drivers/base/interface.c

   1 /*
   2  * drivers/base/interface.c - common driverfs interface that's exported to
   3  *      the world for all devices.
   4  *
   5  * Copyright (c) 2002-3 Patrick Mochel
   6  * Copyright (c) 2002-3 Open Source Development Labs
   7  *
   8  * This file is released under the GPLv2
   9  *
  10  */
  11
  12 #include <linux/device.h>
  13 #include <linux/err.h>
  14 #include <linux/stat.h>
  15 #include <linux/string.h>
  16
  17 /**
  18  *      detach_state - control the default power state for the device.
  19  *
  20  *      This is the state the device enters when it's driver module is
  21  *      unloaded. The value is an unsigned integer, in the range of 0-4.
  22  *      '0' indicates 'On', so no action will be taken when the driver is
  23  *      unloaded. This is the default behavior.
  24  *      '4' indicates 'Off', meaning the driver core will call the driver's
  25  *      shutdown method to quiesce the device.
  26  *      1-3 indicate a low-power state for the device to enter via the
  27  *      driver's suspend method.
  28  */
  29
  30 static ssize_t detach_show(struct device * dev, char * buf)
  31 {
  32         return sprintf(buf, "%u\n", dev->detach_state);
  33 }
  34
  35 static ssize_t detach_store(struct device * dev, const char * buf, size_t n)
  36 {
  37         u32 state;
  38         state = simple_strtoul(buf, NULL, 10);
  39         if (state > 4)
  40                 return -EINVAL;
  41         dev->detach_state = state;
  42         return n;
  43 }
  44
  45 static DEVICE_ATTR(detach_state, 0644, detach_show, detach_store);
  46
  47
  48 struct attribute * dev_default_attrs[] = {
  49         &dev_attr_detach_state.attr,
  50         NULL,
  51 };