ACPI: constify ops structs
[linux-2.6.git] / 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 static int cpu_has_cpufreq(unsigned int cpu)
62 {
63         struct cpufreq_policy policy;
64         if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
65                 return 0;
66         return 1;
67 }
68
69 static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
70                                          unsigned long event, void *data)
71 {
72         struct cpufreq_policy *policy = data;
73         unsigned long max_freq = 0;
74
75         if (event != CPUFREQ_ADJUST)
76                 goto out;
77
78         max_freq = (
79             policy->cpuinfo.max_freq *
80             (100 - per_cpu(cpufreq_thermal_reduction_pctg, policy->cpu) * 20)
81         ) / 100;
82
83         cpufreq_verify_within_limits(policy, 0, max_freq);
84
85       out:
86         return 0;
87 }
88
89 static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
90         .notifier_call = acpi_thermal_cpufreq_notifier,
91 };
92
93 static int cpufreq_get_max_state(unsigned int cpu)
94 {
95         if (!cpu_has_cpufreq(cpu))
96                 return 0;
97
98         return CPUFREQ_THERMAL_MAX_STEP;
99 }
100
101 static int cpufreq_get_cur_state(unsigned int cpu)
102 {
103         if (!cpu_has_cpufreq(cpu))
104                 return 0;
105
106         return per_cpu(cpufreq_thermal_reduction_pctg, cpu);
107 }
108
109 static int cpufreq_set_cur_state(unsigned int cpu, int state)
110 {
111         if (!cpu_has_cpufreq(cpu))
112                 return 0;
113
114         per_cpu(cpufreq_thermal_reduction_pctg, cpu) = state;
115         cpufreq_update_policy(cpu);
116         return 0;
117 }
118
119 void acpi_thermal_cpufreq_init(void)
120 {
121         int i;
122
123         for (i = 0; i < nr_cpu_ids; i++)
124                 if (cpu_present(i))
125                         per_cpu(cpufreq_thermal_reduction_pctg, i) = 0;
126
127         i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
128                                       CPUFREQ_POLICY_NOTIFIER);
129         if (!i)
130                 acpi_thermal_cpufreq_is_init = 1;
131 }
132
133 void acpi_thermal_cpufreq_exit(void)
134 {
135         if (acpi_thermal_cpufreq_is_init)
136                 cpufreq_unregister_notifier
137                     (&acpi_thermal_cpufreq_notifier_block,
138                      CPUFREQ_POLICY_NOTIFIER);
139
140         acpi_thermal_cpufreq_is_init = 0;
141 }
142
143 #else                           /* ! CONFIG_CPU_FREQ */
144 static int cpufreq_get_max_state(unsigned int cpu)
145 {
146         return 0;
147 }
148
149 static int cpufreq_get_cur_state(unsigned int cpu)
150 {
151         return 0;
152 }
153
154 static int cpufreq_set_cur_state(unsigned int cpu, int state)
155 {
156         return 0;
157 }
158
159 #endif
160
161 int acpi_processor_get_limit_info(struct acpi_processor *pr)
162 {
163
164         if (!pr)
165                 return -EINVAL;
166
167         if (pr->flags.throttling)
168                 pr->flags.limit = 1;
169
170         return 0;
171 }
172
173 /* thermal coolign device callbacks */
174 static int acpi_processor_max_state(struct acpi_processor *pr)
175 {
176         int max_state = 0;
177
178         /*
179          * There exists four states according to
180          * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
181          */
182         max_state += cpufreq_get_max_state(pr->id);
183         if (pr->flags.throttling)
184                 max_state += (pr->throttling.state_count -1);
185
186         return max_state;
187 }
188 static int
189 processor_get_max_state(struct thermal_cooling_device *cdev,
190                         unsigned long *state)
191 {
192         struct acpi_device *device = cdev->devdata;
193         struct acpi_processor *pr = acpi_driver_data(device);
194
195         if (!device || !pr)
196                 return -EINVAL;
197
198         *state = acpi_processor_max_state(pr);
199         return 0;
200 }
201
202 static int
203 processor_get_cur_state(struct thermal_cooling_device *cdev,
204                         unsigned long *cur_state)
205 {
206         struct acpi_device *device = cdev->devdata;
207         struct acpi_processor *pr = acpi_driver_data(device);
208
209         if (!device || !pr)
210                 return -EINVAL;
211
212         *cur_state = cpufreq_get_cur_state(pr->id);
213         if (pr->flags.throttling)
214                 *cur_state += pr->throttling.state;
215         return 0;
216 }
217
218 static int
219 processor_set_cur_state(struct thermal_cooling_device *cdev,
220                         unsigned long state)
221 {
222         struct acpi_device *device = cdev->devdata;
223         struct acpi_processor *pr = acpi_driver_data(device);
224         int result = 0;
225         int max_pstate;
226
227         if (!device || !pr)
228                 return -EINVAL;
229
230         max_pstate = cpufreq_get_max_state(pr->id);
231
232         if (state > acpi_processor_max_state(pr))
233                 return -EINVAL;
234
235         if (state <= max_pstate) {
236                 if (pr->flags.throttling && pr->throttling.state)
237                         result = acpi_processor_set_throttling(pr, 0, false);
238                 cpufreq_set_cur_state(pr->id, state);
239         } else {
240                 cpufreq_set_cur_state(pr->id, max_pstate);
241                 result = acpi_processor_set_throttling(pr,
242                                 state - max_pstate, false);
243         }
244         return result;
245 }
246
247 const struct thermal_cooling_device_ops processor_cooling_ops = {
248         .get_max_state = processor_get_max_state,
249         .get_cur_state = processor_get_cur_state,
250         .set_cur_state = processor_set_cur_state,
251 };