本文介绍了一个用于表示输入设备的结构体input_dev。该结构体详细记录了设备的名称、物理路径、唯一标识符等基本信息，并通过位图表示设备支持的各种事件类型及特性，如按键、相对轴、绝对轴等。
- 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
- };
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