linux/drivers/acpi/processor_thermal.c
<<
>>
Prefs
   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 <asm/uaccess.h>
  32
  33#define PREFIX "ACPI: "
  34
  35#define ACPI_PROCESSOR_CLASS            "processor"
  36#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  37ACPI_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
  50static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  51static 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 */
  63static 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
  74static 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
  82static 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
 102static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
 103        .notifier_call = acpi_thermal_cpufreq_notifier,
 104};
 105
 106static 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
 114static 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
 122static 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
 144void 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
 154void 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 */
 165static int cpufreq_get_max_state(unsigned int cpu)
 166{
 167        return 0;
 168}
 169
 170static int cpufreq_get_cur_state(unsigned int cpu)
 171{
 172        return 0;
 173}
 174
 175static int cpufreq_set_cur_state(unsigned int cpu, int state)
 176{
 177        return 0;
 178}
 179
 180#endif
 181
 182/* thermal cooling device callbacks */
 183static 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}
 197static int
 198processor_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
 215static int
 216processor_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
 235static int
 236processor_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
 268const 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};
 273