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 #define PREFIX "ACPI: "
21 
22 #define ACPI_PROCESSOR_CLASS            "processor"
23 
24 #ifdef CONFIG_CPU_FREQ
25 
26 /* If a passive cooling situation is detected, primarily CPUfreq is used, as it
27  * offers (in most cases) voltage scaling in addition to frequency scaling, and
28  * thus a cubic (instead of linear) reduction of energy. Also, we allow for
29  * _any_ cpufreq driver and not only the acpi-cpufreq driver.
30  */
31 
32 #define CPUFREQ_THERMAL_MIN_STEP 0
33 #define CPUFREQ_THERMAL_MAX_STEP 3
34 
35 static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
36 
37 #define reduction_pctg(cpu) \
38 	per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))
39 
40 /*
41  * Emulate "per package data" using per cpu data (which should really be
42  * provided elsewhere)
43  *
44  * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
45  * temporarily. Fortunately that's not a big issue here (I hope)
46  */
47 static int phys_package_first_cpu(int cpu)
48 {
49 	int i;
50 	int id = topology_physical_package_id(cpu);
51 
52 	for_each_online_cpu(i)
53 		if (topology_physical_package_id(i) == id)
54 			return i;
55 	return 0;
56 }
57 
58 static int cpu_has_cpufreq(unsigned int cpu)
59 {
60 	struct cpufreq_policy policy;
61 	if (!acpi_processor_cpufreq_init || cpufreq_get_policy(&policy, cpu))
62 		return 0;
63 	return 1;
64 }
65 
66 static int cpufreq_get_max_state(unsigned int cpu)
67 {
68 	if (!cpu_has_cpufreq(cpu))
69 		return 0;
70 
71 	return CPUFREQ_THERMAL_MAX_STEP;
72 }
73 
74 static int cpufreq_get_cur_state(unsigned int cpu)
75 {
76 	if (!cpu_has_cpufreq(cpu))
77 		return 0;
78 
79 	return reduction_pctg(cpu);
80 }
81 
82 static int cpufreq_set_cur_state(unsigned int cpu, int state)
83 {
84 	struct cpufreq_policy *policy;
85 	struct acpi_processor *pr;
86 	unsigned long max_freq;
87 	int i, ret;
88 
89 	if (!cpu_has_cpufreq(cpu))
90 		return 0;
91 
92 	reduction_pctg(cpu) = state;
93 
94 	/*
95 	 * Update all the CPUs in the same package because they all
96 	 * contribute to the temperature and often share the same
97 	 * frequency.
98 	 */
99 	for_each_online_cpu(i) {
100 		if (topology_physical_package_id(i) !=
101 		    topology_physical_package_id(cpu))
102 			continue;
103 
104 		pr = per_cpu(processors, i);
105 
106 		if (unlikely(!freq_qos_request_active(&pr->thermal_req)))
107 			continue;
108 
109 		policy = cpufreq_cpu_get(i);
110 		if (!policy)
111 			return -EINVAL;
112 
113 		max_freq = (policy->cpuinfo.max_freq * (100 - reduction_pctg(i) * 20)) / 100;
114 
115 		cpufreq_cpu_put(policy);
116 
117 		ret = freq_qos_update_request(&pr->thermal_req, max_freq);
118 		if (ret < 0) {
119 			pr_warn("Failed to update thermal freq constraint: CPU%d (%d)\n",
120 				pr->id, ret);
121 		}
122 	}
123 	return 0;
124 }
125 
126 void acpi_thermal_cpufreq_init(struct cpufreq_policy *policy)
127 {
128 	unsigned int cpu;
129 
130 	for_each_cpu(cpu, policy->related_cpus) {
131 		struct acpi_processor *pr = per_cpu(processors, cpu);
132 		int ret;
133 
134 		if (!pr)
135 			continue;
136 
137 		ret = freq_qos_add_request(&policy->constraints,
138 					   &pr->thermal_req,
139 					   FREQ_QOS_MAX, INT_MAX);
140 		if (ret < 0)
141 			pr_err("Failed to add freq constraint for CPU%d (%d)\n",
142 			       cpu, ret);
143 	}
144 }
145 
146 void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
147 {
148 	unsigned int cpu;
149 
150 	for_each_cpu(cpu, policy->related_cpus) {
151 		struct acpi_processor *pr = per_cpu(processors, policy->cpu);
152 
153 		if (pr)
154 			freq_qos_remove_request(&pr->thermal_req);
155 	}
156 }
157 #else				/* ! CONFIG_CPU_FREQ */
158 static int cpufreq_get_max_state(unsigned int cpu)
159 {
160 	return 0;
161 }
162 
163 static int cpufreq_get_cur_state(unsigned int cpu)
164 {
165 	return 0;
166 }
167 
168 static int cpufreq_set_cur_state(unsigned int cpu, int state)
169 {
170 	return 0;
171 }
172 
173 #endif
174 
175 /* thermal cooling device callbacks */
176 static int acpi_processor_max_state(struct acpi_processor *pr)
177 {
178 	int max_state = 0;
179 
180 	/*
181 	 * There exists four states according to
182 	 * cpufreq_thermal_reduction_pctg. 0, 1, 2, 3
183 	 */
184 	max_state += cpufreq_get_max_state(pr->id);
185 	if (pr->flags.throttling)
186 		max_state += (pr->throttling.state_count -1);
187 
188 	return max_state;
189 }
190 static int
191 processor_get_max_state(struct thermal_cooling_device *cdev,
192 			unsigned long *state)
193 {
194 	struct acpi_device *device = cdev->devdata;
195 	struct acpi_processor *pr;
196 
197 	if (!device)
198 		return -EINVAL;
199 
200 	pr = acpi_driver_data(device);
201 	if (!pr)
202 		return -EINVAL;
203 
204 	*state = acpi_processor_max_state(pr);
205 	return 0;
206 }
207 
208 static int
209 processor_get_cur_state(struct thermal_cooling_device *cdev,
210 			unsigned long *cur_state)
211 {
212 	struct acpi_device *device = cdev->devdata;
213 	struct acpi_processor *pr;
214 
215 	if (!device)
216 		return -EINVAL;
217 
218 	pr = acpi_driver_data(device);
219 	if (!pr)
220 		return -EINVAL;
221 
222 	*cur_state = cpufreq_get_cur_state(pr->id);
223 	if (pr->flags.throttling)
224 		*cur_state += pr->throttling.state;
225 	return 0;
226 }
227 
228 static int
229 processor_set_cur_state(struct thermal_cooling_device *cdev,
230 			unsigned long state)
231 {
232 	struct acpi_device *device = cdev->devdata;
233 	struct acpi_processor *pr;
234 	int result = 0;
235 	int max_pstate;
236 
237 	if (!device)
238 		return -EINVAL;
239 
240 	pr = acpi_driver_data(device);
241 	if (!pr)
242 		return -EINVAL;
243 
244 	max_pstate = cpufreq_get_max_state(pr->id);
245 
246 	if (state > acpi_processor_max_state(pr))
247 		return -EINVAL;
248 
249 	if (state <= max_pstate) {
250 		if (pr->flags.throttling && pr->throttling.state)
251 			result = acpi_processor_set_throttling(pr, 0, false);
252 		cpufreq_set_cur_state(pr->id, state);
253 	} else {
254 		cpufreq_set_cur_state(pr->id, max_pstate);
255 		result = acpi_processor_set_throttling(pr,
256 				state - max_pstate, false);
257 	}
258 	return result;
259 }
260 
261 const struct thermal_cooling_device_ops processor_cooling_ops = {
262 	.get_max_state = processor_get_max_state,
263 	.get_cur_state = processor_get_cur_state,
264 	.set_cur_state = processor_set_cur_state,
265 };
266