Documentation/ABI/testing/sysfs-devices-online

   1 What:           /sys/devices/.../online
   2 Date:           April 2013
   3 Contact:        Rafael J. Wysocki <rafael.j.wysocki@intel.com>
   4 Description:
   5                 The /sys/devices/.../online attribute is only present for
   6                 devices whose bus types provide .online() and .offline()
   7                 callbacks.  The number read from it (0 or 1) reflects the value
   8                 of the device's 'offline' field.  If that number is 1 and '0'
   9                 (or 'n', or 'N') is written to this file, the device bus type's
  10                 .offline() callback is executed for the device and (if
  11                 successful) its 'offline' field is updated accordingly.  In
  12                 turn, if that number is 0 and '1' (or 'y', or 'Y') is written to
  13                 this file, the device bus type's .online() callback is executed
  14                 for the device and (if successful) its 'offline' field is
  15                 updated as appropriate.
  16
  17                 After a successful execution of the bus type's .offline()
  18                 callback the device cannot be used for any purpose until either
  19                 it is removed (i.e. device_del() is called for it), or its bus
  20                 type's .online() is exeucted successfully.