上機實驗

韋老師的 USB 鼠標驅動，只實現了檢測鼠標左鍵、右鍵、中鍵的【按下彈起】功能，沒有實現復雜功能，可以做 demo 學習參考。使用完整 USB 鼠標功能請使用 Linux 內核自帶的 driver，如文章開頭目錄。

/* 參考: drivershidusbhidusbmouse.c */
#include < linux/kernel.h >
#include < linux/slab.h >
#include < linux/module.h >
#include < linux/init.h >
#include < linux/usb.h >
#include < linux/input.h >
#include < linux/hid.h >

struct usb_mouse_as_key_desc {
    struct usb_device *dev;
    struct usb_interface *intf;
    const struct usb_device_id *id;
    int pipe, maxp;
    int bInterval;
    void *data_buffer;
    dma_addr_t data_dma;
    struct urb *urb;
};

/* 1. 構造 usb_driver 
 * 1.1 id_table : 能支持哪些設備
 * 1.2 probe : 記錄某些信息, 分配/設置/注冊 input_dev, 也許"分配/填充/提交 URB"
 */

static struct usb_device_id usb_mouse_as_key_id_table [] = {
 { USB_INTERFACE_INFO(USB_INTERFACE_CLASS_HID, USB_INTERFACE_SUBCLASS_BOOT,
  USB_INTERFACE_PROTOCOL_MOUSE), .driver_info = (kernel_ulong_t)"it is a mouse", },
 { } /* Terminating entry */
};

static void usb_mouse_as_key_irq(struct urb *urb)
{
 struct input_dev *dev = urb- >context;
 struct usb_mouse_as_key_desc *desc = input_get_drvdata(dev);
 signed char *data = desc- >data_buffer;
 int status;

 //printk("%s %s %d, urb- >status = %dn", __FILE__, __FUNCTION__, __LINE__, urb- >status);
 switch (urb- >status) {
 case 0:   /* success */
  break;
 case -ECONNRESET: /* unlink */
 case -ENOENT:
 case -ESHUTDOWN:
  return;
 /* -EPIPE:  should clear the halt */
 default:  /* error */
  goto resubmit;
 }

 //printk("data[1] = 0x%xn", data[1]);
 input_report_key(dev, KEY_L, data[1] & 0x01);
 input_report_key(dev, KEY_S, data[1] & 0x02);
 input_report_key(dev, KEY_ENTER, data[1] & 0x04);

 input_sync(dev);
resubmit:
 status = usb_submit_urb (urb, GFP_ATOMIC);
  //printk("%s %s %d, status = %dn", __FILE__, __FUNCTION__, __LINE__, status);
}

static int usb_mouse_as_key_open(struct input_dev *dev)
{
    struct urb *urb;
    struct usb_mouse_as_key_desc *desc = input_get_drvdata(dev);
    int err;
    
    printk("%s %s %dn", __FILE__, __FUNCTION__, __LINE__);
    /* 分配/填充/提交 URB */
    urb = usb_alloc_urb(0, GFP_KERNEL);

    desc- >urb = urb;

    usb_fill_int_urb(urb,
         desc- >dev,
         desc- >pipe,
         desc- >data_buffer,
         (desc- >maxp > 8 ? 8 : desc- >maxp),
         usb_mouse_as_key_irq,
         dev,
         desc- >bInterval);
    
    urb- >transfer_dma = desc- >data_dma;
    urb- >transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

    err = usb_submit_urb (urb, GFP_ATOMIC);
    
    printk("%s %s %d, err = %dn", __FILE__, __FUNCTION__, __LINE__, err);
    return err;
}

static void usb_mouse_as_key_close(struct input_dev *dev)
{
    struct usb_mouse_as_key_desc *desc = input_get_drvdata(dev);
    
    /* 取消/釋放 URB */
    usb_kill_urb(desc- >urb);
    usb_free_urb(desc- >urb);
}

static int usb_mouse_as_key_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
 struct usb_device *dev = interface_to_usbdev(intf);
 struct input_dev *input_dev;
 struct usb_mouse_as_key_desc *desc;
 int error;
 struct usb_host_interface *interface;
 struct usb_endpoint_descriptor *endpoint;
 int pipe, maxp;

 printk("%s %s %dn", __FILE__, __FUNCTION__, __LINE__);
 /* 1. 記錄設備信息:  intf */
 interface = intf- >cur_altsetting;

 if (interface- >desc.bNumEndpoints != 1)
  return -ENODEV;

 endpoint = &interface- >endpoint[0].desc;
 if (!usb_endpoint_is_int_in(endpoint))
  return -ENODEV;

 pipe = usb_rcvintpipe(dev, endpoint- >bEndpointAddress);
 maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe));

 desc = kmalloc(sizeof(struct usb_mouse_as_key_desc), GFP_KERNEL);
 desc- >dev  = dev;
 desc- >intf = intf;
 desc- >id   = id;
 desc- >pipe = pipe;
 desc- >maxp = maxp;
 desc- >bInterval = endpoint- >bInterval;
 desc- >data_buffer = usb_alloc_coherent(dev, maxp, GFP_ATOMIC, &desc- >data_dma);
 printk("%s %s %d, desc- >data_buffer = 0x%xn", __FILE__, __FUNCTION__, __LINE__, desc- >data_buffer);

 /* 2. 分配/設置/注冊input_dev 
  * 2.1 能產生哪類事件
  * 2.2 能產生這類事件里哪些些事件: L/S/ENTER
  * 2.3 設置函數, 比如open
  * 2.4 在open函數里: 分配/填充/提交 URB
  * 2.5 URB的回調函數: 解析數據, 上報input_event
 */

 input_dev = devm_input_allocate_device(&intf- >dev);
    
 input_set_drvdata(input_dev, desc);

 /* set 1: which type event ? */ 
 __set_bit(EV_KEY, input_dev- >evbit);

 /* set 2: which event ? */ 
 __set_bit(KEY_L, input_dev- >keybit);
 __set_bit(KEY_S, input_dev- >keybit);
 __set_bit(KEY_ENTER, input_dev- >keybit);

 /* set 3: open */
 input_dev- >open  = usb_mouse_as_key_open;
 input_dev- >close = usb_mouse_as_key_close;

 error = input_register_device(input_dev);

 usb_set_intfdata(intf, input_dev);
    
 return 0;
}

static void usb_mouse_as_key_disconnect(struct usb_interface *intf)
{
 struct input_dev *input_dev = usb_get_intfdata (intf);
    struct usb_mouse_as_key_desc *desc = input_get_drvdata(input_dev);

    usb_free_coherent(desc- >dev, desc- >maxp, desc- >data_buffer, desc- >data_dma);
    kfree(desc);
        
    input_unregister_device(input_dev);
    usb_set_intfdata(intf, NULL);
}

static struct usb_driver usb_mouse_as_key_driver = {
 .name  = "usbmouse_as_key",
 .probe  = usb_mouse_as_key_probe,
 .disconnect = usb_mouse_as_key_disconnect,
 .id_table = usb_mouse_as_key_id_table,
};

/* 入口函數  / 出口函數 */
// module_usb_driver(usb_mouse_as_key_driver);
static int __init usb_mouse_as_key__init(void)
{
    printk("%s %s %dn", __FILE__, __FUNCTION__, __LINE__);
 return usb_register(&usb_mouse_as_key_driver);
}

static void __exit usb_mouse_as_key__init_exit(void)
{ 
 usb_deregister(&usb_mouse_as_key_driver);
}

module_init(usb_mouse_as_key__init);
module_exit(usb_mouse_as_key__init_exit);

MODULE_LICENSE("GPL");

測試：

# 把 USB 鼠標查到開發板上
# 先看看原來有哪些設備節點
ls /dev/input/event*

# 安裝驅動程序
insmod usbmouse_as_key.ko

# 再看看新得到了哪個設備節點
ls /dev/input/event*

# 執行命令, 假設 event4 是新節點
hexdump /dev/input/event4

# 點擊鼠標按鍵即可觀察輸出信息

# 第 2 種測試方法: 執行以下命令，按鼠標左鍵、右鍵，再按中鍵就有輸出"ls"
cat /dev/tty0

# 第 3 種測試方法: 執行以下命令(注意"< "號前后沒有空格)，就可以使用鼠標按鍵在控制臺輸入字符
exec 0< /dev/tty0