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b02c999a RW |
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/init.h> | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/pm_domain.h> | |
12 | #include <linux/pm_qos.h> | |
221e9b58 | 13 | #include <linux/hrtimer.h> |
b02c999a | 14 | |
e59a8db8 RW |
15 | #ifdef CONFIG_PM_RUNTIME |
16 | ||
a5bef810 RW |
17 | static int dev_update_qos_constraint(struct device *dev, void *data) |
18 | { | |
19 | s64 *constraint_ns_p = data; | |
20 | s32 constraint_ns = -1; | |
21 | ||
22 | if (dev->power.subsys_data && dev->power.subsys_data->domain_data) | |
23 | constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns; | |
24 | ||
25 | if (constraint_ns < 0) { | |
26 | constraint_ns = dev_pm_qos_read_value(dev); | |
27 | constraint_ns *= NSEC_PER_USEC; | |
28 | } | |
29 | if (constraint_ns == 0) | |
30 | return 0; | |
31 | ||
32 | /* | |
33 | * constraint_ns cannot be negative here, because the device has been | |
34 | * suspended. | |
35 | */ | |
36 | if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0) | |
37 | *constraint_ns_p = constraint_ns; | |
38 | ||
39 | return 0; | |
40 | } | |
41 | ||
b02c999a RW |
42 | /** |
43 | * default_stop_ok - Default PM domain governor routine for stopping devices. | |
44 | * @dev: Device to check. | |
45 | */ | |
46 | bool default_stop_ok(struct device *dev) | |
47 | { | |
48 | struct gpd_timing_data *td = &dev_gpd_data(dev)->td; | |
6ff7bb0d | 49 | unsigned long flags; |
a5bef810 | 50 | s64 constraint_ns; |
b02c999a RW |
51 | |
52 | dev_dbg(dev, "%s()\n", __func__); | |
53 | ||
6ff7bb0d RW |
54 | spin_lock_irqsave(&dev->power.lock, flags); |
55 | ||
56 | if (!td->constraint_changed) { | |
57 | bool ret = td->cached_stop_ok; | |
58 | ||
59 | spin_unlock_irqrestore(&dev->power.lock, flags); | |
60 | return ret; | |
61 | } | |
62 | td->constraint_changed = false; | |
63 | td->cached_stop_ok = false; | |
64 | td->effective_constraint_ns = -1; | |
65 | constraint_ns = __dev_pm_qos_read_value(dev); | |
66 | ||
67 | spin_unlock_irqrestore(&dev->power.lock, flags); | |
68 | ||
a5bef810 RW |
69 | if (constraint_ns < 0) |
70 | return false; | |
b02c999a | 71 | |
a5bef810 RW |
72 | constraint_ns *= NSEC_PER_USEC; |
73 | /* | |
74 | * We can walk the children without any additional locking, because | |
6ff7bb0d RW |
75 | * they all have been suspended at this point and their |
76 | * effective_constraint_ns fields won't be modified in parallel with us. | |
a5bef810 RW |
77 | */ |
78 | if (!dev->power.ignore_children) | |
79 | device_for_each_child(dev, &constraint_ns, | |
80 | dev_update_qos_constraint); | |
81 | ||
82 | if (constraint_ns > 0) { | |
83 | constraint_ns -= td->start_latency_ns; | |
84 | if (constraint_ns == 0) | |
85 | return false; | |
86 | } | |
87 | td->effective_constraint_ns = constraint_ns; | |
6ff7bb0d RW |
88 | td->cached_stop_ok = constraint_ns > td->stop_latency_ns || |
89 | constraint_ns == 0; | |
a5bef810 RW |
90 | /* |
91 | * The children have been suspended already, so we don't need to take | |
92 | * their stop latencies into account here. | |
93 | */ | |
6ff7bb0d | 94 | return td->cached_stop_ok; |
b02c999a RW |
95 | } |
96 | ||
221e9b58 RW |
97 | /** |
98 | * default_power_down_ok - Default generic PM domain power off governor routine. | |
99 | * @pd: PM domain to check. | |
100 | * | |
101 | * This routine must be executed under the PM domain's lock. | |
102 | */ | |
103 | static bool default_power_down_ok(struct dev_pm_domain *pd) | |
104 | { | |
105 | struct generic_pm_domain *genpd = pd_to_genpd(pd); | |
106 | struct gpd_link *link; | |
107 | struct pm_domain_data *pdd; | |
b723b0eb | 108 | s64 min_off_time_ns; |
221e9b58 | 109 | s64 off_on_time_ns; |
221e9b58 | 110 | |
6ff7bb0d RW |
111 | if (genpd->max_off_time_changed) { |
112 | struct gpd_link *link; | |
113 | ||
114 | /* | |
115 | * We have to invalidate the cached results for the masters, so | |
116 | * use the observation that default_power_down_ok() is not | |
117 | * going to be called for any master until this instance | |
118 | * returns. | |
119 | */ | |
120 | list_for_each_entry(link, &genpd->slave_links, slave_node) | |
121 | link->master->max_off_time_changed = true; | |
122 | ||
123 | genpd->max_off_time_changed = false; | |
124 | genpd->cached_power_down_ok = false; | |
125 | genpd->max_off_time_ns = -1; | |
126 | } else { | |
127 | return genpd->cached_power_down_ok; | |
128 | } | |
129 | ||
221e9b58 RW |
130 | off_on_time_ns = genpd->power_off_latency_ns + |
131 | genpd->power_on_latency_ns; | |
132 | /* | |
133 | * It doesn't make sense to remove power from the domain if saving | |
134 | * the state of all devices in it and the power off/power on operations | |
135 | * take too much time. | |
136 | * | |
137 | * All devices in this domain have been stopped already at this point. | |
138 | */ | |
139 | list_for_each_entry(pdd, &genpd->dev_list, list_node) { | |
140 | if (pdd->dev->driver) | |
141 | off_on_time_ns += | |
142 | to_gpd_data(pdd)->td.save_state_latency_ns; | |
143 | } | |
144 | ||
b723b0eb | 145 | min_off_time_ns = -1; |
221e9b58 RW |
146 | /* |
147 | * Check if subdomains can be off for enough time. | |
148 | * | |
149 | * All subdomains have been powered off already at this point. | |
150 | */ | |
151 | list_for_each_entry(link, &genpd->master_links, master_node) { | |
152 | struct generic_pm_domain *sd = link->slave; | |
153 | s64 sd_max_off_ns = sd->max_off_time_ns; | |
154 | ||
155 | if (sd_max_off_ns < 0) | |
156 | continue; | |
157 | ||
221e9b58 RW |
158 | /* |
159 | * Check if the subdomain is allowed to be off long enough for | |
160 | * the current domain to turn off and on (that's how much time | |
161 | * it will have to wait worst case). | |
162 | */ | |
163 | if (sd_max_off_ns <= off_on_time_ns) | |
164 | return false; | |
b723b0eb RW |
165 | |
166 | if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0) | |
167 | min_off_time_ns = sd_max_off_ns; | |
221e9b58 RW |
168 | } |
169 | ||
170 | /* | |
171 | * Check if the devices in the domain can be off enough time. | |
172 | */ | |
221e9b58 RW |
173 | list_for_each_entry(pdd, &genpd->dev_list, list_node) { |
174 | struct gpd_timing_data *td; | |
dd8683e9 | 175 | s64 constraint_ns; |
221e9b58 | 176 | |
dd8683e9 | 177 | if (!pdd->dev->driver) |
221e9b58 RW |
178 | continue; |
179 | ||
dd8683e9 RW |
180 | /* |
181 | * Check if the device is allowed to be off long enough for the | |
182 | * domain to turn off and on (that's how much time it will | |
183 | * have to wait worst case). | |
184 | */ | |
221e9b58 | 185 | td = &to_gpd_data(pdd)->td; |
dd8683e9 RW |
186 | constraint_ns = td->effective_constraint_ns; |
187 | /* default_stop_ok() need not be called before us. */ | |
188 | if (constraint_ns < 0) { | |
189 | constraint_ns = dev_pm_qos_read_value(pdd->dev); | |
190 | constraint_ns *= NSEC_PER_USEC; | |
191 | } | |
192 | if (constraint_ns == 0) | |
193 | continue; | |
221e9b58 | 194 | |
221e9b58 | 195 | /* |
dd8683e9 RW |
196 | * constraint_ns cannot be negative here, because the device has |
197 | * been suspended. | |
221e9b58 | 198 | */ |
dd8683e9 RW |
199 | constraint_ns -= td->restore_state_latency_ns; |
200 | if (constraint_ns <= off_on_time_ns) | |
201 | return false; | |
202 | ||
b723b0eb RW |
203 | if (min_off_time_ns > constraint_ns || min_off_time_ns < 0) |
204 | min_off_time_ns = constraint_ns; | |
221e9b58 RW |
205 | } |
206 | ||
6ff7bb0d RW |
207 | genpd->cached_power_down_ok = true; |
208 | ||
221e9b58 | 209 | /* |
dd8683e9 RW |
210 | * If the computed minimum device off time is negative, there are no |
211 | * latency constraints, so the domain can spend arbitrary time in the | |
212 | * "off" state. | |
221e9b58 | 213 | */ |
b723b0eb | 214 | if (min_off_time_ns < 0) |
dd8683e9 | 215 | return true; |
221e9b58 RW |
216 | |
217 | /* | |
b723b0eb RW |
218 | * The difference between the computed minimum subdomain or device off |
219 | * time and the time needed to turn the domain on is the maximum | |
220 | * theoretical time this domain can spend in the "off" state. | |
221e9b58 | 221 | */ |
b723b0eb | 222 | genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns; |
221e9b58 RW |
223 | return true; |
224 | } | |
225 | ||
925b44a2 MB |
226 | static bool always_on_power_down_ok(struct dev_pm_domain *domain) |
227 | { | |
228 | return false; | |
229 | } | |
230 | ||
e59a8db8 RW |
231 | #else /* !CONFIG_PM_RUNTIME */ |
232 | ||
233 | bool default_stop_ok(struct device *dev) | |
234 | { | |
235 | return false; | |
236 | } | |
237 | ||
238 | #define default_power_down_ok NULL | |
239 | #define always_on_power_down_ok NULL | |
240 | ||
241 | #endif /* !CONFIG_PM_RUNTIME */ | |
242 | ||
243 | struct dev_power_governor simple_qos_governor = { | |
244 | .stop_ok = default_stop_ok, | |
245 | .power_down_ok = default_power_down_ok, | |
246 | }; | |
247 | ||
925b44a2 MB |
248 | /** |
249 | * pm_genpd_gov_always_on - A governor implementing an always-on policy | |
250 | */ | |
251 | struct dev_power_governor pm_domain_always_on_gov = { | |
252 | .power_down_ok = always_on_power_down_ok, | |
253 | .stop_ok = default_stop_ok, | |
254 | }; |