转载: http://blog.csdn.net/fanqipin/article/details/8019512
一.input子系统简介:
linux系统中,input输入子系统驱动主要可以分为:设备驱动层、input core层和input handler事件处理层。设备驱动层为具体用户设备驱动,输入设备由struct input-dev 结构表示,并由input_register_device和input_unregister_device来注册和卸载;input hander事件处理层主要和用户空间交互,接收用户空间下发的file operation操作命令,生成/dev/input/xx设备节点供用户空间进行file operations操作; input core层负责管理系统中的input dev设备 和input hander事件处理,并起到承上启下作用,负责输入设备和input handler之间信息传输,输入子系统结构方框图如图1所示。
二.重要数据结构及函数接口:
1.数据结构
输入设备信息,匹配input hander时主要用下面参数
struct input_id {
__u16 bustype; 总线类型
__u16 vendor; 产家编号
__u16 product; 产品编号
__u16 version; 版本信息
};
用于表示输入设备数据结构:
struct input_dev{
const char *name;
设备名
const char
*phys; 设备在系统中路径
const char *uniq;
struct
input_id id; 用于匹配input hander参数
unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)];
unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; 设备所支持事件类型,主要有EV_SYNC,EV_KEY,EV_REL,EV_ABS等
unsigned long keybit[BITS_TO_LONGS(KEY_CNT)]; 按键所对应的位图
unsigned long relbit[BITS_TO_LONGS(REL_CNT)]; 相对坐标对应位图
unsigned long absbit[BITS_TO_LONGS(ABS_CNT)]; 绝对坐标对应位图
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_slot *mt;
int mtsize;
int slot;
int trkid;
struct input_absinfo *absinfo;
unsigned long key[BITS_TO_LONGS(KEY_CNT)]; 按键对应的键值
unsigned long led[BITS_TO_LONGS(LED_CNT)]; LED对应的指示灯状态
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); 事件处理函数,主要是接收用户下发的命令,如点亮led;
struct input_handle __rcu *grab;
spinlock_t event_lock;
struct mutex mutex;
unsigned int users;
bool going_away;
bool sync;
struct device dev;
struct list_headh_list; 设备所支持的input handle;
struct list_headnode;
};
用于 输入设备事件处理 的数据结构:
struct input_handler {
void *private;
void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);
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); 当输入设备和input handler相匹配时调用该函数;
void (*disconnect)(struct input_handle *handle);
void (*start)(struct input_handle *handle);
const struct file_operations *fops; 所支持的file operation操作;
int minor;
const char *name;
const struct input_device_id *id_table; 所有能够支持的输入设备;
struct list_headh_list;
struct list_headnode;
};
连接input-dev 和input handler的数据结构:
struct input_handle {
void *private;
int open;
const char *name;
struct input_dev *dev; input dev
struct input_handler *handler; input handler
struct list_headd_node;
struct list_headh_node;
};
三. 设备驱动示例usbmouse
static struct usb_device_id usb_mouse_id_table [] = {
{ USB_INTERFACE_INFO(USB_INTERFACE_CLASS_HID, USB_INTERFACE_SUBCLASS_BOOT,
USB_INTERFACE_PROTOCOL_MOUSE) },
{ } /* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, usb_mouse_id_table);
通过USB_INTERFACE_INFO定定义一类USB device,usb
device 和usb driver通过USB_DEVICE_ID_MATCH_INT_CLASS,
USB_DEVICE_ID_MATCH_INT_SUBCLASS三个方面来进行匹配;
static struct usb_driver usb_mouse_driver =
{
.name = "usbmouse",
.probe = usb_mouse_probe,
.disconnect= usb_mouse_disconnect,
.id_table = usb_mouse_id_table,
};
static int __init
usb_mouse_init(void)
{
int retval = usb_register(&usb_mouse_driver);
if (retval == 0)
printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"DRIVER_DESC "\n");
return retval;
}
static void __exit
usb_mouse_exit(void)
{
usb_deregister(&usb_mouse_driver);
}
USB MOUSE通过usb_register和usb_unregister注册驱动到系统,当usb hub检测到USB MOUSE设备时,通过usb_mouse_driver中定义的id_table来进行驱动匹配;
匹配成功后,调用usb_mouse_driver中的usb_mouse_probe;
static int
usb_mouse_probe(struct usb_interface *intf, const struct
usb_device_id *id)
{
struct usb_device *dev = interface_to_usbdev(intf);
struct usb_host_interface *interface;
struct usb_endpoint_descriptor *endpoint;
struct usb_mouse *mouse;
struct input_dev *input_dev;
int pipe, maxp;
int error = -ENOMEM;
interface = intf->cur_altsetting; 获取当前USB配置;
if (interface->desc.bNumEndpoints != 1) 判断usb mouse endpoint个数,usb mouse 一般只有一个interrupt endpoint ;
return -ENODEV;
endpoint = &interface->endpoint[0].desc;
if (!usb_endpoint_is_int_in(endpoint)) 判断endpoint是否为中断类型;
return -ENODEV;
pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress); 创建中断接收类型的pipe,usb 控制器和usb device之间通过pipe来进行传输;
maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe)); 获取endpoint 收发数据大小;
mouse = kzalloc(sizeof(struct usb_mouse), GFP_KERNEL); 为usbmouse申请内存空间;
input_dev = input_allocate_device(); 申请input-dev空间,并进行初始化;
if (!mouse || !input_dev)
goto fail1;
申请用于存放从usb mouse获取得到数据的存储空间,如果USB 主控制器支持DMA方式,则通过变量data_dma来返回用于DMA方式获取数据的内存地址;
mouse->data = usb_alloc_coherent(dev, 8, GFP_ATOMIC,& mouse->data_dma);
if (!mouse->data)
goto fail1;
mouse->irq = usb_alloc_urb(0, GFP_KERNEL); 申请int urb 空间;
if (!mouse->irq)
goto fail2;
mouse->usbdev = dev;
mouse->dev = input_dev;
/*设备设备名字及设备路径;*/
if (dev->manufacturer)
strlcpy(mouse->name, dev->manufacturer, sizeof(mouse->name));
if (dev->product) {
if (dev->manufacturer)
strlcat(mouse->name, " ", sizeof(mouse->name));
strlcat(mouse->name, dev->product, sizeof(mouse->name));
}
if (!strlen(mouse->name))
snprintf(mouse->name, sizeof(mouse->name), "USB HIDBP Mouse %04x:%04x", le16_to_cpu(dev->descriptor.idVendor),le16_to_cpu(dev->descriptor.idProduct));
usb_make_path(dev, mouse->phys, sizeof(mouse->phys));
strlcat(mouse->phys, "/input0", sizeof(mouse->phys));
input_dev->name = mouse->name;
input_dev->phys = mouse->phys;
设置用于匹配input hander的参数信息,这里主要有bustype,vendor,product,version,注意,在usb中数据用大端方式存放,所以要先进行转换;
usb_to_input_id(dev, &input_dev->id);
input_dev->dev.parent = &intf->dev;
input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL); 设置input-dev所支持事件类型,这里usb mouse支持按键和相对坐标事件;
input_dev->keybit[BIT_WORD(BTN_MOUSE)] = BIT_MASK(BTN_LEFT) | BIT_MASK(BTN_RIGHT) | BIT_MASK(BTN_MIDDLE) ; 设置EV_KEY对应按键位图;
input_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y); 设置EV_REL相应位图;
input_dev->keybit[BIT_WORD(BTN_MOUSE)] |= BIT_MASK(BTN_SIDE) | BIT_MASK(BTN_EXTRA);
input_dev->relbit[0] |= BIT_MASK(REL_WHEEL);
input_set_drvdata(input_dev, mouse);
input_dev->open = usb_mouse_open;
input_dev->close = usb_mouse_close;
/*填充int urb基本数据;*/
usb_fill_int_urb(mouse->irq, dev, pipe, mouse->data, (maxp> 8 ? 8 : maxp) , usb_mouse_irq, mouse, endpoint->bInterval);
mouse->irq->transfer_dma = mouse->data_dma;
mouse->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 设置该标志可以防止主控制器再次申请dma空间;
error = input_register_device(mouse->dev); 注册input-dev设备
if (error)
goto fail3;
usb_set_intfdata(intf, mouse);
return 0;
fail3:
usb_free_urb(mouse->irq);
fail2:
usb_free_coherent(dev, 8, mouse->data, mouse->data_dma);
fail1:
input_free_device(input_dev);
kfree(mouse);
return error;
}
input-dev通过input_register_device注册到input core中,并通过input_id来匹配input handler,如果匹配成功,则会调用usb_mouse_open函数;
static int
usb_mouse_open(struct input_dev *dev)
{
struct usb_mouse *mouse = input_get_drvdata(dev);
mouse->irq->dev = mouse->usbdev;
if (usb_submit_urb(mouse->irq, GFP_KERNEL))
return -EIO;
return 0;
}
usb_mouse_open函数主要用于提交usb interrupt urb到usb core中;当urb提交完成后不管usb core层有没有发送成功,都会调用回调函数usb_mouse_irq;
驱动中可以通过urb中的status来判断当前urb是否成功处理;
static
void usb_mouse_irq(struct urb *urb)
{
struct usb_mouse *mouse = urb->context;
signed char *data = mouse->data;
struct input_dev *dev = mouse->dev;
int status;
switch (urb->status) { 通过status来判断urb处理是否成功;
case 0: /* success */
break;
case -ECONNRESET:/* unlink */
case -ENOENT:
case -ESHUTDOWN:
return;
/* -EPIPE: should clear the halt */
default: /* error */
goto resubmit;
}
input_report_key(dev, BTN_LEFT, data[0] & 0x01); 报告按键值;
input_report_key(dev, BTN_RIGHT, data[0] & 0x02);
input_report_key(dev, BTN_MIDDLE, data[0] & 0x04);
input_report_key(dev, BTN_SIDE, data[0] & 0x08);
input_report_key(dev, BTN_EXTRA, data[0] & 0x10);
input_report_rel(dev, REL_X, data[1]); 报告相对坐标信息;
input_report_rel(dev, REL_Y, data[2]);
input_report_rel(dev, REL_WHEEL, data[3]);
input_sync(dev); 输入信息同步,表示报告事件结束;
resubmit:
status = usb_submit_urb (urb, GFP_ATOMIC); 重新提交urb,这样系统就可以不断获取usb mouse信息;
}
在usb_mouse_irq中,通过input_report_key和input_report_rel来上报对应按键信息和坐标信息;并通过 input_sync来结束一次完整事件报告;最后通过usb_submit_urb来重复提交urb,可以使系统不断得到usb mouse信息;
四 总结
从上面示例中可以得出写一个input-dev驱动主要要做事情;
1. 为input-dev申请空间;
2. 设置input-dev的名字及设备路径;
3.设置input-dev的id_table成员,及dev parent;
4. 实现input-dev结构中的open,close,event(有些设备不需要)函数接口;
5.设置input-dev支持的事件类型,及各类型事件code对应的位图;
6.通过input_register_device注册input-dev设备;
7. 通过input_report_key,input_report_rel等函数接口上报相应事件;
8.最后通过input_sync来结束一次完整上报事件;
原文:http://www.cnblogs.com/pengdonglin137/p/3705668.html