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 = ¢aur->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 = ¢aur->freq_table[0]; 359 360 return 0; 361 } 362 363 static void 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 } 371 372 static struct cpufreq_driver eps_driver = { 373 .verify = cpufreq_generic_frequency_table_verify, 374 .target_index = eps_target, 375 .init = eps_cpu_init, 376 .exit = eps_cpu_exit, 377 .get = eps_get, 378 .name = "e_powersaver", 379 .attr = cpufreq_generic_attr, 380 }; 381 382 383 /* This driver will work only on Centaur C7 processors with 384 * Enhanced SpeedStep/PowerSaver registers */ 385 static const struct x86_cpu_id eps_cpu_id[] = { 386 X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_EST, NULL), 387 {} 388 }; 389 MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id); 390 391 static int __init eps_init(void) 392 { 393 if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10) 394 return -ENODEV; 395 if (cpufreq_register_driver(&eps_driver)) 396 return -EINVAL; 397 return 0; 398 } 399 400 static void __exit eps_exit(void) 401 { 402 cpufreq_unregister_driver(&eps_driver); 403 } 404 405 /* Allow user to overclock his machine or to change frequency to higher after 406 * unloading module */ 407 module_param(freq_failsafe_off, int, 0644); 408 MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check"); 409 module_param(voltage_failsafe_off, int, 0644); 410 MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check"); 411 #if IS_ENABLED(CONFIG_ACPI_PROCESSOR) 412 module_param(ignore_acpi_limit, int, 0644); 413 MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit"); 414 #endif 415 module_param(set_max_voltage, int, 0644); 416 MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only"); 417 418 MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>"); 419 MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's."); 420 MODULE_LICENSE("GPL"); 421 422 module_init(eps_init); 423 module_exit(eps_exit); 424