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  *  You should have received a copy of the GNU General Public License along
  23  *  with this program; if not, write to the Free Software Foundation, Inc.,
  24  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  25  *
  26  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  27  */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/init.h>
  32 #include <linux/cpufreq.h>
  33 #include <linux/sysdev.h>
  34
  35 #include <asm/uaccess.h>
  36
  37 #include <acpi/acpi_bus.h>
  38 #include <acpi/processor.h>
  39 #include <acpi/acpi_drivers.h>
  40
  41 #define PREFIX "ACPI: "
  42
  43 #define ACPI_PROCESSOR_CLASS            "processor"
  44 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  45 ACPI_MODULE_NAME("processor_thermal");
  46
  47 #ifdef CONFIG_CPU_FREQ
  48
  49 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
  50  * offers (in most cases) voltage scaling in addition to frequency scaling, and
  51  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
  52  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
  53  */
  54
  55 #define CPUFREQ_THERMAL_MIN_STEP 0
  56 #define CPUFREQ_THERMAL_MAX_STEP 3
  57
  58 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  59 static unsigned int acpi_thermal_cpufreq_is_init = 0;
  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 - per_cpu(cpufreq_thermal_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 per_cpu(cpufreq_thermal_reduction_pctg, cpu);
 107 }
 108
 109 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 110 {
 111         if (!cpu_has_cpufreq(cpu))
 112                 return 0;
 113
 114         per_cpu(cpufreq_thermal_reduction_pctg, cpu) = state;
 115         cpufreq_update_policy(cpu);
 116         return 0;
 117 }
 118
 119 void acpi_thermal_cpufreq_init(void)
 120 {
 121         int i;
 122
 123         for (i = 0; i < nr_cpu_ids; i++)
 124                 if (cpu_present(i))
 125                         per_cpu(cpufreq_thermal_reduction_pctg, i) = 0;
 126
 127         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 128                                       CPUFREQ_POLICY_NOTIFIER);
 129         if (!i)
 130                 acpi_thermal_cpufreq_is_init = 1;
 131 }
 132
 133 void acpi_thermal_cpufreq_exit(void)
 134 {
 135         if (acpi_thermal_cpufreq_is_init)
 136                 cpufreq_unregister_notifier
 137                     (&acpi_thermal_cpufreq_notifier_block,
 138                      CPUFREQ_POLICY_NOTIFIER);
 139
 140         acpi_thermal_cpufreq_is_init = 0;
 141 }
 142
 143 #else                           /* ! CONFIG_CPU_FREQ */
 144 static int cpufreq_get_max_state(unsigned int cpu)
 145 {
 146         return 0;
 147 }
 148
 149 static int cpufreq_get_cur_state(unsigned int cpu)
 150 {
 151         return 0;
 152 }
 153
 154 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 155 {
 156         return 0;
 157 }
 158
 159 #endif
 160
 161 int acpi_processor_get_limit_info(struct acpi_processor *pr)
 162 {
 163
 164         if (!pr)
 165                 return -EINVAL;
 166
 167         if (pr->flags.throttling)
 168                 pr->flags.limit = 1;
 169
 170         return 0;
 171 }
 172
 173 /* thermal coolign device callbacks */
 174 static int acpi_processor_max_state(struct acpi_processor *pr)
 175 {
 176         int max_state = 0;
 177
 178         /*
 179          * There exists four states according to
 180          * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
 181          */
 182         max_state += cpufreq_get_max_state(pr->id);
 183         if (pr->flags.throttling)
 184                 max_state += (pr->throttling.state_count -1);
 185
 186         return max_state;
 187 }
 188 static int
 189 processor_get_max_state(struct thermal_cooling_device *cdev,
 190                         unsigned long *state)
 191 {
 192         struct acpi_device *device = cdev->devdata;
 193         struct acpi_processor *pr = acpi_driver_data(device);
 194
 195         if (!device || !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 = acpi_driver_data(device);
 208
 209         if (!device || !pr)
 210                 return -EINVAL;
 211
 212         *cur_state = cpufreq_get_cur_state(pr->id);
 213         if (pr->flags.throttling)
 214                 *cur_state += pr->throttling.state;
 215         return 0;
 216 }
 217
 218 static int
 219 processor_set_cur_state(struct thermal_cooling_device *cdev,
 220                         unsigned long state)
 221 {
 222         struct acpi_device *device = cdev->devdata;
 223         struct acpi_processor *pr = acpi_driver_data(device);
 224         int result = 0;
 225         int max_pstate;
 226
 227         if (!device || !pr)
 228                 return -EINVAL;
 229
 230         max_pstate = cpufreq_get_max_state(pr->id);
 231
 232         if (state > acpi_processor_max_state(pr))
 233                 return -EINVAL;
 234
 235         if (state <= max_pstate) {
 236                 if (pr->flags.throttling && pr->throttling.state)
 237                         result = acpi_processor_set_throttling(pr, 0, false);
 238                 cpufreq_set_cur_state(pr->id, state);
 239         } else {
 240                 cpufreq_set_cur_state(pr->id, max_pstate);
 241                 result = acpi_processor_set_throttling(pr,
 242                                 state - max_pstate, false);
 243         }
 244         return result;
 245 }
 246
 247 struct thermal_cooling_device_ops processor_cooling_ops = {
 248         .get_max_state = processor_get_max_state,
 249         .get_cur_state = processor_get_cur_state,
 250         .set_cur_state = processor_set_cur_state,
 251 };