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? */__u16match_flags;/* Used for product specific matches; range is inclusive */__u16idVendor;__u16idProduct;__u16bcdDevice_lo;__u16bcdDevice_hi;/* Used for device class matches */__u8bDeviceClass;__u8bDeviceSubClass;__u8bDeviceProtocol;/* Used for interface class matches */__u8bInterfaceClass;__u8bInterfaceSubClass;__u8bInterfaceProtocol;/* not matched against */kernel_ulong_tdriver_info;};
usb_device_id {/* which fields to match against? */__u16match_flags;/* Used for product specific matches; range is inclusive */__u16idVendor;__u16idProduct;__u16bcdDevice_lo;__u16bcdDevice_hi;/* Used for device class matches */__u8bDeviceClass;__u8bDeviceSubClass;__u8bDeviceProtocol;/* Used for interface class matches */__u8bInterfaceClass;__u8bInterfaceSubClass;__u8bInterfaceProtocol;/* not matched against */kernel_ulong_tdriver_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 driverif (!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);elseusb_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_irqusbtouch->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 driverif (!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);elseusb_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_irqusbtouch->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。