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
60#define reduction_pctg(cpu) \
61	per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
62
63/*
64 * Emulate "per package data" using per cpu data (which should really be
65 * provided elsewhere)
66 *
67 * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
68 * temporarily. Fortunately that's not a big issue here (I hope)
69 */
70static int phys_package_first_cpu(int cpu)
71{
72	int i;
73	int id = topology_physical_package_id(cpu);
74
75	for_each_online_cpu(i)
76		if (topology_physical_package_id(i) == id)
77			return i;
78	return 0;
79}
80
81static int cpu_has_cpufreq(unsigned int cpu)
82{
83	struct cpufreq_policy policy;
84	if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
85		return 0;
86	return 1;
87}
88
89static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
90					 unsigned long event, void *data)
91{
92	struct cpufreq_policy *policy = data;
93	unsigned long max_freq = 0;
94
95	if (event != CPUFREQ_ADJUST)
96		goto out;
97
98	max_freq = (
99	    policy->cpuinfo.max_freq *
100	    (100 - reduction_pctg(policy->cpu) * 20)
101	) / 100;
102
103	cpufreq_verify_within_limits(policy, 0, max_freq);
104
105      out:
106	return 0;
107}
108
109static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
110	.notifier_call = acpi_thermal_cpufreq_notifier,
111};
112
113static int cpufreq_get_max_state(unsigned int cpu)
114{
115	if (!cpu_has_cpufreq(cpu))
116		return 0;
117
118	return CPUFREQ_THERMAL_MAX_STEP;
119}
120
121static int cpufreq_get_cur_state(unsigned int cpu)
122{
123	if (!cpu_has_cpufreq(cpu))
124		return 0;
125
126	return reduction_pctg(cpu);
127}
128
129static int cpufreq_set_cur_state(unsigned int cpu, int state)
130{
131	int i;
132
133	if (!cpu_has_cpufreq(cpu))
134		return 0;
135
136	reduction_pctg(cpu) = state;
137
138	/*
139	 * Update all the CPUs in the same package because they all
140	 * contribute to the temperature and often share the same
141	 * frequency.
142	 */
143	for_each_online_cpu(i) {
144		if (topology_physical_package_id(i) ==
145		    topology_physical_package_id(cpu))
146			cpufreq_update_policy(i);
147	}
148	return 0;
149}
150
151void acpi_thermal_cpufreq_init(void)
152{
153	int i;
154
155	i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
156				      CPUFREQ_POLICY_NOTIFIER);
157	if (!i)
158		acpi_thermal_cpufreq_is_init = 1;
159}
160
161void acpi_thermal_cpufreq_exit(void)
162{
163	if (acpi_thermal_cpufreq_is_init)
164		cpufreq_unregister_notifier
165		    (&acpi_thermal_cpufreq_notifier_block,
166		     CPUFREQ_POLICY_NOTIFIER);
167
168	acpi_thermal_cpufreq_is_init = 0;
169}
170
171#else				/* ! CONFIG_CPU_FREQ */
172static int cpufreq_get_max_state(unsigned int cpu)
173{
174	return 0;
175}
176
177static int cpufreq_get_cur_state(unsigned int cpu)
178{
179	return 0;
180}
181
182static int cpufreq_set_cur_state(unsigned int cpu, int state)
183{
184	return 0;
185}
186
187#endif
188
189int acpi_processor_get_limit_info(struct acpi_processor *pr)
190{
191
192	if (!pr)
193		return -EINVAL;
194
195	if (pr->flags.throttling)
196		pr->flags.limit = 1;
197
198	return 0;
199}
200
201/* thermal coolign device callbacks */
202static int acpi_processor_max_state(struct acpi_processor *pr)
203{
204	int max_state = 0;
205
206	/*
207	 * There exists four states according to
208	 * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
209	 */
210	max_state += cpufreq_get_max_state(pr->id);
211	if (pr->flags.throttling)
212		max_state += (pr->throttling.state_count -1);
213
214	return max_state;
215}
216static int
217processor_get_max_state(struct thermal_cooling_device *cdev,
218			unsigned long *state)
219{
220	struct acpi_device *device = cdev->devdata;
221	struct acpi_processor *pr = acpi_driver_data(device);
222
223	if (!device || !pr)
224		return -EINVAL;
225
226	*state = acpi_processor_max_state(pr);
227	return 0;
228}
229
230static int
231processor_get_cur_state(struct thermal_cooling_device *cdev,
232			unsigned long *cur_state)
233{
234	struct acpi_device *device = cdev->devdata;
235	struct acpi_processor *pr = acpi_driver_data(device);
236
237	if (!device || !pr)
238		return -EINVAL;
239
240	*cur_state = cpufreq_get_cur_state(pr->id);
241	if (pr->flags.throttling)
242		*cur_state += pr->throttling.state;
243	return 0;
244}
245
246static int
247processor_set_cur_state(struct thermal_cooling_device *cdev,
248			unsigned long state)
249{
250	struct acpi_device *device = cdev->devdata;
251	struct acpi_processor *pr = acpi_driver_data(device);
252	int result = 0;
253	int max_pstate;
254
255	if (!device || !pr)
256		return -EINVAL;
257
258	max_pstate = cpufreq_get_max_state(pr->id);
259
260	if (state > acpi_processor_max_state(pr))
261		return -EINVAL;
262
263	if (state <= max_pstate) {
264		if (pr->flags.throttling && pr->throttling.state)
265			result = acpi_processor_set_throttling(pr, 0, false);
266		cpufreq_set_cur_state(pr->id, state);
267	} else {
268		cpufreq_set_cur_state(pr->id, max_pstate);
269		result = acpi_processor_set_throttling(pr,
270				state - max_pstate, false);
271	}
272	return result;
273}
274
275const struct thermal_cooling_device_ops processor_cooling_ops = {
276	.get_max_state = processor_get_max_state,
277	.get_cur_state = processor_get_cur_state,
278	.set_cur_state = processor_set_cur_state,
279};
280