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 <[email protected]>
   6  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
   7  *  Copyright (C) 2004       Dominik Brodowski <[email protected]>
   8  *  Copyright (C) 2004  Anil S Keshavamurthy <[email protected]>
   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 #define PREFIX "ACPI: "
  21
  22 #define ACPI_PROCESSOR_CLASS            "processor"
  23 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  24 ACPI_MODULE_NAME("processor_thermal");
  25
  26 #ifdef CONFIG_CPU_FREQ
  27
  28 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
  29  * offers (in most cases) voltage scaling in addition to frequency scaling, and
  30  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
  31  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
  32  */
  33
  34 #define CPUFREQ_THERMAL_MIN_STEP 0
  35 #define CPUFREQ_THERMAL_MAX_STEP 3
  36
  37 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  38 static unsigned int acpi_thermal_cpufreq_is_init = 0;
  39
  40 #define reduction_pctg(cpu) \
  41         per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
  42
  43 /*
  44  * Emulate "per package data" using per cpu data (which should really be
  45  * provided elsewhere)
  46  *
  47  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
  48  * temporarily. Fortunately that's not a big issue here (I hope)
  49  */
  50 static int phys_package_first_cpu(int cpu)
  51 {
  52         int i;
  53         int id = topology_physical_package_id(cpu);
  54
  55         for_each_online_cpu(i)
  56                 if (topology_physical_package_id(i) == id)
  57                         return i;
  58         return 0;
  59 }
  60
  61 static int cpu_has_cpufreq(unsigned int cpu)
  62 {
  63         struct cpufreq_policy policy;
  64         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  65                 return 0;
  66         return 1;
  67 }
  68
  69 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  70                                          unsigned long event, void *data)
  71 {
  72         struct cpufreq_policy *policy = data;
  73         unsigned long max_freq = 0;
  74
  75         if (event != CPUFREQ_ADJUST)
  76                 goto out;
  77
  78         max_freq = (
  79             policy->cpuinfo.max_freq *
  80             (100 - reduction_pctg(policy->cpu) * 20)
  81         ) / 100;
  82
  83         cpufreq_verify_within_limits(policy, 0, max_freq);
  84
  85       out:
  86         return 0;
  87 }
  88
  89 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
  90         .notifier_call = acpi_thermal_cpufreq_notifier,
  91 };
  92
  93 static int cpufreq_get_max_state(unsigned int cpu)
  94 {
  95         if (!cpu_has_cpufreq(cpu))
  96                 return 0;
  97
  98         return CPUFREQ_THERMAL_MAX_STEP;
  99 }
 100
 101 static int cpufreq_get_cur_state(unsigned int cpu)
 102 {
 103         if (!cpu_has_cpufreq(cpu))
 104                 return 0;
 105
 106         return reduction_pctg(cpu);
 107 }
 108
 109 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 110 {
 111         int i;
 112
 113         if (!cpu_has_cpufreq(cpu))
 114                 return 0;
 115
 116         reduction_pctg(cpu) = state;
 117
 118         /*
 119          * Update all the CPUs in the same package because they all
 120          * contribute to the temperature and often share the same
 121          * frequency.
 122          */
 123         for_each_online_cpu(i) {
 124                 if (topology_physical_package_id(i) ==
 125                     topology_physical_package_id(cpu))
 126                         cpufreq_update_policy(i);
 127         }
 128         return 0;
 129 }
 130
 131 void acpi_thermal_cpufreq_init(void)
 132 {
 133         int i;
 134
 135         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 136                                       CPUFREQ_POLICY_NOTIFIER);
 137         if (!i)
 138                 acpi_thermal_cpufreq_is_init = 1;
 139 }
 140
 141 void acpi_thermal_cpufreq_exit(void)
 142 {
 143         if (acpi_thermal_cpufreq_is_init)
 144                 cpufreq_unregister_notifier
 145                     (&acpi_thermal_cpufreq_notifier_block,
 146                      CPUFREQ_POLICY_NOTIFIER);
 147
 148         acpi_thermal_cpufreq_is_init = 0;
 149 }
 150
 151 #else                           /* ! CONFIG_CPU_FREQ */
 152 static int cpufreq_get_max_state(unsigned int cpu)
 153 {
 154         return 0;
 155 }
 156
 157 static int cpufreq_get_cur_state(unsigned int cpu)
 158 {
 159         return 0;
 160 }
 161
 162 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 163 {
 164         return 0;
 165 }
 166
 167 #endif
 168
 169 /* thermal cooling device callbacks */
 170 static int acpi_processor_max_state(struct acpi_processor *pr)
 171 {
 172         int max_state = 0;
 173
 174         /*
 175          * There exists four states according to
 176          * cpufreq_thermal_reduction_pctg. 0, 1, 2, 3
 177          */
 178         max_state += cpufreq_get_max_state(pr->id);
 179         if (pr->flags.throttling)
 180                 max_state += (pr->throttling.state_count -1);
 181
 182         return max_state;
 183 }
 184 static int
 185 processor_get_max_state(struct thermal_cooling_device *cdev,
 186                         unsigned long *state)
 187 {
 188         struct acpi_device *device = cdev->devdata;
 189         struct acpi_processor *pr;
 190
 191         if (!device)
 192                 return -EINVAL;
 193
 194         pr = acpi_driver_data(device);
 195         if (!pr)
 196                 return -EINVAL;
 197
 198         *state = acpi_processor_max_state(pr);
 199         return 0;
 200 }
 201
 202 static int
 203 processor_get_cur_state(struct thermal_cooling_device *cdev,
 204                         unsigned long *cur_state)
 205 {
 206         struct acpi_device *device = cdev->devdata;
 207         struct acpi_processor *pr;
 208
 209         if (!device)
 210                 return -EINVAL;
 211
 212         pr = acpi_driver_data(device);
 213         if (!pr)
 214                 return -EINVAL;
 215
 216         *cur_state = cpufreq_get_cur_state(pr->id);
 217         if (pr->flags.throttling)
 218                 *cur_state += pr->throttling.state;
 219         return 0;
 220 }
 221
 222 static int
 223 processor_set_cur_state(struct thermal_cooling_device *cdev,
 224                         unsigned long state)
 225 {
 226         struct acpi_device *device = cdev->devdata;
 227         struct acpi_processor *pr;
 228         int result = 0;
 229         int max_pstate;
 230
 231         if (!device)
 232                 return -EINVAL;
 233
 234         pr = acpi_driver_data(device);
 235         if (!pr)
 236                 return -EINVAL;
 237
 238         max_pstate = cpufreq_get_max_state(pr->id);
 239
 240         if (state > acpi_processor_max_state(pr))
 241                 return -EINVAL;
 242
 243         if (state <= max_pstate) {
 244                 if (pr->flags.throttling && pr->throttling.state)
 245                         result = acpi_processor_set_throttling(pr, 0, false);
 246                 cpufreq_set_cur_state(pr->id, state);
 247         } else {
 248                 cpufreq_set_cur_state(pr->id, max_pstate);
 249                 result = acpi_processor_set_throttling(pr,
 250                                 state - max_pstate, false);
 251         }
 252         return result;
 253 }
 254
 255 const struct thermal_cooling_device_ops processor_cooling_ops = {
 256         .get_max_state = processor_get_max_state,
 257         .get_cur_state = processor_get_cur_state,
 258         .set_cur_state = processor_set_cur_state,
 259 };