USB鼠标驱动源代码分析

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我是靠谱客的博主忐忑大门，最近开发中收集的这篇文章主要介绍USB鼠标驱动源代码分析，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

学了URB，试着去分析了一下USB鼠标驱动源代码，更好去理解URB处理流程。

/*
* $Id: usbmouse.c,v 1.15 2001/12/27 10:37:41 vojtech Exp $
*
*
Copyright (c) 1999-2001 Vojtech Pavlik
*
*
USB HIDBP Mouse support
*/
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Should you need to contact me, the author, you can do so either by
* e-mail - mail your message to <vojtech@ucw.cz>, or by paper mail:
* Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
*/
#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>
/*
* Version Information
*/
#define DRIVER_VERSION "v1.6"
#define DRIVER_AUTHOR "Vojtech Pavlik <vojtech@ucw.cz>"
#define DRIVER_DESC "USB HID Boot Protocol mouse driver"
#define DRIVER_LICENSE "GPL"
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE(DRIVER_LICENSE);
struct usb_mouse {
char name[128];
char phys[64];
struct usb_device *usbdev;	//usb设备
struct input_dev *dev;
//输入设备
struct urb *irq;
//USB 请求块
signed char *data;
dma_addr_t data_dma;
};
/*一个urb完成时被调用的完成处理函数*/
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;
/*urb处理完成后，状态判断*/
switch (urb->status) {
case 0:
/* success */
break;
case -ECONNRESET:	/* unlink */
case -ENOENT:
case -ESHUTDOWN:
return;
/* -EPIPE:
should clear the halt */
default:
/* error */
goto resubmit;
}
/*报告按键状态*/
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]);
/*报告完成*/
input_sync(dev);
resubmit:
/*提交下一次URB*/
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);
}
static int usb_mouse_open(struct input_dev *dev)
{
struct usb_mouse *mouse = input_get_drvdata(dev);
/*当鼠标打开时，提交URB*/
mouse->irq->dev = mouse->usbdev;
if (usb_submit_urb(mouse->irq, GFP_KERNEL))
return -EIO;
return 0;
}
static void usb_mouse_close(struct input_dev *dev)
{
struct usb_mouse *mouse = input_get_drvdata(dev);
/*鼠标关闭，取消urb,终止urb的生命周期*/
usb_kill_urb(mouse->irq);
}
/*usb设备检测函数*/
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;
/*获 取 当 前 接 口 设 置*/
interface = intf->cur_altsetting;
/* 根 据 HID 规 范 鼠 标 只 有 一 个 的 端 点*/
if (interface->desc.bNumEndpoints != 1)
return -ENODEV;
/* 获 取 0号 端 点*/
endpoint = &interface->endpoint[0].desc;
/* 根 据 HID 规 范， 鼠 标 的 唯 一
的 端 点 是中 断 端 点*/
if (!usb_endpoint_is_int_in(endpoint))
return -ENODEV;
/*产生中断管道,这个urb要被发送到的usb设备的特定端点*/
pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress);
/*返回端点能够传送数据包的最大长度，鼠标返回最大数据包为4*/
maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe));
/*创建输入型设备，鼠标属于输入设备*/
mouse = kzalloc(sizeof(struct usb_mouse), GFP_KERNEL);
input_dev = input_allocate_device();
if (!mouse || !input_dev)
goto fail1;
/*申请空间用于数据传输，data为用户空间的地址*/
mouse->data = usb_buffer_alloc(dev, 8, GFP_ATOMIC, &mouse->data_dma);
if (!mouse->data)
goto fail1;
//分配 URB(USB请求块)
mouse->irq = usb_alloc_urb(0, GFP_KERNEL);
if (!mouse->irq)
goto fail2;
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
-- returns stable device path in the usb tree */
usb_make_path(dev, mouse->phys, sizeof(mouse->phys));
strlcat(mouse->phys, "/input0", sizeof(mouse->phys));
/*字符设备初始化*/
input_dev->name = mouse->name;
input_dev->phys = mouse->phys;
usb_to_input_id(dev, &input_dev->id);
input_dev->dev.parent = &intf->dev;
/*设置输入事件*/
input_dev->evbit[0] = BIT(EV_KEY) | BIT(EV_REL);
input_dev->keybit[LONG(BTN_MOUSE)] = BIT(BTN_LEFT) | BIT(BTN_RIGHT) | BIT(BTN_MIDDLE);
input_dev->relbit[0] = BIT(REL_X) | BIT(REL_Y);
input_dev->keybit[LONG(BTN_MOUSE)] |= BIT(BTN_SIDE) | BIT(BTN_EXTRA);
input_dev->relbit[0] |= BIT(REL_WHEEL);
/*设置输入设备的私有数据*/
input_set_drvdata(input_dev, mouse);
input_dev->open = usb_mouse_open;//打开设备：提交URB
input_dev->close = usb_mouse_close;
/*初始化中断URB,从pipe获取数据存放到data中，usb_mouse_irq：这个urb完成时被调用
的完成处理函数，bInterval应当被调度的间隔*/
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;
/*注册输入设备*/
error = input_register_device(mouse->dev);
if (error)
goto fail3;
/*把已经初始化的usb_mouse保存到usb_interface中*/
usb_set_intfdata(intf, mouse);
return 0;
fail3:
usb_free_urb(mouse->irq);
fail2:
usb_buffer_free(dev, 8, mouse->data, mouse->data_dma);
fail1:
input_free_device(input_dev);
kfree(mouse);
return error;
}
static void usb_mouse_disconnect(struct usb_interface *intf)
{
struct usb_mouse *mouse = usb_get_intfdata (intf);
/*设置usb_interface的私有数据为null*/
usb_set_intfdata(intf, NULL);
if (mouse) {
usb_kill_urb(mouse->irq);/*取消urb,终止urb的生命周期*/
input_unregister_device(mouse->dev);//注销输入设备
usb_free_urb(mouse->irq);//释放urb
usb_buffer_free(interface_to_usbdev(intf), 8, mouse->data, mouse->data_dma);
kfree(mouse);
}
}
/*创建一个匹配接口制定类型的usb_device_id结构体实例*/
static struct usb_device_id usb_mouse_id_table [] = {
{ USB_INTERFACE_INFO(USB_INTERFACE_CLASS_HID, USB_INTERFACE_SUBCLASS_BOOT,
USB_INTERFACE_PROTOCOL_MOUSE) },
{ }	/* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, usb_mouse_id_table);
static struct usb_driver usb_mouse_driver = {
.name
= "usbmouse",/*驱动名称*/
.probe
= usb_mouse_probe,/*探测函数*/
.disconnect	= usb_mouse_disconnect,/*断开函数*/
.id_table	= usb_mouse_id_table,/*这个驱动所支持的USB设备列表*/
};
static int __init usb_mouse_init(void)
{
int retval = usb_register(&usb_mouse_driver);
if (retval == 0)
info(DRIVER_VERSION ":" DRIVER_DESC);
return retval;
}
static void __exit usb_mouse_exit(void)
{
usb_deregister(&usb_mouse_driver);
}
module_init(usb_mouse_init);
module_exit(usb_mouse_exit);