drivers/acpi/processor_thermal.c

   1 /*
   2  * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   6  *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
   7  *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   8  *                      - Added processor hotplug support
   9  *
  10  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  11  *
  12  *  This program is free software; you can redistribute it and/or modify
  13  *  it under the terms of the GNU General Public License as published by
  14  *  the Free Software Foundation; either version 2 of the License, or (at
  15  *  your option) any later version.
  16  *
  17  *  This program is distributed in the hope that it will be useful, but
  18  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  *  General Public License for more details.
  21  *
  22  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/init.h>
  28 #include <linux/cpufreq.h>
  29 #include <linux/acpi.h>
  30 #include <acpi/processor.h>
  31 #include <linux/uaccess.h>
  32
  33 #define PREFIX "ACPI: "
  34
  35 #define ACPI_PROCESSOR_CLASS            "processor"
  36 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  37 ACPI_MODULE_NAME("processor_thermal");
  38
  39 #ifdef CONFIG_CPU_FREQ
  40
  41 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
  42  * offers (in most cases) voltage scaling in addition to frequency scaling, and
  43  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
  44  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
  45  */
  46
  47 #define CPUFREQ_THERMAL_MIN_STEP 0
  48 #define CPUFREQ_THERMAL_MAX_STEP 3
  49
  50 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  51 static unsigned int acpi_thermal_cpufreq_is_init = 0;
  52
  53 #define reduction_pctg(cpu) \
  54         per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
  55
  56 /*
  57  * Emulate "per package data" using per cpu data (which should really be
  58  * provided elsewhere)
  59  *
  60  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
  61  * temporarily. Fortunately that's not a big issue here (I hope)
  62  */
  63 static int phys_package_first_cpu(int cpu)
  64 {
  65         int i;
  66         int id = topology_physical_package_id(cpu);
  67
  68         for_each_online_cpu(i)
  69                 if (topology_physical_package_id(i) == id)
  70                         return i;
  71         return 0;
  72 }
  73
  74 static int cpu_has_cpufreq(unsigned int cpu)
  75 {
  76         struct cpufreq_policy policy;
  77         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  78                 return 0;
  79         return 1;
  80 }
  81
  82 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  83                                          unsigned long event, void *data)
  84 {
  85         struct cpufreq_policy *policy = data;
  86         unsigned long max_freq = 0;
  87
  88         if (event != CPUFREQ_ADJUST)
  89                 goto out;
  90
  91         max_freq = (
  92             policy->cpuinfo.max_freq *
  93             (100 - reduction_pctg(policy->cpu) * 20)
  94         ) / 100;
  95
  96         cpufreq_verify_within_limits(policy, 0, max_freq);
  97
  98       out:
  99         return 0;
 100 }
 101
 102 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
 103         .notifier_call = acpi_thermal_cpufreq_notifier,
 104 };
 105
 106 static int cpufreq_get_max_state(unsigned int cpu)
 107 {
 108         if (!cpu_has_cpufreq(cpu))
 109                 return 0;
 110
 111         return CPUFREQ_THERMAL_MAX_STEP;
 112 }
 113
 114 static int cpufreq_get_cur_state(unsigned int cpu)
 115 {
 116         if (!cpu_has_cpufreq(cpu))
 117                 return 0;
 118
 119         return reduction_pctg(cpu);
 120 }
 121
 122 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 123 {
 124         int i;
 125
 126         if (!cpu_has_cpufreq(cpu))
 127                 return 0;
 128
 129         reduction_pctg(cpu) = state;
 130
 131         /*
 132          * Update all the CPUs in the same package because they all
 133          * contribute to the temperature and often share the same
 134          * frequency.
 135          */
 136         for_each_online_cpu(i) {
 137                 if (topology_physical_package_id(i) ==
 138                     topology_physical_package_id(cpu))
 139                         cpufreq_update_policy(i);
 140         }
 141         return 0;
 142 }
 143
 144 void acpi_thermal_cpufreq_init(void)
 145 {
 146         int i;
 147
 148         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 149                                       CPUFREQ_POLICY_NOTIFIER);
 150         if (!i)
 151                 acpi_thermal_cpufreq_is_init = 1;
 152 }
 153
 154 void acpi_thermal_cpufreq_exit(void)
 155 {
 156         if (acpi_thermal_cpufreq_is_init)
 157                 cpufreq_unregister_notifier
 158                     (&acpi_thermal_cpufreq_notifier_block,
 159                      CPUFREQ_POLICY_NOTIFIER);
 160
 161         acpi_thermal_cpufreq_is_init = 0;
 162 }
 163
 164 #else                           /* ! CONFIG_CPU_FREQ */
 165 static int cpufreq_get_max_state(unsigned int cpu)
 166 {
 167         return 0;
 168 }
 169
 170 static int cpufreq_get_cur_state(unsigned int cpu)
 171 {
 172         return 0;
 173 }
 174
 175 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 176 {
 177         return 0;
 178 }
 179
 180 #endif
 181
 182 /* thermal cooling device callbacks */
 183 static int acpi_processor_max_state(struct acpi_processor *pr)
 184 {
 185         int max_state = 0;
 186
 187         /*
 188          * There exists four states according to
 189          * cpufreq_thermal_reduction_pctg. 0, 1, 2, 3
 190          */
 191         max_state += cpufreq_get_max_state(pr->id);
 192         if (pr->flags.throttling)
 193                 max_state += (pr->throttling.state_count -1);
 194
 195         return max_state;
 196 }
 197 static int
 198 processor_get_max_state(struct thermal_cooling_device *cdev,
 199                         unsigned long *state)
 200 {
 201         struct acpi_device *device = cdev->devdata;
 202         struct acpi_processor *pr;
 203
 204         if (!device)
 205                 return -EINVAL;
 206
 207         pr = acpi_driver_data(device);
 208         if (!pr)
 209                 return -EINVAL;
 210
 211         *state = acpi_processor_max_state(pr);
 212         return 0;
 213 }
 214
 215 static int
 216 processor_get_cur_state(struct thermal_cooling_device *cdev,
 217                         unsigned long *cur_state)
 218 {
 219         struct acpi_device *device = cdev->devdata;
 220         struct acpi_processor *pr;
 221
 222         if (!device)
 223                 return -EINVAL;
 224
 225         pr = acpi_driver_data(device);
 226         if (!pr)
 227                 return -EINVAL;
 228
 229         *cur_state = cpufreq_get_cur_state(pr->id);
 230         if (pr->flags.throttling)
 231                 *cur_state += pr->throttling.state;
 232         return 0;
 233 }
 234
 235 static int
 236 processor_set_cur_state(struct thermal_cooling_device *cdev,
 237                         unsigned long state)
 238 {
 239         struct acpi_device *device = cdev->devdata;
 240         struct acpi_processor *pr;
 241         int result = 0;
 242         int max_pstate;
 243
 244         if (!device)
 245                 return -EINVAL;
 246
 247         pr = acpi_driver_data(device);
 248         if (!pr)
 249                 return -EINVAL;
 250
 251         max_pstate = cpufreq_get_max_state(pr->id);
 252
 253         if (state > acpi_processor_max_state(pr))
 254                 return -EINVAL;
 255
 256         if (state <= max_pstate) {
 257                 if (pr->flags.throttling && pr->throttling.state)
 258                         result = acpi_processor_set_throttling(pr, 0, false);
 259                 cpufreq_set_cur_state(pr->id, state);
 260         } else {
 261                 cpufreq_set_cur_state(pr->id, max_pstate);
 262                 result = acpi_processor_set_throttling(pr,
 263                                 state - max_pstate, false);
 264         }
 265         return result;
 266 }
 267
 268 const struct thermal_cooling_device_ops processor_cooling_ops = {
 269         .get_max_state = processor_get_max_state,
 270         .get_cur_state = processor_get_cur_state,
 271         .set_cur_state = processor_set_cur_state,
 272 };