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 <asm/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