kernel/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/acpi.h>
  34 #include <acpi/processor.h>
  35 #include <asm/uaccess.h>
  36
  37 #define PREFIX "ACPI: "
  38
  39 #define ACPI_PROCESSOR_CLASS            "processor"
  40 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  41 ACPI_MODULE_NAME("processor_thermal");
  42
  43 #ifdef CONFIG_CPU_FREQ
  44
  45 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
  46  * offers (in most cases) voltage scaling in addition to frequency scaling, and
  47  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
  48  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
  49  */
  50
  51 #define CPUFREQ_THERMAL_MIN_STEP 0
  52 #define CPUFREQ_THERMAL_MAX_STEP 3
  53
  54 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
  55 static unsigned int acpi_thermal_cpufreq_is_init = 0;
  56
  57 #define reduction_pctg(cpu) \
  58         per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
  59
  60 /*
  61  * Emulate "per package data" using per cpu data (which should really be
  62  * provided elsewhere)
  63  *
  64  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
  65  * temporarily. Fortunately that's not a big issue here (I hope)
  66  */
  67 static int phys_package_first_cpu(int cpu)
  68 {
  69         int i;
  70         int id = topology_physical_package_id(cpu);
  71
  72         for_each_online_cpu(i)
  73                 if (topology_physical_package_id(i) == id)
  74                         return i;
  75         return 0;
  76 }
  77
  78 static int cpu_has_cpufreq(unsigned int cpu)
  79 {
  80         struct cpufreq_policy policy;
  81         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  82                 return 0;
  83         return 1;
  84 }
  85
  86 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  87                                          unsigned long event, void *data)
  88 {
  89         struct cpufreq_policy *policy = data;
  90         unsigned long max_freq = 0;
  91
  92         if (event != CPUFREQ_ADJUST)
  93                 goto out;
  94
  95         max_freq = (
  96             policy->cpuinfo.max_freq *
  97             (100 - reduction_pctg(policy->cpu) * 20)
  98         ) / 100;
  99
 100         cpufreq_verify_within_limits(policy, 0, max_freq);
 101
 102       out:
 103         return 0;
 104 }
 105
 106 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
 107         .notifier_call = acpi_thermal_cpufreq_notifier,
 108 };
 109
 110 static int cpufreq_get_max_state(unsigned int cpu)
 111 {
 112         if (!cpu_has_cpufreq(cpu))
 113                 return 0;
 114
 115         return CPUFREQ_THERMAL_MAX_STEP;
 116 }
 117
 118 static int cpufreq_get_cur_state(unsigned int cpu)
 119 {
 120         if (!cpu_has_cpufreq(cpu))
 121                 return 0;
 122
 123         return reduction_pctg(cpu);
 124 }
 125
 126 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 127 {
 128         int i;
 129
 130         if (!cpu_has_cpufreq(cpu))
 131                 return 0;
 132
 133         reduction_pctg(cpu) = state;
 134
 135         /*
 136          * Update all the CPUs in the same package because they all
 137          * contribute to the temperature and often share the same
 138          * frequency.
 139          */
 140         for_each_online_cpu(i) {
 141                 if (topology_physical_package_id(i) ==
 142                     topology_physical_package_id(cpu))
 143                         cpufreq_update_policy(i);
 144         }
 145         return 0;
 146 }
 147
 148 void acpi_thermal_cpufreq_init(void)
 149 {
 150         int i;
 151
 152         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 153                                       CPUFREQ_POLICY_NOTIFIER);
 154         if (!i)
 155                 acpi_thermal_cpufreq_is_init = 1;
 156 }
 157
 158 void acpi_thermal_cpufreq_exit(void)
 159 {
 160         if (acpi_thermal_cpufreq_is_init)
 161                 cpufreq_unregister_notifier
 162                     (&acpi_thermal_cpufreq_notifier_block,
 163                      CPUFREQ_POLICY_NOTIFIER);
 164
 165         acpi_thermal_cpufreq_is_init = 0;
 166 }
 167
 168 #else                           /* ! CONFIG_CPU_FREQ */
 169 static int cpufreq_get_max_state(unsigned int cpu)
 170 {
 171         return 0;
 172 }
 173
 174 static int cpufreq_get_cur_state(unsigned int cpu)
 175 {
 176         return 0;
 177 }
 178
 179 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 180 {
 181         return 0;
 182 }
 183
 184 #endif
 185
 186 /* thermal cooling device callbacks */
 187 static int acpi_processor_max_state(struct acpi_processor *pr)
 188 {
 189         int max_state = 0;
 190
 191         /*
 192          * There exists four states according to
 193          * cpufreq_thermal_reduction_pctg. 0, 1, 2, 3
 194          */
 195         max_state += cpufreq_get_max_state(pr->id);
 196         if (pr->flags.throttling)
 197                 max_state += (pr->throttling.state_count -1);
 198
 199         return max_state;
 200 }
 201 static int
 202 processor_get_max_state(struct thermal_cooling_device *cdev,
 203                         unsigned long *state)
 204 {
 205         struct acpi_device *device = cdev->devdata;
 206         struct acpi_processor *pr;
 207
 208         if (!device)
 209                 return -EINVAL;
 210
 211         pr = acpi_driver_data(device);
 212         if (!pr)
 213                 return -EINVAL;
 214
 215         *state = acpi_processor_max_state(pr);
 216         return 0;
 217 }
 218
 219 static int
 220 processor_get_cur_state(struct thermal_cooling_device *cdev,
 221                         unsigned long *cur_state)
 222 {
 223         struct acpi_device *device = cdev->devdata;
 224         struct acpi_processor *pr;
 225
 226         if (!device)
 227                 return -EINVAL;
 228
 229         pr = acpi_driver_data(device);
 230         if (!pr)
 231                 return -EINVAL;
 232
 233         *cur_state = cpufreq_get_cur_state(pr->id);
 234         if (pr->flags.throttling)
 235                 *cur_state += pr->throttling.state;
 236         return 0;
 237 }
 238
 239 static int
 240 processor_set_cur_state(struct thermal_cooling_device *cdev,
 241                         unsigned long state)
 242 {
 243         struct acpi_device *device = cdev->devdata;
 244         struct acpi_processor *pr;
 245         int result = 0;
 246         int max_pstate;
 247
 248         if (!device)
 249                 return -EINVAL;
 250
 251         pr = acpi_driver_data(device);
 252         if (!pr)
 253                 return -EINVAL;
 254
 255         max_pstate = cpufreq_get_max_state(pr->id);
 256
 257         if (state > acpi_processor_max_state(pr))
 258                 return -EINVAL;
 259
 260         if (state <= max_pstate) {
 261                 if (pr->flags.throttling && pr->throttling.state)
 262                         result = acpi_processor_set_throttling(pr, 0, false);
 263                 cpufreq_set_cur_state(pr->id, state);
 264         } else {
 265                 cpufreq_set_cur_state(pr->id, max_pstate);
 266                 result = acpi_processor_set_throttling(pr,
 267                                 state - max_pstate, false);
 268         }
 269         return result;
 270 }
 271
 272 const struct thermal_cooling_device_ops processor_cooling_ops = {
 273         .get_max_state = processor_get_max_state,
 274         .get_cur_state = processor_get_cur_state,
 275         .set_cur_state = processor_set_cur_state,
 276 };