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