input子系统一 主要数据结构

一、input子系统的分层结构

linux系统实现了很多子系统架构，每个子系统都是分层的；input子系统也不例外，主要分为三层：

(1) 硬件驱动层：与硬件相关，是驱动开发的部分。

(2) 系统核心层：是连接其他两层的纽带，对应的代码为drivers/input/input.c、input-mt.c等。

(3) 事件处理层：真正的事件处理部分，为应用程序提供读写接口；对应的代码为drivers/input/evdev.c、mousedev.c等。

二、主要数据结构

struct input_value {
__u16 type;
__u16 code;
__s32 value;
};

input设备report数据最终调用的函数是void input_event(struct input_dev *dev, unsigned int type, unsigned int code, int value)；这个函数的参数最终会填到上述结构中。

struct input_dev {
const char *name;
const char *phys;
const char *uniq;
struct input_id id;

unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)];

unsigned long evbit[BITS_TO_LONGS(EV_CNT)];
unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];
unsigned long relbit[BITS_TO_LONGS(REL_CNT)];
unsigned long absbit[BITS_TO_LONGS(ABS_CNT)];
unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)];
unsigned long ledbit[BITS_TO_LONGS(LED_CNT)];
unsigned long sndbit[BITS_TO_LONGS(SND_CNT)];
unsigned long ffbit[BITS_TO_LONGS(FF_CNT)];
unsigned long swbit[BITS_TO_LONGS(SW_CNT)];

unsigned int hint_events_per_packet;

unsigned int keycodemax;
unsigned int keycodesize;
void *keycode;

int (*setkeycode)(struct input_dev *dev,
const struct input_keymap_entry *ke,
unsigned int *old_keycode);
int (*getkeycode)(struct input_dev *dev,
struct input_keymap_entry *ke);

struct ff_device *ff;

unsigned int repeat_key;
struct timer_list timer;

int rep[REP_CNT];

struct input_mt *mt;

struct input_absinfo *absinfo;

unsigned long key[BITS_TO_LONGS(KEY_CNT)];
unsigned long led[BITS_TO_LONGS(LED_CNT)];
unsigned long snd[BITS_TO_LONGS(SND_CNT)];
unsigned long sw[BITS_TO_LONGS(SW_CNT)];

int (*open)(struct input_dev *dev);
void (*close)(struct input_dev *dev);
int (*flush)(struct input_dev *dev, struct file *file);
int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value);

struct input_handle __rcu *grab;

spinlock_t event_lock;
struct mutex mutex;

unsigned int users;
bool going_away;

struct device dev;

struct list_head	h_list;
struct list_head	node;

unsigned int num_vals;
unsigned int max_vals;
struct input_value *vals;

bool devres_managed;
};

input_dev代表一个输入设备，每个输入设备的驱动文件中都能找到它，h_list用于挂handle，node用于挂自己到全局的list上。

struct input_id {
__u16 bustype;
__u16 vendor;
__u16 product;
__u16 version;
};

struct input_handler {

void *private;

void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
void (*events)(struct input_handle *handle,
const struct input_value *vals, unsigned int count);
bool (*filter)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
bool (*match)(struct input_handler *handler, struct input_dev *dev);
int (*connect)(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id);
void (*disconnect)(struct input_handle *handle);
void (*start)(struct input_handle *handle);

bool legacy_minors;
int minor;
const char *name;

const struct input_device_id *id_table;

struct list_head	h_list;
struct list_head	node;
};

input_handler是一个事件处理，包含各种事件处理方法。h_list用于挂handle，node用于挂自己到全局的list上。

struct input_handle {

void *private;

int open;
const char *name;

struct input_dev *dev;
struct input_handler *handler;

struct list_head	d_node;
struct list_head	h_node;
};

input_handle是连接handler和dev的纽带。d_node用于挂dev，h_node用于挂handler。

在dev和handler匹配成功时，connect的时候会创建evdev->handle结构，handle会分别挂在已经匹配的dev和handler结构中。

struct input_event {
struct timeval time;
__u16 type;
__u16 code;
__s32 value;
};

struct evdev {
int open;
struct input_handle handle;
wait_queue_head_t wait;
struct evdev_client __rcu *grab;
struct list_head client_list;
spinlock_t client_lock; /* protects client_list */
struct mutex mutex;
struct device dev;
struct cdev cdev;
bool exist;
};

struct evdev_client {
unsigned int head;
unsigned int tail;
unsigned int packet_head; /* [future] position of the first element of next packet */
spinlock_t buffer_lock; /* protects access to buffer, head and tail */
struct wake_lock wake_lock;
bool use_wake_lock;
char name[28];
struct fasync_struct *fasync;
struct evdev *evdev;
struct list_head node;
int clkid;
unsigned int bufsize;
struct input_event buffer[];
};