2 * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
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
10 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.
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.
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.
26 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
29 #include <linux/kernel.h>
30 #include <linux/module.h>
31 #include <linux/init.h>
32 #include <linux/cpufreq.h>
34 #include <asm/uaccess.h>
36 #include <acpi/acpi_bus.h>
37 #include <acpi/processor.h>
38 #include <acpi/acpi_drivers.h>
40 #define PREFIX "ACPI: "
42 #define ACPI_PROCESSOR_CLASS "processor"
43 #define _COMPONENT ACPI_PROCESSOR_COMPONENT
44 ACPI_MODULE_NAME("processor_thermal");
46 #ifdef CONFIG_CPU_FREQ
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.
54 #define CPUFREQ_THERMAL_MIN_STEP 0
55 #define CPUFREQ_THERMAL_MAX_STEP 3
57 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
58 static unsigned int acpi_thermal_cpufreq_is_init = 0;
60 static int cpu_has_cpufreq(unsigned int cpu)
62 struct cpufreq_policy policy;
63 if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
68 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
69 unsigned long event, void *data)
71 struct cpufreq_policy *policy = data;
72 unsigned long max_freq = 0;
74 if (event != CPUFREQ_ADJUST)
78 policy->cpuinfo.max_freq *
79 (100 - per_cpu(cpufreq_thermal_reduction_pctg, policy->cpu) * 20)
82 cpufreq_verify_within_limits(policy, 0, max_freq);
88 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
89 .notifier_call = acpi_thermal_cpufreq_notifier,
92 static int cpufreq_get_max_state(unsigned int cpu)
94 if (!cpu_has_cpufreq(cpu))
97 return CPUFREQ_THERMAL_MAX_STEP;
100 static int cpufreq_get_cur_state(unsigned int cpu)
102 if (!cpu_has_cpufreq(cpu))
105 return per_cpu(cpufreq_thermal_reduction_pctg, cpu);
108 static int cpufreq_set_cur_state(unsigned int cpu, int state)
110 if (!cpu_has_cpufreq(cpu))
113 per_cpu(cpufreq_thermal_reduction_pctg, cpu) = state;
114 cpufreq_update_policy(cpu);
118 void acpi_thermal_cpufreq_init(void)
122 for (i = 0; i < nr_cpu_ids; i++)
124 per_cpu(cpufreq_thermal_reduction_pctg, i) = 0;
126 i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
127 CPUFREQ_POLICY_NOTIFIER);
129 acpi_thermal_cpufreq_is_init = 1;
132 void acpi_thermal_cpufreq_exit(void)
134 if (acpi_thermal_cpufreq_is_init)
135 cpufreq_unregister_notifier
136 (&acpi_thermal_cpufreq_notifier_block,
137 CPUFREQ_POLICY_NOTIFIER);
139 acpi_thermal_cpufreq_is_init = 0;
142 #else /* ! CONFIG_CPU_FREQ */
143 static int cpufreq_get_max_state(unsigned int cpu)
148 static int cpufreq_get_cur_state(unsigned int cpu)
153 static int cpufreq_set_cur_state(unsigned int cpu, int state)
160 int acpi_processor_get_limit_info(struct acpi_processor *pr)
166 if (pr->flags.throttling)
172 /* thermal coolign device callbacks */
173 static int acpi_processor_max_state(struct acpi_processor *pr)
178 * There exists four states according to
179 * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
181 max_state += cpufreq_get_max_state(pr->id);
182 if (pr->flags.throttling)
183 max_state += (pr->throttling.state_count -1);
188 processor_get_max_state(struct thermal_cooling_device *cdev,
189 unsigned long *state)
191 struct acpi_device *device = cdev->devdata;
192 struct acpi_processor *pr = acpi_driver_data(device);
197 *state = acpi_processor_max_state(pr);
202 processor_get_cur_state(struct thermal_cooling_device *cdev,
203 unsigned long *cur_state)
205 struct acpi_device *device = cdev->devdata;
206 struct acpi_processor *pr = acpi_driver_data(device);
211 *cur_state = cpufreq_get_cur_state(pr->id);
212 if (pr->flags.throttling)
213 *cur_state += pr->throttling.state;
218 processor_set_cur_state(struct thermal_cooling_device *cdev,
221 struct acpi_device *device = cdev->devdata;
222 struct acpi_processor *pr = acpi_driver_data(device);
229 max_pstate = cpufreq_get_max_state(pr->id);
231 if (state > acpi_processor_max_state(pr))
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);
239 cpufreq_set_cur_state(pr->id, max_pstate);
240 result = acpi_processor_set_throttling(pr,
241 state - max_pstate, false);
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,