usb输入子系统键盘(四)

title: usb输入子系统键盘
tags: linux
date: 2018/12/20/ 17:05:08
toc: true

usb输入子系统键盘

参考文档 https://www.cnblogs.com/lifexy/p/7645527.html

目录

设计思路

  1. 修改匹配的id_table为键盘

    static struct usb_device_id myusb_kbd_id_table [] = {
       { USB_INTERFACE_INFO(
              USB_INTERFACE_CLASS_HID,                      //接口类:hid类
              USB_INTERFACE_SUBCLASS_BOOT,             //子类:启动设备类
              USB_INTERFACE_PROTOCOL_KEYBOARD) }, //USB协议:键盘协议
};

  2. 按键键值的转换，上传的按键数据是8字节的

    buf[0]

        |--bit0:   Left Control是否按下，按下为1 
    |--bit1:   Left Shift  是否按下，按下为1 
    |--bit2:   Left Alt    是否按下，按下为1 
    |--bit3:   Left GUI    是否按下，按下为1 
    |--bit4:   Right Control是否按下，按下为1  
    |--bit5:   Right Shift 是否按下，按下为1 
    |--bit6:   Right Alt   是否按下，按下为1 
    |--bit7:   Right GUI   是否按下，按下为1

    buf[1]

    保留

    buf[2~6]

    按键值，也就是表示支持最多6个按键一起按，这里的数据需要转换，以按键A为例

    //input中上报
#define KEY_A			30

//buf中上传的数据
=04

  3. 按键上报

    这里就会有一个映射表/drivers/hid/usbhid/usbkbd.c，可以发现usb_kbd_keycode[4]=30也就是实际值，其中0表示保留的意思。

    static unsigned char usb_kbd_keycode[256] = {
	  0,  0,  0,  0, 30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38,
	 50, 49, 24, 25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44,  2,  3,
	  4,  5,  6,  7,  8,  9, 10, 11, 28,  1, 14, 15, 57, 12, 13, 26,
	 27, 43, 43, 39, 40, 41, 51, 52, 53, 58, 59, 60, 61, 62, 63, 64,
	 65, 66, 67, 68, 87, 88, 99, 70,119,110,102,104,111,107,109,106,
	105,108,103, 69, 98, 55, 74, 78, 96, 79, 80, 81, 75, 76, 77, 71,
	 72, 73, 82, 83, 86,127,116,117,183,184,185,186,187,188,189,190,
	191,192,193,194,134,138,130,132,128,129,131,137,133,135,136,113,
	115,114,  0,  0,  0,121,  0, 89, 93,124, 92, 94, 95,  0,  0,  0,
	122,123, 90, 91, 85,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
	  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
	  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
	  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
	  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
	 29, 42, 56,125, 97, 54,100,126,164,166,165,163,161,115,114,113,
	150,158,159,128,136,177,178,176,142,152,173,140
};

    如何转换特殊的按键值也就是buf[0]，搜索这个索引表有以下函数

    for (i = 0; i < 8; i++)
input_report_key(kbd->dev, usb_kbd_keycode[i + 224], (kbd->new[0] >> i) & 1);

    也就是对于kbd->new[0]的每一位上报的是usb_kbd_keycode[i + 224]，查看下226的索引是56

    #define KEY_LEFTALT		56

  4. 具体的参考上报

    void my_memcpy(unsigned char *dest,unsigned char *src,int len)      //复制缓存
{
       while(len--)
        {
            *dest++= *src++;
        }
}

static void myusb_kbd_irq(struct urb *urb)               //键盘中断函数
{
   static unsigned char buf1[8]={0,0,0,0,0,0,0,0};
   int i;

      /*上传crtl、shift、atl、windows 等按键*/
     for (i = 0; i < 8; i++)
     if(((myusb_kbd_buf[0]>>i)&1)!=((buf1[0]>>i)&1))
     {    
             input_report_key(myusb_kbd_dev, usb_kbd_keycode[i + 224], (myusb_kbd_buf[0]>> i) & 1);
             input_sync(myusb_kbd_dev);             //上传同步事件
      }


     /*上传普通按键*/
    for(i=2;i<8;i++)
    if(myusb_kbd_buf[i]!=buf1[i])
    {
     if(myusb_kbd_buf[i] )      //按下事件
    input_report_key(myusb_kbd_dev,usb_kbd_keycode[myusb_kbd_buf[i]], 1);   
    else  if(buf1[i])                                             //松开事件
    input_report_key(myusb_kbd_dev,usb_kbd_keycode[buf1[i]], 0);
    input_sync(myusb_kbd_dev);             //上传同步事件
    }

  my_memcpy(buf1, myusb_kbd_buf, 8);       //更新数据    
  usb_submit_urb(myusb_kbd_urb, GFP_KERNEL);
}

内核的上报代码

static void usb_kbd_irq(struct urb *urb)
{
       struct usb_kbd *kbd = urb->context;
       int i;
       switch (urb->status) {                        // 只有urb->status==0时,说明数据传输成功
       case 0:                  /* success */
              break;
       case -ECONNRESET:     /* unlink */
       case -ENOENT:
       case -ESHUTDOWN:
              return;
       /* -EPIPE:  should clear the halt */
       default:          /* error */
              goto resubmit;
       }

       for (i = 0; i < 8; i++)                           //上传crtl、shift、atl、windows 等按键
              input_report_key(kbd->dev, usb_kbd_keycode[i + 224], (kbd->new[0] >> i) & 1);

       for (i = 2; i < 8; i++) {                  //上传普通按键
              /*通过上个状态的按键数据kbd->old[i]的非0值,来查找当前状态的按键数据,若没有找到,说明已经松开了该按键 */
          if (kbd->old[i] > 3 && memscan(kbd->new + 2, kbd->old[i], 6) == kbd->new + 8) {
              if (usb_kbd_keycode[kbd->old[i]])              //再次判断键盘描述码表的值是否非0
                input_report_key(kbd->dev, usb_kbd_keycode[kbd->old[i]], 0); //上传松开事件
               else
                info("Unknown key (scancode %#x) released.", kbd->old[i]);
              }

　　　　　　/*通过当前状态的按键数据kbd->new[i]的非0值,来查找上个状态的按键数据,若没有找到,说明已经按下了该按键 */
         if (kbd->new[i] > 3 && memscan(kbd->old + 2, kbd->new[i], 6) == kbd->old + 8) {
             if (usb_kbd_keycode[kbd->new[i]]) //再次判断键盘描述码表的值是否非0
                input_report_key(kbd->dev, usb_kbd_keycode[kbd->new[i]], 1);      //上传按下事件
             else
                info("Unknown key (scancode %#x) pressed.", kbd->new[i]);
              }
       }

       input_sync(kbd->dev); 
       memcpy(kbd->old, kbd->new, 8);                     //更新上个状态值 
resubmit:
       i = usb_submit_urb (urb, GFP_ATOMIC);
       if (i)
         err ("can't resubmit intr, %s-%s/input0, status %d",
         kbd->usbdev->bus->bus_name,
         kbd->usbdev->devpath, i);
}

  • 判断按键中if (kbd->old[i] > 3 因为按键值的索引是从A也就是4开始的

  • memscan 是在某个内存中寻找一个自身，这里memscan(kbd->new + 2, kbd->old[i], 6) == kbd->new + 8)也就是表示找不到的意思，也就是放置类似这种情况

    第一次扫描 A 按下，在 buf[3]

    第二次扫描 A按下，但是在buf[4],但是依然不去上报

    void *memscan(void *addr, int c, size_t size)
{
	unsigned char *p = addr;

	while (size) {
		if (*p == c)
			return (void *)p;
		p++;
		size--;
	}
  	return (void *)p;
}

完整代码

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/usb/input.h>
#include <linux/hid.h>

static struct input_dev *myusb_kbd_dev;           //input_dev
static unsigned char *myusb_kbd_buf;                //虚拟地址缓存区
static dma_addr_t myusb_kbd_phyc;                  //DMA缓存区;

static __le16 myusb_kbd_size;                            //数据包长度
static struct urb  *myusb_kbd_urb;                     //urb

static const unsigned char usb_kbd_keycode[252] = {
         0,  0,  0,  0, 30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38,
        50, 49, 24, 25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44,  2,  3,
         4,  5,  6,  7,  8,  9, 10, 11, 28,  1, 14, 15, 57, 12, 13, 26,
        27, 43, 43, 39, 40, 41, 51, 52, 53, 58, 59, 60, 61, 62, 63, 64,
        65, 66, 67, 68, 87, 88, 99, 70,119,110,102,104,111,107,109,106,
       105,108,103, 69, 98, 55, 74, 78, 96, 79, 80, 81, 75, 76, 77, 71,
        72, 73, 82, 83, 86,127,116,117,183,184,185,186,187,188,189,190,
       191,192,193,194,134,138,130,132,128,129,131,137,133,135,136,113,
       115,114,  0,  0,  0,121,  0, 89, 93,124, 92, 94, 95,  0,  0,  0,
       122,123, 90, 91, 85,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
         0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        29, 42, 56,125, 97, 54,100,126,164,166,165,163,161,115,114,113,
       150,158,159,128,136,177,178,176,142,152,173,140
};       //键盘码表共有252个数据

 
void my_memcpy(unsigned char *dest,unsigned char *src,int len)      //复制缓存
{
       while(len--)
        {
            *dest++= *src++;
        }
}

static void myusb_kbd_irq(struct urb *urb)               //键盘中断函数
{
   static unsigned char buf1[8]={0,0,0,0,0,0,0,0};
   int i;

      /*上传crtl、shift、atl、windows 等按键*/
     for (i = 0; i < 8; i++)
     if(((myusb_kbd_buf[0]>>i)&1)!=((buf1[0]>>i)&1))
     {    
             input_report_key(myusb_kbd_dev, usb_kbd_keycode[i + 224], (myusb_kbd_buf[0]>> i) & 1);
             input_sync(myusb_kbd_dev);             //上传同步事件
      }


     /*上传普通按键*/
    for(i=2;i<8;i++)
    if(myusb_kbd_buf[i]!=buf1[i])
    {
     if(myusb_kbd_buf[i] )      //按下事件
    input_report_key(myusb_kbd_dev,usb_kbd_keycode[myusb_kbd_buf[i]], 1);   
    else  if(buf1[i])                                             //松开事件
    input_report_key(myusb_kbd_dev,usb_kbd_keycode[buf1[i]], 0);
    input_sync(myusb_kbd_dev);             //上传同步事件
    }

  my_memcpy(buf1, myusb_kbd_buf, 8);       //更新数据    
  usb_submit_urb(myusb_kbd_urb, GFP_KERNEL);
}

static int myusb_kbd_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
       volatile unsigned char  i;
       struct usb_device *dev = interface_to_usbdev(intf);                 //设备
       struct usb_endpoint_descriptor *endpoint;                            
       struct usb_host_interface *interface;                                              //当前接口
       int pipe;                                                                               //端点管道
       interface=intf->cur_altsetting;                                                                   
       endpoint = &interface->endpoint[0].desc;                                    //当前接口下的端点描述符
       printk("VID=%x,PID=%x
",dev->descriptor.idVendor,dev->descriptor.idProduct);   

 /*   1)分配一个input_dev结构体  */
       myusb_kbd_dev=input_allocate_device();

 /*   2)设置input_dev支持 按键事件*/
       set_bit(EV_KEY, myusb_kbd_dev->evbit);
       set_bit(EV_REP, myusb_kbd_dev->evbit);        //支持重复按功能

       for (i = 0; i < 252; i++)
       set_bit(usb_kbd_keycode[i], myusb_kbd_dev->keybit);     //添加所有键
       clear_bit(0, myusb_kbd_dev->keybit);

 /*   3)注册input_dev结构体*/
       input_register_device(myusb_kbd_dev);

 /*   4)设置USB键盘数据传输 */
 /*->4.1)通过usb_rcvintpipe()创建一个端点管道*/
       pipe=usb_rcvintpipe(dev,endpoint->bEndpointAddress); 

  /*->4.2)通过usb_buffer_alloc()申请USB缓冲区*/
      myusb_kbd_size=endpoint->wMaxPacketSize;
      myusb_kbd_buf=usb_buffer_alloc(dev,myusb_kbd_size,GFP_ATOMIC,&myusb_kbd_phyc);

  /*->4.3)通过usb_alloc_urb()和usb_fill_int_urb()申请并初始化urb结构体 */
       myusb_kbd_urb=usb_alloc_urb(0,GFP_KERNEL);
       usb_fill_int_urb (myusb_kbd_urb,              //urb结构体
                                 dev,                                       //usb设备
                                 pipe,                                      //端点管道
                                 myusb_kbd_buf,               //缓存区地址
                                 myusb_kbd_size,              //数据长度
                                 myusb_kbd_irq,               //中断函数
                                 0,
                                 endpoint->bInterval);              //中断间隔时间
 
  /*->4.4) 因为我们2440支持DMA,所以要告诉urb结构体,使用DMA缓冲区地址*/
        myusb_kbd_urb->transfer_dma   =myusb_kbd_phyc;                  //设置DMA地址
        myusb_kbd_urb->transfer_flags   =URB_NO_TRANSFER_DMA_MAP;     //设置使用DMA地址

  /*->4.5)使用usb_submit_urb()提交urb*/
        usb_submit_urb(myusb_kbd_urb, GFP_KERNEL);   
       return 0;
}

static void myusb_kbd_disconnect(struct usb_interface *intf)
{
    struct usb_device *dev = interface_to_usbdev(intf);        //设备
    usb_kill_urb(myusb_kbd_urb);
    usb_free_urb(myusb_kbd_urb);
    usb_buffer_free(dev, myusb_kbd_size, myusb_kbd_buf,myusb_kbd_phyc);
    input_unregister_device(myusb_kbd_dev);               //注销内核中的input_dev
    input_free_device(myusb_kbd_dev);                        //释放input_dev
}

static struct usb_device_id myusb_kbd_id_table [] = {
       { USB_INTERFACE_INFO(
              USB_INTERFACE_CLASS_HID,                      //接口类:hid类
              USB_INTERFACE_SUBCLASS_BOOT,             //子类:启动设备类
              USB_INTERFACE_PROTOCOL_KEYBOARD) }, //USB协议:键盘协议
};

static struct usb_driver myusb_kbd_drv = {
       .name            = "myusb_kbd",
       .probe           = myusb_kbd_probe,                        
       .disconnect     = myusb_kbd_disconnect,
       .id_table  = myusb_kbd_id_table,
};

/*入口函数*/
static int myusb_kbd_init(void)
{ 
       usb_register(&myusb_kbd_drv);
       return 0;
}
 
/*出口函数*/
static void myusb_kbd_exit(void)
{
       usb_deregister(&myusb_kbd_drv);
}

module_init(myusb_kbd_init);
module_exit(myusb_kbd_exit);
MODULE_LICENSE("GPL");
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原文地址：https://www.cnblogs.com/zongzi10010/p/10155330.html