1 /* 2 * POWERNV cpufreq driver for the IBM POWER processors 3 * 4 * (C) Copyright IBM 2014 5 * 6 * Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2, or (at your option) 11 * any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 */ 19 20 #define pr_fmt(fmt) "powernv-cpufreq: " fmt 21 22 #include <linux/kernel.h> 23 #include <linux/sysfs.h> 24 #include <linux/cpumask.h> 25 #include <linux/module.h> 26 #include <linux/cpufreq.h> 27 #include <linux/smp.h> 28 #include <linux/of.h> 29 #include <linux/reboot.h> 30 31 #include <asm/cputhreads.h> 32 #include <asm/firmware.h> 33 #include <asm/reg.h> 34 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */ 35 36 #define POWERNV_MAX_PSTATES 256 37 #define PMSR_PSAFE_ENABLE (1UL << 30) 38 #define PMSR_SPR_EM_DISABLE (1UL << 31) 39 #define PMSR_MAX(x) ((x >> 32) & 0xFF) 40 #define PMSR_LP(x) ((x >> 48) & 0xFF) 41 42 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; 43 static bool rebooting, throttled; 44 45 /* 46 * Note: The set of pstates consists of contiguous integers, the 47 * smallest of which is indicated by powernv_pstate_info.min, the 48 * largest of which is indicated by powernv_pstate_info.max. 49 * 50 * The nominal pstate is the highest non-turbo pstate in this 51 * platform. This is indicated by powernv_pstate_info.nominal. 52 */ 53 static struct powernv_pstate_info { 54 int min; 55 int max; 56 int nominal; 57 int nr_pstates; 58 } powernv_pstate_info; 59 60 /* 61 * Initialize the freq table based on data obtained 62 * from the firmware passed via device-tree 63 */ 64 static int init_powernv_pstates(void) 65 { 66 struct device_node *power_mgt; 67 int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0; 68 const __be32 *pstate_ids, *pstate_freqs; 69 u32 len_ids, len_freqs; 70 71 power_mgt = of_find_node_by_path("/ibm,opal/power-mgt"); 72 if (!power_mgt) { 73 pr_warn("power-mgt node not found\n"); 74 return -ENODEV; 75 } 76 77 if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) { 78 pr_warn("ibm,pstate-min node not found\n"); 79 return -ENODEV; 80 } 81 82 if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) { 83 pr_warn("ibm,pstate-max node not found\n"); 84 return -ENODEV; 85 } 86 87 if (of_property_read_u32(power_mgt, "ibm,pstate-nominal", 88 &pstate_nominal)) { 89 pr_warn("ibm,pstate-nominal not found\n"); 90 return -ENODEV; 91 } 92 pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min, 93 pstate_nominal, pstate_max); 94 95 pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids); 96 if (!pstate_ids) { 97 pr_warn("ibm,pstate-ids not found\n"); 98 return -ENODEV; 99 } 100 101 pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz", 102 &len_freqs); 103 if (!pstate_freqs) { 104 pr_warn("ibm,pstate-frequencies-mhz not found\n"); 105 return -ENODEV; 106 } 107 108 if (len_ids != len_freqs) { 109 pr_warn("Entries in ibm,pstate-ids and " 110 "ibm,pstate-frequencies-mhz does not match\n"); 111 } 112 113 nr_pstates = min(len_ids, len_freqs) / sizeof(u32); 114 if (!nr_pstates) { 115 pr_warn("No PStates found\n"); 116 return -ENODEV; 117 } 118 119 pr_debug("NR PStates %d\n", nr_pstates); 120 for (i = 0; i < nr_pstates; i++) { 121 u32 id = be32_to_cpu(pstate_ids[i]); 122 u32 freq = be32_to_cpu(pstate_freqs[i]); 123 124 pr_debug("PState id %d freq %d MHz\n", id, freq); 125 powernv_freqs[i].frequency = freq * 1000; /* kHz */ 126 powernv_freqs[i].driver_data = id; 127 } 128 /* End of list marker entry */ 129 powernv_freqs[i].frequency = CPUFREQ_TABLE_END; 130 131 powernv_pstate_info.min = pstate_min; 132 powernv_pstate_info.max = pstate_max; 133 powernv_pstate_info.nominal = pstate_nominal; 134 powernv_pstate_info.nr_pstates = nr_pstates; 135 136 return 0; 137 } 138 139 /* Returns the CPU frequency corresponding to the pstate_id. */ 140 static unsigned int pstate_id_to_freq(int pstate_id) 141 { 142 int i; 143 144 i = powernv_pstate_info.max - pstate_id; 145 if (i >= powernv_pstate_info.nr_pstates || i < 0) { 146 pr_warn("PState id %d outside of PState table, " 147 "reporting nominal id %d instead\n", 148 pstate_id, powernv_pstate_info.nominal); 149 i = powernv_pstate_info.max - powernv_pstate_info.nominal; 150 } 151 152 return powernv_freqs[i].frequency; 153 } 154 155 /* 156 * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by 157 * the firmware 158 */ 159 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy, 160 char *buf) 161 { 162 return sprintf(buf, "%u\n", 163 pstate_id_to_freq(powernv_pstate_info.nominal)); 164 } 165 166 struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq = 167 __ATTR_RO(cpuinfo_nominal_freq); 168 169 static struct freq_attr *powernv_cpu_freq_attr[] = { 170 &cpufreq_freq_attr_scaling_available_freqs, 171 &cpufreq_freq_attr_cpuinfo_nominal_freq, 172 NULL, 173 }; 174 175 /* Helper routines */ 176 177 /* Access helpers to power mgt SPR */ 178 179 static inline unsigned long get_pmspr(unsigned long sprn) 180 { 181 switch (sprn) { 182 case SPRN_PMCR: 183 return mfspr(SPRN_PMCR); 184 185 case SPRN_PMICR: 186 return mfspr(SPRN_PMICR); 187 188 case SPRN_PMSR: 189 return mfspr(SPRN_PMSR); 190 } 191 BUG(); 192 } 193 194 static inline void set_pmspr(unsigned long sprn, unsigned long val) 195 { 196 switch (sprn) { 197 case SPRN_PMCR: 198 mtspr(SPRN_PMCR, val); 199 return; 200 201 case SPRN_PMICR: 202 mtspr(SPRN_PMICR, val); 203 return; 204 } 205 BUG(); 206 } 207 208 /* 209 * Use objects of this type to query/update 210 * pstates on a remote CPU via smp_call_function. 211 */ 212 struct powernv_smp_call_data { 213 unsigned int freq; 214 int pstate_id; 215 }; 216 217 /* 218 * powernv_read_cpu_freq: Reads the current frequency on this CPU. 219 * 220 * Called via smp_call_function. 221 * 222 * Note: The caller of the smp_call_function should pass an argument of 223 * the type 'struct powernv_smp_call_data *' along with this function. 224 * 225 * The current frequency on this CPU will be returned via 226 * ((struct powernv_smp_call_data *)arg)->freq; 227 */ 228 static void powernv_read_cpu_freq(void *arg) 229 { 230 unsigned long pmspr_val; 231 s8 local_pstate_id; 232 struct powernv_smp_call_data *freq_data = arg; 233 234 pmspr_val = get_pmspr(SPRN_PMSR); 235 236 /* 237 * The local pstate id corresponds bits 48..55 in the PMSR. 238 * Note: Watch out for the sign! 239 */ 240 local_pstate_id = (pmspr_val >> 48) & 0xFF; 241 freq_data->pstate_id = local_pstate_id; 242 freq_data->freq = pstate_id_to_freq(freq_data->pstate_id); 243 244 pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n", 245 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id, 246 freq_data->freq); 247 } 248 249 /* 250 * powernv_cpufreq_get: Returns the CPU frequency as reported by the 251 * firmware for CPU 'cpu'. This value is reported through the sysfs 252 * file cpuinfo_cur_freq. 253 */ 254 static unsigned int powernv_cpufreq_get(unsigned int cpu) 255 { 256 struct powernv_smp_call_data freq_data; 257 258 smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq, 259 &freq_data, 1); 260 261 return freq_data.freq; 262 } 263 264 /* 265 * set_pstate: Sets the pstate on this CPU. 266 * 267 * This is called via an smp_call_function. 268 * 269 * The caller must ensure that freq_data is of the type 270 * (struct powernv_smp_call_data *) and the pstate_id which needs to be set 271 * on this CPU should be present in freq_data->pstate_id. 272 */ 273 static void set_pstate(void *freq_data) 274 { 275 unsigned long val; 276 unsigned long pstate_ul = 277 ((struct powernv_smp_call_data *) freq_data)->pstate_id; 278 279 val = get_pmspr(SPRN_PMCR); 280 val = val & 0x0000FFFFFFFFFFFFULL; 281 282 pstate_ul = pstate_ul & 0xFF; 283 284 /* Set both global(bits 56..63) and local(bits 48..55) PStates */ 285 val = val | (pstate_ul << 56) | (pstate_ul << 48); 286 287 pr_debug("Setting cpu %d pmcr to %016lX\n", 288 raw_smp_processor_id(), val); 289 set_pmspr(SPRN_PMCR, val); 290 } 291 292 /* 293 * get_nominal_index: Returns the index corresponding to the nominal 294 * pstate in the cpufreq table 295 */ 296 static inline unsigned int get_nominal_index(void) 297 { 298 return powernv_pstate_info.max - powernv_pstate_info.nominal; 299 } 300 301 static void powernv_cpufreq_throttle_check(unsigned int cpu) 302 { 303 unsigned long pmsr; 304 int pmsr_pmax, pmsr_lp; 305 306 pmsr = get_pmspr(SPRN_PMSR); 307 308 /* Check for Pmax Capping */ 309 pmsr_pmax = (s8)PMSR_MAX(pmsr); 310 if (pmsr_pmax != powernv_pstate_info.max) { 311 throttled = true; 312 pr_info("CPU %d Pmax is reduced to %d\n", cpu, pmsr_pmax); 313 pr_info("Max allowed Pstate is capped\n"); 314 } 315 316 /* 317 * Check for Psafe by reading LocalPstate 318 * or check if Psafe_mode_active is set in PMSR. 319 */ 320 pmsr_lp = (s8)PMSR_LP(pmsr); 321 if ((pmsr_lp < powernv_pstate_info.min) || 322 (pmsr & PMSR_PSAFE_ENABLE)) { 323 throttled = true; 324 pr_info("Pstate set to safe frequency\n"); 325 } 326 327 /* Check if SPR_EM_DISABLE is set in PMSR */ 328 if (pmsr & PMSR_SPR_EM_DISABLE) { 329 throttled = true; 330 pr_info("Frequency Control disabled from OS\n"); 331 } 332 333 if (throttled) { 334 pr_info("PMSR = %16lx\n", pmsr); 335 pr_crit("CPU Frequency could be throttled\n"); 336 } 337 } 338 339 /* 340 * powernv_cpufreq_target_index: Sets the frequency corresponding to 341 * the cpufreq table entry indexed by new_index on the cpus in the 342 * mask policy->cpus 343 */ 344 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, 345 unsigned int new_index) 346 { 347 struct powernv_smp_call_data freq_data; 348 349 if (unlikely(rebooting) && new_index != get_nominal_index()) 350 return 0; 351 352 if (!throttled) 353 powernv_cpufreq_throttle_check(smp_processor_id()); 354 355 freq_data.pstate_id = powernv_freqs[new_index].driver_data; 356 357 /* 358 * Use smp_call_function to send IPI and execute the 359 * mtspr on target CPU. We could do that without IPI 360 * if current CPU is within policy->cpus (core) 361 */ 362 smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1); 363 364 return 0; 365 } 366 367 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy) 368 { 369 int base, i; 370 371 base = cpu_first_thread_sibling(policy->cpu); 372 373 for (i = 0; i < threads_per_core; i++) 374 cpumask_set_cpu(base + i, policy->cpus); 375 376 return cpufreq_table_validate_and_show(policy, powernv_freqs); 377 } 378 379 static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb, 380 unsigned long action, void *unused) 381 { 382 int cpu; 383 struct cpufreq_policy cpu_policy; 384 385 rebooting = true; 386 for_each_online_cpu(cpu) { 387 cpufreq_get_policy(&cpu_policy, cpu); 388 powernv_cpufreq_target_index(&cpu_policy, get_nominal_index()); 389 } 390 391 return NOTIFY_DONE; 392 } 393 394 static struct notifier_block powernv_cpufreq_reboot_nb = { 395 .notifier_call = powernv_cpufreq_reboot_notifier, 396 }; 397 398 static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy) 399 { 400 struct powernv_smp_call_data freq_data; 401 402 freq_data.pstate_id = powernv_pstate_info.min; 403 smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1); 404 } 405 406 static struct cpufreq_driver powernv_cpufreq_driver = { 407 .name = "powernv-cpufreq", 408 .flags = CPUFREQ_CONST_LOOPS, 409 .init = powernv_cpufreq_cpu_init, 410 .verify = cpufreq_generic_frequency_table_verify, 411 .target_index = powernv_cpufreq_target_index, 412 .get = powernv_cpufreq_get, 413 .stop_cpu = powernv_cpufreq_stop_cpu, 414 .attr = powernv_cpu_freq_attr, 415 }; 416 417 static int __init powernv_cpufreq_init(void) 418 { 419 int rc = 0; 420 421 /* Don't probe on pseries (guest) platforms */ 422 if (!firmware_has_feature(FW_FEATURE_OPALv3)) 423 return -ENODEV; 424 425 /* Discover pstates from device tree and init */ 426 rc = init_powernv_pstates(); 427 if (rc) { 428 pr_info("powernv-cpufreq disabled. System does not support PState control\n"); 429 return rc; 430 } 431 432 register_reboot_notifier(&powernv_cpufreq_reboot_nb); 433 return cpufreq_register_driver(&powernv_cpufreq_driver); 434 } 435 module_init(powernv_cpufreq_init); 436 437 static void __exit powernv_cpufreq_exit(void) 438 { 439 unregister_reboot_notifier(&powernv_cpufreq_reboot_nb); 440 cpufreq_unregister_driver(&powernv_cpufreq_driver); 441 } 442 module_exit(powernv_cpufreq_exit); 443 444 MODULE_LICENSE("GPL"); 445 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>"); 446