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 #define reduction_pctg(cpu) \
  62         per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
  63
  64 /*
  65  * Emulate "per package data" using per cpu data (which should really be
  66  * provided elsewhere)
  67  *
  68  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
  69  * temporarily. Fortunately that's not a big issue here (I hope)
  70  */
  71 static int phys_package_first_cpu(int cpu)
  72 {
  73         int i;
  74         int id = topology_physical_package_id(cpu);
  75
  76         for_each_online_cpu(i)
  77                 if (topology_physical_package_id(i) == id)
  78                         return i;
  79         return 0;
  80 }
  81
  82 static int cpu_has_cpufreq(unsigned int cpu)
  83 {
  84         struct cpufreq_policy policy;
  85         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  86                 return 0;
  87         return 1;
  88 }
  89
  90 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  91                                          unsigned long event, void *data)
  92 {
  93         struct cpufreq_policy *policy = data;
  94         unsigned long max_freq = 0;
  95
  96         if (event != CPUFREQ_ADJUST)
  97                 goto out;
  98
  99         max_freq = (
 100             policy->cpuinfo.max_freq *
 101             (100 - reduction_pctg(policy->cpu) * 20)
 102         ) / 100;
 103
 104         cpufreq_verify_within_limits(policy, 0, max_freq);
 105
 106       out:
 107         return 0;
 108 }
 109
 110 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
 111         .notifier_call = acpi_thermal_cpufreq_notifier,
 112 };
 113
 114 static int cpufreq_get_max_state(unsigned int cpu)
 115 {
 116         if (!cpu_has_cpufreq(cpu))
 117                 return 0;
 118
 119         return CPUFREQ_THERMAL_MAX_STEP;
 120 }
 121
 122 static int cpufreq_get_cur_state(unsigned int cpu)
 123 {
 124         if (!cpu_has_cpufreq(cpu))
 125                 return 0;
 126
 127         return reduction_pctg(cpu);
 128 }
 129
 130 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 131 {
 132         int i;
 133
 134         if (!cpu_has_cpufreq(cpu))
 135                 return 0;
 136
 137         reduction_pctg(cpu) = state;
 138
 139         /*
 140          * Update all the CPUs in the same package because they all
 141          * contribute to the temperature and often share the same
 142          * frequency.
 143          */
 144         for_each_online_cpu(i) {
 145                 if (topology_physical_package_id(i) ==
 146                     topology_physical_package_id(cpu))
 147                         cpufreq_update_policy(i);
 148         }
 149         return 0;
 150 }
 151
 152 void acpi_thermal_cpufreq_init(void)
 153 {
 154         int i;
 155
 156         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 157                                       CPUFREQ_POLICY_NOTIFIER);
 158         if (!i)
 159                 acpi_thermal_cpufreq_is_init = 1;
 160 }
 161
 162 void acpi_thermal_cpufreq_exit(void)
 163 {
 164         if (acpi_thermal_cpufreq_is_init)
 165                 cpufreq_unregister_notifier
 166                     (&acpi_thermal_cpufreq_notifier_block,
 167                      CPUFREQ_POLICY_NOTIFIER);
 168
 169         acpi_thermal_cpufreq_is_init = 0;
 170 }
 171
 172 #else                           /* ! CONFIG_CPU_FREQ */
 173 static int cpufreq_get_max_state(unsigned int cpu)
 174 {
 175         return 0;
 176 }
 177
 178 static int cpufreq_get_cur_state(unsigned int cpu)
 179 {
 180         return 0;
 181 }
 182
 183 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 184 {
 185         return 0;
 186 }
 187
 188 #endif
 189
 190 int acpi_processor_get_limit_info(struct acpi_processor *pr)
 191 {
 192
 193         if (!pr)
 194                 return -EINVAL;
 195
 196         if (pr->flags.throttling)
 197                 pr->flags.limit = 1;
 198
 199         return 0;
 200 }
 201
 202 /* thermal coolign device callbacks */
 203 static int acpi_processor_max_state(struct acpi_processor *pr)
 204 {
 205         int max_state = 0;
 206
 207         /*
 208          * There exists four states according to
 209          * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
 210          */
 211         max_state += cpufreq_get_max_state(pr->id);
 212         if (pr->flags.throttling)
 213                 max_state += (pr->throttling.state_count -1);
 214
 215         return max_state;
 216 }
 217 static int
 218 processor_get_max_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
 224         if (!device || !pr)
 225                 return -EINVAL;
 226
 227         *state = acpi_processor_max_state(pr);
 228         return 0;
 229 }
 230
 231 static int
 232 processor_get_cur_state(struct thermal_cooling_device *cdev,
 233                         unsigned long *cur_state)
 234 {
 235         struct acpi_device *device = cdev->devdata;
 236         struct acpi_processor *pr = acpi_driver_data(device);
 237
 238         if (!device || !pr)
 239                 return -EINVAL;
 240
 241         *cur_state = cpufreq_get_cur_state(pr->id);
 242         if (pr->flags.throttling)
 243                 *cur_state += pr->throttling.state;
 244         return 0;
 245 }
 246
 247 static int
 248 processor_set_cur_state(struct thermal_cooling_device *cdev,
 249                         unsigned long state)
 250 {
 251         struct acpi_device *device = cdev->devdata;
 252         struct acpi_processor *pr = acpi_driver_data(device);
 253         int result = 0;
 254         int max_pstate;
 255
 256         if (!device || !pr)
 257                 return -EINVAL;
 258
 259         max_pstate = cpufreq_get_max_state(pr->id);
 260
 261         if (state > acpi_processor_max_state(pr))
 262                 return -EINVAL;
 263
 264         if (state <= max_pstate) {
 265                 if (pr->flags.throttling && pr->throttling.state)
 266                         result = acpi_processor_set_throttling(pr, 0, false);
 267                 cpufreq_set_cur_state(pr->id, state);
 268         } else {
 269                 cpufreq_set_cur_state(pr->id, max_pstate);
 270                 result = acpi_processor_set_throttling(pr,
 271                                 state - max_pstate, false);
 272         }
 273         return result;
 274 }
 275
 276 struct thermal_cooling_device_ops processor_cooling_ops = {
 277         .get_max_state = processor_get_max_state,
 278         .get_cur_state = processor_get_cur_state,
 279         .set_cur_state = processor_set_cur_state,
 280 };