基于OHCI的USB主机 —— USB设备枚举

   USB设备接入以后，必须进行设备枚举，得到设备参数，设置设备运行配置等参数，下面的代码就是对U盘设备进行枚举的过程。
    因为没有使用操作系统，所以函数使用状态迁移的方式完成枚举，该函数在主循环中被调用。

/**
 * USB设备枚举处理
 * @return 当前枚举处理的状态
 */
short usbEnumDev(void)
{
    unsigned short i, oldState;
    unsigned char cc, *pBuf, epBulkIn, epBulkOut;
 
    if (!isUsbConnected())
    {
       enumDev.state = ENUM_DEV_IDLE;
       return USB_DEV_NOT_CONNECTED;
    }
 
    oldState = enumDev.state;
    switch (enumDev.state)
    {
    case ENUM_DEV_IDLE:
       if (usbTimer >= 200)
       {
           //对硬件进行初始化，端口开电
           ohciHardInit();
           usbTimer = 0;
           enumDev.state = ENUM_DEV_IDLE_DALAY;
       }
       break;
 
    case ENUM_DEV_IDLE_DALAY:
       //进行端口复位
       ohciPortReset(0);
 
       usbTimer = 0;
       enumDev.errReason = 0;
       enumDev.oldState = enumDev.state;
       enumDev.state = ENUM_DEV_RESET_ING;
       break;
      
    case ENUM_DEV_RESET_ING:
       if (ohciIsPortResetOver(0))// == OCHI_PORT_RESET_OVER)
       {
           usbTimer = 0;
           enumDev.state = ENUM_DEV_WAIT_RESET_OVER;
       }
       if (usbTimer >= 200)
       {
           enumDev.errReason = DEV_ERROR_RESET_TIME_OUT;
           enumDev.state =ENUM_DEV_OVER;
       }
       break;
 
    case ENUM_DEV_WAIT_RESET_OVER:
       //端口复位完成后延时120ms，然后进行端口初始化
       if (usbTimer <= 12) break;
       ohciPortInit(0);
       usbTimer = 0;
       enumDev.oldState = enumDev.state;
       enumDev.state = ENUM_DEV_SEND_DEV_DESC_0;
 
       break;
 
    case ENUM_DEV_SEND_DEV_DESC_0:
       usbInfoSetAddr(0);
 
       //从地址0，端口0取得设备描述符
        usbGetDeviceDesc(usbBuf);
 
       usbTimer = 0;
        enumDev.newState = ENUM_DEV_SET_ADDRESS;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_WAIT_CMD_OVER;
       break;
 
    case ENUM_DEV_SET_ADDRESS:
        //为USB设备设置新的地址
       usbSetAddress(usbBuf, 2);
 
       usbTimer = 0;
        enumDev.newState = ENUM_DEV_SEND_DEV_DESC_1;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_WAIT_CMD_OVER;
       break;
 
    case ENUM_DEV_SEND_DEV_DESC_1:
       //从新地址，端口0取得设备描述符
        usbGetDeviceDesc(usbBuf);
 
       usbTimer = 0;
        enumDev.newState = ENUM_DEV_FILL_DESC_DEV;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_WAIT_CMD_OVER;
       break;
 
    case ENUM_DEV_FILL_DESC_DEV:
       //得到了端口描述符
       bytesCopy((BYTE *)&usbDeviceInfo.devDesc, (BYTE *)usbBuf, sizeof(DEVICE_DESC));
 
       usbTimer = 0;
       enumDev.oldState = enumDev.state;
       enumDev.state = ENUM_DEV_GET_DESC_CFG;
       break;
 
    case ENUM_DEV_GET_DESC_CFG:
        //取得配置描述符集合
        usbGetConfigDesc(usbBuf);
 
       usbTimer = 0;
        enumDev.newState = ENUM_DEV_FILL_DESC_SET;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_WAIT_CMD_OVER;
        break;
 
    case ENUM_DEV_FILL_DESC_SET:
       pBuf = usbBuf;
        //取得返回数据中的配置描述符
        bytesCopy((BYTE *)&usbDeviceInfo.cfgDesc, pBuf, sizeof(CFG_DESC));
 
        //取得返回数据中的接口描述符
        pBuf += 9;
        bytesCopy((BYTE *)&usbDeviceInfo.intfDesc, pBuf, sizeof(INTF_DESC));
 
        //取得返回数据中的端点描述符
        pBuf += 9;
        for(i = 0; i < usbDeviceInfo.intfDesc.bEndPoints; i++)
        {
           bytesCopy((BYTE *)&usbDeviceInfo.epDesc[i], pBuf, sizeof(ED_DESC));
            if (usbDeviceInfo.epDesc[i].bAttr == 0x02)
            {
               if ((usbDeviceInfo.epDesc[i].bEPAdd & 0x80) == 0x80)
                  epBulkIn = usbDeviceInfo.epDesc[i].bEPAdd & 0x0F;
               else
                  epBulkOut = usbDeviceInfo.epDesc[i].bEPAdd & 0x0F;
            }
 
            pBuf += 7;
        }
 
        //保存得到的批量端口信息
        usbInfoSetBulkPort(epBulkIn, epBulkOut);
 
       usbTimer = 0;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_SET_CONFIGURATION;
        break;
 
    case ENUM_DEV_SET_CONFIGURATION:
        //设置设备配置值
        usbSetConfiguration(usbBuf);
 
       usbTimer = 0;
        enumDev.newState = ENUM_DEV_GET_CONFIGURATION;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_WAIT_CMD_OVER;
       break;
 
    case ENUM_DEV_GET_CONFIGURATION:
        //取得设备配置值
        usbGetConfiguration(usbBuf);
 
       usbTimer = 0;
        enumDev.newState = ENUM_DEV_CHECK_CONFIG;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_WAIT_CMD_OVER;
       break;
 
    case ENUM_DEV_CHECK_CONFIG:
       //检查设备配置是否正确
       if (usbBuf[0] != 1)
       {
           enumDev.errReason = DEV_ERROR_CONFIGURATION;
           enumDev.state =ENUM_DEV_OVER;
           break;
       }
 
       usbTimer = 0;
       enumDev.oldState = enumDev.state;
        enumDev.state = ENUM_DEV_OVER;
       break;
 
    case ENUM_DEV_WAIT_CMD_OVER:
        //命令执行完毕
       if (usbIsCmdOver() == USB_CMD_OVER)
       {
           cc = checkGenTd();
           if (cc != 0)
           {
              if (cc == CC_STALL)
              {
                  usbClearFeature(2, 0);
                  break;
              }
              else
              {
                  enumDev.errReason = DEV_ERROR_TD;
                  enumDev.state =ENUM_DEV_OVER;
                  break;
              }
           }
 
           enumDev.state = enumDev.newState;
       }
      
        //命令执行超时，则重新初始化
       if (usbTimer >= 200)
       {
           ohciHardDisable();
           usbTimer = 0;
           enumDev.state = ENUM_DEV_IDLE;
       }
       break;
 
    case ENUM_DEV_OVER:
       break;
    default:
       enumDev.state = ENUM_DEV_IDLE;
    }
 
    return enumDev.state;
}

本文转自 tywali 51CTO博客，原文链接：http://blog.51cto.com/lancelot/283056，如需转载请自行联系原作者