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