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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/base/power/domain_governor.c - Governors for device PM domains.
4 *
5 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
6 */
7#include <linux/kernel.h>
8#include <linux/pm_domain.h>
9#include <linux/pm_qos.h>
10#include <linux/hrtimer.h>
11#include <linux/cpuidle.h>
12#include <linux/cpumask.h>
13#include <linux/ktime.h>
14
15static int dev_update_qos_constraint(struct device *dev, void *data)
16{
17 s64 *constraint_ns_p = data;
18 s64 constraint_ns;
19
20 if (dev->power.subsys_data && dev->power.subsys_data->domain_data) {
21 /*
22 * Only take suspend-time QoS constraints of devices into
23 * account, because constraints updated after the device has
24 * been suspended are not guaranteed to be taken into account
25 * anyway. In order for them to take effect, the device has to
26 * be resumed and suspended again.
27 */
28 constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
29 } else {
30 /*
31 * The child is not in a domain and there's no info on its
32 * suspend/resume latencies, so assume them to be negligible and
33 * take its current PM QoS constraint (that's the only thing
34 * known at this point anyway).
35 */
36 constraint_ns = dev_pm_qos_read_value(dev, DEV_PM_QOS_RESUME_LATENCY);
37 constraint_ns *= NSEC_PER_USEC;
38 }
39
40 if (constraint_ns < *constraint_ns_p)
41 *constraint_ns_p = constraint_ns;
42
43 return 0;
44}
45
46/**
47 * default_suspend_ok - Default PM domain governor routine to suspend devices.
48 * @dev: Device to check.
49 */
50static bool default_suspend_ok(struct device *dev)
51{
52 struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
53 unsigned long flags;
54 s64 constraint_ns;
55
56 dev_dbg(dev, "%s()\n", __func__);
57
58 spin_lock_irqsave(&dev->power.lock, flags);
59
60 if (!td->constraint_changed) {
61 bool ret = td->cached_suspend_ok;
62
63 spin_unlock_irqrestore(&dev->power.lock, flags);
64 return ret;
65 }
66 td->constraint_changed = false;
67 td->cached_suspend_ok = false;
68 td->effective_constraint_ns = 0;
69 constraint_ns = __dev_pm_qos_resume_latency(dev);
70
71 spin_unlock_irqrestore(&dev->power.lock, flags);
72
73 if (constraint_ns == 0)
74 return false;
75
76 constraint_ns *= NSEC_PER_USEC;
77 /*
78 * We can walk the children without any additional locking, because
79 * they all have been suspended at this point and their
80 * effective_constraint_ns fields won't be modified in parallel with us.
81 */
82 if (!dev->power.ignore_children)
83 device_for_each_child(dev, &constraint_ns,
84 dev_update_qos_constraint);
85
86 if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS) {
87 /* "No restriction", so the device is allowed to suspend. */
88 td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS;
89 td->cached_suspend_ok = true;
90 } else if (constraint_ns == 0) {
91 /*
92 * This triggers if one of the children that don't belong to a
93 * domain has a zero PM QoS constraint and it's better not to
94 * suspend then. effective_constraint_ns is zero already and
95 * cached_suspend_ok is false, so bail out.
96 */
97 return false;
98 } else {
99 constraint_ns -= td->suspend_latency_ns +
100 td->resume_latency_ns;
101 /*
102 * effective_constraint_ns is zero already and cached_suspend_ok
103 * is false, so if the computed value is not positive, return
104 * right away.
105 */
106 if (constraint_ns <= 0)
107 return false;
108
109 td->effective_constraint_ns = constraint_ns;
110 td->cached_suspend_ok = true;
111 }
112
113 /*
114 * The children have been suspended already, so we don't need to take
115 * their suspend latencies into account here.
116 */
117 return td->cached_suspend_ok;
118}
119
120static bool __default_power_down_ok(struct dev_pm_domain *pd,
121 unsigned int state)
122{
123 struct generic_pm_domain *genpd = pd_to_genpd(pd);
124 struct gpd_link *link;
125 struct pm_domain_data *pdd;
126 s64 min_off_time_ns;
127 s64 off_on_time_ns;
128
129 off_on_time_ns = genpd->states[state].power_off_latency_ns +
130 genpd->states[state].power_on_latency_ns;
131
132 min_off_time_ns = -1;
133 /*
134 * Check if subdomains can be off for enough time.
135 *
136 * All subdomains have been powered off already at this point.
137 */
138 list_for_each_entry(link, &genpd->parent_links, parent_node) {
139 struct generic_pm_domain *sd = link->child;
140 s64 sd_max_off_ns = sd->max_off_time_ns;
141
142 if (sd_max_off_ns < 0)
143 continue;
144
145 /*
146 * Check if the subdomain is allowed to be off long enough for
147 * the current domain to turn off and on (that's how much time
148 * it will have to wait worst case).
149 */
150 if (sd_max_off_ns <= off_on_time_ns)
151 return false;
152
153 if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
154 min_off_time_ns = sd_max_off_ns;
155 }
156
157 /*
158 * Check if the devices in the domain can be off enough time.
159 */
160 list_for_each_entry(pdd, &genpd->dev_list, list_node) {
161 struct gpd_timing_data *td;
162 s64 constraint_ns;
163
164 /*
165 * Check if the device is allowed to be off long enough for the
166 * domain to turn off and on (that's how much time it will
167 * have to wait worst case).
168 */
169 td = &to_gpd_data(pdd)->td;
170 constraint_ns = td->effective_constraint_ns;
171 /*
172 * Zero means "no suspend at all" and this runs only when all
173 * devices in the domain are suspended, so it must be positive.
174 */
175 if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS)
176 continue;
177
178 if (constraint_ns <= off_on_time_ns)
179 return false;
180
181 if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
182 min_off_time_ns = constraint_ns;
183 }
184
185 /*
186 * If the computed minimum device off time is negative, there are no
187 * latency constraints, so the domain can spend arbitrary time in the
188 * "off" state.
189 */
190 if (min_off_time_ns < 0)
191 return true;
192
193 /*
194 * The difference between the computed minimum subdomain or device off
195 * time and the time needed to turn the domain on is the maximum
196 * theoretical time this domain can spend in the "off" state.
197 */
198 genpd->max_off_time_ns = min_off_time_ns -
199 genpd->states[state].power_on_latency_ns;
200 return true;
201}
202
203/**
204 * default_power_down_ok - Default generic PM domain power off governor routine.
205 * @pd: PM domain to check.
206 *
207 * This routine must be executed under the PM domain's lock.
208 */
209static bool default_power_down_ok(struct dev_pm_domain *pd)
210{
211 struct generic_pm_domain *genpd = pd_to_genpd(pd);
212 struct gpd_link *link;
213
214 if (!genpd->max_off_time_changed) {
215 genpd->state_idx = genpd->cached_power_down_state_idx;
216 return genpd->cached_power_down_ok;
217 }
218
219 /*
220 * We have to invalidate the cached results for the parents, so
221 * use the observation that default_power_down_ok() is not
222 * going to be called for any parent until this instance
223 * returns.
224 */
225 list_for_each_entry(link, &genpd->child_links, child_node)
226 link->parent->max_off_time_changed = true;
227
228 genpd->max_off_time_ns = -1;
229 genpd->max_off_time_changed = false;
230 genpd->cached_power_down_ok = true;
231 genpd->state_idx = genpd->state_count - 1;
232
233 /* Find a state to power down to, starting from the deepest. */
234 while (!__default_power_down_ok(pd, genpd->state_idx)) {
235 if (genpd->state_idx == 0) {
236 genpd->cached_power_down_ok = false;
237 break;
238 }
239 genpd->state_idx--;
240 }
241
242 genpd->cached_power_down_state_idx = genpd->state_idx;
243 return genpd->cached_power_down_ok;
244}
245
246static bool always_on_power_down_ok(struct dev_pm_domain *domain)
247{
248 return false;
249}
250
251#ifdef CONFIG_CPU_IDLE
252static bool cpu_power_down_ok(struct dev_pm_domain *pd)
253{
254 struct generic_pm_domain *genpd = pd_to_genpd(pd);
255 struct cpuidle_device *dev;
256 ktime_t domain_wakeup, next_hrtimer;
257 s64 idle_duration_ns;
258 int cpu, i;
259
260 /* Validate dev PM QoS constraints. */
261 if (!default_power_down_ok(pd))
262 return false;
263
264 if (!(genpd->flags & GENPD_FLAG_CPU_DOMAIN))
265 return true;
266
267 /*
268 * Find the next wakeup for any of the online CPUs within the PM domain
269 * and its subdomains. Note, we only need the genpd->cpus, as it already
270 * contains a mask of all CPUs from subdomains.
271 */
272 domain_wakeup = ktime_set(KTIME_SEC_MAX, 0);
273 for_each_cpu_and(cpu, genpd->cpus, cpu_online_mask) {
274 dev = per_cpu(cpuidle_devices, cpu);
275 if (dev) {
276 next_hrtimer = READ_ONCE(dev->next_hrtimer);
277 if (ktime_before(next_hrtimer, domain_wakeup))
278 domain_wakeup = next_hrtimer;
279 }
280 }
281
282 /* The minimum idle duration is from now - until the next wakeup. */
283 idle_duration_ns = ktime_to_ns(ktime_sub(domain_wakeup, ktime_get()));
284 if (idle_duration_ns <= 0)
285 return false;
286
287 /*
288 * Find the deepest idle state that has its residency value satisfied
289 * and by also taking into account the power off latency for the state.
290 * Start at the state picked by the dev PM QoS constraint validation.
291 */
292 i = genpd->state_idx;
293 do {
294 if (idle_duration_ns >= (genpd->states[i].residency_ns +
295 genpd->states[i].power_off_latency_ns)) {
296 genpd->state_idx = i;
297 return true;
298 }
299 } while (--i >= 0);
300
301 return false;
302}
303
304struct dev_power_governor pm_domain_cpu_gov = {
305 .suspend_ok = default_suspend_ok,
306 .power_down_ok = cpu_power_down_ok,
307};
308#endif
309
310struct dev_power_governor simple_qos_governor = {
311 .suspend_ok = default_suspend_ok,
312 .power_down_ok = default_power_down_ok,
313};
314
315/**
316 * pm_genpd_gov_always_on - A governor implementing an always-on policy
317 */
318struct dev_power_governor pm_domain_always_on_gov = {
319 .power_down_ok = always_on_power_down_ok,
320 .suspend_ok = default_suspend_ok,
321};
1/*
2 * drivers/base/power/domain_governor.c - Governors for device PM domains.
3 *
4 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
5 *
6 * This file is released under the GPLv2.
7 */
8
9#include <linux/kernel.h>
10#include <linux/pm_domain.h>
11#include <linux/pm_qos.h>
12#include <linux/hrtimer.h>
13
14#ifdef CONFIG_PM_RUNTIME
15
16static int dev_update_qos_constraint(struct device *dev, void *data)
17{
18 s64 *constraint_ns_p = data;
19 s32 constraint_ns = -1;
20
21 if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
22 constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
23
24 if (constraint_ns < 0) {
25 constraint_ns = dev_pm_qos_read_value(dev);
26 constraint_ns *= NSEC_PER_USEC;
27 }
28 if (constraint_ns == 0)
29 return 0;
30
31 /*
32 * constraint_ns cannot be negative here, because the device has been
33 * suspended.
34 */
35 if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
36 *constraint_ns_p = constraint_ns;
37
38 return 0;
39}
40
41/**
42 * default_stop_ok - Default PM domain governor routine for stopping devices.
43 * @dev: Device to check.
44 */
45bool default_stop_ok(struct device *dev)
46{
47 struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
48 unsigned long flags;
49 s64 constraint_ns;
50
51 dev_dbg(dev, "%s()\n", __func__);
52
53 spin_lock_irqsave(&dev->power.lock, flags);
54
55 if (!td->constraint_changed) {
56 bool ret = td->cached_stop_ok;
57
58 spin_unlock_irqrestore(&dev->power.lock, flags);
59 return ret;
60 }
61 td->constraint_changed = false;
62 td->cached_stop_ok = false;
63 td->effective_constraint_ns = -1;
64 constraint_ns = __dev_pm_qos_read_value(dev);
65
66 spin_unlock_irqrestore(&dev->power.lock, flags);
67
68 if (constraint_ns < 0)
69 return false;
70
71 constraint_ns *= NSEC_PER_USEC;
72 /*
73 * We can walk the children without any additional locking, because
74 * they all have been suspended at this point and their
75 * effective_constraint_ns fields won't be modified in parallel with us.
76 */
77 if (!dev->power.ignore_children)
78 device_for_each_child(dev, &constraint_ns,
79 dev_update_qos_constraint);
80
81 if (constraint_ns > 0) {
82 constraint_ns -= td->start_latency_ns;
83 if (constraint_ns == 0)
84 return false;
85 }
86 td->effective_constraint_ns = constraint_ns;
87 td->cached_stop_ok = constraint_ns > td->stop_latency_ns ||
88 constraint_ns == 0;
89 /*
90 * The children have been suspended already, so we don't need to take
91 * their stop latencies into account here.
92 */
93 return td->cached_stop_ok;
94}
95
96/**
97 * default_power_down_ok - Default generic PM domain power off governor routine.
98 * @pd: PM domain to check.
99 *
100 * This routine must be executed under the PM domain's lock.
101 */
102static bool default_power_down_ok(struct dev_pm_domain *pd)
103{
104 struct generic_pm_domain *genpd = pd_to_genpd(pd);
105 struct gpd_link *link;
106 struct pm_domain_data *pdd;
107 s64 min_off_time_ns;
108 s64 off_on_time_ns;
109
110 if (genpd->max_off_time_changed) {
111 struct gpd_link *link;
112
113 /*
114 * We have to invalidate the cached results for the masters, so
115 * use the observation that default_power_down_ok() is not
116 * going to be called for any master until this instance
117 * returns.
118 */
119 list_for_each_entry(link, &genpd->slave_links, slave_node)
120 link->master->max_off_time_changed = true;
121
122 genpd->max_off_time_changed = false;
123 genpd->cached_power_down_ok = false;
124 genpd->max_off_time_ns = -1;
125 } else {
126 return genpd->cached_power_down_ok;
127 }
128
129 off_on_time_ns = genpd->power_off_latency_ns +
130 genpd->power_on_latency_ns;
131 /*
132 * It doesn't make sense to remove power from the domain if saving
133 * the state of all devices in it and the power off/power on operations
134 * take too much time.
135 *
136 * All devices in this domain have been stopped already at this point.
137 */
138 list_for_each_entry(pdd, &genpd->dev_list, list_node) {
139 if (pdd->dev->driver)
140 off_on_time_ns +=
141 to_gpd_data(pdd)->td.save_state_latency_ns;
142 }
143
144 min_off_time_ns = -1;
145 /*
146 * Check if subdomains can be off for enough time.
147 *
148 * All subdomains have been powered off already at this point.
149 */
150 list_for_each_entry(link, &genpd->master_links, master_node) {
151 struct generic_pm_domain *sd = link->slave;
152 s64 sd_max_off_ns = sd->max_off_time_ns;
153
154 if (sd_max_off_ns < 0)
155 continue;
156
157 /*
158 * Check if the subdomain is allowed to be off long enough for
159 * the current domain to turn off and on (that's how much time
160 * it will have to wait worst case).
161 */
162 if (sd_max_off_ns <= off_on_time_ns)
163 return false;
164
165 if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
166 min_off_time_ns = sd_max_off_ns;
167 }
168
169 /*
170 * Check if the devices in the domain can be off enough time.
171 */
172 list_for_each_entry(pdd, &genpd->dev_list, list_node) {
173 struct gpd_timing_data *td;
174 s64 constraint_ns;
175
176 if (!pdd->dev->driver)
177 continue;
178
179 /*
180 * Check if the device is allowed to be off long enough for the
181 * domain to turn off and on (that's how much time it will
182 * have to wait worst case).
183 */
184 td = &to_gpd_data(pdd)->td;
185 constraint_ns = td->effective_constraint_ns;
186 /* default_stop_ok() need not be called before us. */
187 if (constraint_ns < 0) {
188 constraint_ns = dev_pm_qos_read_value(pdd->dev);
189 constraint_ns *= NSEC_PER_USEC;
190 }
191 if (constraint_ns == 0)
192 continue;
193
194 /*
195 * constraint_ns cannot be negative here, because the device has
196 * been suspended.
197 */
198 constraint_ns -= td->restore_state_latency_ns;
199 if (constraint_ns <= off_on_time_ns)
200 return false;
201
202 if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
203 min_off_time_ns = constraint_ns;
204 }
205
206 genpd->cached_power_down_ok = true;
207
208 /*
209 * If the computed minimum device off time is negative, there are no
210 * latency constraints, so the domain can spend arbitrary time in the
211 * "off" state.
212 */
213 if (min_off_time_ns < 0)
214 return true;
215
216 /*
217 * The difference between the computed minimum subdomain or device off
218 * time and the time needed to turn the domain on is the maximum
219 * theoretical time this domain can spend in the "off" state.
220 */
221 genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
222 return true;
223}
224
225static bool always_on_power_down_ok(struct dev_pm_domain *domain)
226{
227 return false;
228}
229
230#else /* !CONFIG_PM_RUNTIME */
231
232bool default_stop_ok(struct device *dev)
233{
234 return false;
235}
236
237#define default_power_down_ok NULL
238#define always_on_power_down_ok NULL
239
240#endif /* !CONFIG_PM_RUNTIME */
241
242struct dev_power_governor simple_qos_governor = {
243 .stop_ok = default_stop_ok,
244 .power_down_ok = default_power_down_ok,
245};
246
247/**
248 * pm_genpd_gov_always_on - A governor implementing an always-on policy
249 */
250struct dev_power_governor pm_domain_always_on_gov = {
251 .power_down_ok = always_on_power_down_ok,
252 .stop_ok = default_stop_ok,
253};