processor_thermal.c

  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 bool cpu_has_cpufreq(unsigned int cpu)
 66{
 67	if (!acpi_processor_cpufreq_init)
 68		return 0;
 69
 70	struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
 71
 72	return policy != NULL;
 73}
 74
 75static int cpufreq_get_max_state(unsigned int cpu)
 76{
 77	if (!cpu_has_cpufreq(cpu))
 78		return 0;
 79
 80	return cpufreq_thermal_max_step;
 81}
 82
 83static int cpufreq_get_cur_state(unsigned int cpu)
 84{
 85	if (!cpu_has_cpufreq(cpu))
 86		return 0;
 87
 88	return reduction_step(cpu);
 89}
 90
 91static bool cpufreq_update_thermal_limit(unsigned int cpu, struct acpi_processor *pr)
 92{
 93	unsigned long max_freq;
 94	int ret;
 95
 96	struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
 97	if (!policy)
 98		return false;
 99
100	max_freq = (policy->cpuinfo.max_freq *
101		(100 - reduction_step(cpu) * cpufreq_thermal_reduction_pctg)) / 100;
102
103	ret = freq_qos_update_request(&pr->thermal_req, max_freq);
104	if (ret < 0) {
105		pr_warn("Failed to update thermal freq constraint: CPU%d (%d)\n",
106			pr->id, ret);
107	}
108
109	return true;
110}
111
112static int cpufreq_set_cur_state(unsigned int cpu, int state)
113{
114	struct acpi_processor *pr;
115	int i;
116
117	if (!cpu_has_cpufreq(cpu))
118		return 0;
119
120	reduction_step(cpu) = state;
121
122	/*
123	 * Update all the CPUs in the same package because they all
124	 * contribute to the temperature and often share the same
125	 * frequency.
126	 */
127	for_each_online_cpu(i) {
128		if (topology_physical_package_id(i) !=
129		    topology_physical_package_id(cpu))
130			continue;
131
132		pr = per_cpu(processors, i);
133
134		if (unlikely(!freq_qos_request_active(&pr->thermal_req)))
135			continue;
136
137		if (!cpufreq_update_thermal_limit(i, pr))
138			return -EINVAL;
139	}
140	return 0;
141}
142
143static void acpi_thermal_cpufreq_config(void)
144{
145	int cpufreq_pctg = acpi_arch_thermal_cpufreq_pctg();
146
147	if (!cpufreq_pctg)
148		return;
149
150	cpufreq_thermal_reduction_pctg = cpufreq_pctg;
151
152	/*
153	 * Derive the MAX_STEP from minimum throttle percentage so that the reduction
154	 * percentage doesn't end up becoming negative. Also, cap the MAX_STEP so that
155	 * the CPU performance doesn't become 0.
156	 */
157	cpufreq_thermal_max_step = (100 / cpufreq_pctg) - 2;
158}
159
160void acpi_thermal_cpufreq_init(struct cpufreq_policy *policy)
161{
162	unsigned int cpu;
163
164	acpi_thermal_cpufreq_config();
165
166	for_each_cpu(cpu, policy->related_cpus) {
167		struct acpi_processor *pr = per_cpu(processors, cpu);
168		int ret;
169
170		if (!pr)
171			continue;
172
173		ret = freq_qos_add_request(&policy->constraints,
174					   &pr->thermal_req,
175					   FREQ_QOS_MAX, INT_MAX);
176		if (ret < 0) {
177			pr_err("Failed to add freq constraint for CPU%d (%d)\n",
178			       cpu, ret);
179			continue;
180		}
181
182		thermal_cooling_device_update(pr->cdev);
183	}
184}
185
186void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
187{
188	unsigned int cpu;
189
190	for_each_cpu(cpu, policy->related_cpus) {
191		struct acpi_processor *pr = per_cpu(processors, cpu);
192
193		if (!pr)
194			continue;
195
196		freq_qos_remove_request(&pr->thermal_req);
197
198		thermal_cooling_device_update(pr->cdev);
199	}
200}
201#else				/* ! CONFIG_CPU_FREQ */
202static int cpufreq_get_max_state(unsigned int cpu)
203{
204	return 0;
205}
206
207static int cpufreq_get_cur_state(unsigned int cpu)
208{
209	return 0;
210}
211
212static int cpufreq_set_cur_state(unsigned int cpu, int state)
213{
214	return 0;
215}
216
217#endif
218
219/* thermal cooling device callbacks */
220static int acpi_processor_max_state(struct acpi_processor *pr)
221{
222	int max_state = 0;
223
224	/*
225	 * There exists four states according to
226	 * cpufreq_thermal_reduction_step. 0, 1, 2, 3
227	 */
228	max_state += cpufreq_get_max_state(pr->id);
229	if (pr->flags.throttling)
230		max_state += (pr->throttling.state_count -1);
231
232	return max_state;
233}
234static int
235processor_get_max_state(struct thermal_cooling_device *cdev,
236			unsigned long *state)
237{
238	struct acpi_device *device = cdev->devdata;
239	struct acpi_processor *pr;
240
241	if (!device)
242		return -EINVAL;
243
244	pr = acpi_driver_data(device);
245	if (!pr)
246		return -EINVAL;
247
248	*state = acpi_processor_max_state(pr);
249	return 0;
250}
251
252static int
253processor_get_cur_state(struct thermal_cooling_device *cdev,
254			unsigned long *cur_state)
255{
256	struct acpi_device *device = cdev->devdata;
257	struct acpi_processor *pr;
258
259	if (!device)
260		return -EINVAL;
261
262	pr = acpi_driver_data(device);
263	if (!pr)
264		return -EINVAL;
265
266	*cur_state = cpufreq_get_cur_state(pr->id);
267	if (pr->flags.throttling)
268		*cur_state += pr->throttling.state;
269	return 0;
270}
271
272static int
273processor_set_cur_state(struct thermal_cooling_device *cdev,
274			unsigned long state)
275{
276	struct acpi_device *device = cdev->devdata;
277	struct acpi_processor *pr;
278	int result = 0;
279	int max_pstate;
280
281	if (!device)
282		return -EINVAL;
283
284	pr = acpi_driver_data(device);
285	if (!pr)
286		return -EINVAL;
287
288	max_pstate = cpufreq_get_max_state(pr->id);
289
290	if (state > acpi_processor_max_state(pr))
291		return -EINVAL;
292
293	if (state <= max_pstate) {
294		if (pr->flags.throttling && pr->throttling.state)
295			result = acpi_processor_set_throttling(pr, 0, false);
296		cpufreq_set_cur_state(pr->id, state);
297	} else {
298		cpufreq_set_cur_state(pr->id, max_pstate);
299		result = acpi_processor_set_throttling(pr,
300				state - max_pstate, false);
301	}
302	return result;
303}
304
305const struct thermal_cooling_device_ops processor_cooling_ops = {
306	.get_max_state = processor_get_max_state,
307	.get_cur_state = processor_get_cur_state,
308	.set_cur_state = processor_set_cur_state,
309};
310
311int acpi_processor_thermal_init(struct acpi_processor *pr,
312				struct acpi_device *device)
313{
314	int result = 0;
315
316	pr->cdev = thermal_cooling_device_register("Processor", device,
317						   &processor_cooling_ops);
318	if (IS_ERR(pr->cdev)) {
319		result = PTR_ERR(pr->cdev);
320		return result;
321	}
322
323	dev_dbg(&device->dev, "registered as cooling_device%d\n",
324		pr->cdev->id);
325
326	result = sysfs_create_link(&device->dev.kobj,
327				   &pr->cdev->device.kobj,
328				   "thermal_cooling");
329	if (result) {
330		dev_err(&device->dev,
331			"Failed to create sysfs link 'thermal_cooling'\n");
332		goto err_thermal_unregister;
333	}
334
335	result = sysfs_create_link(&pr->cdev->device.kobj,
336				   &device->dev.kobj,
337				   "device");
338	if (result) {
339		dev_err(&pr->cdev->device,
340			"Failed to create sysfs link 'device'\n");
341		goto err_remove_sysfs_thermal;
342	}
343
344	return 0;
345
346err_remove_sysfs_thermal:
347	sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
348err_thermal_unregister:
349	thermal_cooling_device_unregister(pr->cdev);
350
351	return result;
352}
353
354void acpi_processor_thermal_exit(struct acpi_processor *pr,
355				 struct acpi_device *device)
356{
357	if (pr->cdev) {
358		sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
359		sysfs_remove_link(&pr->cdev->device.kobj, "device");
360		thermal_cooling_device_unregister(pr->cdev);
361		pr->cdev = NULL;
362	}
363}