processor_thermal.c revision 8a25a2fd126c621f44f3aeaef80d51f00fc11639 
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
44ACPI_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
57static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
58static unsigned int acpi_thermal_cpufreq_is_init = 0;
59
60static int cpu_has_cpufreq(unsigned int cpu)
61{
62	struct cpufreq_policy policy;
63	if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
64		return 0;
65	return 1;
66}
67
68static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
69					 unsigned long event, void *data)
70{
71	struct cpufreq_policy *policy = data;
72	unsigned long max_freq = 0;
73
74	if (event != CPUFREQ_ADJUST)
75		goto out;
76
77	max_freq = (
78	    policy->cpuinfo.max_freq *
79	    (100 - per_cpu(cpufreq_thermal_reduction_pctg, policy->cpu) * 20)
80	) / 100;
81
82	cpufreq_verify_within_limits(policy, 0, max_freq);
83
84      out:
85	return 0;
86}
87
88static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
89	.notifier_call = acpi_thermal_cpufreq_notifier,
90};
91
92static int cpufreq_get_max_state(unsigned int cpu)
93{
94	if (!cpu_has_cpufreq(cpu))
95		return 0;
96
97	return CPUFREQ_THERMAL_MAX_STEP;
98}
99
100static int cpufreq_get_cur_state(unsigned int cpu)
101{
102	if (!cpu_has_cpufreq(cpu))
103		return 0;
104
105	return per_cpu(cpufreq_thermal_reduction_pctg, cpu);
106}
107
108static int cpufreq_set_cur_state(unsigned int cpu, int state)
109{
110	if (!cpu_has_cpufreq(cpu))
111		return 0;
112
113	per_cpu(cpufreq_thermal_reduction_pctg, cpu) = state;
114	cpufreq_update_policy(cpu);
115	return 0;
116}
117
118void acpi_thermal_cpufreq_init(void)
119{
120	int i;
121
122	for (i = 0; i < nr_cpu_ids; i++)
123		if (cpu_present(i))
124			per_cpu(cpufreq_thermal_reduction_pctg, i) = 0;
125
126	i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
127				      CPUFREQ_POLICY_NOTIFIER);
128	if (!i)
129		acpi_thermal_cpufreq_is_init = 1;
130}
131
132void acpi_thermal_cpufreq_exit(void)
133{
134	if (acpi_thermal_cpufreq_is_init)
135		cpufreq_unregister_notifier
136		    (&acpi_thermal_cpufreq_notifier_block,
137		     CPUFREQ_POLICY_NOTIFIER);
138
139	acpi_thermal_cpufreq_is_init = 0;
140}
141
142#else				/* ! CONFIG_CPU_FREQ */
143static int cpufreq_get_max_state(unsigned int cpu)
144{
145	return 0;
146}
147
148static int cpufreq_get_cur_state(unsigned int cpu)
149{
150	return 0;
151}
152
153static int cpufreq_set_cur_state(unsigned int cpu, int state)
154{
155	return 0;
156}
157
158#endif
159
160int acpi_processor_get_limit_info(struct acpi_processor *pr)
161{
162
163	if (!pr)
164		return -EINVAL;
165
166	if (pr->flags.throttling)
167		pr->flags.limit = 1;
168
169	return 0;
170}
171
172/* thermal coolign device callbacks */
173static int acpi_processor_max_state(struct acpi_processor *pr)
174{
175	int max_state = 0;
176
177	/*
178	 * There exists four states according to
179	 * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
180	 */
181	max_state += cpufreq_get_max_state(pr->id);
182	if (pr->flags.throttling)
183		max_state += (pr->throttling.state_count -1);
184
185	return max_state;
186}
187static int
188processor_get_max_state(struct thermal_cooling_device *cdev,
189			unsigned long *state)
190{
191	struct acpi_device *device = cdev->devdata;
192	struct acpi_processor *pr = acpi_driver_data(device);
193
194	if (!device || !pr)
195		return -EINVAL;
196
197	*state = acpi_processor_max_state(pr);
198	return 0;
199}
200
201static int
202processor_get_cur_state(struct thermal_cooling_device *cdev,
203			unsigned long *cur_state)
204{
205	struct acpi_device *device = cdev->devdata;
206	struct acpi_processor *pr = acpi_driver_data(device);
207
208	if (!device || !pr)
209		return -EINVAL;
210
211	*cur_state = cpufreq_get_cur_state(pr->id);
212	if (pr->flags.throttling)
213		*cur_state += pr->throttling.state;
214	return 0;
215}
216
217static int
218processor_set_cur_state(struct thermal_cooling_device *cdev,
219			unsigned long state)
220{
221	struct acpi_device *device = cdev->devdata;
222	struct acpi_processor *pr = acpi_driver_data(device);
223	int result = 0;
224	int max_pstate;
225
226	if (!device || !pr)
227		return -EINVAL;
228
229	max_pstate = cpufreq_get_max_state(pr->id);
230
231	if (state > acpi_processor_max_state(pr))
232		return -EINVAL;
233
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);
238	} else {
239		cpufreq_set_cur_state(pr->id, max_pstate);
240		result = acpi_processor_set_throttling(pr,
241				state - max_pstate, false);
242	}
243	return result;
244}
245
246const 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,
250};
251