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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
14static int dev_update_qos_constraint(struct device *dev, void *data)
15{
16 s64 *constraint_ns_p = data;
17 s32 constraint_ns = -1;
18
19 if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
20 constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
21
22 if (constraint_ns < 0) {
23 constraint_ns = dev_pm_qos_read_value(dev);
24 constraint_ns *= NSEC_PER_USEC;
25 }
26 if (constraint_ns == 0)
27 return 0;
28
29 /*
30 * constraint_ns cannot be negative here, because the device has been
31 * suspended.
32 */
33 if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
34 *constraint_ns_p = constraint_ns;
35
36 return 0;
37}
38
39/**
40 * default_stop_ok - Default PM domain governor routine for stopping devices.
41 * @dev: Device to check.
42 */
43static bool default_stop_ok(struct device *dev)
44{
45 struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
46 unsigned long flags;
47 s64 constraint_ns;
48
49 dev_dbg(dev, "%s()\n", __func__);
50
51 spin_lock_irqsave(&dev->power.lock, flags);
52
53 if (!td->constraint_changed) {
54 bool ret = td->cached_stop_ok;
55
56 spin_unlock_irqrestore(&dev->power.lock, flags);
57 return ret;
58 }
59 td->constraint_changed = false;
60 td->cached_stop_ok = false;
61 td->effective_constraint_ns = -1;
62 constraint_ns = __dev_pm_qos_read_value(dev);
63
64 spin_unlock_irqrestore(&dev->power.lock, flags);
65
66 if (constraint_ns < 0)
67 return false;
68
69 constraint_ns *= NSEC_PER_USEC;
70 /*
71 * We can walk the children without any additional locking, because
72 * they all have been suspended at this point and their
73 * effective_constraint_ns fields won't be modified in parallel with us.
74 */
75 if (!dev->power.ignore_children)
76 device_for_each_child(dev, &constraint_ns,
77 dev_update_qos_constraint);
78
79 if (constraint_ns > 0) {
80 constraint_ns -= td->suspend_latency_ns +
81 td->resume_latency_ns;
82 if (constraint_ns == 0)
83 return false;
84 }
85 td->effective_constraint_ns = constraint_ns;
86 td->cached_stop_ok = constraint_ns >= 0;
87
88 /*
89 * The children have been suspended already, so we don't need to take
90 * their stop latencies into account here.
91 */
92 return td->cached_stop_ok;
93}
94
95/**
96 * default_power_down_ok - Default generic PM domain power off governor routine.
97 * @pd: PM domain to check.
98 *
99 * This routine must be executed under the PM domain's lock.
100 */
101static bool __default_power_down_ok(struct dev_pm_domain *pd,
102 unsigned int state)
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 off_on_time_ns = genpd->states[state].power_off_latency_ns +
111 genpd->states[state].power_on_latency_ns;
112
113
114 min_off_time_ns = -1;
115 /*
116 * Check if subdomains can be off for enough time.
117 *
118 * All subdomains have been powered off already at this point.
119 */
120 list_for_each_entry(link, &genpd->master_links, master_node) {
121 struct generic_pm_domain *sd = link->slave;
122 s64 sd_max_off_ns = sd->max_off_time_ns;
123
124 if (sd_max_off_ns < 0)
125 continue;
126
127 /*
128 * Check if the subdomain is allowed to be off long enough for
129 * the current domain to turn off and on (that's how much time
130 * it will have to wait worst case).
131 */
132 if (sd_max_off_ns <= off_on_time_ns)
133 return false;
134
135 if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
136 min_off_time_ns = sd_max_off_ns;
137 }
138
139 /*
140 * Check if the devices in the domain can be off enough time.
141 */
142 list_for_each_entry(pdd, &genpd->dev_list, list_node) {
143 struct gpd_timing_data *td;
144 s64 constraint_ns;
145
146 /*
147 * Check if the device is allowed to be off long enough for the
148 * domain to turn off and on (that's how much time it will
149 * have to wait worst case).
150 */
151 td = &to_gpd_data(pdd)->td;
152 constraint_ns = td->effective_constraint_ns;
153 /* default_stop_ok() need not be called before us. */
154 if (constraint_ns < 0) {
155 constraint_ns = dev_pm_qos_read_value(pdd->dev);
156 constraint_ns *= NSEC_PER_USEC;
157 }
158 if (constraint_ns == 0)
159 continue;
160
161 /*
162 * constraint_ns cannot be negative here, because the device has
163 * been suspended.
164 */
165 if (constraint_ns <= off_on_time_ns)
166 return false;
167
168 if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
169 min_off_time_ns = constraint_ns;
170 }
171
172 /*
173 * If the computed minimum device off time is negative, there are no
174 * latency constraints, so the domain can spend arbitrary time in the
175 * "off" state.
176 */
177 if (min_off_time_ns < 0)
178 return true;
179
180 /*
181 * The difference between the computed minimum subdomain or device off
182 * time and the time needed to turn the domain on is the maximum
183 * theoretical time this domain can spend in the "off" state.
184 */
185 genpd->max_off_time_ns = min_off_time_ns -
186 genpd->states[state].power_on_latency_ns;
187 return true;
188}
189
190static bool default_power_down_ok(struct dev_pm_domain *pd)
191{
192 struct generic_pm_domain *genpd = pd_to_genpd(pd);
193 struct gpd_link *link;
194
195 if (!genpd->max_off_time_changed)
196 return genpd->cached_power_down_ok;
197
198 /*
199 * We have to invalidate the cached results for the masters, so
200 * use the observation that default_power_down_ok() is not
201 * going to be called for any master until this instance
202 * returns.
203 */
204 list_for_each_entry(link, &genpd->slave_links, slave_node)
205 link->master->max_off_time_changed = true;
206
207 genpd->max_off_time_ns = -1;
208 genpd->max_off_time_changed = false;
209 genpd->cached_power_down_ok = true;
210 genpd->state_idx = genpd->state_count - 1;
211
212 /* Find a state to power down to, starting from the deepest. */
213 while (!__default_power_down_ok(pd, genpd->state_idx)) {
214 if (genpd->state_idx == 0) {
215 genpd->cached_power_down_ok = false;
216 break;
217 }
218 genpd->state_idx--;
219 }
220
221 return genpd->cached_power_down_ok;
222}
223
224static bool always_on_power_down_ok(struct dev_pm_domain *domain)
225{
226 return false;
227}
228
229struct dev_power_governor simple_qos_governor = {
230 .stop_ok = default_stop_ok,
231 .power_down_ok = default_power_down_ok,
232};
233
234/**
235 * pm_genpd_gov_always_on - A governor implementing an always-on policy
236 */
237struct dev_power_governor pm_domain_always_on_gov = {
238 .power_down_ok = always_on_power_down_ok,
239 .stop_ok = default_stop_ok,
240};