drivers/cpufreq/e_powersaver.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Based on documentation provided by Dave Jones. Thanks!
   4  *
   5  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/cpufreq.h>
  14 #include <linux/ioport.h>
  15 #include <linux/slab.h>
  16 #include <linux/timex.h>
  17 #include <linux/io.h>
  18 #include <linux/delay.h>
  19
  20 #include <asm/cpu_device_id.h>
  21 #include <asm/msr.h>
  22 #include <asm/tsc.h>
  23
  24 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
  25 #include <linux/acpi.h>
  26 #include <acpi/processor.h>
  27 #endif
  28
  29 #define EPS_BRAND_C7M   0
  30 #define EPS_BRAND_C7    1
  31 #define EPS_BRAND_EDEN  2
  32 #define EPS_BRAND_C3    3
  33 #define EPS_BRAND_C7D   4
  34
  35 struct eps_cpu_data {
  36         u32 fsb;
  37 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
  38         u32 bios_limit;
  39 #endif
  40         struct cpufreq_frequency_table freq_table[];
  41 };
  42
  43 static struct eps_cpu_data *eps_cpu[NR_CPUS];
  44
  45 /* Module parameters */
  46 static int freq_failsafe_off;
  47 static int voltage_failsafe_off;
  48 static int set_max_voltage;
  49
  50 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
  51 static int ignore_acpi_limit;
  52
  53 static struct acpi_processor_performance *eps_acpi_cpu_perf;
  54
  55 /* Minimum necessary to get acpi_processor_get_bios_limit() working */
  56 static int eps_acpi_init(void)
  57 {
  58         eps_acpi_cpu_perf = kzalloc(sizeof(*eps_acpi_cpu_perf),
  59                                       GFP_KERNEL);
  60         if (!eps_acpi_cpu_perf)
  61                 return -ENOMEM;
  62
  63         if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
  64                                                                 GFP_KERNEL)) {
  65                 kfree(eps_acpi_cpu_perf);
  66                 eps_acpi_cpu_perf = NULL;
  67                 return -ENOMEM;
  68         }
  69
  70         if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
  71                 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
  72                 kfree(eps_acpi_cpu_perf);
  73                 eps_acpi_cpu_perf = NULL;
  74                 return -EIO;
  75         }
  76         return 0;
  77 }
  78
  79 static int eps_acpi_exit(struct cpufreq_policy *policy)
  80 {
  81         if (eps_acpi_cpu_perf) {
  82                 acpi_processor_unregister_performance(0);
  83                 free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
  84                 kfree(eps_acpi_cpu_perf);
  85                 eps_acpi_cpu_perf = NULL;
  86         }
  87         return 0;
  88 }
  89 #endif
  90
  91 static unsigned int eps_get(unsigned int cpu)
  92 {
  93         struct eps_cpu_data *centaur;
  94         u32 lo, hi;
  95
  96         if (cpu)
  97                 return 0;
  98         centaur = eps_cpu[cpu];
  99         if (centaur == NULL)
 100                 return 0;
 101
 102         /* Return current frequency */
 103         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 104         return centaur->fsb * ((lo >> 8) & 0xff);
 105 }
 106
 107 static int eps_set_state(struct eps_cpu_data *centaur,
 108                          struct cpufreq_policy *policy,
 109                          u32 dest_state)
 110 {
 111         u32 lo, hi;
 112         int i;
 113
 114         /* Wait while CPU is busy */
 115         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 116         i = 0;
 117         while (lo & ((1 << 16) | (1 << 17))) {
 118                 udelay(16);
 119                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 120                 i++;
 121                 if (unlikely(i > 64)) {
 122                         return -ENODEV;
 123                 }
 124         }
 125         /* Set new multiplier and voltage */
 126         wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
 127         /* Wait until transition end */
 128         i = 0;
 129         do {
 130                 udelay(16);
 131                 rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 132                 i++;
 133                 if (unlikely(i > 64)) {
 134                         return -ENODEV;
 135                 }
 136         } while (lo & ((1 << 16) | (1 << 17)));
 137
 138 #ifdef DEBUG
 139         {
 140         u8 current_multiplier, current_voltage;
 141
 142         /* Print voltage and multiplier */
 143         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 144         current_voltage = lo & 0xff;
 145         pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
 146         current_multiplier = (lo >> 8) & 0xff;
 147         pr_info("Current multiplier = %d\n", current_multiplier);
 148         }
 149 #endif
 150         return 0;
 151 }
 152
 153 static int eps_target(struct cpufreq_policy *policy, unsigned int index)
 154 {
 155         struct eps_cpu_data *centaur;
 156         unsigned int cpu = policy->cpu;
 157         unsigned int dest_state;
 158         int ret;
 159
 160         if (unlikely(eps_cpu[cpu] == NULL))
 161                 return -ENODEV;
 162         centaur = eps_cpu[cpu];
 163
 164         /* Make frequency transition */
 165         dest_state = centaur->freq_table[index].driver_data & 0xffff;
 166         ret = eps_set_state(centaur, policy, dest_state);
 167         if (ret)
 168                 pr_err("Timeout!\n");
 169         return ret;
 170 }
 171
 172 static int eps_cpu_init(struct cpufreq_policy *policy)
 173 {
 174         unsigned int i;
 175         u32 lo, hi;
 176         u64 val;
 177         u8 current_multiplier, current_voltage;
 178         u8 max_multiplier, max_voltage;
 179         u8 min_multiplier, min_voltage;
 180         u8 brand = 0;
 181         u32 fsb;
 182         struct eps_cpu_data *centaur;
 183         struct cpuinfo_x86 *c = &cpu_data(0);
 184         struct cpufreq_frequency_table *f_table;
 185         int k, step, voltage;
 186         int states;
 187 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 188         unsigned int limit;
 189 #endif
 190
 191         if (policy->cpu != 0)
 192                 return -ENODEV;
 193
 194         /* Check brand */
 195         pr_info("Detected VIA ");
 196
 197         switch (c->x86_model) {
 198         case 10:
 199                 rdmsr(0x1153, lo, hi);
 200                 brand = (((lo >> 2) ^ lo) >> 18) & 3;
 201                 pr_cont("Model A ");
 202                 break;
 203         case 13:
 204                 rdmsr(0x1154, lo, hi);
 205                 brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
 206                 pr_cont("Model D ");
 207                 break;
 208         }
 209
 210         switch (brand) {
 211         case EPS_BRAND_C7M:
 212                 pr_cont("C7-M\n");
 213                 break;
 214         case EPS_BRAND_C7:
 215                 pr_cont("C7\n");
 216                 break;
 217         case EPS_BRAND_EDEN:
 218                 pr_cont("Eden\n");
 219                 break;
 220         case EPS_BRAND_C7D:
 221                 pr_cont("C7-D\n");
 222                 break;
 223         case EPS_BRAND_C3:
 224                 pr_cont("C3\n");
 225                 return -ENODEV;
 226         }
 227         /* Enable Enhanced PowerSaver */
 228         rdmsrl(MSR_IA32_MISC_ENABLE, val);
 229         if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 230                 val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
 231                 wrmsrl(MSR_IA32_MISC_ENABLE, val);
 232                 /* Can be locked at 0 */
 233                 rdmsrl(MSR_IA32_MISC_ENABLE, val);
 234                 if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 235                         pr_info("Can't enable Enhanced PowerSaver\n");
 236                         return -ENODEV;
 237                 }
 238         }
 239
 240         /* Print voltage and multiplier */
 241         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 242         current_voltage = lo & 0xff;
 243         pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
 244         current_multiplier = (lo >> 8) & 0xff;
 245         pr_info("Current multiplier = %d\n", current_multiplier);
 246
 247         /* Print limits */
 248         max_voltage = hi & 0xff;
 249         pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
 250         max_multiplier = (hi >> 8) & 0xff;
 251         pr_info("Highest multiplier = %d\n", max_multiplier);
 252         min_voltage = (hi >> 16) & 0xff;
 253         pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
 254         min_multiplier = (hi >> 24) & 0xff;
 255         pr_info("Lowest multiplier = %d\n", min_multiplier);
 256
 257         /* Sanity checks */
 258         if (current_multiplier == 0 || max_multiplier == 0
 259             || min_multiplier == 0)
 260                 return -EINVAL;
 261         if (current_multiplier > max_multiplier
 262             || max_multiplier <= min_multiplier)
 263                 return -EINVAL;
 264         if (current_voltage > 0x1f || max_voltage > 0x1f)
 265                 return -EINVAL;
 266         if (max_voltage < min_voltage
 267             || current_voltage < min_voltage
 268             || current_voltage > max_voltage)
 269                 return -EINVAL;
 270
 271         /* Check for systems using underclocked CPU */
 272         if (!freq_failsafe_off && max_multiplier != current_multiplier) {
 273                 pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
 274                 pr_info("You can use freq_failsafe_off option to disable this check.\n");
 275                 return -EINVAL;
 276         }
 277         if (!voltage_failsafe_off && max_voltage != current_voltage) {
 278                 pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
 279                 pr_info("You can use voltage_failsafe_off option to disable this check.\n");
 280                 return -EINVAL;
 281         }
 282
 283         /* Calc FSB speed */
 284         fsb = cpu_khz / current_multiplier;
 285
 286 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 287         /* Check for ACPI processor speed limit */
 288         if (!ignore_acpi_limit && !eps_acpi_init()) {
 289                 if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
 290                         pr_info("ACPI limit %u.%uGHz\n",
 291                                 limit/1000000,
 292                                 (limit%1000000)/10000);
 293                         eps_acpi_exit(policy);
 294                         /* Check if max_multiplier is in BIOS limits */
 295                         if (limit && max_multiplier * fsb > limit) {
 296                                 pr_info("Aborting\n");
 297                                 return -EINVAL;
 298                         }
 299                 }
 300         }
 301 #endif
 302
 303         /* Allow user to set lower maximum voltage then that reported
 304          * by processor */
 305         if (brand == EPS_BRAND_C7M && set_max_voltage) {
 306                 u32 v;
 307
 308                 /* Change mV to something hardware can use */
 309                 v = (set_max_voltage - 700) / 16;
 310                 /* Check if voltage is within limits */
 311                 if (v >= min_voltage && v <= max_voltage) {
 312                         pr_info("Setting %dmV as maximum\n", v * 16 + 700);
 313                         max_voltage = v;
 314                 }
 315         }
 316
 317         /* Calc number of p-states supported */
 318         if (brand == EPS_BRAND_C7M)
 319                 states = max_multiplier - min_multiplier + 1;
 320         else
 321                 states = 2;
 322
 323         /* Allocate private data and frequency table for current cpu */
 324         centaur = kzalloc(struct_size(centaur, freq_table, states + 1),
 325                           GFP_KERNEL);
 326         if (!centaur)
 327                 return -ENOMEM;
 328         eps_cpu[0] = centaur;
 329
 330         /* Copy basic values */
 331         centaur->fsb = fsb;
 332 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 333         centaur->bios_limit = limit;
 334 #endif
 335
 336         /* Fill frequency and MSR value table */
 337         f_table = &centaur->freq_table[0];
 338         if (brand != EPS_BRAND_C7M) {
 339                 f_table[0].frequency = fsb * min_multiplier;
 340                 f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
 341                 f_table[1].frequency = fsb * max_multiplier;
 342                 f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
 343                 f_table[2].frequency = CPUFREQ_TABLE_END;
 344         } else {
 345                 k = 0;
 346                 step = ((max_voltage - min_voltage) * 256)
 347                         / (max_multiplier - min_multiplier);
 348                 for (i = min_multiplier; i <= max_multiplier; i++) {
 349                         voltage = (k * step) / 256 + min_voltage;
 350                         f_table[k].frequency = fsb * i;
 351                         f_table[k].driver_data = (i << 8) | voltage;
 352                         k++;
 353                 }
 354                 f_table[k].frequency = CPUFREQ_TABLE_END;
 355         }
 356
 357         policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
 358         policy->freq_table = &centaur->freq_table[0];
 359
 360         return 0;
 361 }
 362
 363 static int eps_cpu_exit(struct cpufreq_policy *policy)
 364 {
 365         unsigned int cpu = policy->cpu;
 366
 367         /* Bye */
 368         kfree(eps_cpu[cpu]);
 369         eps_cpu[cpu] = NULL;
 370         return 0;
 371 }
 372
 373 static struct cpufreq_driver eps_driver = {
 374         .verify         = cpufreq_generic_frequency_table_verify,
 375         .target_index   = eps_target,
 376         .init           = eps_cpu_init,
 377         .exit           = eps_cpu_exit,
 378         .get            = eps_get,
 379         .name           = "e_powersaver",
 380         .attr           = cpufreq_generic_attr,
 381 };
 382
 383
 384 /* This driver will work only on Centaur C7 processors with
 385  * Enhanced SpeedStep/PowerSaver registers */
 386 static const struct x86_cpu_id eps_cpu_id[] = {
 387         X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_EST, NULL),
 388         {}
 389 };
 390 MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
 391
 392 static int __init eps_init(void)
 393 {
 394         if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
 395                 return -ENODEV;
 396         if (cpufreq_register_driver(&eps_driver))
 397                 return -EINVAL;
 398         return 0;
 399 }
 400
 401 static void __exit eps_exit(void)
 402 {
 403         cpufreq_unregister_driver(&eps_driver);
 404 }
 405
 406 /* Allow user to overclock his machine or to change frequency to higher after
 407  * unloading module */
 408 module_param(freq_failsafe_off, int, 0644);
 409 MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
 410 module_param(voltage_failsafe_off, int, 0644);
 411 MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
 412 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
 413 module_param(ignore_acpi_limit, int, 0644);
 414 MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
 415 #endif
 416 module_param(set_max_voltage, int, 0644);
 417 MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
 418
 419 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
 420 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
 421 MODULE_LICENSE("GPL");
 422
 423 module_init(eps_init);
 424 module_exit(eps_exit);