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 30 #include <asm/cputhreads.h> 31 #include <asm/firmware.h> 32 #include <asm/reg.h> 33 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */ 34 35 #define POWERNV_MAX_PSTATES 256 36 37 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; 38 39 /* 40 * Note: The set of pstates consists of contiguous integers, the 41 * smallest of which is indicated by powernv_pstate_info.min, the 42 * largest of which is indicated by powernv_pstate_info.max. 43 * 44 * The nominal pstate is the highest non-turbo pstate in this 45 * platform. This is indicated by powernv_pstate_info.nominal. 46 */ 47 static struct powernv_pstate_info { 48 int min; 49 int max; 50 int nominal; 51 int nr_pstates; 52 } powernv_pstate_info; 53 54 /* 55 * Initialize the freq table based on data obtained 56 * from the firmware passed via device-tree 57 */ 58 static int init_powernv_pstates(void) 59 { 60 struct device_node *power_mgt; 61 int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0; 62 const __be32 *pstate_ids, *pstate_freqs; 63 u32 len_ids, len_freqs; 64 65 power_mgt = of_find_node_by_path("/ibm,opal/power-mgt"); 66 if (!power_mgt) { 67 pr_warn("power-mgt node not found\n"); 68 return -ENODEV; 69 } 70 71 if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) { 72 pr_warn("ibm,pstate-min node not found\n"); 73 return -ENODEV; 74 } 75 76 if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) { 77 pr_warn("ibm,pstate-max node not found\n"); 78 return -ENODEV; 79 } 80 81 if (of_property_read_u32(power_mgt, "ibm,pstate-nominal", 82 &pstate_nominal)) { 83 pr_warn("ibm,pstate-nominal not found\n"); 84 return -ENODEV; 85 } 86 pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min, 87 pstate_nominal, pstate_max); 88 89 pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids); 90 if (!pstate_ids) { 91 pr_warn("ibm,pstate-ids not found\n"); 92 return -ENODEV; 93 } 94 95 pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz", 96 &len_freqs); 97 if (!pstate_freqs) { 98 pr_warn("ibm,pstate-frequencies-mhz not found\n"); 99 return -ENODEV; 100 } 101 102 if (len_ids != len_freqs) { 103 pr_warn("Entries in ibm,pstate-ids and " 104 "ibm,pstate-frequencies-mhz does not match\n"); 105 } 106 107 nr_pstates = min(len_ids, len_freqs) / sizeof(u32); 108 if (!nr_pstates) { 109 pr_warn("No PStates found\n"); 110 return -ENODEV; 111 } 112 113 pr_debug("NR PStates %d\n", nr_pstates); 114 for (i = 0; i < nr_pstates; i++) { 115 u32 id = be32_to_cpu(pstate_ids[i]); 116 u32 freq = be32_to_cpu(pstate_freqs[i]); 117 118 pr_debug("PState id %d freq %d MHz\n", id, freq); 119 powernv_freqs[i].frequency = freq * 1000; /* kHz */ 120 powernv_freqs[i].driver_data = id; 121 } 122 /* End of list marker entry */ 123 powernv_freqs[i].frequency = CPUFREQ_TABLE_END; 124 125 powernv_pstate_info.min = pstate_min; 126 powernv_pstate_info.max = pstate_max; 127 powernv_pstate_info.nominal = pstate_nominal; 128 powernv_pstate_info.nr_pstates = nr_pstates; 129 130 return 0; 131 } 132 133 /* Returns the CPU frequency corresponding to the pstate_id. */ 134 static unsigned int pstate_id_to_freq(int pstate_id) 135 { 136 int i; 137 138 i = powernv_pstate_info.max - pstate_id; 139 if (i >= powernv_pstate_info.nr_pstates || i < 0) { 140 pr_warn("PState id %d outside of PState table, " 141 "reporting nominal id %d instead\n", 142 pstate_id, powernv_pstate_info.nominal); 143 i = powernv_pstate_info.max - powernv_pstate_info.nominal; 144 } 145 146 return powernv_freqs[i].frequency; 147 } 148 149 /* 150 * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by 151 * the firmware 152 */ 153 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy, 154 char *buf) 155 { 156 return sprintf(buf, "%u\n", 157 pstate_id_to_freq(powernv_pstate_info.nominal)); 158 } 159 160 struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq = 161 __ATTR_RO(cpuinfo_nominal_freq); 162 163 static struct freq_attr *powernv_cpu_freq_attr[] = { 164 &cpufreq_freq_attr_scaling_available_freqs, 165 &cpufreq_freq_attr_cpuinfo_nominal_freq, 166 NULL, 167 }; 168 169 /* Helper routines */ 170 171 /* Access helpers to power mgt SPR */ 172 173 static inline unsigned long get_pmspr(unsigned long sprn) 174 { 175 switch (sprn) { 176 case SPRN_PMCR: 177 return mfspr(SPRN_PMCR); 178 179 case SPRN_PMICR: 180 return mfspr(SPRN_PMICR); 181 182 case SPRN_PMSR: 183 return mfspr(SPRN_PMSR); 184 } 185 BUG(); 186 } 187 188 static inline void set_pmspr(unsigned long sprn, unsigned long val) 189 { 190 switch (sprn) { 191 case SPRN_PMCR: 192 mtspr(SPRN_PMCR, val); 193 return; 194 195 case SPRN_PMICR: 196 mtspr(SPRN_PMICR, val); 197 return; 198 } 199 BUG(); 200 } 201 202 /* 203 * Use objects of this type to query/update 204 * pstates on a remote CPU via smp_call_function. 205 */ 206 struct powernv_smp_call_data { 207 unsigned int freq; 208 int pstate_id; 209 }; 210 211 /* 212 * powernv_read_cpu_freq: Reads the current frequency on this CPU. 213 * 214 * Called via smp_call_function. 215 * 216 * Note: The caller of the smp_call_function should pass an argument of 217 * the type 'struct powernv_smp_call_data *' along with this function. 218 * 219 * The current frequency on this CPU will be returned via 220 * ((struct powernv_smp_call_data *)arg)->freq; 221 */ 222 static void powernv_read_cpu_freq(void *arg) 223 { 224 unsigned long pmspr_val; 225 s8 local_pstate_id; 226 struct powernv_smp_call_data *freq_data = arg; 227 228 pmspr_val = get_pmspr(SPRN_PMSR); 229 230 /* 231 * The local pstate id corresponds bits 48..55 in the PMSR. 232 * Note: Watch out for the sign! 233 */ 234 local_pstate_id = (pmspr_val >> 48) & 0xFF; 235 freq_data->pstate_id = local_pstate_id; 236 freq_data->freq = pstate_id_to_freq(freq_data->pstate_id); 237 238 pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n", 239 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id, 240 freq_data->freq); 241 } 242 243 /* 244 * powernv_cpufreq_get: Returns the CPU frequency as reported by the 245 * firmware for CPU 'cpu'. This value is reported through the sysfs 246 * file cpuinfo_cur_freq. 247 */ 248 static unsigned int powernv_cpufreq_get(unsigned int cpu) 249 { 250 struct powernv_smp_call_data freq_data; 251 252 smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq, 253 &freq_data, 1); 254 255 return freq_data.freq; 256 } 257 258 /* 259 * set_pstate: Sets the pstate on this CPU. 260 * 261 * This is called via an smp_call_function. 262 * 263 * The caller must ensure that freq_data is of the type 264 * (struct powernv_smp_call_data *) and the pstate_id which needs to be set 265 * on this CPU should be present in freq_data->pstate_id. 266 */ 267 static void set_pstate(void *freq_data) 268 { 269 unsigned long val; 270 unsigned long pstate_ul = 271 ((struct powernv_smp_call_data *) freq_data)->pstate_id; 272 273 val = get_pmspr(SPRN_PMCR); 274 val = val & 0x0000FFFFFFFFFFFFULL; 275 276 pstate_ul = pstate_ul & 0xFF; 277 278 /* Set both global(bits 56..63) and local(bits 48..55) PStates */ 279 val = val | (pstate_ul << 56) | (pstate_ul << 48); 280 281 pr_debug("Setting cpu %d pmcr to %016lX\n", 282 raw_smp_processor_id(), val); 283 set_pmspr(SPRN_PMCR, val); 284 } 285 286 /* 287 * powernv_cpufreq_target_index: Sets the frequency corresponding to 288 * the cpufreq table entry indexed by new_index on the cpus in the 289 * mask policy->cpus 290 */ 291 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, 292 unsigned int new_index) 293 { 294 struct powernv_smp_call_data freq_data; 295 296 freq_data.pstate_id = powernv_freqs[new_index].driver_data; 297 298 /* 299 * Use smp_call_function to send IPI and execute the 300 * mtspr on target CPU. We could do that without IPI 301 * if current CPU is within policy->cpus (core) 302 */ 303 smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1); 304 305 return 0; 306 } 307 308 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy) 309 { 310 int base, i; 311 312 base = cpu_first_thread_sibling(policy->cpu); 313 314 for (i = 0; i < threads_per_core; i++) 315 cpumask_set_cpu(base + i, policy->cpus); 316 317 return cpufreq_table_validate_and_show(policy, powernv_freqs); 318 } 319 320 static struct cpufreq_driver powernv_cpufreq_driver = { 321 .name = "powernv-cpufreq", 322 .flags = CPUFREQ_CONST_LOOPS, 323 .init = powernv_cpufreq_cpu_init, 324 .verify = cpufreq_generic_frequency_table_verify, 325 .target_index = powernv_cpufreq_target_index, 326 .get = powernv_cpufreq_get, 327 .attr = powernv_cpu_freq_attr, 328 }; 329 330 static int __init powernv_cpufreq_init(void) 331 { 332 int rc = 0; 333 334 /* Don't probe on pseries (guest) platforms */ 335 if (!firmware_has_feature(FW_FEATURE_OPALv3)) 336 return -ENODEV; 337 338 /* Discover pstates from device tree and init */ 339 rc = init_powernv_pstates(); 340 if (rc) { 341 pr_info("powernv-cpufreq disabled. System does not support PState control\n"); 342 return rc; 343 } 344 345 return cpufreq_register_driver(&powernv_cpufreq_driver); 346 } 347 module_init(powernv_cpufreq_init); 348 349 static void __exit powernv_cpufreq_exit(void) 350 { 351 cpufreq_unregister_driver(&powernv_cpufreq_driver); 352 } 353 module_exit(powernv_cpufreq_exit); 354 355 MODULE_LICENSE("GPL"); 356 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>"); 357