努力成为linux kernel hacker的人李万鹏原创作品,为梦而战。出处
http://blog.csdn.net/woshixingaaa/archive/2011/05/19/6431094.aspx
内核的输入子系统是对分散的,多种不同类别的输入设备(如键盘,鼠标,跟踪球,操纵杆,触摸屏,加速计和手写板)等字符设备进行统一处理的一层抽象,就是在字符设备驱动上抽象出的一层。输入子系统包括两类驱动程序:事件驱动程序和设备驱动程序。事件驱动程序负责和应用程序的接口,而设备驱动程序负责和底层输入设备的通信。鼠标事件生成文件mousedev属于事件驱动程序,而PS/2鼠标驱动程序是设备驱动程序。事件驱动程序是标准的,对所有的输入类都是可用的,所以要实现的是设备驱动程序而不是事件驱动程序。设备驱动程序可以利用一个已经存在的,合适的事件驱动程序通过输入核心和用户应用程序接口。
输入子系统带来了如下好处:
1.统一了物理形态各异的相似的输入设备的处理功能
2.提供了用于分发输入报告给用户应用程序的简单的事件接口
3.抽取出了输入驱动程序的通用部分,简化了驱动,并引入了一致性
如下图,input子系统分三层,最上一层是event handler,中间是intput core,底层是input driver。input driver把event report到input core层。input core对event进行分发,传到event handler,相应的event handler层把event放到event buffer中,等待用户进程来取。
现在了解了input子系统的基本思想,下面来看一下input子系统的3个基本的数据结构:
- struct input_dev {
- const char *name;
- const char *phys;
- const char *uniq;
- struct input_id id;
-
- 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 keycodemax;
- unsigned int keycodesize;
- void *keycode;
- int (*setkeycode)(struct input_dev *dev, int scancode, int keycode);
- int (*getkeycode)(struct input_dev *dev, int scancode, int *keycode);
-
- struct ff_device *ff;
-
- unsigned int repeat_key;
- struct timer_list timer;
-
- int sync;
-
- int abs[ABS_MAX + 1];
- int rep[REP_MAX + 1];
- 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 absmax[ABS_MAX + 1];
- int absmin[ABS_MAX + 1];
- int absfuzz[ABS_MAX + 1];
- int absflat[ABS_MAX + 1];
-
- 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 *grab;
-
- spinlock_t event_lock;
- struct mutex mutex;
-
- unsigned int users;
- int going_away;
-
- struct device dev;
-
- struct list_head h_list;
- struct list_head node;
- };
-
- struct input_handler {
-
- void *private;
-
- void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
- 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);
-
- const struct file_operations *fops;
- int minor;
- const char *name;
-
- const struct input_device_id *id_table;
- const struct input_device_id *blacklist;
-
- struct list_head h_list;
- struct list_head node;
- };
-
- 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;
- };
- struct input_dev {
- const char *name;
- const char *phys;
- const char *uniq;
- struct input_id id;
-
- 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 keycodemax;
- unsigned int keycodesize;
- void *keycode;
- int (*setkeycode)(struct input_dev *dev, int scancode, int keycode);
- int (*getkeycode)(struct input_dev *dev, int scancode, int *keycode);
-
- struct ff_device *ff;
-
- unsigned int repeat_key;
- struct timer_list timer;
-
- int sync;
-
- int abs[ABS_MAX + 1];
- int rep[REP_MAX + 1];
- 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 absmax[ABS_MAX + 1];
- int absmin[ABS_MAX + 1];
- int absfuzz[ABS_MAX + 1];
- int absflat[ABS_MAX + 1];
-
- 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 *grab;
-
- spinlock_t event_lock;
- struct mutex mutex;
-
- unsigned int users;
- int going_away;
-
- struct device dev;
-
- struct list_head h_list;
- struct list_head node;
- };
-
- struct input_handler {
-
- void *private;
-
- void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
- 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);
-
- const struct file_operations *fops;
- int minor;
- const char *name;
-
- const struct input_device_id *id_table;
- const struct input_device_id *blacklist;
-
- struct list_head h_list;
- struct list_head node;
- };
-
- 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;
- };
- struct input_dev
- { const char *name;
- const char *phys;
- const char *uniq;
- struct input_id id; //与input_handler匹配的时会用到
- unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; //支持的所有事件类型
- unsigned long keybit[BITS_TO_LONGS(KEY_CNT)]; //按键事件支持的子事件
- unsigned long relbit[BITS_TO_LONGS(REL_CNT)]; //相对坐标事件支持的子事件
- unsigned long absbit[BITS_TO_LONGS(ABS_CNT)]; //绝对坐标事件支持的子事件
- unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)]; //其他事件支持的子事件
- unsigned long ledbit[BITS_TO_LONGS(LED_CNT)]; //LED灯事件支持的子事件
- unsigned long sndbit[BITS_TO_LONGS(SND_CNT)]; //声音事件支持的子事件
- unsigned long ffbit[BITS_TO_LONGS(FF_CNT)]; //受力事件支持的子事件
- unsigned long swbit[BITS_TO_LONGS(SW_CNT)]; //开关事件支持的子事件
- unsigned int keycodemax;
- unsigned int keycodesize;
- void *keycode;
- int (*setkeycode)(struct input_dev *dev, int scancode, int keycode);
- int (*getkeycode)(struct input_dev *dev, int scancode, int *keycode);
- struct ff_device *ff;
- unsigned int repeat_key;
- struct timer_list timer;
- int sync; int abs[ABS_MAX + 1]; //绝对坐标上报的当前值
- int rep[REP_MAX + 1]; //这个参数主要是处理重复按键,后面遇到再讲
- unsigned long key[BITS_TO_LONGS(KEY_CNT)]; //按键有两种状态,按下和抬起,这个字段就是记录这两个状态。
- 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 absmax[ABS_MAX + 1]; //绝对坐标的最大值
- int absmin[ABS_MAX + 1]; //绝对坐标的最小值
- int absfuzz[ABS_MAX + 1];
- int absflat[ABS_MAX + 1];
- 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 *grab; //当前使用的
- handle spinlock_t event_lock;
- struct mutex mutex;
- unsigned int users;
- int going_away;
- struct device dev;
- struct list_head h_list; //h_list是一个链表头,用来把handle挂载在这个上
- struct list_head node; //这个node是用来连到input_dev_list上的
- };
- struct input_handler
- { void *private;
- void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
- 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);
- const struct file_operations *fops;
- int minor; //次设备号
- const char *name;
- const struct input_device_id *id_table;
- const struct input_device_id *blacklist;
- struct list_head h_list; //h_list是一个链表头,用来把handle挂载在这个上
- struct list_head node; //这个node是用来连到input_handler_list上的
- };
- struct input_handle
- { void *private;
- int open;
- const char *name;
- struct input_dev *dev; //指向input_dev
- struct input_handler *handler; //指向input_handler
- struct list_head d_node; //连到input_dev的h_list上
- struct list_head h_node; //连到input_handler的h_list上
- };
如下图代表了input_dev,input_handler,input_handle,3者之间的关系。一类handler可以和多个硬件设备相关联,一个硬件设备可以和多个handler相关联。例如:一个触摸屏设备可以作为一个event设备,作为一个鼠标设备,也可以作为一个触摸设备,所以一个设备需要与多个平台驱动进行连接。而一个平台驱动也不只为一个设备服务,一个触摸平台驱动可能要为A,B,C3个触摸设备提供上层驱动,所以需要这样一对多的连接。
下面来看看input子系统的初始化函数:
- static int __init input_init(void)
- {
- int err;
-
- input_init_abs_bypass();
-
- err = class_register(&input_class);
- if (err) {
- printk(KERN_ERR "input: unable to register input_dev class/n");
- return err;
- }
-
- err = input_proc_init();
- if (err)
- goto fail1;
-
- err = register_chrdev(INPUT_MAJOR, "input", &input_fops);
- if (err) {
- printk(KERN_ERR "input: unable to register char major %d", INPUT_MAJOR);
- goto fail2;
- }
-
- return 0;
-
- fail2: input_proc_exit();
- fail1: class_unregister(&input_class);
- return err;
- }
- subsys_initcall(input_init);
- static int __init input_init(void)
- {
- int err;
-
- input_init_abs_bypass();
-
- err = class_register(&input_class);
- if (err) {
- printk(KERN_ERR "input: unable to register input_dev class/n");
- return err;
- }
-
- err = input_proc_init();
- if (err)
- goto fail1;
-
- err = register_chrdev(INPUT_MAJOR, "input", &input_fops);
- if (err) {
- printk(KERN_ERR "input: unable to register char major %d", INPUT_MAJOR);
- goto fail2;
- }
-
- return 0;
-
- fail2: input_proc_exit();
- fail1: class_unregister(&input_class);
- return err;
- }
- subsys_initcall(input_init);
static int __init input_init(void)
{ int err; input_init_abs_bypass(); /*创建一个类input_class*/
err = class_register(&input_class);
if (err)
{ printk(KERN_ERR "input: unable to register input_dev class/n");
return err;
} /*在/proc下创建入口项*/
err = input_proc_init();
if (err) goto fail1; /*注册设备号INPUT_MAJOR的设备,记住input子系统的设备的主设备号都是13,即INPUT_MAJOR为13,并与input_fops相关联*/
err = register_chrdev(INPUT_MAJOR, "input", &input_fops);
if (err) { printk(KERN_ERR "input: unable to register char major %d", INPUT_MAJOR);
goto fail2;
}
return 0;
fail2: input_proc_exit();
fail1: class_unregister(&input_class);
return err;
}
subsys_initcall(input_init);
下面来看input子系统的file_operations,这里只有一个打开函数input_open_file,这个在事件传递部分讲解。
- static const struct file_operations input_fops = {
- .owner = THIS_MODULE,
- .open = input_open_file,
- };
- static const struct file_operations input_fops = {
- .owner = THIS_MODULE,
- .open = input_open_file,
- };
static const struct file_operations input_fops = { .owner = THIS_MODULE, .open = input_open_file, };
下边来看input_dev设备的注册:
- int input_register_device(struct input_dev *dev)
- {
- static atomic_t input_no = ATOMIC_INIT(0);
- struct input_handler *handler;
- const char *path;
- int error;
-
- __set_bit(EV_SYN, dev->evbit);
-
-
-
-
-
-
- init_timer(&dev->timer);
-
-
-
-
-
- if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
- dev->timer.data = (long) dev;
- dev->timer.function = input_repeat_key;
- dev->rep[REP_DELAY] = 250;
- dev->rep[REP_PERIOD] = 33;
- }
-
- if (!dev->getkeycode)
- dev->getkeycode = input_default_getkeycode;
-
- if (!dev->setkeycode)
- dev->setkeycode = input_default_setkeycode;
-
- dev_set_name(&dev->dev, "input%ld",
- (unsigned long) atomic_inc_return(&input_no) - 1);
-
- error = device_add(&dev->dev);
- if (error)
- return error;
-
- path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
- printk(KERN_INFO "input: %s as %s/n",
- dev->name ? dev->name : "Unspecified device", path ? path : "N/A");
- kfree(path);
-
- error = mutex_lock_interruptible(&input_mutex);
- if (error) {
- device_del(&dev->dev);
- return error;
- }
-
- list_add_tail(&dev->node, &input_dev_list);
-
- list_for_each_entry(handler, &input_handler_list, node)
- input_attach_handler(dev, handler);
-
- input_wakeup_procfs_readers();
-
- mutex_unlock(&input_mutex);
-
- return 0;
- }
- int input_register_device(struct input_dev *dev)
- {
- static atomic_t input_no = ATOMIC_INIT(0);
- struct input_handler *handler;
- const char *path;
- int error;
-
- __set_bit(EV_SYN, dev->evbit);
-
-
-
-
-
-
- init_timer(&dev->timer);
-
-
-
-
-
- if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
- dev->timer.data = (long) dev;
- dev->timer.function = input_repeat_key;
- dev->rep[REP_DELAY] = 250;
- dev->rep[REP_PERIOD] = 33;
- }
-
- if (!dev->getkeycode)
- dev->getkeycode = input_default_getkeycode;
-
- if (!dev->setkeycode)
- dev->setkeycode = input_default_setkeycode;
-
- dev_set_name(&dev->dev, "input%ld",
- (unsigned long) atomic_inc_return(&input_no) - 1);
-
- error = device_add(&dev->dev);
- if (error)
- return error;
-
- path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
- printk(KERN_INFO "input: %s as %s/n",
- dev->name ? dev->name : "Unspecified device", path ? path : "N/A");
- kfree(path);
-
- error = mutex_lock_interruptible(&input_mutex);
- if (error) {
- device_del(&dev->dev);
- return error;
- }
-
- list_add_tail(&dev->node, &input_dev_list);
-
- list_for_each_entry(handler, &input_handler_list, node)
- input_attach_handler(dev, handler);
-
- input_wakeup_procfs_readers();
-
- mutex_unlock(&input_mutex);
-
- return 0;
- }
int input_register_device(struct input_dev *dev)
{ static atomic_t input_no = ATOMIC_INIT(0);
struct input_handler *handler;
const char *path;
int error;
__set_bit(EV_SYN, dev->evbit); /* * If delay and period are pre-set by the driver, then autorepeating * is handled by the driver itself and we don't do it in input.c. */ init_timer(&dev->timer); /* *rep主要是处理重复按键,如果没有定义dev->rep[REP_DELAY]和dev->rep[REP_PERIOD], *则将其赋值为默认值。dev->rep[REP_DELAY]是指第一次按下多久算一次,这里是250ms, *dev->rep[REP_PERIOD]指如果按键没有被抬起,每33ms算一次。 */ if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) { dev->timer.data = (long) dev; dev->timer.function = input_repeat_key; dev->rep[REP_DELAY] = 250; dev->rep[REP_PERIOD] = 33; } /*如果dev没有定义getkeycode和setkeycode,则赋默认值。他们的作用一个是获得键的扫描码,一个是设置键的扫描码*/ if (!dev->getkeycode) dev->getkeycode = input_default_getkeycode; if (!dev->setkeycode) dev->setkeycode = input_default_setkeycode; dev_set_name(&dev->dev, "input%ld", (unsigned long) atomic_inc_return(&input_no) - 1); /*将input_dev封装的dev注册到sysfs*/ error = device_add(&dev->dev); if (error) return error; path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL); printk(KERN_INFO "input: %s as %s/n", dev->name ? dev->name : "Unspecified device", path ? path : "N/A"); kfree(path); error = mutex_lock_interruptible(&input_mutex); if (error) { device_del(&dev->dev); return error; } /*将input_dev挂在input_dev_list上*/ list_add_tail(&dev->node, &input_dev_list); /*匹配所有的input_handler,这个就是刚才那幅图里的一个设备对应多个handler的由来*/ list_for_each_entry(handler, &input_handler_list, node) input_attach_handler(dev, handler); input_wakeup_procfs_readers(); mutex_unlock(&input_mutex); return 0; }
跟踪程序,来看看input_attach_handler的实现:
- static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
- {
- const struct input_device_id *id;
- int error;
-
- if (handler->blacklist && input_match_device(handler->blacklist, dev))
- return -ENODEV;
-
- id = input_match_device(handler->id_table, dev);
- if (!id)
- return -ENODEV;
-
- error = handler->connect(handler, dev, id);
- if (error && error != -ENODEV)
- printk(KERN_ERR
- "input: failed to attach handler %s to device %s, "
- "error: %d/n",
- handler->name, kobject_name(&dev->dev.kobj), error);
-
- return error;
- }
- static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
- {
- const struct input_device_id *id;
- int error;
-
- if (handler->blacklist && input_match_device(handler->blacklist, dev))
- return -ENODEV;
-
- id = input_match_device(handler->id_table, dev);
- if (!id)
- return -ENODEV;
-
- error = handler->connect(handler, dev, id);
- if (error && error != -ENODEV)
- printk(KERN_ERR
- "input: failed to attach handler %s to device %s, "
- "error: %d/n",
- handler->name, kobject_name(&dev->dev.kobj), error);
-
- return error;
- }
static int input_attach_handler(struct input_dev *dev, struct input_handler *handler) { const struct input_device_id *id; int error; /*handler有一个黑名单,如果存在黑名单,并且这个id匹配就退出*/ if (handler->blacklist && input_match_device(handler->blacklist, dev)) return -ENODEV; /*匹配id,实现在下边可以看到*/ id = input_match_device(handler->id_table, dev); if (!id) return -ENODEV; /*如果匹配,则调用具体的handler的connect函数*/ error = handler->connect(handler, dev, id); if (error && error != -ENODEV) printk(KERN_ERR "input: failed to attach handler %s to device %s, " "error: %d/n", handler->name, kobject_name(&dev->dev.kobj), error); return error; }
下边来看看这个匹配函数:如果id->flags存在,并且相应的标志为被设定则进行比较。
- static const struct input_device_id *input_match_device(const struct input_device_id *id,
- struct input_dev *dev)
- {
- int i;
-
- for (; id->flags || id->driver_info; id++) {
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
- if (id->bustype != dev->id.bustype)
- continue;
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)
- if (id->vendor != dev->id.vendor)
- continue;
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)
- if (id->product != dev->id.product)
- continue;
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)
- if (id->version != dev->id.version)
- continue;
-
- MATCH_BIT(evbit, EV_MAX);
- MATCH_BIT(keybit, KEY_MAX);
- MATCH_BIT(relbit, REL_MAX);
- MATCH_BIT(absbit, ABS_MAX);
- MATCH_BIT(mscbit, MSC_MAX);
- MATCH_BIT(ledbit, LED_MAX);
- MATCH_BIT(sndbit, SND_MAX);
- MATCH_BIT(ffbit, FF_MAX);
- MATCH_BIT(swbit, SW_MAX);
-
- return id;
- }
-
- return NULL;
- }
- static const struct input_device_id *input_match_device(const struct input_device_id *id,
- struct input_dev *dev)
- {
- int i;
-
- for (; id->flags || id->driver_info; id++) {
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
- if (id->bustype != dev->id.bustype)
- continue;
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)
- if (id->vendor != dev->id.vendor)
- continue;
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)
- if (id->product != dev->id.product)
- continue;
-
- if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)
- if (id->version != dev->id.version)
- continue;
-
- MATCH_BIT(evbit, EV_MAX);
- MATCH_BIT(keybit, KEY_MAX);
- MATCH_BIT(relbit, REL_MAX);
- MATCH_BIT(absbit, ABS_MAX);
- MATCH_BIT(mscbit, MSC_MAX);
- MATCH_BIT(ledbit, LED_MAX);
- MATCH_BIT(sndbit, SND_MAX);
- MATCH_BIT(ffbit, FF_MAX);
- MATCH_BIT(swbit, SW_MAX);
-
- return id;
- }
-
- return NULL;
- }
static const struct input_device_id *input_match_device(const struct input_device_id *id, struct input_dev *dev) { int i; for (; id->flags || id->driver_info; id++) { if (id->flags & INPUT_DEVICE_ID_MATCH_BUS) if (id->bustype != dev->id.bustype) continue; if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR) if (id->vendor != dev->id.vendor) continue; if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT) if (id->product != dev->id.product) continue; if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION) if (id->version != dev->id.version) continue; MATCH_BIT(evbit, EV_MAX); MATCH_BIT(keybit, KEY_MAX); MATCH_BIT(relbit, REL_MAX); MATCH_BIT(absbit, ABS_MAX); MATCH_BIT(mscbit, MSC_MAX); MATCH_BIT(ledbit, LED_MAX); MATCH_BIT(sndbit, SND_MAX); MATCH_BIT(ffbit, FF_MAX); MATCH_BIT(swbit, SW_MAX); return id; } return NULL; }
- #define MATCH_BIT(bit, max) /
- for (i = 0; i < BITS_TO_LONGS(max); i++) /
- if ((id->bit[i] & dev->bit[i]) != id->bit[i]) /
- break; /
- if (i != BITS_TO_LONGS(max)) /
- continue;
- #define MATCH_BIT(bit, max) /
- for (i = 0; i < BITS_TO_LONGS(max); i++) /
- if ((id->bit[i] & dev->bit[i]) != id->bit[i]) /
- break; /
- if (i != BITS_TO_LONGS(max)) /
- continue;
#define MATCH_BIT(bit, max) / for (i = 0; i < BITS_TO_LONGS(max); i++) / if ((id->bit[i] & dev->bit[i]) != id->bit[i]) / break; / if (i != BITS_TO_LONGS(max)) / continue;
下边是刚刚看到的connect,这里假设这个handler是evdev_handler。如果匹配上了就会创建一个evdev,它里边封装了一个handle,会把input_dev和input_handler关联到一起。
-
-
-
-
- static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
- const struct input_device_id *id)
- {
- struct evdev *evdev;
- int minor;
- int error;
-
-
-
-
-
-
-
-
-
-
-
- for (minor = 0; minor < EVDEV_MINORS; minor++)
- if (!evdev_table[minor])
- break;
-
- if (minor == EVDEV_MINORS) {
- printk(KERN_ERR "evdev: no more free evdev devices/n");
- return -ENFILE;
- }
-
- evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
- if (!evdev)
- return -ENOMEM;
-
- INIT_LIST_HEAD(&evdev->client_list);
- spin_lock_init(&evdev->client_lock);
- mutex_init(&evdev->mutex);
- init_waitqueue_head(&evdev->wait);
-
- snprintf(evdev->name, sizeof(evdev->name), "event%d", minor);
- evdev->exist = 1;
- evdev->minor = minor;
-
- evdev->handle.dev = input_get_device(dev);
- evdev->handle.name = evdev->name;
- evdev->handle.handler = handler;
- evdev->handle.private = evdev;
-
- dev_set_name(&evdev->dev, evdev->name);
- evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
- evdev->dev.class = &input_class;
- evdev->dev.parent = &dev->dev;
- evdev->dev.release = evdev_free;
-
- device_initialize(&evdev->dev);
-
-
-
-
-
- error = input_register_handle(&evdev->handle);
- if (error)
- goto err_free_evdev;
-
- error = evdev_install_chrdev(evdev);
- if (error)
- goto err_unregister_handle;
-
- error = device_add(&evdev->dev);
- if (error)
- goto err_cleanup_evdev;
-
- return 0;
- 。。。。。。。。。。
- }
-
-
-
-
- static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
- const struct input_device_id *id)
- {
- struct evdev *evdev;
- int minor;
- int error;
-
-
-
-
-
-
-
-
-
-
-
- for (minor = 0; minor < EVDEV_MINORS; minor++)
- if (!evdev_table[minor])
- break;
-
- if (minor == EVDEV_MINORS) {
- printk(KERN_ERR "evdev: no more free evdev devices/n");
- return -ENFILE;
- }
-
- evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
- if (!evdev)
- return -ENOMEM;
-
- INIT_LIST_HEAD(&evdev->client_list);
- spin_lock_init(&evdev->client_lock);
- mutex_init(&evdev->mutex);
- init_waitqueue_head(&evdev->wait);
-
- snprintf(evdev->name, sizeof(evdev->name), "event%d", minor);
- evdev->exist = 1;
- evdev->minor = minor;
-
- evdev->handle.dev = input_get_device(dev);
- evdev->handle.name = evdev->name;
- evdev->handle.handler = handler;
- evdev->handle.private = evdev;
-
- dev_set_name(&evdev->dev, evdev->name);
- evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
- evdev->dev.class = &input_class;
- evdev->dev.parent = &dev->dev;
- evdev->dev.release = evdev_free;
-
- device_initialize(&evdev->dev);
-
-
-
-
-
- error = input_register_handle(&evdev->handle);
- if (error)
- goto err_free_evdev;
-
- error = evdev_install_chrdev(evdev);
- if (error)
- goto err_unregister_handle;
-
- error = device_add(&evdev->dev);
- if (error)
- goto err_cleanup_evdev;
-
- return 0;
- 。。。。。。。。。。
- }
/* * Create new evdev device. Note that input core serializes calls * to connect and disconnect so we don't need to lock evdev_table here. */ static int evdev_connect(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id) { struct evdev *evdev; int minor; int error; /* *首先补充几个知识点: *static struct input_handler *input_table[8]; *#define INPUT_DEVICES 256 *一共有8个input_handler,对应256个设备,所以一个handler对应32个设备。 *这个问题在我参加的一次linux驱动的面试中被问到,当时真是汗啊!!! *static struct evdev *evdev_table[EVDEV_MINORS]; *#define EVDEV_MINORS 32 *evdev理论上可对应32个设备,其对应的设备节点一般位于/dev/input/event0~/dev/input/event4 *下边的for循环,在evdev_table数组中找一个未使用的地方 */ for (minor = 0; minor < EVDEV_MINORS; minor++) if (!evdev_table[minor]) break; if (minor == EVDEV_MINORS) { printk(KERN_ERR "evdev: no more free evdev devices/n"); return -ENFILE; } /*下边的代码是分配一个evdev结构体,并对成员进行初始化*/ evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL); if (!evdev) return -ENOMEM; INIT_LIST_HEAD(&evdev->client_list); spin_lock_init(&evdev->client_lock); mutex_init(&evdev->mutex); init_waitqueue_head(&evdev->wait); snprintf(evdev->name, sizeof(evdev->name), "event%d", minor); evdev->exist = 1; evdev->minor = minor; evdev->handle.dev = input_get_device(dev); evdev->handle.name = evdev->name; evdev->handle.handler = handler; evdev->handle.private = evdev; dev_set_name(&evdev->dev, evdev->name); evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor); evdev->dev.class = &input_class; evdev->dev.parent = &dev->dev; evdev->dev.release = evdev_free; /**/ device_initialize(&evdev->dev); /* *input_register_handle完成的主要功能是: *list_add_tail_rcu(&handle->d_node, &dev->h_list); *list_add_tail(&handle->h_node, &handler->h_list); */ error = input_register_handle(&evdev->handle); if (error) goto err_free_evdev; /*evdev_install_chrdev完成的功能是evdev_table[evdev->minor]=evdev;*/ error = evdev_install_chrdev(evdev); if (error) goto err_unregister_handle; error = device_add(&evdev->dev); if (error) goto err_cleanup_evdev; return 0; 。。。。。。。。。。 }
看一下这张图会对上边的结构有清楚的认知了:
本文选自:http://blog.csdn.net/l627859442/article/details/7550923