Branch data Line data Source code
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 : :
15 : 0 : static int dev_update_qos_constraint(struct device *dev, void *data)
16 : : {
17 : : s64 *constraint_ns_p = data;
18 : : s64 constraint_ns;
19 : :
20 [ # # # # ]: 0 : 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 : 0 : 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 : 0 : constraint_ns = dev_pm_qos_read_value(dev, DEV_PM_QOS_RESUME_LATENCY);
37 : 0 : constraint_ns *= NSEC_PER_USEC;
38 : : }
39 : :
40 [ # # ]: 0 : if (constraint_ns < *constraint_ns_p)
41 : 0 : *constraint_ns_p = constraint_ns;
42 : :
43 : 0 : return 0;
44 : : }
45 : :
46 : : /**
47 : : * default_suspend_ok - Default PM domain governor routine to suspend devices.
48 : : * @dev: Device to check.
49 : : */
50 : 0 : static 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 : 0 : spin_lock_irqsave(&dev->power.lock, flags);
59 : :
60 [ # # ]: 0 : if (!td->constraint_changed) {
61 : 0 : bool ret = td->cached_suspend_ok;
62 : :
63 : : spin_unlock_irqrestore(&dev->power.lock, flags);
64 : 0 : return ret;
65 : : }
66 : 0 : td->constraint_changed = false;
67 : 0 : td->cached_suspend_ok = false;
68 : 0 : td->effective_constraint_ns = 0;
69 : 0 : constraint_ns = __dev_pm_qos_resume_latency(dev);
70 : :
71 : : spin_unlock_irqrestore(&dev->power.lock, flags);
72 : :
73 [ # # ]: 0 : if (constraint_ns == 0)
74 : : return false;
75 : :
76 : 0 : 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 [ # # ]: 0 : if (!dev->power.ignore_children)
83 : 0 : device_for_each_child(dev, &constraint_ns,
84 : : dev_update_qos_constraint);
85 : :
86 [ # # ]: 0 : if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS) {
87 : : /* "No restriction", so the device is allowed to suspend. */
88 : 0 : td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS;
89 : 0 : td->cached_suspend_ok = true;
90 [ # # ]: 0 : } 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 : 0 : constraint_ns -= td->suspend_latency_ns +
100 : 0 : 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 [ # # ]: 0 : if (constraint_ns <= 0)
107 : : return false;
108 : :
109 : 0 : td->effective_constraint_ns = constraint_ns;
110 : 0 : 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 : 0 : return td->cached_suspend_ok;
118 : : }
119 : :
120 : 0 : static 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 : 0 : off_on_time_ns = genpd->states[state].power_off_latency_ns +
130 : 0 : 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 [ # # ]: 0 : list_for_each_entry(link, &genpd->master_links, master_node) {
139 : 0 : struct generic_pm_domain *sd = link->slave;
140 : 0 : s64 sd_max_off_ns = sd->max_off_time_ns;
141 : :
142 [ # # ]: 0 : if (sd_max_off_ns < 0)
143 : 0 : 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 [ # # ]: 0 : if (sd_max_off_ns <= off_on_time_ns)
151 : : return false;
152 : :
153 [ # # ]: 0 : 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 [ # # ]: 0 : 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 : 0 : 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 [ # # ]: 0 : if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS)
176 : 0 : continue;
177 : :
178 [ # # ]: 0 : if (constraint_ns <= off_on_time_ns)
179 : : return false;
180 : :
181 [ # # ]: 0 : 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 [ # # ]: 0 : 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 : 0 : genpd->max_off_time_ns = min_off_time_ns -
199 : : genpd->states[state].power_on_latency_ns;
200 : 0 : 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 : : */
209 : 0 : static 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 [ # # ]: 0 : if (!genpd->max_off_time_changed) {
215 : 0 : genpd->state_idx = genpd->cached_power_down_state_idx;
216 : 0 : return genpd->cached_power_down_ok;
217 : : }
218 : :
219 : : /*
220 : : * We have to invalidate the cached results for the masters, so
221 : : * use the observation that default_power_down_ok() is not
222 : : * going to be called for any master until this instance
223 : : * returns.
224 : : */
225 [ # # ]: 0 : list_for_each_entry(link, &genpd->slave_links, slave_node)
226 : 0 : link->master->max_off_time_changed = true;
227 : :
228 : 0 : genpd->max_off_time_ns = -1;
229 : 0 : genpd->max_off_time_changed = false;
230 : 0 : genpd->cached_power_down_ok = true;
231 : 0 : genpd->state_idx = genpd->state_count - 1;
232 : :
233 : : /* Find a state to power down to, starting from the deepest. */
234 [ # # ]: 0 : while (!__default_power_down_ok(pd, genpd->state_idx)) {
235 [ # # ]: 0 : if (genpd->state_idx == 0) {
236 : 0 : genpd->cached_power_down_ok = false;
237 : 0 : break;
238 : : }
239 : 0 : genpd->state_idx--;
240 : : }
241 : :
242 : 0 : genpd->cached_power_down_state_idx = genpd->state_idx;
243 : 0 : return genpd->cached_power_down_ok;
244 : : }
245 : :
246 : 0 : static bool always_on_power_down_ok(struct dev_pm_domain *domain)
247 : : {
248 : 0 : return false;
249 : : }
250 : :
251 : : #ifdef CONFIG_CPU_IDLE
252 : : static 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 : :
304 : : struct 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 : :
310 : : struct 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 : : */
318 : : struct dev_power_governor pm_domain_always_on_gov = {
319 : : .power_down_ok = always_on_power_down_ok,
320 : : .suspend_ok = default_suspend_ok,
321 : : };
|
