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 #define reduction_pctg(cpu) \
  61         per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
  62
  63 /*
  64  * Emulate "per package data" using per cpu data (which should really be
  65  * provided elsewhere)
  66  *
  67  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
  68  * temporarily. Fortunately that's not a big issue here (I hope)
  69  */
  70 static int phys_package_first_cpu(int cpu)
  71 {
  72         int i;
  73         int id = topology_physical_package_id(cpu);
  74
  75         for_each_online_cpu(i)
  76                 if (topology_physical_package_id(i) == id)
  77                         return i;
  78         return 0;
  79 }
  80
  81 static int cpu_has_cpufreq(unsigned int cpu)
  82 {
  83         struct cpufreq_policy policy;
  84         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
  85                 return 0;
  86         return 1;
  87 }
  88
  89 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
  90                                          unsigned long event, void *data)
  91 {
  92         struct cpufreq_policy *policy = data;
  93         unsigned long max_freq = 0;
  94
  95         if (event != CPUFREQ_ADJUST)
  96                 goto out;
  97
  98         max_freq = (
  99             policy->cpuinfo.max_freq *
 100             (100 - reduction_pctg(policy->cpu) * 20)
 101         ) / 100;
 102
 103         cpufreq_verify_within_limits(policy, 0, max_freq);
 104
 105       out:
 106         return 0;
 107 }
 108
 109 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
 110         .notifier_call = acpi_thermal_cpufreq_notifier,
 111 };
 112
 113 static int cpufreq_get_max_state(unsigned int cpu)
 114 {
 115         if (!cpu_has_cpufreq(cpu))
 116                 return 0;
 117
 118         return CPUFREQ_THERMAL_MAX_STEP;
 119 }
 120
 121 static int cpufreq_get_cur_state(unsigned int cpu)
 122 {
 123         if (!cpu_has_cpufreq(cpu))
 124                 return 0;
 125
 126         return reduction_pctg(cpu);
 127 }
 128
 129 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 130 {
 131         int i;
 132
 133         if (!cpu_has_cpufreq(cpu))
 134                 return 0;
 135
 136         reduction_pctg(cpu) = state;
 137
 138         /*
 139          * Update all the CPUs in the same package because they all
 140          * contribute to the temperature and often share the same
 141          * frequency.
 142          */
 143         for_each_online_cpu(i) {
 144                 if (topology_physical_package_id(i) ==
 145                     topology_physical_package_id(cpu))
 146                         cpufreq_update_policy(i);
 147         }
 148         return 0;
 149 }
 150
 151 void acpi_thermal_cpufreq_init(void)
 152 {
 153         int i;
 154
 155         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
 156                                       CPUFREQ_POLICY_NOTIFIER);
 157         if (!i)
 158                 acpi_thermal_cpufreq_is_init = 1;
 159 }
 160
 161 void acpi_thermal_cpufreq_exit(void)
 162 {
 163         if (acpi_thermal_cpufreq_is_init)
 164                 cpufreq_unregister_notifier
 165                     (&acpi_thermal_cpufreq_notifier_block,
 166                      CPUFREQ_POLICY_NOTIFIER);
 167
 168         acpi_thermal_cpufreq_is_init = 0;
 169 }
 170
 171 #else                           /* ! CONFIG_CPU_FREQ */
 172 static int cpufreq_get_max_state(unsigned int cpu)
 173 {
 174         return 0;
 175 }
 176
 177 static int cpufreq_get_cur_state(unsigned int cpu)
 178 {
 179         return 0;
 180 }
 181
 182 static int cpufreq_set_cur_state(unsigned int cpu, int state)
 183 {
 184         return 0;
 185 }
 186
 187 #endif
 188
 189 /* thermal coolign device callbacks */
 190 static int acpi_processor_max_state(struct acpi_processor *pr)
 191 {
 192         int max_state = 0;
 193
 194         /*
 195          * There exists four states according to
 196          * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
 197          */
 198         max_state += cpufreq_get_max_state(pr->id);
 199         if (pr->flags.throttling)
 200                 max_state += (pr->throttling.state_count -1);
 201
 202         return max_state;
 203 }
 204 static int
 205 processor_get_max_state(struct thermal_cooling_device *cdev,
 206                         unsigned long *state)
 207 {
 208         struct acpi_device *device = cdev->devdata;
 209         struct acpi_processor *pr;
 210
 211         if (!device)
 212                 return -EINVAL;
 213
 214         pr = acpi_driver_data(device);
 215         if (!pr)
 216                 return -EINVAL;
 217
 218         *state = acpi_processor_max_state(pr);
 219         return 0;
 220 }
 221
 222 static int
 223 processor_get_cur_state(struct thermal_cooling_device *cdev,
 224                         unsigned long *cur_state)
 225 {
 226         struct acpi_device *device = cdev->devdata;
 227         struct acpi_processor *pr;
 228
 229         if (!device)
 230                 return -EINVAL;
 231
 232         pr = acpi_driver_data(device);
 233         if (!pr)
 234                 return -EINVAL;
 235
 236         *cur_state = cpufreq_get_cur_state(pr->id);
 237         if (pr->flags.throttling)
 238                 *cur_state += pr->throttling.state;
 239         return 0;
 240 }
 241
 242 static int
 243 processor_set_cur_state(struct thermal_cooling_device *cdev,
 244                         unsigned long state)
 245 {
 246         struct acpi_device *device = cdev->devdata;
 247         struct acpi_processor *pr;
 248         int result = 0;
 249         int max_pstate;
 250
 251         if (!device)
 252                 return -EINVAL;
 253
 254         pr = acpi_driver_data(device);
 255         if (!pr)
 256                 return -EINVAL;
 257
 258         max_pstate = cpufreq_get_max_state(pr->id);
 259
 260         if (state > acpi_processor_max_state(pr))
 261                 return -EINVAL;
 262
 263         if (state <= max_pstate) {
 264                 if (pr->flags.throttling && pr->throttling.state)
 265                         result = acpi_processor_set_throttling(pr, 0, false);
 266                 cpufreq_set_cur_state(pr->id, state);
 267         } else {
 268                 cpufreq_set_cur_state(pr->id, max_pstate);
 269                 result = acpi_processor_set_throttling(pr,
 270                                 state - max_pstate, false);
 271         }
 272         return result;
 273 }
 274
 275 const struct thermal_cooling_device_ops processor_cooling_ops = {
 276         .get_max_state = processor_get_max_state,
 277         .get_cur_state = processor_get_cur_state,
 278         .set_cur_state = processor_set_cur_state,
 279 };