
 142
 143         /* Print voltage and multiplier */
 144         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 145         current_voltage = lo & 0xff;
 146         pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
 147         current_multiplier = (lo >> 8) & 0xff;
 148         pr_info("Current multiplier = %d\n", current_multiplier);
 149         }
 150 #endif
 151         return 0;
 152 }
 153
 154 static int eps_target(struct cpufreq_policy *policy, unsigned int index)
 155 {
 156         struct eps_cpu_data *centaur;
 157         unsigned int cpu = policy->cpu;
 158         unsigned int dest_state;
 159         int ret;
 160
 161         if (unlikely(eps_cpu[cpu] == NULL))
 162                 return -ENODEV;
 163         centaur = eps_cpu[cpu];
 164
 165         /* Make frequency transition */
 166         dest_state = centaur->freq_table[index].driver_data & 0xffff;
 167         ret = eps_set_state(centaur, policy, dest_state);
 168         if (ret)
 169                 pr_err("Timeout!\n");
 170         return ret;
 171 }
 172
 173 static int eps_cpu_init(struct cpufreq_policy *policy)
 174 {
 175         unsigned int i;
 176         u32 lo, hi;
 177         u64 val;
 178         u8 current_multiplier, current_voltage;
 179         u8 max_multiplier, max_voltage;
 180         u8 min_multiplier, min_voltage;
 181         u8 brand = 0;
 182         u32 fsb;
 183         struct eps_cpu_data *centaur;
 184         struct cpuinfo_x86 *c = &cpu_data(0);
 185         struct cpufreq_frequency_table *f_table;
 186         int k, step, voltage;
 187         int states;
 188 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 189         unsigned int limit;
 190 #endif
 191
 192         if (policy->cpu != 0)
 193                 return -ENODEV;
 194
 195         /* Check brand */
 196         pr_info("Detected VIA ");
 197
 198         switch (c->x86_model) {
 199         case 10:
 200                 rdmsr(0x1153, lo, hi);
 201                 brand = (((lo >> 2) ^ lo) >> 18) & 3;
 202                 pr_cont("Model A ");
 203                 break;
 204         case 13:
 205                 rdmsr(0x1154, lo, hi);
 206                 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
 207                 pr_cont("Model D ");
 208                 break;
 209         }
 210
 211         switch (brand) {
 212         case EPS_BRAND_C7M:
 213                 pr_cont("C7-M\n");
 214                 break;
 215         case EPS_BRAND_C7:
 216                 pr_cont("C7\n");
 217                 break;
 218         case EPS_BRAND_EDEN:
 219                 pr_cont("Eden\n");
 220                 break;
 221         case EPS_BRAND_C7D:
 222                 pr_cont("C7-D\n");
 223                 break;
 224         case EPS_BRAND_C3:
 225                 pr_cont("C3\n");
 226                 return -ENODEV;
 227                 break;
 228         }
 229         /* Enable Enhanced PowerSaver */
 230         rdmsrl(MSR_IA32_MISC_ENABLE, val);
 231         if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 232                 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
 233                 wrmsrl(MSR_IA32_MISC_ENABLE, val);
 234                 /* Can be locked at 0 */
 235                 rdmsrl(MSR_IA32_MISC_ENABLE, val);
 236                 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 237                         pr_info("Can't enable Enhanced PowerSaver\n");
 238                         return -ENODEV;
 239                 }
 240         }
 241
 242         /* Print voltage and multiplier */
 243         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 244         current_voltage = lo & 0xff;
 245         pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
 246         current_multiplier = (lo >> 8) & 0xff;
 247         pr_info("Current multiplier = %d\n", current_multiplier);
 248
 249         /* Print limits */
 250         max_voltage = hi & 0xff;
 251         pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
 252         max_multiplier = (hi >> 8) & 0xff;
 253         pr_info("Highest multiplier = %d\n", max_multiplier);
 254         min_voltage = (hi >> 16) & 0xff;
 255         pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
 256         min_multiplier = (hi >> 24) & 0xff;
 257         pr_info("Lowest multiplier = %d\n", min_multiplier);
 258
 259         /* Sanity checks */
 260         if (current_multiplier == 0 || max_multiplier == 0
 261             || min_multiplier == 0)
 262                 return -EINVAL;
 263         if (current_multiplier > max_multiplier
 264             || max_multiplier <= min_multiplier)
 265                 return -EINVAL;
 266         if (current_voltage > 0x1f || max_voltage > 0x1f)
 267                 return -EINVAL;
 268         if (max_voltage < min_voltage
 269             || current_voltage < min_voltage
 270             || current_voltage > max_voltage)
 271                 return -EINVAL;
 272
 273         /* Check for systems using underclocked CPU */
 274         if (!freq_failsafe_off && max_multiplier != current_multiplier) {
 275                 pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
 276                 pr_info("You can use freq_failsafe_off option to disable this check.\n");
 277                 return -EINVAL;
 278         }
 279         if (!voltage_failsafe_off && max_voltage != current_voltage) {
 280                 pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
 281                 pr_info("You can use voltage_failsafe_off option to disable this check.\n");
 282                 return -EINVAL;
 283         }
 284
 285         /* Calc FSB speed */
 286         fsb = cpu_khz / current_multiplier;
 287
 288 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 289         /* Check for ACPI processor speed limit */
 290         if (!ignore_acpi_limit && !eps_acpi_init()) {
 291                 if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
 292                         pr_info("ACPI limit %u.%uGHz\n",
 293                                 limit/1000000,
 294                                 (limit%1000000)/10000);
 295                         eps_acpi_exit(policy);
 296                         /* Check if max_multiplier is in BIOS limits */
 297                         if (limit && max_multiplier * fsb > limit) {
 298                                 pr_info("Aborting\n");
 299                                 return -EINVAL;
 300                         }
 301                 }
 302         }
 303 #endif
 304
 305         /* Allow user to set lower maximum voltage then that reported
 306          * by processor */
 307         if (brand == EPS_BRAND_C7M && set_max_voltage) {
 308                 u32 v;
 309
 310                 /* Change mV to something hardware can use */
 311                 v = (set_max_voltage - 700) / 16;
 312                 /* Check if voltage is within limits */
 313                 if (v >= min_voltage && v <= max_voltage) {
 314                         pr_info("Setting %dmV as maximum\n", v * 16 + 700);
 315                         max_voltage = v;
 316                 }
 317         }
 318
 319         /* Calc number of p-states supported */
 320         if (brand == EPS_BRAND_C7M)
 321                 states = max_multiplier - min_multiplier + 1;
 322         else
 323                 states = 2;
 324
 325         /* Allocate private data and frequency table for current cpu */
 326         centaur = kzalloc(sizeof(*centaur)
 327                     + (states + 1) * sizeof(struct cpufreq_frequency_table),
 328                     GFP_KERNEL);
 329         if (!centaur)
 330                 return -ENOMEM;
 331         eps_cpu[0] = centaur;
 332
 333         /* Copy basic values */
 334         centaur->fsb = fsb;
 335 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 336         centaur->bios_limit = limit;
 337 #endif
 338
 339         /* Fill frequency and MSR value table */
 340         f_table = &centaur->freq_table[0];
 341         if (brand != EPS_BRAND_C7M) {
 342                 f_table[0].frequency = fsb * min_multiplier;
 343                 f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
 344                 f_table[1].frequency = fsb * max_multiplier;
 345                 f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
 346                 f_table[2].frequency = CPUFREQ_TABLE_END;
 347         } else {
 348                 k = 0;
 349                 step = ((max_voltage - min_voltage) * 256)
 350                         / (max_multiplier - min_multiplier);
 351                 for (i = min_multiplier; i <= max_multiplier; i++) {
 352                         voltage = (k * step) / 256 + min_voltage;
 353                         f_table[k].frequency = fsb * i;
 354                         f_table[k].driver_data = (i << 8) | voltage;
 355                         k++;
 356                 }
 357                 f_table[k].frequency = CPUFREQ_TABLE_END;
 358         }
 359
 360         policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
 361         policy->freq_table = &centaur->freq_table[0];
 362
 363         return 0;
 364 }
 365
 366 static int eps_cpu_exit(struct cpufreq_policy *policy)
 367 {
 368         unsigned int cpu = policy->cpu;
 369
 370         /* Bye */
 371         kfree(eps_cpu[cpu]);
 372         eps_cpu[cpu] = NULL;
 373         return 0;
 374 }
 375
 376 static struct cpufreq_driver eps_driver = {
 377         .verify         = cpufreq_generic_frequency_table_verify,
 378         .target_index   = eps_target,
 379         .init           = eps_cpu_init,
 380         .exit           = eps_cpu_exit,
 381         .get            = eps_get,
 382         .name           = "e_powersaver",
 383         .attr           = cpufreq_generic_attr,
 384 };
 385
 386
 387 /* This driver will work only on Centaur C7 processors with
 388  * Enhanced SpeedStep/PowerSaver registers */
 389 static const struct x86_cpu_id eps_cpu_id[] = {
 390         { X86_VENDOR_CENTAUR, 6, X86_MODEL_ANY, X86_FEATURE_EST },
 391         {}
 392 };
 393 MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
 394
 395 static int __init eps_init(void)
 396 {
 397         if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
 398                 return -ENODEV;
 399         if (cpufreq_register_driver(&eps_driver))
 400                 return -EINVAL;
 401         return 0;
 402 }
 403
 404 static void __exit eps_exit(void)
 405 {
 406         cpufreq_unregister_driver(&eps_driver);
 407 }
 408
 409 /* Allow user to overclock his machine or to change frequency to higher after
 410  * unloading module */
 411 module_param(freq_failsafe_off, int, 0644);
 412 MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
 413 module_param(voltage_failsafe_off, int, 0644);
 414 MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
 415 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 416 module_param(ignore_acpi_limit, int, 0644);
 417 MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
 418 #endif
 419 module_param(set_max_voltage, int, 0644);
 420 MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
 421
 422 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
 423 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
 424 MODULE_LICENSE("GPL");
 425
 426 module_init(eps_init);
 427 module_exit(eps_exit);