1 /* 2 * drivers/base/power/sysfs.c - sysfs entries for device PM 3 */ 4 5 #include <linux/device.h> 6 #include <linux/string.h> 7 #include "power.h" 8 9 10 #ifdef CONFIG_PM_SYSFS_DEPRECATED 11 12 /** 13 * state - Control current power state of device 14 * 15 * show() returns the current power state of the device. '0' indicates 16 * the device is on. Other values (2) indicate the device is in some low 17 * power state. 18 * 19 * store() sets the current power state, which is an integer valued 20 * 0, 2, or 3. Devices with bus.suspend_late(), or bus.resume_early() 21 * methods fail this operation; those methods couldn't be called. 22 * Otherwise, 23 * 24 * - If the recorded dev->power.power_state.event matches the 25 * target value, nothing is done. 26 * - If the recorded event code is nonzero, the device is reactivated 27 * by calling bus.resume() and/or class.resume(). 28 * - If the target value is nonzero, the device is suspended by 29 * calling class.suspend() and/or bus.suspend() with event code 30 * PM_EVENT_SUSPEND. 31 * 32 * This mechanism is DEPRECATED and should only be used for testing. 33 */ 34 35 static ssize_t state_show(struct device * dev, struct device_attribute *attr, char * buf) 36 { 37 if (dev->power.power_state.event) 38 return sprintf(buf, "2\n"); 39 else 40 return sprintf(buf, "0\n"); 41 } 42 43 static ssize_t state_store(struct device * dev, struct device_attribute *attr, const char * buf, size_t n) 44 { 45 pm_message_t state; 46 int error = -EINVAL; 47 48 /* disallow incomplete suspend sequences */ 49 if (dev->bus && (dev->bus->suspend_late || dev->bus->resume_early)) 50 return error; 51 52 state.event = PM_EVENT_SUSPEND; 53 /* Older apps expected to write "3" here - confused with PCI D3 */ 54 if ((n == 1) && !strcmp(buf, "3")) 55 error = dpm_runtime_suspend(dev, state); 56 57 if ((n == 1) && !strcmp(buf, "2")) 58 error = dpm_runtime_suspend(dev, state); 59 60 if ((n == 1) && !strcmp(buf, "0")) { 61 dpm_runtime_resume(dev); 62 error = 0; 63 } 64 65 return error ? error : n; 66 } 67 68 static DEVICE_ATTR(state, 0644, state_show, state_store); 69 70 71 #endif /* CONFIG_PM_SYSFS_DEPRECATED */ 72 73 /* 74 * wakeup - Report/change current wakeup option for device 75 * 76 * Some devices support "wakeup" events, which are hardware signals 77 * used to activate devices from suspended or low power states. Such 78 * devices have one of three values for the sysfs power/wakeup file: 79 * 80 * + "enabled\n" to issue the events; 81 * + "disabled\n" not to do so; or 82 * + "\n" for temporary or permanent inability to issue wakeup. 83 * 84 * (For example, unconfigured USB devices can't issue wakeups.) 85 * 86 * Familiar examples of devices that can issue wakeup events include 87 * keyboards and mice (both PS2 and USB styles), power buttons, modems, 88 * "Wake-On-LAN" Ethernet links, GPIO lines, and more. Some events 89 * will wake the entire system from a suspend state; others may just 90 * wake up the device (if the system as a whole is already active). 91 * Some wakeup events use normal IRQ lines; other use special out 92 * of band signaling. 93 * 94 * It is the responsibility of device drivers to enable (or disable) 95 * wakeup signaling as part of changing device power states, respecting 96 * the policy choices provided through the driver model. 97 * 98 * Devices may not be able to generate wakeup events from all power 99 * states. Also, the events may be ignored in some configurations; 100 * for example, they might need help from other devices that aren't 101 * active, or which may have wakeup disabled. Some drivers rely on 102 * wakeup events internally (unless they are disabled), keeping 103 * their hardware in low power modes whenever they're unused. This 104 * saves runtime power, without requiring system-wide sleep states. 105 */ 106 107 static const char enabled[] = "enabled"; 108 static const char disabled[] = "disabled"; 109 110 static ssize_t 111 wake_show(struct device * dev, struct device_attribute *attr, char * buf) 112 { 113 return sprintf(buf, "%s\n", device_can_wakeup(dev) 114 ? (device_may_wakeup(dev) ? enabled : disabled) 115 : ""); 116 } 117 118 static ssize_t 119 wake_store(struct device * dev, struct device_attribute *attr, 120 const char * buf, size_t n) 121 { 122 char *cp; 123 int len = n; 124 125 if (!device_can_wakeup(dev)) 126 return -EINVAL; 127 128 cp = memchr(buf, '\n', n); 129 if (cp) 130 len = cp - buf; 131 if (len == sizeof enabled - 1 132 && strncmp(buf, enabled, sizeof enabled - 1) == 0) 133 device_set_wakeup_enable(dev, 1); 134 else if (len == sizeof disabled - 1 135 && strncmp(buf, disabled, sizeof disabled - 1) == 0) 136 device_set_wakeup_enable(dev, 0); 137 else 138 return -EINVAL; 139 return n; 140 } 141 142 static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store); 143 144 145 static struct attribute * power_attrs[] = { 146 #ifdef CONFIG_PM_SYSFS_DEPRECATED 147 &dev_attr_state.attr, 148 #endif 149 &dev_attr_wakeup.attr, 150 NULL, 151 }; 152 static struct attribute_group pm_attr_group = { 153 .name = "power", 154 .attrs = power_attrs, 155 }; 156 157 int dpm_sysfs_add(struct device * dev) 158 { 159 return sysfs_create_group(&dev->kobj, &pm_attr_group); 160 } 161 162 void dpm_sysfs_remove(struct device * dev) 163 { 164 sysfs_remove_group(&dev->kobj, &pm_attr_group); 165 } 166