drivers/cpufreq/cppc_cpufreq.c

   1 /*
   2  * CPPC (Collaborative Processor Performance Control) driver for
   3  * interfacing with the CPUfreq layer and governors. See
   4  * cppc_acpi.c for CPPC specific methods.
   5  *
   6  * (C) Copyright 2014, 2015 Linaro Ltd.
   7  * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation; version 2
  12  * of the License.
  13  */
  14
  15 #define pr_fmt(fmt)     "CPPC Cpufreq:" fmt
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/delay.h>
  20 #include <linux/cpu.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/dmi.h>
  23 #include <linux/time.h>
  24 #include <linux/vmalloc.h>
  25
  26 #include <asm/unaligned.h>
  27
  28 #include <acpi/cppc_acpi.h>
  29
  30 /* Minimum struct length needed for the DMI processor entry we want */
  31 #define DMI_ENTRY_PROCESSOR_MIN_LENGTH  48
  32
  33 /* Offest in the DMI processor structure for the max frequency */
  34 #define DMI_PROCESSOR_MAX_SPEED  0x14
  35
  36 /*
  37  * These structs contain information parsed from per CPU
  38  * ACPI _CPC structures.
  39  * e.g. For each CPU the highest, lowest supported
  40  * performance capabilities, desired performance level
  41  * requested etc.
  42  */
  43 static struct cppc_cpudata **all_cpu_data;
  44
  45 /* Callback function used to retrieve the max frequency from DMI */
  46 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
  47 {
  48         const u8 *dmi_data = (const u8 *)dm;
  49         u16 *mhz = (u16 *)private;
  50
  51         if (dm->type == DMI_ENTRY_PROCESSOR &&
  52             dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
  53                 u16 val = (u16)get_unaligned((const u16 *)
  54                                 (dmi_data + DMI_PROCESSOR_MAX_SPEED));
  55                 *mhz = val > *mhz ? val : *mhz;
  56         }
  57 }
  58
  59 /* Look up the max frequency in DMI */
  60 static u64 cppc_get_dmi_max_khz(void)
  61 {
  62         u16 mhz = 0;
  63
  64         dmi_walk(cppc_find_dmi_mhz, &mhz);
  65
  66         /*
  67          * Real stupid fallback value, just in case there is no
  68          * actual value set.
  69          */
  70         mhz = mhz ? mhz : 1;
  71
  72         return (1000 * mhz);
  73 }
  74
  75 /*
  76  * If CPPC lowest_freq and nominal_freq registers are exposed then we can
  77  * use them to convert perf to freq and vice versa
  78  *
  79  * If the perf/freq point lies between Nominal and Lowest, we can treat
  80  * (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
  81  * and extrapolate the rest
  82  * For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
  83  */
  84 static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu,
  85                                         unsigned int perf)
  86 {
  87         static u64 max_khz;
  88         struct cppc_perf_caps *caps = &cpu->perf_caps;
  89         u64 mul, div;
  90
  91         if (caps->lowest_freq && caps->nominal_freq) {
  92                 if (perf >= caps->nominal_perf) {
  93                         mul = caps->nominal_freq;
  94                         div = caps->nominal_perf;
  95                 } else {
  96                         mul = caps->nominal_freq - caps->lowest_freq;
  97                         div = caps->nominal_perf - caps->lowest_perf;
  98                 }
  99         } else {
 100                 if (!max_khz)
 101                         max_khz = cppc_get_dmi_max_khz();
 102                 mul = max_khz;
 103                 div = cpu->perf_caps.highest_perf;
 104         }
 105         return (u64)perf * mul / div;
 106 }
 107
 108 static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu,
 109                                         unsigned int freq)
 110 {
 111         static u64 max_khz;
 112         struct cppc_perf_caps *caps = &cpu->perf_caps;
 113         u64  mul, div;
 114
 115         if (caps->lowest_freq && caps->nominal_freq) {
 116                 if (freq >= caps->nominal_freq) {
 117                         mul = caps->nominal_perf;
 118                         div = caps->nominal_freq;
 119                 } else {
 120                         mul = caps->lowest_perf;
 121                         div = caps->lowest_freq;
 122                 }
 123         } else {
 124                 if (!max_khz)
 125                         max_khz = cppc_get_dmi_max_khz();
 126                 mul = cpu->perf_caps.highest_perf;
 127                 div = max_khz;
 128         }
 129
 130         return (u64)freq * mul / div;
 131 }
 132
 133 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
 134                 unsigned int target_freq,
 135                 unsigned int relation)
 136 {
 137         struct cppc_cpudata *cpu;
 138         struct cpufreq_freqs freqs;
 139         u32 desired_perf;
 140         int ret = 0;
 141
 142         cpu = all_cpu_data[policy->cpu];
 143
 144         desired_perf = cppc_cpufreq_khz_to_perf(cpu, target_freq);
 145         /* Return if it is exactly the same perf */
 146         if (desired_perf == cpu->perf_ctrls.desired_perf)
 147                 return ret;
 148
 149         cpu->perf_ctrls.desired_perf = desired_perf;
 150         freqs.old = policy->cur;
 151         freqs.new = target_freq;
 152
 153         cpufreq_freq_transition_begin(policy, &freqs);
 154         ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
 155         cpufreq_freq_transition_end(policy, &freqs, ret != 0);
 156
 157         if (ret)
 158                 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
 159                                 cpu->cpu, ret);
 160
 161         return ret;
 162 }
 163
 164 static int cppc_verify_policy(struct cpufreq_policy *policy)
 165 {
 166         cpufreq_verify_within_cpu_limits(policy);
 167         return 0;
 168 }
 169
 170 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 171 {
 172         int cpu_num = policy->cpu;
 173         struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
 174         int ret;
 175
 176         cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
 177
 178         ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
 179         if (ret)
 180                 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 181                                 cpu->perf_caps.lowest_perf, cpu_num, ret);
 182 }
 183
 184 /*
 185  * The PCC subspace describes the rate at which platform can accept commands
 186  * on the shared PCC channel (including READs which do not count towards freq
 187  * trasition requests), so ideally we need to use the PCC values as a fallback
 188  * if we don't have a platform specific transition_delay_us
 189  */
 190 #ifdef CONFIG_ARM64
 191 #include <asm/cputype.h>
 192
 193 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
 194 {
 195         unsigned long implementor = read_cpuid_implementor();
 196         unsigned long part_num = read_cpuid_part_number();
 197         unsigned int delay_us = 0;
 198
 199         switch (implementor) {
 200         case ARM_CPU_IMP_QCOM:
 201                 switch (part_num) {
 202                 case QCOM_CPU_PART_FALKOR_V1:
 203                 case QCOM_CPU_PART_FALKOR:
 204                         delay_us = 10000;
 205                         break;
 206                 default:
 207                         delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
 208                         break;
 209                 }
 210                 break;
 211         default:
 212                 delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
 213                 break;
 214         }
 215
 216         return delay_us;
 217 }
 218
 219 #else
 220
 221 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
 222 {
 223         return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
 224 }
 225 #endif
 226
 227 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 228 {
 229         struct cppc_cpudata *cpu;
 230         unsigned int cpu_num = policy->cpu;
 231         int ret = 0;
 232
 233         cpu = all_cpu_data[policy->cpu];
 234
 235         cpu->cpu = cpu_num;
 236         ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
 237
 238         if (ret) {
 239                 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
 240                                 cpu_num, ret);
 241                 return ret;
 242         }
 243
 244         /* Convert the lowest and nominal freq from MHz to KHz */
 245         cpu->perf_caps.lowest_freq *= 1000;
 246         cpu->perf_caps.nominal_freq *= 1000;
 247
 248         /*
 249          * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
 250          * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
 251          */
 252         policy->min = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_nonlinear_perf);
 253         policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
 254
 255         /*
 256          * Set cpuinfo.min_freq to Lowest to make the full range of performance
 257          * available if userspace wants to use any perf between lowest & lowest
 258          * nonlinear perf
 259          */
 260         policy->cpuinfo.min_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_perf);
 261         policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
 262
 263         policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
 264         policy->shared_type = cpu->shared_type;
 265
 266         if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
 267                 int i;
 268
 269                 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
 270
 271                 for_each_cpu(i, policy->cpus) {
 272                         if (unlikely(i == policy->cpu))
 273                                 continue;
 274
 275                         memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
 276                                sizeof(cpu->perf_caps));
 277                 }
 278         } else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
 279                 /* Support only SW_ANY for now. */
 280                 pr_debug("Unsupported CPU co-ord type\n");
 281                 return -EFAULT;
 282         }
 283
 284         cpu->cur_policy = policy;
 285
 286         /* Set policy->cur to max now. The governors will adjust later. */
 287         policy->cur = cppc_cpufreq_perf_to_khz(cpu,
 288                                         cpu->perf_caps.highest_perf);
 289         cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
 290
 291         ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
 292         if (ret)
 293                 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 294                                 cpu->perf_caps.highest_perf, cpu_num, ret);
 295
 296         return ret;
 297 }
 298
 299 static struct cpufreq_driver cppc_cpufreq_driver = {
 300         .flags = CPUFREQ_CONST_LOOPS,
 301         .verify = cppc_verify_policy,
 302         .target = cppc_cpufreq_set_target,
 303         .init = cppc_cpufreq_cpu_init,
 304         .stop_cpu = cppc_cpufreq_stop_cpu,
 305         .name = "cppc_cpufreq",
 306 };
 307
 308 static int __init cppc_cpufreq_init(void)
 309 {
 310         int i, ret = 0;
 311         struct cppc_cpudata *cpu;
 312
 313         if (acpi_disabled)
 314                 return -ENODEV;
 315
 316         all_cpu_data = kcalloc(num_possible_cpus(), sizeof(void *),
 317                                GFP_KERNEL);
 318         if (!all_cpu_data)
 319                 return -ENOMEM;
 320
 321         for_each_possible_cpu(i) {
 322                 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
 323                 if (!all_cpu_data[i])
 324                         goto out;
 325
 326                 cpu = all_cpu_data[i];
 327                 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
 328                         goto out;
 329         }
 330
 331         ret = acpi_get_psd_map(all_cpu_data);
 332         if (ret) {
 333                 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
 334                 goto out;
 335         }
 336
 337         ret = cpufreq_register_driver(&cppc_cpufreq_driver);
 338         if (ret)
 339                 goto out;
 340
 341         return ret;
 342
 343 out:
 344         for_each_possible_cpu(i) {
 345                 cpu = all_cpu_data[i];
 346                 if (!cpu)
 347                         break;
 348                 free_cpumask_var(cpu->shared_cpu_map);
 349                 kfree(cpu);
 350         }
 351
 352         kfree(all_cpu_data);
 353         return -ENODEV;
 354 }
 355
 356 static void __exit cppc_cpufreq_exit(void)
 357 {
 358         struct cppc_cpudata *cpu;
 359         int i;
 360
 361         cpufreq_unregister_driver(&cppc_cpufreq_driver);
 362
 363         for_each_possible_cpu(i) {
 364                 cpu = all_cpu_data[i];
 365                 free_cpumask_var(cpu->shared_cpu_map);
 366                 kfree(cpu);
 367         }
 368
 369         kfree(all_cpu_data);
 370 }
 371
 372 module_exit(cppc_cpufreq_exit);
 373 MODULE_AUTHOR("Ashwin Chaugule");
 374 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
 375 MODULE_LICENSE("GPL");
 376
 377 late_initcall(cppc_cpufreq_init);
 378
 379 static const struct acpi_device_id cppc_acpi_ids[] = {
 380         {ACPI_PROCESSOR_DEVICE_HID, },
 381         {}
 382 };
 383
 384 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);