input_dev 结构体成员注释

Name
struct input_dev — represents an input device

Synopsis
struct input_dev {
  const char * name;  //name of the device
  const char * phys;  //physical path to the device in the system hierarchy
  const char * uniq;  //unique identification code for the device (if device has it)
  struct input_id id;  //id of the device (struct input_id)
  unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; //bitmap of types of events supported by the device (EV_KEY, EV_REL, etc.)
  unsigned long keybit[BITS_TO_LONGS(KEY_CNT)]; //bitmap of keys/buttons this device has
  unsigned long relbit[BITS_TO_LONGS(REL_CNT)]; //bitmap of relative axes for the device
  unsigned long absbit[BITS_TO_LONGS(ABS_CNT)]; //bitmap of absolute axes for the device
  unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)]; //bitmap of miscellaneous events supported by the device
  unsigned long ledbit[BITS_TO_LONGS(LED_CNT)];  //bitmap of leds present on the device
  unsigned long sndbit[BITS_TO_LONGS(SND_CNT)];  //bitmap of sound effects supported by the device
  unsigned long ffbit[BITS_TO_LONGS(FF_CNT)];   //bitmap of force feedback effects supported by the device
  unsigned long swbit[BITS_TO_LONGS(SW_CNT)];  //bitmap of switches present on the device
  unsigned int keycodemax;  //size of keycode table
  unsigned int keycodesize;  //size of elements in keycode table
  void * keycode;    //map of scancodes to keycodes for this device
  /*optional method to alter current keymap, used to implement sparse keymaps.
    If not supplied default mechanism will be used*/
  int (* setkeycode) (struct input_dev *dev, int scancode, int keycode);
 /*optional method to retrieve current keymap. If not supplied default mechanism will be used*/
  int (* getkeycode) (struct input_dev *dev, int scancode, int *keycode);
  struct ff_device * ff;   //force feedback structure associated with the device if device supports force feedback effects
  unsigned int repeat_key;   //stores key code of the last key pressed; used to implement software autorepeat
  struct timer_list timer;   //timer for software autorepeat
  int sync;    //set to 1 when there were no new events since last EV_SYNC
  int abs[ABS_MAX + 1]; //current values for reports from absolute axes
  int rep[REP_MAX + 1];  //current values for autorepeat parameters (delay, rate)
  unsigned long key[BITS_TO_LONGS(KEY_CNT)]; //reflects current state of device's keys/buttons
  unsigned long led[BITS_TO_LONGS(LED_CNT)];  //reflects current state of device's LEDs
  unsigned long snd[BITS_TO_LONGS(SND_CNT)];  //reflects current state of sound effects
  unsigned long sw[BITS_TO_LONGS(SW_CNT)];  //reflects current state of device's switches
  int absmax[ABS_MAX + 1];  //maximum values for events coming from absolute axes
  int absmin[ABS_MAX + 1];  //minimum values for events coming from absolute axes
  int absfuzz[ABS_MAX + 1];  //describes noisiness for axes
  int absflat[ABS_MAX + 1];  //size of the center flat position (used by joydev)
/*this method is called when the very first user calls input_open_device.
 The driver must prepare the device to start generating events (start polling
 thread, request an IRQ, submit URB, etc.) */
  int (* open) (struct input_dev *dev);
  void (* close) (struct input_dev *dev);   //this method is called when the very last user calls input_close_device.
/*purges the device. Most commonly used to get rid of force feedback effects
  loaded into the device when disconnecting from it */
  int (* flush) (struct input_dev *dev, struct file *file);
/*event handler for events sent _to_ the device, like EV_LED or EV_SND.
  The device is expected to carry out the requested action (turn on a LED, play sound, etc.)
  The call is protected by event_lock and must not sleep */
  int (* event) (struct input_dev *dev, unsigned int type, unsigned int code, int value);
/*input handle that currently has the device grabbed (via EVIOCGRAB ioctl).
  When a handle grabs a device it becomes sole recipient for all input events coming from the device */
  struct input_handle * grab;
/*this spinlock is is taken when input core receives and processes a new event for the device (in input_event). Code that accesses and/or modifies parameters of a device (such as keymap or absmin, absmax, absfuzz, etc.) after device has been  registered with input core must take this lock. */
  spinlock_t event_lock;
  struct mutex mutex; //serializes calls to open, close and flush methods
/*stores number of users (input handlers) that opened this device. It is used by input_open_device and input_close_device to make sure that dev->open is only called when the first user opens device and dev->close is called when the very last user closes the device */
  unsigned int users;
  int going_away; //marks devices that are in a middle of unregistering and causes input_open_device*() fail with -ENODEV.
  struct device dev; //driver model's view of this device

  struct list_head h_list; //list of input handles associated with the device. When accessing the list dev->mutex must be held
  struct list_head node; //used to place the device onto input_dev_list
};