usb: xhci-plat: properly handle probe deferral for devm_clk_get()
[linux/fpc-iii.git] / drivers / base / power / domain_governor.c
blob00a5436dd44b6ca056eab506c5b4f05d17eb5f49
1 /*
2 * drivers/base/power/domain_governor.c - Governors for device PM domains.
4 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
6 * This file is released under the GPLv2.
7 */
9 #include <linux/kernel.h>
10 #include <linux/pm_domain.h>
11 #include <linux/pm_qos.h>
12 #include <linux/hrtimer.h>
14 static int dev_update_qos_constraint(struct device *dev, void *data)
16 s64 *constraint_ns_p = data;
17 s32 constraint_ns = -1;
19 if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
20 constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
22 if (constraint_ns < 0) {
23 constraint_ns = dev_pm_qos_read_value(dev);
24 constraint_ns *= NSEC_PER_USEC;
26 if (constraint_ns == 0)
27 return 0;
30 * constraint_ns cannot be negative here, because the device has been
31 * suspended.
33 if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
34 *constraint_ns_p = constraint_ns;
36 return 0;
39 /**
40 * default_stop_ok - Default PM domain governor routine for stopping devices.
41 * @dev: Device to check.
43 static bool default_stop_ok(struct device *dev)
45 struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
46 unsigned long flags;
47 s64 constraint_ns;
49 dev_dbg(dev, "%s()\n", __func__);
51 spin_lock_irqsave(&dev->power.lock, flags);
53 if (!td->constraint_changed) {
54 bool ret = td->cached_stop_ok;
56 spin_unlock_irqrestore(&dev->power.lock, flags);
57 return ret;
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);
64 spin_unlock_irqrestore(&dev->power.lock, flags);
66 if (constraint_ns < 0)
67 return false;
69 constraint_ns *= NSEC_PER_USEC;
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.
75 if (!dev->power.ignore_children)
76 device_for_each_child(dev, &constraint_ns,
77 dev_update_qos_constraint);
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;
85 td->effective_constraint_ns = constraint_ns;
86 td->cached_stop_ok = constraint_ns >= 0;
89 * The children have been suspended already, so we don't need to take
90 * their stop latencies into account here.
92 return td->cached_stop_ok;
95 /**
96 * default_power_down_ok - Default generic PM domain power off governor routine.
97 * @pd: PM domain to check.
99 * This routine must be executed under the PM domain's lock.
101 static bool __default_power_down_ok(struct dev_pm_domain *pd,
102 unsigned int state)
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;
110 off_on_time_ns = genpd->states[state].power_off_latency_ns +
111 genpd->states[state].power_on_latency_ns;
114 min_off_time_ns = -1;
116 * Check if subdomains can be off for enough time.
118 * All subdomains have been powered off already at this point.
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;
124 if (sd_max_off_ns < 0)
125 continue;
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).
132 if (sd_max_off_ns <= off_on_time_ns)
133 return false;
135 if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
136 min_off_time_ns = sd_max_off_ns;
140 * Check if the devices in the domain can be off enough time.
142 list_for_each_entry(pdd, &genpd->dev_list, list_node) {
143 struct gpd_timing_data *td;
144 s64 constraint_ns;
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).
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;
158 if (constraint_ns == 0)
159 continue;
162 * constraint_ns cannot be negative here, because the device has
163 * been suspended.
165 if (constraint_ns <= off_on_time_ns)
166 return false;
168 if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
169 min_off_time_ns = constraint_ns;
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.
177 if (min_off_time_ns < 0)
178 return true;
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.
185 genpd->max_off_time_ns = min_off_time_ns -
186 genpd->states[state].power_on_latency_ns;
187 return true;
190 static bool default_power_down_ok(struct dev_pm_domain *pd)
192 struct generic_pm_domain *genpd = pd_to_genpd(pd);
193 struct gpd_link *link;
195 if (!genpd->max_off_time_changed)
196 return genpd->cached_power_down_ok;
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.
204 list_for_each_entry(link, &genpd->slave_links, slave_node)
205 link->master->max_off_time_changed = true;
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;
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;
218 genpd->state_idx--;
221 return genpd->cached_power_down_ok;
224 static bool always_on_power_down_ok(struct dev_pm_domain *domain)
226 return false;
229 struct dev_power_governor simple_qos_governor = {
230 .stop_ok = default_stop_ok,
231 .power_down_ok = default_power_down_ok,
235 * pm_genpd_gov_always_on - A governor implementing an always-on policy
237 struct dev_power_governor pm_domain_always_on_gov = {
238 .power_down_ok = always_on_power_down_ok,
239 .stop_ok = default_stop_ok,