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
  34 #include <asm/uaccess.h>
  35
  36 #include <acpi/acpi_bus.h>
  37 #include <acpi/processor.h>
  38 #include <acpi/acpi_drivers.h>
  39
  40 #define PREFIX "ACPI: "
  41
  42 #define ACPI_PROCESSOR_CLASS            "processor"
  43 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  44 ACPI_MODULE_NAME("processor_thermal");
  45
  46 #ifdef CONFIG_CPU_FREQ
  47
  48 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
  49  * offers (in most cases) voltage scaling in addition to frequency scaling, and
  50  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
  51  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
  52  */
  53
  54 #define CPUFREQ_THERMAL_MIN_STEP 0
  55 #define CPUFREQ_THERMAL_MAX_STEP 3
  56
  57 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  58 static unsigned int acpi_thermal_cpufreq_is_init = 0;
  59
  60 static int cpu_has_cpufreq(unsigned int cpu)
  61 {
  62         struct cpufreq_policy policy;
  63         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  64                 return 0;
  65         return 1;
  66 }
  67
  68 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  69                                          unsigned long event, void *data)
  70 {
  71         struct cpufreq_policy *policy = data;
  72         unsigned long max_freq = 0;
  73
  74         if (event != CPUFREQ_ADJUST)
  75                 goto out;
  76
  77         max_freq = (
  78             policy->cpuinfo.max_freq *
  79             (100 - per_cpu(cpufreq_thermal_reduction_pctg, policy->cpu) * 20)
  80         ) / 100;
  81
  82         cpufreq_verify_within_limits(policy, 0, max_freq);
  83
  84       out:
  85         return 0;
  86 }
  87
  88 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
  89         .notifier_call = acpi_thermal_cpufreq_notifier,
  90 };
  91
  92 static int cpufreq_get_max_state(unsigned int cpu)
  93 {
  94         if (!cpu_has_cpufreq(cpu))
  95                 return 0;
  96
  97         return CPUFREQ_THERMAL_MAX_STEP;
  98 }
  99
 100 static int cpufreq_get_cur_state(unsigned int cpu)
 101 {
 102         if (!cpu_has_cpufreq(cpu))
 103                 return 0;
 104
 105         return per_cpu(cpufreq_thermal_reduction_pctg, cpu);
 106 }
 107
 108 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 109 {
 110         if (!cpu_has_cpufreq(cpu))
 111                 return 0;
 112
 113         per_cpu(cpufreq_thermal_reduction_pctg, cpu) = state;
 114         cpufreq_update_policy(cpu);
 115         return 0;
 116 }
 117
 118 void acpi_thermal_cpufreq_init(void)
 119 {
 120         int i;
 121
 122         for (i = 0; i < nr_cpu_ids; i++)
 123                 if (cpu_present(i))
 124                         per_cpu(cpufreq_thermal_reduction_pctg, i) = 0;
 125
 126         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 127                                       CPUFREQ_POLICY_NOTIFIER);
 128         if (!i)
 129                 acpi_thermal_cpufreq_is_init = 1;
 130 }
 131
 132 void acpi_thermal_cpufreq_exit(void)
 133 {
 134         if (acpi_thermal_cpufreq_is_init)
 135                 cpufreq_unregister_notifier
 136                     (&acpi_thermal_cpufreq_notifier_block,
 137                      CPUFREQ_POLICY_NOTIFIER);
 138
 139         acpi_thermal_cpufreq_is_init = 0;
 140 }
 141
 142 #else                           /* ! CONFIG_CPU_FREQ */
 143 static int cpufreq_get_max_state(unsigned int cpu)
 144 {
 145         return 0;
 146 }
 147
 148 static int cpufreq_get_cur_state(unsigned int cpu)
 149 {
 150         return 0;
 151 }
 152
 153 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 154 {
 155         return 0;
 156 }
 157
 158 #endif
 159
 160 int acpi_processor_get_limit_info(struct acpi_processor *pr)
 161 {
 162
 163         if (!pr)
 164                 return -EINVAL;
 165
 166         if (pr->flags.throttling)
 167                 pr->flags.limit = 1;
 168
 169         return 0;
 170 }
 171
 172 /* thermal coolign device callbacks */
 173 static int acpi_processor_max_state(struct acpi_processor *pr)
 174 {
 175         int max_state = 0;
 176
 177         /*
 178          * There exists four states according to
 179          * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
 180          */
 181         max_state += cpufreq_get_max_state(pr->id);
 182         if (pr->flags.throttling)
 183                 max_state += (pr->throttling.state_count -1);
 184
 185         return max_state;
 186 }
 187 static int
 188 processor_get_max_state(struct thermal_cooling_device *cdev,
 189                         unsigned long *state)
 190 {
 191         struct acpi_device *device = cdev->devdata;
 192         struct acpi_processor *pr = acpi_driver_data(device);
 193
 194         if (!device || !pr)
 195                 return -EINVAL;
 196
 197         *state = acpi_processor_max_state(pr);
 198         return 0;
 199 }
 200
 201 static int
 202 processor_get_cur_state(struct thermal_cooling_device *cdev,
 203                         unsigned long *cur_state)
 204 {
 205         struct acpi_device *device = cdev->devdata;
 206         struct acpi_processor *pr = acpi_driver_data(device);
 207
 208         if (!device || !pr)
 209                 return -EINVAL;
 210
 211         *cur_state = cpufreq_get_cur_state(pr->id);
 212         if (pr->flags.throttling)
 213                 *cur_state += pr->throttling.state;
 214         return 0;
 215 }
 216
 217 static int
 218 processor_set_cur_state(struct thermal_cooling_device *cdev,
 219                         unsigned long state)
 220 {
 221         struct acpi_device *device = cdev->devdata;
 222         struct acpi_processor *pr = acpi_driver_data(device);
 223         int result = 0;
 224         int max_pstate;
 225
 226         if (!device || !pr)
 227                 return -EINVAL;
 228
 229         max_pstate = cpufreq_get_max_state(pr->id);
 230
 231         if (state > acpi_processor_max_state(pr))
 232                 return -EINVAL;
 233
 234         if (state <= max_pstate) {
 235                 if (pr->flags.throttling && pr->throttling.state)
 236                         result = acpi_processor_set_throttling(pr, 0, false);
 237                 cpufreq_set_cur_state(pr->id, state);
 238         } else {
 239                 cpufreq_set_cur_state(pr->id, max_pstate);
 240                 result = acpi_processor_set_throttling(pr,
 241                                 state - max_pstate, false);
 242         }
 243         return result;
 244 }
 245
 246 const struct thermal_cooling_device_ops processor_cooling_ops = {
 247         .get_max_state = processor_get_max_state,
 248         .get_cur_state = processor_get_cur_state,
 249         .set_cur_state = processor_set_cur_state,
 250 };