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