usb触摸屏驱动 - usbtouchscreen

驱动编译:

目前的kernel中都是自带了usbtouchscreen驱动的,我的版本3.1.10

源码位于:/kernel/drivers/input/touchscreen/usbtouchscreen.c

从这个路径可以看出所属驱动分支,我这边平台本身是没放开的,并没有编译进kernel,谁会想到触摸电视呢~

可以在make menuconfig之后,通过Device Drivers——>Input device support——>Touchscreens——>USB Touchscreen Driver 然后选取需要的touchscreen类型

通过查看相关目录下的的Kconfig Makefile,可参考:Kernel 编译配置机制

注册usb驱动:

熟悉linux驱动的都知道模块入口:module_init(usbtouch_init) ,这里看下这个init:

static int __init usbtouch_init(void)
{
    return usb_register(&usbtouch_driver);  //调用了usb 核心的注册函数,传入的是一个usb_driver结构体指针
} int __init usbtouch_init(void)
{
    return usb_register(&usbtouch_driver);  //调用了usb 核心的注册函数,传入的是一个usb_driver结构体指针
}

usb_register实现在/kernel/include/linux/usb.h中:

static inline int usb_register(struct usb_driver *driver)
{
    return usb_register_driver(driver, THIS_MODULE, KBUILD_MODNAME);//这里再往后就是usb核心驱动的事,注册这个module驱动到usb总线上
} inline int usb_register(struct usb_driver *driver)
{
    return usb_register_driver(driver, THIS_MODULE, KBUILD_MODNAME);//这里再往后就是usb核心驱动的事,注册这个module驱动到usb总线上
}

这里必须是要先注册的总线,当一个USB设备被插入的时候,USB设备驱动,也就是usb_generic_driver会跟USB设备交互,得到其所有的各种描述符,并为每个接口都定义成为一个device,之后再加载到usb_bus上,让其去匹配其对应的接口驱动程序,有兴趣可以去看下/kernel/drivers/base/bus.c中的 bus_for_each_drv

函数。

这里注册到总线的接口驱动就是 usbtouch_driver

usbtouch_driver:

这个usb_driver类型的变量 usbtouch_driver就是整个usbtouchscreen的灵魂核心,可以在上面说到的usb.h中查看usb_driver结构原型,

这里usbtouch_driver使用了部分接口:

static struct usb_driver usbtouch_driver = {
  .name		= "usbtouchscreen", //driver name
  .probe		= usbtouch_probe,  //probe接口,用于总线上匹配检测到这个驱动对应的设备之后,/kernel/drivers/usb/core/driver.c中的usb_probe_interface调用到我们这个驱动的接口
  .disconnect	= usbtouch_disconnect,  //与probe相反,断开的时候调用
  .suspend	= usbtouch_suspend, //usb 设备挂起
  .resume		= usbtouch_resume,  // 和上面挂起相反,唤醒
  .reset_resume	= usbtouch_reset_resume,  // 重置唤醒
  .id_table	= usbtouch_devices, //支持的设备ID表
  .supports_autosuspend = 1,
};
 struct usb_driver usbtouch_driver = {
  .name		= "usbtouchscreen", //driver name
  .probe		= usbtouch_probe,  //probe接口,用于总线上匹配检测到这个驱动对应的设备之后,/kernel/drivers/usb/core/driver.c中的usb_probe_interface调用到我们这个驱动的接口
  .disconnect	= usbtouch_disconnect,  //与probe相反,断开的时候调用
  .suspend	= usbtouch_suspend, //usb 设备挂起
  .resume		= usbtouch_resume,  // 和上面挂起相反,唤醒
  .reset_resume	= usbtouch_reset_resume,  // 重置唤醒
  .id_table	= usbtouch_devices, //支持的设备ID表
  .supports_autosuspend = 1,
};

id_table:

首先可以关注一下 id_table 这个变量,代表支持的设备id列表,数据类型为:

struct usb_device_id {
  /* which fields to match against? */
  __u16		match_flags;

  /* Used for product specific matches; range is inclusive */
  __u16		idVendor;
  __u16		idProduct;
  __u16		bcdDevice_lo;
  __u16		bcdDevice_hi;

  /* Used for device class matches */
  __u8		bDeviceClass;
  __u8		bDeviceSubClass;
  __u8		bDeviceProtocol;

  /* Used for interface class matches */
  __u8		bInterfaceClass;
  __u8		bInterfaceSubClass;
  __u8		bInterfaceProtocol;

  /* not matched against */
  kernel_ulong_t	driver_info;
}; usb_device_id {
  /* which fields to match against? */
  __u16		match_flags;

  /* Used for product specific matches; range is inclusive */
  __u16		idVendor;
  __u16		idProduct;
  __u16		bcdDevice_lo;
  __u16		bcdDevice_hi;

  /* Used for device class matches */
  __u8		bDeviceClass;
  __u8		bDeviceSubClass;
  __u8		bDeviceProtocol;

  /* Used for interface class matches */
  __u8		bInterfaceClass;
  __u8		bInterfaceSubClass;
  __u8		bInterfaceProtocol;

  /* not matched against */
  kernel_ulong_t	driver_info;
};

这些设备信息会被上面说到的usb bus 来匹配对应的驱动,只有这里的信息跟usb设备驱动那边收集到的设备信息匹配上,才会调用进这个驱动.

目前已有的 id_table:

static const struct usb_device_id usbtouch_devices[] = {
#ifdef CONFIG_TOUCHSCREEN_USB_EGALAX
  /* ignore the HID capable devices, handled by usbhid */
  {USB_DEVICE_HID_CLASS(0x0eef, 0x0001), .driver_info = DEVTYPE_IGNORE},
  {USB_DEVICE_HID_CLASS(0x0eef, 0x0002), .driver_info = DEVTYPE_IGNORE},
...
#endif
...
};
 const struct usb_device_id usbtouch_devices[] = {
#ifdef CONFIG_TOUCHSCREEN_USB_EGALAX
  /* ignore the HID capable devices, handled by usbhid */
  {USB_DEVICE_HID_CLASS(0x0eef, 0x0001), .driver_info = DEVTYPE_IGNORE},
  {USB_DEVICE_HID_CLASS(0x0eef, 0x0002), .driver_info = DEVTYPE_IGNORE},
...
#endif
...
};

其中可以看到 两个字节的十六进制数字,第一个代表idVendor 厂商ID,idProduct 产品ID ,这两个一般作为设备的标识.

driver_info:

像上面的 usbtouch_devices的数组中driver_info 设置为枚举值:

/* device types */
enum {
  DEVTYPE_IGNORE = -1,
  DEVTYPE_EGALAX,
  DEVTYPE_PANJIT,
  DEVTYPE_3M,
  DEVTYPE_ITM,
  DEVTYPE_ETURBO,
  DEVTYPE_GUNZE,
  DEVTYPE_DMC_TSC10,
  DEVTYPE_IRTOUCH,
  DEVTYPE_IDEALTEK,
  DEVTYPE_GENERAL_TOUCH,
  DEVTYPE_GOTOP,
  DEVTYPE_JASTEC,
  DEVTYPE_E2I,
  DEVTYPE_ZYTRONIC,
  DEVTYPE_TC45USB,
  DEVTYPE_NEXIO,
};
enum {
  DEVTYPE_IGNORE = -1,
  DEVTYPE_EGALAX,
  DEVTYPE_PANJIT,
  DEVTYPE_3M,
  DEVTYPE_ITM,
  DEVTYPE_ETURBO,
  DEVTYPE_GUNZE,
  DEVTYPE_DMC_TSC10,
  DEVTYPE_IRTOUCH,
  DEVTYPE_IDEALTEK,
  DEVTYPE_GENERAL_TOUCH,
  DEVTYPE_GOTOP,
  DEVTYPE_JASTEC,
  DEVTYPE_E2I,
  DEVTYPE_ZYTRONIC,
  DEVTYPE_TC45USB,
  DEVTYPE_NEXIO,
};

那么这些driver 的真正的info保存在哪里呢? 在注册的时候,现在只是注册上去一个枚举数字而已,

真正有设备识别到的时候这些个枚举值就起到作用了! 在下面的 usbtouch_probe会介绍!

usbtouch_probe:

在前面有稍微提到,usbtouchscreen驱动是怎么被映射到的,这个过程暂时不做深入,作为这个驱动中的第一个接入点就是usbtouch_probe.

static int usbtouch_probe(struct usb_interface *intf,
        const struct usb_device_id *id)
{
  struct usbtouch_usb *usbtouch;  //usbtouch 设备
  struct input_dev *input_dev;  //输入设备
  struct usb_endpoint_descriptor *endpoint;  //usb 的端点
  struct usb_device *udev = interface_to_usbdev(intf);  //从usb接口获取对应的设备
  struct usbtouch_device_info *type;   //这个就是上面说的真正的 driver info了
  endpoint = usbtouch_get_input_endpoint(intf->cur_altsetting);  //获取端点
  if (!endpoint)
    return -ENXIO;
  usbtouch = kzalloc(sizeof(struct usbtouch_usb), GFP_KERNEL);
  input_dev = input_allocate_device();  //分配内存,申请input 设备结构
...
  type = &usbtouch_dev_info[id->driver_info];   // 这里就用到了 上面说到的枚举值了, 真正的info 是放在这个数组里面的!
...
  usbtouch->irq = usb_alloc_urb(0, GFP_KERNEL);  //分配了一个urb 用于 获得触摸屏设备返回的触摸事件的数据,urb的概念可参考usb driver
  if (!usbtouch->irq) {
    dbg("%s - usb_alloc_urb failed: usbtouch->irq", __func__);
    goto out_free_buffers;
  }
...
//往下都是一些分配内存,input注册,初始化操作了
  input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); //这里是就是input设备触摸坐标的初始化赋值了,为ABS 绝对坐标
  input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
  input_set_abs_params(input_dev, ABS_X, type->min_xc, type->max_xc, 0, 0);
  input_set_abs_params(input_dev, ABS_Y, type->min_yc, type->max_yc, 0, 0);
...
  if (usb_endpoint_type(endpoint) == USB_ENDPOINT_XFER_INT)
    usb_fill_int_urb(usbtouch->irq, udev,
       usb_rcvintpipe(udev, endpoint->bEndpointAddress),
       usbtouch->data, type->rept_size,
       usbtouch_irq, usbtouch, endpoint->bInterval);
  else
    usb_fill_bulk_urb(usbtouch->irq, udev,
       usb_rcvbulkpipe(udev, endpoint->bEndpointAddress),
       usbtouch->data, type->rept_size,
       usbtouch_irq, usbtouch);  //初始化urb的回调函数为 usbtouch_irq
  usbtouch->irq->dev = udev;
  usbtouch->irq->transfer_dma = usbtouch->data_dma;
  usbtouch->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
...
}
int usbtouch_probe(struct usb_interface *intf,
        const struct usb_device_id *id)
{
  struct usbtouch_usb *usbtouch;  //usbtouch 设备
  struct input_dev *input_dev;  //输入设备
  struct usb_endpoint_descriptor *endpoint;  //usb 的端点
  struct usb_device *udev = interface_to_usbdev(intf);  //从usb接口获取对应的设备
  struct usbtouch_device_info *type;   //这个就是上面说的真正的 driver info了
  endpoint = usbtouch_get_input_endpoint(intf->cur_altsetting);  //获取端点
  if (!endpoint)
    return -ENXIO;
  usbtouch = kzalloc(sizeof(struct usbtouch_usb), GFP_KERNEL);
  input_dev = input_allocate_device();  //分配内存,申请input 设备结构
...
  type = &usbtouch_dev_info[id->driver_info];   // 这里就用到了 上面说到的枚举值了, 真正的info 是放在这个数组里面的!
...
  usbtouch->irq = usb_alloc_urb(0, GFP_KERNEL);  //分配了一个urb 用于 获得触摸屏设备返回的触摸事件的数据,urb的概念可参考usb driver
  if (!usbtouch->irq) {
    dbg("%s - usb_alloc_urb failed: usbtouch->irq", __func__);
    goto out_free_buffers;
  }
...
//往下都是一些分配内存,input注册,初始化操作了
  input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS); //这里是就是input设备触摸坐标的初始化赋值了,为ABS 绝对坐标
  input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
  input_set_abs_params(input_dev, ABS_X, type->min_xc, type->max_xc, 0, 0);
  input_set_abs_params(input_dev, ABS_Y, type->min_yc, type->max_yc, 0, 0);
...
  if (usb_endpoint_type(endpoint) == USB_ENDPOINT_XFER_INT)
    usb_fill_int_urb(usbtouch->irq, udev,
       usb_rcvintpipe(udev, endpoint->bEndpointAddress),
       usbtouch->data, type->rept_size,
       usbtouch_irq, usbtouch, endpoint->bInterval);
  else
    usb_fill_bulk_urb(usbtouch->irq, udev,
       usb_rcvbulkpipe(udev, endpoint->bEndpointAddress),
       usbtouch->data, type->rept_size,
       usbtouch_irq, usbtouch);  //初始化urb的回调函数为 usbtouch_irq
  usbtouch->irq->dev = udev;
  usbtouch->irq->transfer_dma = usbtouch->data_dma;
  usbtouch->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
...
}

usbtouch_device_info:

这个就是上面driver_info 以及usbtouch_probe 中抽取的驱动模块的info数组,不同的usbtouchscreen 注册的时候就是注册了一个枚举值,这个值就是 usbtouch_dev_info数组的第几元素.

struct usbtouch_device_info {
  int min_xc, max_xc;
  int min_yc, max_yc;
  int min_press, max_press;
  int rept_size;
  /*
   * Always service the USB devices irq not just when the input device is
   * open. This is useful when devices have a watchdog which prevents us
   * from periodically polling the device. Leave this unset unless your
   * touchscreen device requires it, as it does consume more of the USB
   * bandwidth.
   */
  bool irq_always;
  void (*process_pkt) (struct usbtouch_usb *usbtouch, unsigned char *pkt, int len);  //这个函数指针是用来接收处理中断的。
  /*
   * used to get the packet len. possible return values:
   * > 0: packet len
   * = 0: skip one byte
   * < 0: -return value more bytes needed
   */
  int  (*get_pkt_len) (unsigned char *pkt, int len);
  int  (*read_data)   (struct usbtouch_usb *usbtouch, unsigned char *pkt);
  int  (*alloc)	   (struct usbtouch_usb *usbtouch);
  int  (*init)		(struct usbtouch_usb *usbtouch);
  void (*exit)		(struct usbtouch_usb *usbtouch);
};
  int min_xc, max_xc;
  int min_yc, max_yc;
  int min_press, max_press;
  int rept_size;
  /*
   * Always service the USB devices irq not just when the input device is
   * open. This is useful when devices have a watchdog which prevents us
   * from periodically polling the device. Leave this unset unless your
   * touchscreen device requires it, as it does consume more of the USB
   * bandwidth.
   */
  bool irq_always;
  void (*process_pkt) (struct usbtouch_usb *usbtouch, unsigned char *pkt, int len);  //这个函数指针是用来接收处理中断的。
  /*
   * used to get the packet len. possible return values:
   * > 0: packet len
   * = 0: skip one byte
   * < 0: -return value more bytes needed
   */
  int  (*get_pkt_len) (unsigned char *pkt, int len);
  int  (*read_data)   (struct usbtouch_usb *usbtouch, unsigned char *pkt);
  int  (*alloc)	   (struct usbtouch_usb *usbtouch);
  int  (*init)		(struct usbtouch_usb *usbtouch);
  void (*exit)		(struct usbtouch_usb *usbtouch);
};

usbtouch_dev_info

数组:

static struct usbtouch_device_info usbtouch_dev_info[] = {
#ifdef CONFIG_TOUCHSCREEN_USB_EGALAX
  [DEVTYPE_EGALAX] = {
    .min_xc		= 0x0,
    .max_xc		= 0x07ff,
    .min_yc		= 0x0,
    .max_yc		= 0x07ff,
    .rept_size	= 16,
    .process_pkt	= usbtouch_process_multi,//用于中断回调函数,用于处理中断,得到input的event,上传数据
    .get_pkt_len	= egalax_get_pkt_len,
    .read_data	= egalax_read_data, //用于中断回调函数,用于读取数据
  },
#endif
...
#ifdef CONFIG_TOUCHSCREEN_USB_IRTOUCH
  [DEVTYPE_IRTOUCH] = {
    .min_xc		= 0x0,
    .max_xc		= 0x0fff,
    .min_yc		= 0x0,
    .max_yc		= 0x0fff,
    .rept_size	= 8,
    .read_data	= irtouch_read_data,
  },
#endif 
...
};
 struct usbtouch_device_info usbtouch_dev_info[] = {
#ifdef CONFIG_TOUCHSCREEN_USB_EGALAX
  [DEVTYPE_EGALAX] = {
    .min_xc		= 0x0,
    .max_xc		= 0x07ff,
    .min_yc		= 0x0,
    .max_yc		= 0x07ff,
    .rept_size	= 16,
    .process_pkt	= usbtouch_process_multi,//用于中断回调函数,用于处理中断,得到input的event,上传数据
    .get_pkt_len	= egalax_get_pkt_len,
    .read_data	= egalax_read_data, //用于中断回调函数,用于读取数据
  },
#endif
...
#ifdef CONFIG_TOUCHSCREEN_USB_IRTOUCH
  [DEVTYPE_IRTOUCH] = {
    .min_xc		= 0x0,
    .max_xc		= 0x0fff,
    .min_yc		= 0x0,
    .max_yc		= 0x0fff,
    .rept_size	= 8,
    .read_data	= irtouch_read_data,
  },
#endif 
...
};

可以看到这个数组的成员都是以前面说到的注册枚举值来区分的!这些x,y 参数以及回调函数,都在上面说到的 usbtouch_probe 中被抽离出来使用.

usbtouch_irq:

这个函数作为中断响应函数,在上面的 usbtouch_probe中初始化,看下函数主要实现:

static void usbtouch_irq(struct urb *urb)
{
...
  usbtouch->type->process_pkt(usbtouch, usbtouch->data, urb->actual_length);  
//这个type的类型就是 usbtouch_device_info,此时的process_pkt指针自然指向的是上面对应的函数,如果此时是触发的设备type为 DEVTYPE_EGALAX,那么这里调用的 usbtouch_process_multi
//如果此时是DEVTYPE_IRTOUCH 那么就是执行 usbtouch_process_pkt函数,因为usbtouch_probe中:
//	if (!type->process_pkt)
//		type->process_pkt = usbtouch_process_pkt;
...
}
q(struct urb *urb)
{
...
  usbtouch->type->process_pkt(usbtouch, usbtouch->data, urb->actual_length);  
//这个type的类型就是 usbtouch_device_info,此时的process_pkt指针自然指向的是上面对应的函数,如果此时是触发的设备type为 DEVTYPE_EGALAX,那么这里调用的 usbtouch_process_multi
//如果此时是DEVTYPE_IRTOUCH 那么就是执行 usbtouch_process_pkt函数,因为usbtouch_probe中:
//	if (!type->process_pkt)
//		type->process_pkt = usbtouch_process_pkt;
...
}

接下来的都会调用到usbtouch_process_pkt中,通过type->read_data,和上面一样的指针读取,然后调用input_report_key发送,input_sync用于同步.

关于usbtouchscreen的驱动部分就分析到这里。

你可能感兴趣的:(USB)