1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
4 *
5 * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
6 * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
7 * Copyright (C) 2004 Dominik Brodowski <linux@brodo.de>
8 * Copyright (C) 2004 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
9 * - Added processor hotplug support
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/init.h>
15#include <linux/cpufreq.h>
16#include <linux/acpi.h>
17#include <acpi/processor.h>
18#include <linux/uaccess.h>
19
20#include "internal.h"
21
22#ifdef CONFIG_CPU_FREQ
23
24/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
25 * offers (in most cases) voltage scaling in addition to frequency scaling, and
26 * thus a cubic (instead of linear) reduction of energy. Also, we allow for
27 * _any_ cpufreq driver and not only the acpi-cpufreq driver.
28 */
29
30#define CPUFREQ_THERMAL_MIN_STEP 0
31
32static int cpufreq_thermal_max_step __read_mostly = 3;
33
34/*
35 * Minimum throttle percentage for processor_thermal cooling device.
36 * The processor_thermal driver uses it to calculate the percentage amount by
37 * which cpu frequency must be reduced for each cooling state. This is also used
38 * to calculate the maximum number of throttling steps or cooling states.
39 */
40static int cpufreq_thermal_reduction_pctg __read_mostly = 20;
41
42static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_step);
43
44#define reduction_step(cpu) \
45 per_cpu(cpufreq_thermal_reduction_step, phys_package_first_cpu(cpu))
46
47/*
48 * Emulate "per package data" using per cpu data (which should really be
49 * provided elsewhere)
50 *
51 * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
52 * temporarily. Fortunately that's not a big issue here (I hope)
53 */
54static int phys_package_first_cpu(int cpu)
55{
56 int i;
57 int id = topology_physical_package_id(cpu);
58
59 for_each_online_cpu(i)
60 if (topology_physical_package_id(i) == id)
61 return i;
62 return 0;
63}
64
65static int cpu_has_cpufreq(unsigned int cpu)
66{
67 struct cpufreq_policy *policy;
68
69 if (!acpi_processor_cpufreq_init)
70 return 0;
71
72 policy = cpufreq_cpu_get(cpu);
73 if (policy) {
74 cpufreq_cpu_put(policy);
75 return 1;
76 }
77 return 0;
78}
79
80static int cpufreq_get_max_state(unsigned int cpu)
81{
82 if (!cpu_has_cpufreq(cpu))
83 return 0;
84
85 return cpufreq_thermal_max_step;
86}
87
88static int cpufreq_get_cur_state(unsigned int cpu)
89{
90 if (!cpu_has_cpufreq(cpu))
91 return 0;
92
93 return reduction_step(cpu);
94}
95
96static int cpufreq_set_cur_state(unsigned int cpu, int state)
97{
98 struct cpufreq_policy *policy;
99 struct acpi_processor *pr;
100 unsigned long max_freq;
101 int i, ret;
102
103 if (!cpu_has_cpufreq(cpu))
104 return 0;
105
106 reduction_step(cpu) = state;
107
108 /*
109 * Update all the CPUs in the same package because they all
110 * contribute to the temperature and often share the same
111 * frequency.
112 */
113 for_each_online_cpu(i) {
114 if (topology_physical_package_id(i) !=
115 topology_physical_package_id(cpu))
116 continue;
117
118 pr = per_cpu(processors, i);
119
120 if (unlikely(!freq_qos_request_active(&pr->thermal_req)))
121 continue;
122
123 policy = cpufreq_cpu_get(cpu: i);
124 if (!policy)
125 return -EINVAL;
126
127 max_freq = (policy->cpuinfo.max_freq *
128 (100 - reduction_step(i) * cpufreq_thermal_reduction_pctg)) / 100;
129
130 cpufreq_cpu_put(policy);
131
132 ret = freq_qos_update_request(req: &pr->thermal_req, new_value: max_freq);
133 if (ret < 0) {
134 pr_warn("Failed to update thermal freq constraint: CPU%d (%d)\n",
135 pr->id, ret);
136 }
137 }
138 return 0;
139}
140
141static void acpi_thermal_cpufreq_config(void)
142{
143 int cpufreq_pctg = acpi_arch_thermal_cpufreq_pctg();
144
145 if (!cpufreq_pctg)
146 return;
147
148 cpufreq_thermal_reduction_pctg = cpufreq_pctg;
149
150 /*
151 * Derive the MAX_STEP from minimum throttle percentage so that the reduction
152 * percentage doesn't end up becoming negative. Also, cap the MAX_STEP so that
153 * the CPU performance doesn't become 0.
154 */
155 cpufreq_thermal_max_step = (100 / cpufreq_pctg) - 2;
156}
157
158void acpi_thermal_cpufreq_init(struct cpufreq_policy *policy)
159{
160 unsigned int cpu;
161
162 acpi_thermal_cpufreq_config();
163
164 for_each_cpu(cpu, policy->related_cpus) {
165 struct acpi_processor *pr = per_cpu(processors, cpu);
166 int ret;
167
168 if (!pr)
169 continue;
170
171 ret = freq_qos_add_request(qos: &policy->constraints,
172 req: &pr->thermal_req,
173 type: FREQ_QOS_MAX, INT_MAX);
174 if (ret < 0) {
175 pr_err("Failed to add freq constraint for CPU%d (%d)\n",
176 cpu, ret);
177 continue;
178 }
179
180 thermal_cooling_device_update(pr->cdev);
181 }
182}
183
184void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
185{
186 unsigned int cpu;
187
188 for_each_cpu(cpu, policy->related_cpus) {
189 struct acpi_processor *pr = per_cpu(processors, cpu);
190
191 if (!pr)
192 continue;
193
194 freq_qos_remove_request(req: &pr->thermal_req);
195
196 thermal_cooling_device_update(pr->cdev);
197 }
198}
199#else /* ! CONFIG_CPU_FREQ */
200static int cpufreq_get_max_state(unsigned int cpu)
201{
202 return 0;
203}
204
205static int cpufreq_get_cur_state(unsigned int cpu)
206{
207 return 0;
208}
209
210static int cpufreq_set_cur_state(unsigned int cpu, int state)
211{
212 return 0;
213}
214
215#endif
216
217/* thermal cooling device callbacks */
218static int acpi_processor_max_state(struct acpi_processor *pr)
219{
220 int max_state = 0;
221
222 /*
223 * There exists four states according to
224 * cpufreq_thermal_reduction_step. 0, 1, 2, 3
225 */
226 max_state += cpufreq_get_max_state(cpu: pr->id);
227 if (pr->flags.throttling)
228 max_state += (pr->throttling.state_count -1);
229
230 return max_state;
231}
232static int
233processor_get_max_state(struct thermal_cooling_device *cdev,
234 unsigned long *state)
235{
236 struct acpi_device *device = cdev->devdata;
237 struct acpi_processor *pr;
238
239 if (!device)
240 return -EINVAL;
241
242 pr = acpi_driver_data(d: device);
243 if (!pr)
244 return -EINVAL;
245
246 *state = acpi_processor_max_state(pr);
247 return 0;
248}
249
250static int
251processor_get_cur_state(struct thermal_cooling_device *cdev,
252 unsigned long *cur_state)
253{
254 struct acpi_device *device = cdev->devdata;
255 struct acpi_processor *pr;
256
257 if (!device)
258 return -EINVAL;
259
260 pr = acpi_driver_data(d: device);
261 if (!pr)
262 return -EINVAL;
263
264 *cur_state = cpufreq_get_cur_state(cpu: pr->id);
265 if (pr->flags.throttling)
266 *cur_state += pr->throttling.state;
267 return 0;
268}
269
270static int
271processor_set_cur_state(struct thermal_cooling_device *cdev,
272 unsigned long state)
273{
274 struct acpi_device *device = cdev->devdata;
275 struct acpi_processor *pr;
276 int result = 0;
277 int max_pstate;
278
279 if (!device)
280 return -EINVAL;
281
282 pr = acpi_driver_data(d: device);
283 if (!pr)
284 return -EINVAL;
285
286 max_pstate = cpufreq_get_max_state(cpu: pr->id);
287
288 if (state > acpi_processor_max_state(pr))
289 return -EINVAL;
290
291 if (state <= max_pstate) {
292 if (pr->flags.throttling && pr->throttling.state)
293 result = acpi_processor_set_throttling(pr, state: 0, force: false);
294 cpufreq_set_cur_state(cpu: pr->id, state);
295 } else {
296 cpufreq_set_cur_state(cpu: pr->id, state: max_pstate);
297 result = acpi_processor_set_throttling(pr,
298 state: state - max_pstate, force: false);
299 }
300 return result;
301}
302
303const struct thermal_cooling_device_ops processor_cooling_ops = {
304 .get_max_state = processor_get_max_state,
305 .get_cur_state = processor_get_cur_state,
306 .set_cur_state = processor_set_cur_state,
307};
308
309int acpi_processor_thermal_init(struct acpi_processor *pr,
310 struct acpi_device *device)
311{
312 int result = 0;
313
314 pr->cdev = thermal_cooling_device_register("Processor", device,
315 &processor_cooling_ops);
316 if (IS_ERR(ptr: pr->cdev)) {
317 result = PTR_ERR(ptr: pr->cdev);
318 return result;
319 }
320
321 dev_dbg(&device->dev, "registered as cooling_device%d\n",
322 pr->cdev->id);
323
324 result = sysfs_create_link(kobj: &device->dev.kobj,
325 target: &pr->cdev->device.kobj,
326 name: "thermal_cooling");
327 if (result) {
328 dev_err(&device->dev,
329 "Failed to create sysfs link 'thermal_cooling'\n");
330 goto err_thermal_unregister;
331 }
332
333 result = sysfs_create_link(kobj: &pr->cdev->device.kobj,
334 target: &device->dev.kobj,
335 name: "device");
336 if (result) {
337 dev_err(&pr->cdev->device,
338 "Failed to create sysfs link 'device'\n");
339 goto err_remove_sysfs_thermal;
340 }
341
342 return 0;
343
344err_remove_sysfs_thermal:
345 sysfs_remove_link(kobj: &device->dev.kobj, name: "thermal_cooling");
346err_thermal_unregister:
347 thermal_cooling_device_unregister(pr->cdev);
348
349 return result;
350}
351
352void acpi_processor_thermal_exit(struct acpi_processor *pr,
353 struct acpi_device *device)
354{
355 if (pr->cdev) {
356 sysfs_remove_link(kobj: &device->dev.kobj, name: "thermal_cooling");
357 sysfs_remove_link(kobj: &pr->cdev->device.kobj, name: "device");
358 thermal_cooling_device_unregister(pr->cdev);
359 pr->cdev = NULL;
360 }
361}
362

Provided by KDAB

Privacy Policy
Improve your Profiling and Debugging skills
Find out more

source code of linux/drivers/acpi/processor_thermal.c