drivers/acpi/processor_thermal.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
   4  *
   5  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   6  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   7  *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
   8  *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   9  *                      - Added processor hotplug support
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/cpufreq.h>
  16 #include <linux/acpi.h>
  17 #include <acpi/processor.h>
  18 #include <linux/uaccess.h>
  19
  20 #include "internal.h"
  21
  22 #ifdef CONFIG_CPU_FREQ
  23
  24 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
  25  * offers (in most cases) voltage scaling in addition to frequency scaling, and
  26  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
  27  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
  28  */
  29
  30 #define CPUFREQ_THERMAL_MIN_STEP 0
  31
  32 static int cpufreq_thermal_max_step __read_mostly = 3;
  33
  34 /*
  35  * Minimum throttle percentage for processor_thermal cooling device.
  36  * The processor_thermal driver uses it to calculate the percentage amount by
  37  * which cpu frequency must be reduced for each cooling state. This is also used
  38  * to calculate the maximum number of throttling steps or cooling states.
  39  */
  40 static int cpufreq_thermal_reduction_pctg __read_mostly = 20;
  41
  42 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_step);
  43
  44 #define reduction_step(cpu) \
  45         per_cpu(cpufreq_thermal_reduction_step, phys_package_first_cpu(cpu))
  46
  47 /*
  48  * Emulate "per package data" using per cpu data (which should really be
  49  * provided elsewhere)
  50  *
  51  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
  52  * temporarily. Fortunately that's not a big issue here (I hope)
  53  */
  54 static int phys_package_first_cpu(int cpu)
  55 {
  56         int i;
  57         int id = topology_physical_package_id(cpu);
  58
  59         for_each_online_cpu(i)
  60                 if (topology_physical_package_id(i) == id)
  61                         return i;
  62         return 0;
  63 }
  64
  65 static int cpu_has_cpufreq(unsigned int cpu)
  66 {
  67         struct cpufreq_policy *policy;
  68
  69         if (!acpi_processor_cpufreq_init)
  70                 return 0;
  71
  72         policy = cpufreq_cpu_get(cpu);
  73         if (policy) {
  74                 cpufreq_cpu_put(policy);
  75                 return 1;
  76         }
  77         return 0;
  78 }
  79
  80 static int cpufreq_get_max_state(unsigned int cpu)
  81 {
  82         if (!cpu_has_cpufreq(cpu))
  83                 return 0;
  84
  85         return cpufreq_thermal_max_step;
  86 }
  87
  88 static int cpufreq_get_cur_state(unsigned int cpu)
  89 {
  90         if (!cpu_has_cpufreq(cpu))
  91                 return 0;
  92
  93         return reduction_step(cpu);
  94 }
  95
  96 static int cpufreq_set_cur_state(unsigned int cpu, int state)
  97 {
  98         struct cpufreq_policy *policy;
  99         struct acpi_processor *pr;
 100         unsigned long max_freq;
 101         int i, ret;
 102
 103         if (!cpu_has_cpufreq(cpu))
 104                 return 0;
 105
 106         reduction_step(cpu) = state;
 107
 108         /*
 109          * Update all the CPUs in the same package because they all
 110          * contribute to the temperature and often share the same
 111          * frequency.
 112          */
 113         for_each_online_cpu(i) {
 114                 if (topology_physical_package_id(i) !=
 115                     topology_physical_package_id(cpu))
 116                         continue;
 117
 118                 pr = per_cpu(processors, i);
 119
 120                 if (unlikely(!freq_qos_request_active(&pr->thermal_req)))
 121                         continue;
 122
 123                 policy = cpufreq_cpu_get(i);
 124                 if (!policy)
 125                         return -EINVAL;
 126
 127                 max_freq = (policy->cpuinfo.max_freq *
 128                             (100 - reduction_step(i) * cpufreq_thermal_reduction_pctg)) / 100;
 129
 130                 cpufreq_cpu_put(policy);
 131
 132                 ret = freq_qos_update_request(&pr->thermal_req, max_freq);
 133                 if (ret < 0) {
 134                         pr_warn("Failed to update thermal freq constraint: CPU%d (%d)\n",
 135                                 pr->id, ret);
 136                 }
 137         }
 138         return 0;
 139 }
 140
 141 static void acpi_thermal_cpufreq_config(void)
 142 {
 143         int cpufreq_pctg = acpi_arch_thermal_cpufreq_pctg();
 144
 145         if (!cpufreq_pctg)
 146                 return;
 147
 148         cpufreq_thermal_reduction_pctg = cpufreq_pctg;
 149
 150         /*
 151          * Derive the MAX_STEP from minimum throttle percentage so that the reduction
 152          * percentage doesn't end up becoming negative. Also, cap the MAX_STEP so that
 153          * the CPU performance doesn't become 0.
 154          */
 155         cpufreq_thermal_max_step = (100 / cpufreq_pctg) - 2;
 156 }
 157
 158 void acpi_thermal_cpufreq_init(struct cpufreq_policy *policy)
 159 {
 160         unsigned int cpu;
 161
 162         acpi_thermal_cpufreq_config();
 163
 164         for_each_cpu(cpu, policy->related_cpus) {
 165                 struct acpi_processor *pr = per_cpu(processors, cpu);
 166                 int ret;
 167
 168                 if (!pr)
 169                         continue;
 170
 171                 ret = freq_qos_add_request(&policy->constraints,
 172                                            &pr->thermal_req,
 173                                            FREQ_QOS_MAX, INT_MAX);
 174                 if (ret < 0) {
 175                         pr_err("Failed to add freq constraint for CPU%d (%d)\n",
 176                                cpu, ret);
 177                         continue;
 178                 }
 179
 180                 thermal_cooling_device_update(pr->cdev);
 181         }
 182 }
 183
 184 void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
 185 {
 186         unsigned int cpu;
 187
 188         for_each_cpu(cpu, policy->related_cpus) {
 189                 struct acpi_processor *pr = per_cpu(processors, cpu);
 190
 191                 if (!pr)
 192                         continue;
 193
 194                 freq_qos_remove_request(&pr->thermal_req);
 195
 196                 thermal_cooling_device_update(pr->cdev);
 197         }
 198 }
 199 #else                           /* ! CONFIG_CPU_FREQ */
 200 static int cpufreq_get_max_state(unsigned int cpu)
 201 {
 202         return 0;
 203 }
 204
 205 static int cpufreq_get_cur_state(unsigned int cpu)
 206 {
 207         return 0;
 208 }
 209
 210 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 211 {
 212         return 0;
 213 }
 214
 215 #endif
 216
 217 /* thermal cooling device callbacks */
 218 static int acpi_processor_max_state(struct acpi_processor *pr)
 219 {
 220         int max_state = 0;
 221
 222         /*
 223          * There exists four states according to
 224          * cpufreq_thermal_reduction_step. 0, 1, 2, 3
 225          */
 226         max_state += cpufreq_get_max_state(pr->id);
 227         if (pr->flags.throttling)
 228                 max_state += (pr->throttling.state_count -1);
 229
 230         return max_state;
 231 }
 232 static int
 233 processor_get_max_state(struct thermal_cooling_device *cdev,
 234                         unsigned long *state)
 235 {
 236         struct acpi_device *device = cdev->devdata;
 237         struct acpi_processor *pr;
 238
 239         if (!device)
 240                 return -EINVAL;
 241
 242         pr = acpi_driver_data(device);
 243         if (!pr)
 244                 return -EINVAL;
 245
 246         *state = acpi_processor_max_state(pr);
 247         return 0;
 248 }
 249
 250 static int
 251 processor_get_cur_state(struct thermal_cooling_device *cdev,
 252                         unsigned long *cur_state)
 253 {
 254         struct acpi_device *device = cdev->devdata;
 255         struct acpi_processor *pr;
 256
 257         if (!device)
 258                 return -EINVAL;
 259
 260         pr = acpi_driver_data(device);
 261         if (!pr)
 262                 return -EINVAL;
 263
 264         *cur_state = cpufreq_get_cur_state(pr->id);
 265         if (pr->flags.throttling)
 266                 *cur_state += pr->throttling.state;
 267         return 0;
 268 }
 269
 270 static int
 271 processor_set_cur_state(struct thermal_cooling_device *cdev,
 272                         unsigned long state)
 273 {
 274         struct acpi_device *device = cdev->devdata;
 275         struct acpi_processor *pr;
 276         int result = 0;
 277         int max_pstate;
 278
 279         if (!device)
 280                 return -EINVAL;
 281
 282         pr = acpi_driver_data(device);
 283         if (!pr)
 284                 return -EINVAL;
 285
 286         max_pstate = cpufreq_get_max_state(pr->id);
 287
 288         if (state > acpi_processor_max_state(pr))
 289                 return -EINVAL;
 290
 291         if (state <= max_pstate) {
 292                 if (pr->flags.throttling && pr->throttling.state)
 293                         result = acpi_processor_set_throttling(pr, 0, false);
 294                 cpufreq_set_cur_state(pr->id, state);
 295         } else {
 296                 cpufreq_set_cur_state(pr->id, max_pstate);
 297                 result = acpi_processor_set_throttling(pr,
 298                                 state - max_pstate, false);
 299         }
 300         return result;
 301 }
 302
 303 const struct thermal_cooling_device_ops processor_cooling_ops = {
 304         .get_max_state = processor_get_max_state,
 305         .get_cur_state = processor_get_cur_state,
 306         .set_cur_state = processor_set_cur_state,
 307 };
 308
 309 int acpi_processor_thermal_init(struct acpi_processor *pr,
 310                                 struct acpi_device *device)
 311 {
 312         int result = 0;
 313
 314         pr->cdev = thermal_cooling_device_register("Processor", device,
 315                                                    &processor_cooling_ops);
 316         if (IS_ERR(pr->cdev)) {
 317                 result = PTR_ERR(pr->cdev);
 318                 return result;
 319         }
 320
 321         dev_dbg(&device->dev, "registered as cooling_device%d\n",
 322                 pr->cdev->id);
 323
 324         result = sysfs_create_link(&device->dev.kobj,
 325                                    &pr->cdev->device.kobj,
 326                                    "thermal_cooling");
 327         if (result) {
 328                 dev_err(&device->dev,
 329                         "Failed to create sysfs link 'thermal_cooling'\n");
 330                 goto err_thermal_unregister;
 331         }
 332
 333         result = sysfs_create_link(&pr->cdev->device.kobj,
 334                                    &device->dev.kobj,
 335                                    "device");
 336         if (result) {
 337                 dev_err(&pr->cdev->device,
 338                         "Failed to create sysfs link 'device'\n");
 339                 goto err_remove_sysfs_thermal;
 340         }
 341
 342         return 0;
 343
 344 err_remove_sysfs_thermal:
 345         sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
 346 err_thermal_unregister:
 347         thermal_cooling_device_unregister(pr->cdev);
 348
 349         return result;
 350 }
 351
 352 void acpi_processor_thermal_exit(struct acpi_processor *pr,
 353                                  struct acpi_device *device)
 354 {
 355         if (pr->cdev) {
 356                 sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
 357                 sysfs_remove_link(&pr->cdev->device.kobj, "device");
 358                 thermal_cooling_device_unregister(pr->cdev);
 359                 pr->cdev = NULL;
 360         }
 361 }