USB驱动程序(三)——鼠标驱动程序(中断传输)
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本文以 usbmouse.c 为例,简单分析usb鼠标驱动程序。
- 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;
- }
使用 usb_register 注册到内核的驱动程序都是对应于一个usb设备的接口(逻辑设备)。- static struct usb_driver usb_mouse_driver = {
- .name = "usbmouse",
- .probe = usb_mouse_probe,
- .disconnect = usb_mouse_disconnect,
- .id_table = usb_mouse_id_table,
- };
id_table 中指明了这个驱动程序支持哪些类型的接口- static struct usb_device_id usb_mouse_id_table [] = {
- { USB_INTERFACE_INFO(USB_INTERFACE_CLASS_HID, USB_INTERFACE_SUBCLASS_BOOT,
- USB_INTERFACE_PROTOCOL_MOUSE) },
- { }
- };
USB_INTERFACE_INFO ,通过接口信息来匹配,内核里还有一些其它的宏,例如 USB_DEVICE ,使用它可以根据厂商ID、设备ID来匹配,让你的驱动程序仅仅支持某一个厂家的某一款设备。还有一些其它的匹配方法不再赘述。 匹配成功之后,便会调用 probe 函数。
- 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;
-
-
- endpoint = &interface->endpoint[0].desc;
-
-
- pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress);
-
-
- maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe));
-
-
- input_dev = input_allocate_device();
-
-
- mouse = kzalloc(sizeof(struct usb_mouse), GFP_KERNEL);
-
-
- mouse->data = usb_buffer_alloc(dev, 8, GFP_ATOMIC, &mouse->data_dma);
-
-
- mouse->irq = usb_alloc_urb(0, GFP_KERNEL);
-
- mouse->usbdev = dev;
- mouse->dev = input_dev;
-
-
- 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;
- 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);
- input_dev->keybit[BIT_WORD(BTN_MOUSE)] = BIT_MASK(BTN_LEFT) |
- BIT_MASK(BTN_RIGHT) | BIT_MASK(BTN_MIDDLE);
- input_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y);
- 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;
-
-
- 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;
-
-
- error = input_register_device(mouse->dev);
-
- usb_set_intfdata(intf, mouse);
- return 0;
- }
- 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;
- }
open 输入设备的时候,urb 就被提交了。每次鼠标有信息要提交给usb主机时,就会调用到
- 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) {
- case 0:
- break;
- case -ECONNRESET:
- case -ENOENT:
- case -ESHUTDOWN:
- return;
-
- default:
- goto resubmit;
- }
-
- input_report_key(dev, BTN_LEFT, data[0] & 0x01);
- 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]);
- input_report_rel(dev, REL_Y, data[2]);
- input_report_rel(dev, REL_WHEEL, data[3]);
-
- input_sync(dev);
- resubmit:
- status = usb_submit_urb (urb, GFP_ATOMIC);
- if (status)
- err ("can't resubmit intr, %s-%s/input0, status %d",
- mouse->usbdev->bus->bus_name,
- mouse->usbdev->devpath, status);
- }