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 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
23 */
24
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/init.h>
28#include <linux/cpufreq.h>
29#include <linux/acpi.h>
30#include <acpi/processor.h>
31#include <linux/uaccess.h>
32
33#define PREFIX "ACPI: "
34
35#define ACPI_PROCESSOR_CLASS "processor"
36#define _COMPONENT ACPI_PROCESSOR_COMPONENT
37ACPI_MODULE_NAME("processor_thermal");
38
39#ifdef CONFIG_CPU_FREQ
40
41/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
42 * offers (in most cases) voltage scaling in addition to frequency scaling, and
43 * thus a cubic (instead of linear) reduction of energy. Also, we allow for
44 * _any_ cpufreq driver and not only the acpi-cpufreq driver.
45 */
46
47#define CPUFREQ_THERMAL_MIN_STEP 0
48#define CPUFREQ_THERMAL_MAX_STEP 3
49
50static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
51static unsigned int acpi_thermal_cpufreq_is_init = 0;
52
53#define reduction_pctg(cpu) \
54 per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
55
56/*
57 * Emulate "per package data" using per cpu data (which should really be
58 * provided elsewhere)
59 *
60 * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
61 * temporarily. Fortunately that's not a big issue here (I hope)
62 */
63static int phys_package_first_cpu(int cpu)
64{
65 int i;
66 int id = topology_physical_package_id(cpu);
67
68 for_each_online_cpu(i)
69 if (topology_physical_package_id(i) == id)
70 return i;
71 return 0;
72}
73
74static int cpu_has_cpufreq(unsigned int cpu)
75{
76 struct cpufreq_policy policy;
77 if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
78 return 0;
79 return 1;
80}
81
82static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
83 unsigned long event, void *data)
84{
85 struct cpufreq_policy *policy = data;
86 unsigned long max_freq = 0;
87
88 if (event != CPUFREQ_ADJUST)
89 goto out;
90
91 max_freq = (
92 policy->cpuinfo.max_freq *
93 (100 - reduction_pctg(policy->cpu) * 20)
94 ) / 100;
95
96 cpufreq_verify_within_limits(policy, 0, max_freq);
97
98 out:
99 return 0;
100}
101
102static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
103 .notifier_call = acpi_thermal_cpufreq_notifier,
104};
105
106static int cpufreq_get_max_state(unsigned int cpu)
107{
108 if (!cpu_has_cpufreq(cpu))
109 return 0;
110
111 return CPUFREQ_THERMAL_MAX_STEP;
112}
113
114static int cpufreq_get_cur_state(unsigned int cpu)
115{
116 if (!cpu_has_cpufreq(cpu))
117 return 0;
118
119 return reduction_pctg(cpu);
120}
121
122static int cpufreq_set_cur_state(unsigned int cpu, int state)
123{
124 int i;
125
126 if (!cpu_has_cpufreq(cpu))
127 return 0;
128
129 reduction_pctg(cpu) = state;
130
131 /*
132 * Update all the CPUs in the same package because they all
133 * contribute to the temperature and often share the same
134 * frequency.
135 */
136 for_each_online_cpu(i) {
137 if (topology_physical_package_id(i) ==
138 topology_physical_package_id(cpu))
139 cpufreq_update_policy(i);
140 }
141 return 0;
142}
143
144void acpi_thermal_cpufreq_init(void)
145{
146 int i;
147
148 i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
149 CPUFREQ_POLICY_NOTIFIER);
150 if (!i)
151 acpi_thermal_cpufreq_is_init = 1;
152}
153
154void acpi_thermal_cpufreq_exit(void)
155{
156 if (acpi_thermal_cpufreq_is_init)
157 cpufreq_unregister_notifier
158 (&acpi_thermal_cpufreq_notifier_block,
159 CPUFREQ_POLICY_NOTIFIER);
160
161 acpi_thermal_cpufreq_is_init = 0;
162}
163
164#else /* ! CONFIG_CPU_FREQ */
165static int cpufreq_get_max_state(unsigned int cpu)
166{
167 return 0;
168}
169
170static int cpufreq_get_cur_state(unsigned int cpu)
171{
172 return 0;
173}
174
175static int cpufreq_set_cur_state(unsigned int cpu, int state)
176{
177 return 0;
178}
179
180#endif
181
182/* thermal cooling device callbacks */
183static int acpi_processor_max_state(struct acpi_processor *pr)
184{
185 int max_state = 0;
186
187 /*
188 * There exists four states according to
189 * cpufreq_thermal_reduction_pctg. 0, 1, 2, 3
190 */
191 max_state += cpufreq_get_max_state(pr->id);
192 if (pr->flags.throttling)
193 max_state += (pr->throttling.state_count -1);
194
195 return max_state;
196}
197static int
198processor_get_max_state(struct thermal_cooling_device *cdev,
199 unsigned long *state)
200{
201 struct acpi_device *device = cdev->devdata;
202 struct acpi_processor *pr;
203
204 if (!device)
205 return -EINVAL;
206
207 pr = acpi_driver_data(device);
208 if (!pr)
209 return -EINVAL;
210
211 *state = acpi_processor_max_state(pr);
212 return 0;
213}
214
215static int
216processor_get_cur_state(struct thermal_cooling_device *cdev,
217 unsigned long *cur_state)
218{
219 struct acpi_device *device = cdev->devdata;
220 struct acpi_processor *pr;
221
222 if (!device)
223 return -EINVAL;
224
225 pr = acpi_driver_data(device);
226 if (!pr)
227 return -EINVAL;
228
229 *cur_state = cpufreq_get_cur_state(pr->id);
230 if (pr->flags.throttling)
231 *cur_state += pr->throttling.state;
232 return 0;
233}
234
235static int
236processor_set_cur_state(struct thermal_cooling_device *cdev,
237 unsigned long state)
238{
239 struct acpi_device *device = cdev->devdata;
240 struct acpi_processor *pr;
241 int result = 0;
242 int max_pstate;
243
244 if (!device)
245 return -EINVAL;
246
247 pr = acpi_driver_data(device);
248 if (!pr)
249 return -EINVAL;
250
251 max_pstate = cpufreq_get_max_state(pr->id);
252
253 if (state > acpi_processor_max_state(pr))
254 return -EINVAL;
255
256 if (state <= max_pstate) {
257 if (pr->flags.throttling && pr->throttling.state)
258 result = acpi_processor_set_throttling(pr, 0, false);
259 cpufreq_set_cur_state(pr->id, state);
260 } else {
261 cpufreq_set_cur_state(pr->id, max_pstate);
262 result = acpi_processor_set_throttling(pr,
263 state - max_pstate, false);
264 }
265 return result;
266}
267
268const struct thermal_cooling_device_ops processor_cooling_ops = {
269 .get_max_state = processor_get_max_state,
270 .get_cur_state = processor_get_cur_state,
271 .set_cur_state = processor_set_cur_state,
272};
273