drivers/base/power/sysfs.c

   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 }