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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Energy Model of CPUs
4 *
5 * Copyright (c) 2018, Arm ltd.
6 * Written by: Quentin Perret, Arm ltd.
7 */
8
9#define pr_fmt(fmt) "energy_model: " fmt
10
11#include <linux/cpu.h>
12#include <linux/cpumask.h>
13#include <linux/debugfs.h>
14#include <linux/energy_model.h>
15#include <linux/sched/topology.h>
16#include <linux/slab.h>
17
18/* Mapping of each CPU to the performance domain to which it belongs. */
19static DEFINE_PER_CPU(struct em_perf_domain *, em_data);
20
21/*
22 * Mutex serializing the registrations of performance domains and letting
23 * callbacks defined by drivers sleep.
24 */
25static DEFINE_MUTEX(em_pd_mutex);
26
27#ifdef CONFIG_DEBUG_FS
28static struct dentry *rootdir;
29
30static void em_debug_create_cs(struct em_cap_state *cs, struct dentry *pd)
31{
32 struct dentry *d;
33 char name[24];
34
35 snprintf(name, sizeof(name), "cs:%lu", cs->frequency);
36
37 /* Create per-cs directory */
38 d = debugfs_create_dir(name, pd);
39 debugfs_create_ulong("frequency", 0444, d, &cs->frequency);
40 debugfs_create_ulong("power", 0444, d, &cs->power);
41 debugfs_create_ulong("cost", 0444, d, &cs->cost);
42}
43
44static int em_debug_cpus_show(struct seq_file *s, void *unused)
45{
46 seq_printf(s, "%*pbl\n", cpumask_pr_args(to_cpumask(s->private)));
47
48 return 0;
49}
50DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);
51
52static void em_debug_create_pd(struct em_perf_domain *pd, int cpu)
53{
54 struct dentry *d;
55 char name[8];
56 int i;
57
58 snprintf(name, sizeof(name), "pd%d", cpu);
59
60 /* Create the directory of the performance domain */
61 d = debugfs_create_dir(name, rootdir);
62
63 debugfs_create_file("cpus", 0444, d, pd->cpus, &em_debug_cpus_fops);
64
65 /* Create a sub-directory for each capacity state */
66 for (i = 0; i < pd->nr_cap_states; i++)
67 em_debug_create_cs(&pd->table[i], d);
68}
69
70static int __init em_debug_init(void)
71{
72 /* Create /sys/kernel/debug/energy_model directory */
73 rootdir = debugfs_create_dir("energy_model", NULL);
74
75 return 0;
76}
77core_initcall(em_debug_init);
78#else /* CONFIG_DEBUG_FS */
79static void em_debug_create_pd(struct em_perf_domain *pd, int cpu) {}
80#endif
81static struct em_perf_domain *em_create_pd(cpumask_t *span, int nr_states,
82 struct em_data_callback *cb)
83{
84 unsigned long opp_eff, prev_opp_eff = ULONG_MAX;
85 unsigned long power, freq, prev_freq = 0;
86 int i, ret, cpu = cpumask_first(span);
87 struct em_cap_state *table;
88 struct em_perf_domain *pd;
89 u64 fmax;
90
91 if (!cb->active_power)
92 return NULL;
93
94 pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
95 if (!pd)
96 return NULL;
97
98 table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL);
99 if (!table)
100 goto free_pd;
101
102 /* Build the list of capacity states for this performance domain */
103 for (i = 0, freq = 0; i < nr_states; i++, freq++) {
104 /*
105 * active_power() is a driver callback which ceils 'freq' to
106 * lowest capacity state of 'cpu' above 'freq' and updates
107 * 'power' and 'freq' accordingly.
108 */
109 ret = cb->active_power(&power, &freq, cpu);
110 if (ret) {
111 pr_err("pd%d: invalid cap. state: %d\n", cpu, ret);
112 goto free_cs_table;
113 }
114
115 /*
116 * We expect the driver callback to increase the frequency for
117 * higher capacity states.
118 */
119 if (freq <= prev_freq) {
120 pr_err("pd%d: non-increasing freq: %lu\n", cpu, freq);
121 goto free_cs_table;
122 }
123
124 /*
125 * The power returned by active_state() is expected to be
126 * positive, in milli-watts and to fit into 16 bits.
127 */
128 if (!power || power > EM_CPU_MAX_POWER) {
129 pr_err("pd%d: invalid power: %lu\n", cpu, power);
130 goto free_cs_table;
131 }
132
133 table[i].power = power;
134 table[i].frequency = prev_freq = freq;
135
136 /*
137 * The hertz/watts efficiency ratio should decrease as the
138 * frequency grows on sane platforms. But this isn't always
139 * true in practice so warn the user if a higher OPP is more
140 * power efficient than a lower one.
141 */
142 opp_eff = freq / power;
143 if (opp_eff >= prev_opp_eff)
144 pr_warn("pd%d: hertz/watts ratio non-monotonically decreasing: em_cap_state %d >= em_cap_state%d\n",
145 cpu, i, i - 1);
146 prev_opp_eff = opp_eff;
147 }
148
149 /* Compute the cost of each capacity_state. */
150 fmax = (u64) table[nr_states - 1].frequency;
151 for (i = 0; i < nr_states; i++) {
152 table[i].cost = div64_u64(fmax * table[i].power,
153 table[i].frequency);
154 }
155
156 pd->table = table;
157 pd->nr_cap_states = nr_states;
158 cpumask_copy(to_cpumask(pd->cpus), span);
159
160 em_debug_create_pd(pd, cpu);
161
162 return pd;
163
164free_cs_table:
165 kfree(table);
166free_pd:
167 kfree(pd);
168
169 return NULL;
170}
171
172/**
173 * em_cpu_get() - Return the performance domain for a CPU
174 * @cpu : CPU to find the performance domain for
175 *
176 * Return: the performance domain to which 'cpu' belongs, or NULL if it doesn't
177 * exist.
178 */
179struct em_perf_domain *em_cpu_get(int cpu)
180{
181 return READ_ONCE(per_cpu(em_data, cpu));
182}
183EXPORT_SYMBOL_GPL(em_cpu_get);
184
185/**
186 * em_register_perf_domain() - Register the Energy Model of a performance domain
187 * @span : Mask of CPUs in the performance domain
188 * @nr_states : Number of capacity states to register
189 * @cb : Callback functions providing the data of the Energy Model
190 *
191 * Create Energy Model tables for a performance domain using the callbacks
192 * defined in cb.
193 *
194 * If multiple clients register the same performance domain, all but the first
195 * registration will be ignored.
196 *
197 * Return 0 on success
198 */
199int em_register_perf_domain(cpumask_t *span, unsigned int nr_states,
200 struct em_data_callback *cb)
201{
202 unsigned long cap, prev_cap = 0;
203 struct em_perf_domain *pd;
204 int cpu, ret = 0;
205
206 if (!span || !nr_states || !cb)
207 return -EINVAL;
208
209 /*
210 * Use a mutex to serialize the registration of performance domains and
211 * let the driver-defined callback functions sleep.
212 */
213 mutex_lock(&em_pd_mutex);
214
215 for_each_cpu(cpu, span) {
216 /* Make sure we don't register again an existing domain. */
217 if (READ_ONCE(per_cpu(em_data, cpu))) {
218 ret = -EEXIST;
219 goto unlock;
220 }
221
222 /*
223 * All CPUs of a domain must have the same micro-architecture
224 * since they all share the same table.
225 */
226 cap = arch_scale_cpu_capacity(cpu);
227 if (prev_cap && prev_cap != cap) {
228 pr_err("CPUs of %*pbl must have the same capacity\n",
229 cpumask_pr_args(span));
230 ret = -EINVAL;
231 goto unlock;
232 }
233 prev_cap = cap;
234 }
235
236 /* Create the performance domain and add it to the Energy Model. */
237 pd = em_create_pd(span, nr_states, cb);
238 if (!pd) {
239 ret = -EINVAL;
240 goto unlock;
241 }
242
243 for_each_cpu(cpu, span) {
244 /*
245 * The per-cpu array can be read concurrently from em_cpu_get().
246 * The barrier enforces the ordering needed to make sure readers
247 * can only access well formed em_perf_domain structs.
248 */
249 smp_store_release(per_cpu_ptr(&em_data, cpu), pd);
250 }
251
252 pr_debug("Created perf domain %*pbl\n", cpumask_pr_args(span));
253unlock:
254 mutex_unlock(&em_pd_mutex);
255
256 return ret;
257}
258EXPORT_SYMBOL_GPL(em_register_perf_domain);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Energy Model of devices
4 *
5 * Copyright (c) 2018-2020, Arm ltd.
6 * Written by: Quentin Perret, Arm ltd.
7 * Improvements provided by: Lukasz Luba, Arm ltd.
8 */
9
10#define pr_fmt(fmt) "energy_model: " fmt
11
12#include <linux/cpu.h>
13#include <linux/cpumask.h>
14#include <linux/debugfs.h>
15#include <linux/energy_model.h>
16#include <linux/sched/topology.h>
17#include <linux/slab.h>
18
19/*
20 * Mutex serializing the registrations of performance domains and letting
21 * callbacks defined by drivers sleep.
22 */
23static DEFINE_MUTEX(em_pd_mutex);
24
25static bool _is_cpu_device(struct device *dev)
26{
27 return (dev->bus == &cpu_subsys);
28}
29
30#ifdef CONFIG_DEBUG_FS
31static struct dentry *rootdir;
32
33static void em_debug_create_ps(struct em_perf_state *ps, struct dentry *pd)
34{
35 struct dentry *d;
36 char name[24];
37
38 snprintf(name, sizeof(name), "ps:%lu", ps->frequency);
39
40 /* Create per-ps directory */
41 d = debugfs_create_dir(name, pd);
42 debugfs_create_ulong("frequency", 0444, d, &ps->frequency);
43 debugfs_create_ulong("power", 0444, d, &ps->power);
44 debugfs_create_ulong("cost", 0444, d, &ps->cost);
45}
46
47static int em_debug_cpus_show(struct seq_file *s, void *unused)
48{
49 seq_printf(s, "%*pbl\n", cpumask_pr_args(to_cpumask(s->private)));
50
51 return 0;
52}
53DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);
54
55static void em_debug_create_pd(struct device *dev)
56{
57 struct dentry *d;
58 int i;
59
60 /* Create the directory of the performance domain */
61 d = debugfs_create_dir(dev_name(dev), rootdir);
62
63 if (_is_cpu_device(dev))
64 debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus,
65 &em_debug_cpus_fops);
66
67 /* Create a sub-directory for each performance state */
68 for (i = 0; i < dev->em_pd->nr_perf_states; i++)
69 em_debug_create_ps(&dev->em_pd->table[i], d);
70
71}
72
73static void em_debug_remove_pd(struct device *dev)
74{
75 struct dentry *debug_dir;
76
77 debug_dir = debugfs_lookup(dev_name(dev), rootdir);
78 debugfs_remove_recursive(debug_dir);
79}
80
81static int __init em_debug_init(void)
82{
83 /* Create /sys/kernel/debug/energy_model directory */
84 rootdir = debugfs_create_dir("energy_model", NULL);
85
86 return 0;
87}
88core_initcall(em_debug_init);
89#else /* CONFIG_DEBUG_FS */
90static void em_debug_create_pd(struct device *dev) {}
91static void em_debug_remove_pd(struct device *dev) {}
92#endif
93
94static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
95 int nr_states, struct em_data_callback *cb)
96{
97 unsigned long opp_eff, prev_opp_eff = ULONG_MAX;
98 unsigned long power, freq, prev_freq = 0;
99 struct em_perf_state *table;
100 int i, ret;
101 u64 fmax;
102
103 table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL);
104 if (!table)
105 return -ENOMEM;
106
107 /* Build the list of performance states for this performance domain */
108 for (i = 0, freq = 0; i < nr_states; i++, freq++) {
109 /*
110 * active_power() is a driver callback which ceils 'freq' to
111 * lowest performance state of 'dev' above 'freq' and updates
112 * 'power' and 'freq' accordingly.
113 */
114 ret = cb->active_power(&power, &freq, dev);
115 if (ret) {
116 dev_err(dev, "EM: invalid perf. state: %d\n",
117 ret);
118 goto free_ps_table;
119 }
120
121 /*
122 * We expect the driver callback to increase the frequency for
123 * higher performance states.
124 */
125 if (freq <= prev_freq) {
126 dev_err(dev, "EM: non-increasing freq: %lu\n",
127 freq);
128 goto free_ps_table;
129 }
130
131 /*
132 * The power returned by active_state() is expected to be
133 * positive, in milli-watts and to fit into 16 bits.
134 */
135 if (!power || power > EM_MAX_POWER) {
136 dev_err(dev, "EM: invalid power: %lu\n",
137 power);
138 goto free_ps_table;
139 }
140
141 table[i].power = power;
142 table[i].frequency = prev_freq = freq;
143
144 /*
145 * The hertz/watts efficiency ratio should decrease as the
146 * frequency grows on sane platforms. But this isn't always
147 * true in practice so warn the user if a higher OPP is more
148 * power efficient than a lower one.
149 */
150 opp_eff = freq / power;
151 if (opp_eff >= prev_opp_eff)
152 dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
153 i, i - 1);
154 prev_opp_eff = opp_eff;
155 }
156
157 /* Compute the cost of each performance state. */
158 fmax = (u64) table[nr_states - 1].frequency;
159 for (i = 0; i < nr_states; i++) {
160 table[i].cost = div64_u64(fmax * table[i].power,
161 table[i].frequency);
162 }
163
164 pd->table = table;
165 pd->nr_perf_states = nr_states;
166
167 return 0;
168
169free_ps_table:
170 kfree(table);
171 return -EINVAL;
172}
173
174static int em_create_pd(struct device *dev, int nr_states,
175 struct em_data_callback *cb, cpumask_t *cpus)
176{
177 struct em_perf_domain *pd;
178 struct device *cpu_dev;
179 int cpu, ret;
180
181 if (_is_cpu_device(dev)) {
182 pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
183 if (!pd)
184 return -ENOMEM;
185
186 cpumask_copy(em_span_cpus(pd), cpus);
187 } else {
188 pd = kzalloc(sizeof(*pd), GFP_KERNEL);
189 if (!pd)
190 return -ENOMEM;
191 }
192
193 ret = em_create_perf_table(dev, pd, nr_states, cb);
194 if (ret) {
195 kfree(pd);
196 return ret;
197 }
198
199 if (_is_cpu_device(dev))
200 for_each_cpu(cpu, cpus) {
201 cpu_dev = get_cpu_device(cpu);
202 cpu_dev->em_pd = pd;
203 }
204
205 dev->em_pd = pd;
206
207 return 0;
208}
209
210/**
211 * em_pd_get() - Return the performance domain for a device
212 * @dev : Device to find the performance domain for
213 *
214 * Returns the performance domain to which @dev belongs, or NULL if it doesn't
215 * exist.
216 */
217struct em_perf_domain *em_pd_get(struct device *dev)
218{
219 if (IS_ERR_OR_NULL(dev))
220 return NULL;
221
222 return dev->em_pd;
223}
224EXPORT_SYMBOL_GPL(em_pd_get);
225
226/**
227 * em_cpu_get() - Return the performance domain for a CPU
228 * @cpu : CPU to find the performance domain for
229 *
230 * Returns the performance domain to which @cpu belongs, or NULL if it doesn't
231 * exist.
232 */
233struct em_perf_domain *em_cpu_get(int cpu)
234{
235 struct device *cpu_dev;
236
237 cpu_dev = get_cpu_device(cpu);
238 if (!cpu_dev)
239 return NULL;
240
241 return em_pd_get(cpu_dev);
242}
243EXPORT_SYMBOL_GPL(em_cpu_get);
244
245/**
246 * em_dev_register_perf_domain() - Register the Energy Model (EM) for a device
247 * @dev : Device for which the EM is to register
248 * @nr_states : Number of performance states to register
249 * @cb : Callback functions providing the data of the Energy Model
250 * @cpus : Pointer to cpumask_t, which in case of a CPU device is
251 * obligatory. It can be taken from i.e. 'policy->cpus'. For other
252 * type of devices this should be set to NULL.
253 *
254 * Create Energy Model tables for a performance domain using the callbacks
255 * defined in cb.
256 *
257 * If multiple clients register the same performance domain, all but the first
258 * registration will be ignored.
259 *
260 * Return 0 on success
261 */
262int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
263 struct em_data_callback *cb, cpumask_t *cpus)
264{
265 unsigned long cap, prev_cap = 0;
266 int cpu, ret;
267
268 if (!dev || !nr_states || !cb)
269 return -EINVAL;
270
271 /*
272 * Use a mutex to serialize the registration of performance domains and
273 * let the driver-defined callback functions sleep.
274 */
275 mutex_lock(&em_pd_mutex);
276
277 if (dev->em_pd) {
278 ret = -EEXIST;
279 goto unlock;
280 }
281
282 if (_is_cpu_device(dev)) {
283 if (!cpus) {
284 dev_err(dev, "EM: invalid CPU mask\n");
285 ret = -EINVAL;
286 goto unlock;
287 }
288
289 for_each_cpu(cpu, cpus) {
290 if (em_cpu_get(cpu)) {
291 dev_err(dev, "EM: exists for CPU%d\n", cpu);
292 ret = -EEXIST;
293 goto unlock;
294 }
295 /*
296 * All CPUs of a domain must have the same
297 * micro-architecture since they all share the same
298 * table.
299 */
300 cap = arch_scale_cpu_capacity(cpu);
301 if (prev_cap && prev_cap != cap) {
302 dev_err(dev, "EM: CPUs of %*pbl must have the same capacity\n",
303 cpumask_pr_args(cpus));
304
305 ret = -EINVAL;
306 goto unlock;
307 }
308 prev_cap = cap;
309 }
310 }
311
312 ret = em_create_pd(dev, nr_states, cb, cpus);
313 if (ret)
314 goto unlock;
315
316 em_debug_create_pd(dev);
317 dev_info(dev, "EM: created perf domain\n");
318
319unlock:
320 mutex_unlock(&em_pd_mutex);
321 return ret;
322}
323EXPORT_SYMBOL_GPL(em_dev_register_perf_domain);
324
325/**
326 * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device
327 * @dev : Device for which the EM is registered
328 *
329 * Unregister the EM for the specified @dev (but not a CPU device).
330 */
331void em_dev_unregister_perf_domain(struct device *dev)
332{
333 if (IS_ERR_OR_NULL(dev) || !dev->em_pd)
334 return;
335
336 if (_is_cpu_device(dev))
337 return;
338
339 /*
340 * The mutex separates all register/unregister requests and protects
341 * from potential clean-up/setup issues in the debugfs directories.
342 * The debugfs directory name is the same as device's name.
343 */
344 mutex_lock(&em_pd_mutex);
345 em_debug_remove_pd(dev);
346
347 kfree(dev->em_pd->table);
348 kfree(dev->em_pd);
349 dev->em_pd = NULL;
350 mutex_unlock(&em_pd_mutex);
351}
352EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);