Rafael J. Wysocki | b02c999 | 2011-12-01 00:02:05 +0100 | [diff] [blame] | 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> |
Rafael J. Wysocki | 221e9b5 | 2011-12-01 00:02:10 +0100 | [diff] [blame] | 13 | #include <linux/hrtimer.h> |
Rafael J. Wysocki | b02c999 | 2011-12-01 00:02:05 +0100 | [diff] [blame] | 14 | |
Rafael J. Wysocki | e59a8db | 2012-01-14 00:39:36 +0100 | [diff] [blame] | 15 | #ifdef CONFIG_PM_RUNTIME |
| 16 | |
Rafael J. Wysocki | b02c999 | 2011-12-01 00:02:05 +0100 | [diff] [blame] | 17 | /** |
| 18 | * default_stop_ok - Default PM domain governor routine for stopping devices. |
| 19 | * @dev: Device to check. |
| 20 | */ |
| 21 | bool default_stop_ok(struct device *dev) |
| 22 | { |
| 23 | struct gpd_timing_data *td = &dev_gpd_data(dev)->td; |
| 24 | |
| 25 | dev_dbg(dev, "%s()\n", __func__); |
| 26 | |
| 27 | if (dev->power.max_time_suspended_ns < 0 || td->break_even_ns == 0) |
| 28 | return true; |
| 29 | |
| 30 | return td->stop_latency_ns + td->start_latency_ns < td->break_even_ns |
| 31 | && td->break_even_ns < dev->power.max_time_suspended_ns; |
| 32 | } |
| 33 | |
Rafael J. Wysocki | 221e9b5 | 2011-12-01 00:02:10 +0100 | [diff] [blame] | 34 | /** |
| 35 | * default_power_down_ok - Default generic PM domain power off governor routine. |
| 36 | * @pd: PM domain to check. |
| 37 | * |
| 38 | * This routine must be executed under the PM domain's lock. |
| 39 | */ |
| 40 | static bool default_power_down_ok(struct dev_pm_domain *pd) |
| 41 | { |
| 42 | struct generic_pm_domain *genpd = pd_to_genpd(pd); |
| 43 | struct gpd_link *link; |
| 44 | struct pm_domain_data *pdd; |
| 45 | s64 min_dev_off_time_ns; |
| 46 | s64 off_on_time_ns; |
| 47 | ktime_t time_now = ktime_get(); |
| 48 | |
| 49 | off_on_time_ns = genpd->power_off_latency_ns + |
| 50 | genpd->power_on_latency_ns; |
| 51 | /* |
| 52 | * It doesn't make sense to remove power from the domain if saving |
| 53 | * the state of all devices in it and the power off/power on operations |
| 54 | * take too much time. |
| 55 | * |
| 56 | * All devices in this domain have been stopped already at this point. |
| 57 | */ |
| 58 | list_for_each_entry(pdd, &genpd->dev_list, list_node) { |
| 59 | if (pdd->dev->driver) |
| 60 | off_on_time_ns += |
| 61 | to_gpd_data(pdd)->td.save_state_latency_ns; |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * Check if subdomains can be off for enough time. |
| 66 | * |
| 67 | * All subdomains have been powered off already at this point. |
| 68 | */ |
| 69 | list_for_each_entry(link, &genpd->master_links, master_node) { |
| 70 | struct generic_pm_domain *sd = link->slave; |
| 71 | s64 sd_max_off_ns = sd->max_off_time_ns; |
| 72 | |
| 73 | if (sd_max_off_ns < 0) |
| 74 | continue; |
| 75 | |
| 76 | sd_max_off_ns -= ktime_to_ns(ktime_sub(time_now, |
| 77 | sd->power_off_time)); |
| 78 | /* |
| 79 | * Check if the subdomain is allowed to be off long enough for |
| 80 | * the current domain to turn off and on (that's how much time |
| 81 | * it will have to wait worst case). |
| 82 | */ |
| 83 | if (sd_max_off_ns <= off_on_time_ns) |
| 84 | return false; |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * Check if the devices in the domain can be off enough time. |
| 89 | */ |
| 90 | min_dev_off_time_ns = -1; |
| 91 | list_for_each_entry(pdd, &genpd->dev_list, list_node) { |
| 92 | struct gpd_timing_data *td; |
| 93 | struct device *dev = pdd->dev; |
| 94 | s64 dev_off_time_ns; |
| 95 | |
| 96 | if (!dev->driver || dev->power.max_time_suspended_ns < 0) |
| 97 | continue; |
| 98 | |
| 99 | td = &to_gpd_data(pdd)->td; |
| 100 | dev_off_time_ns = dev->power.max_time_suspended_ns - |
| 101 | (td->start_latency_ns + td->restore_state_latency_ns + |
| 102 | ktime_to_ns(ktime_sub(time_now, |
| 103 | dev->power.suspend_time))); |
| 104 | if (dev_off_time_ns <= off_on_time_ns) |
| 105 | return false; |
| 106 | |
| 107 | if (min_dev_off_time_ns > dev_off_time_ns |
| 108 | || min_dev_off_time_ns < 0) |
| 109 | min_dev_off_time_ns = dev_off_time_ns; |
| 110 | } |
| 111 | |
| 112 | if (min_dev_off_time_ns < 0) { |
| 113 | /* |
| 114 | * There are no latency constraints, so the domain can spend |
| 115 | * arbitrary time in the "off" state. |
| 116 | */ |
| 117 | genpd->max_off_time_ns = -1; |
| 118 | return true; |
| 119 | } |
| 120 | |
| 121 | /* |
| 122 | * The difference between the computed minimum delta and the time needed |
| 123 | * to turn the domain on is the maximum theoretical time this domain can |
| 124 | * spend in the "off" state. |
| 125 | */ |
| 126 | min_dev_off_time_ns -= genpd->power_on_latency_ns; |
| 127 | |
| 128 | /* |
| 129 | * If the difference between the computed minimum delta and the time |
| 130 | * needed to turn the domain off and back on on is smaller than the |
| 131 | * domain's power break even time, removing power from the domain is not |
| 132 | * worth it. |
| 133 | */ |
| 134 | if (genpd->break_even_ns > |
| 135 | min_dev_off_time_ns - genpd->power_off_latency_ns) |
| 136 | return false; |
| 137 | |
| 138 | genpd->max_off_time_ns = min_dev_off_time_ns; |
| 139 | return true; |
| 140 | } |
| 141 | |
Mark Brown | 925b44a | 2011-12-08 23:27:28 +0100 | [diff] [blame] | 142 | static bool always_on_power_down_ok(struct dev_pm_domain *domain) |
| 143 | { |
| 144 | return false; |
| 145 | } |
| 146 | |
Rafael J. Wysocki | e59a8db | 2012-01-14 00:39:36 +0100 | [diff] [blame] | 147 | #else /* !CONFIG_PM_RUNTIME */ |
| 148 | |
| 149 | bool default_stop_ok(struct device *dev) |
| 150 | { |
| 151 | return false; |
| 152 | } |
| 153 | |
| 154 | #define default_power_down_ok NULL |
| 155 | #define always_on_power_down_ok NULL |
| 156 | |
| 157 | #endif /* !CONFIG_PM_RUNTIME */ |
| 158 | |
| 159 | struct dev_power_governor simple_qos_governor = { |
| 160 | .stop_ok = default_stop_ok, |
| 161 | .power_down_ok = default_power_down_ok, |
| 162 | }; |
| 163 | |
Mark Brown | 925b44a | 2011-12-08 23:27:28 +0100 | [diff] [blame] | 164 | /** |
| 165 | * pm_genpd_gov_always_on - A governor implementing an always-on policy |
| 166 | */ |
| 167 | struct dev_power_governor pm_domain_always_on_gov = { |
| 168 | .power_down_ok = always_on_power_down_ok, |
| 169 | .stop_ok = default_stop_ok, |
| 170 | }; |