基于OHCI的USB主机 —— OHCI（批量端口读数据）

 

对于U盘来说，进行U盘的数据传输时需要通过批量传输端口收发数据，所使用的协议为Mass Storage协议，参见《Universal Serial Bus Mass Storage Class Bulk-Only Transport》 。该协议是批量端口数据传输的底层协议，为了完成U盘扇区读写，还需要在该协议上面实现UFI协议，参见《Universal Serial Bus Mass Storage Class UFI Command Specification》 。

在本函数内只处理Mass Storage协议，不理会UFI协议：

/**  * 从批量端点读取数据  * @param *pCbw CBW数据区指针  * @param *pData 存放读取结果的数据区指针  * @param *pCsw CSW数据区指针  */ short bulkRead(unsigned char *pCbw, unsigned char *pData, unsigned char *pCsw) {     BYTE toggle;         //得到批量出端点的下一次发送数据区编号     toggle = usbGetEdToggle(bulkEd[0]);     //初始化批量出端点ED     AT91F_CreateEd(        (unsigned int) &bulkEd[0],  // ED Address        64 ,                        // Max packet        0,                          // TD format        0,                          // Skip        0,                          // Speed        ED_OUT,                     // Direction        usbDevInfo.bulkOutPort,     // Endpoint        usbDevInfo.addr,            // Func Address        (unsigned int) &genTd[1],   // TDQTailPointer        (unsigned int) &genTd[0],   // TDQHeadPointer        toggle,                     // ToggleCarry        (unsigned int) &bulkEd[1]); // NextED       //设置批量出端点的TD，用于发送CBW命令     AT91F_CreateGenTd(        (unsigned int) &genTd[0],    // TD Address        0,                           // Data Toggle        TD_DELAY_INT,                // DelayInterrupt        TD_OUT,                      // Direction        1,                           // Buffer Rounding        (unsigned int) pCbw,         // Current Buffer Pointer        (unsigned int) &genTd[1],    // Next TD        31);                         // Buffer Length         AT91F_CreateGenTd(        (unsigned int) &genTd[1],    // TD Address        0,                           // Data Toggle        TD_DELAY_INT,                // DelayInterrupt        TD_OUT,                      // Direction        1,                           // Buffer Rounding        0x0,                         // Current Buffer Pointer        (unsigned int) 0,            // Next TD        0x0);                        // Buffer Length       //得到批量入端点的下一次发送数据区编号     toggle = usbGetEdToggle(bulkEd[1]);     //初始化批量入端点ED     AT91F_CreateEd(        (unsigned int) &bulkEd[1],    // ED Address        64 ,                          // Max packet        0,                            // TD format        0,                            // Skip        0,                            // Speed        ED_IN,                        // Direction        usbDevInfo.bulkInPort,        // Endpoint        usbDevInfo.addr,              // Func Address        (unsigned int) &genTd[4],     // TDQTailPointer        (unsigned int) &genTd[2],     // TDQHeadPointer        toggle,                       // ToggleCarry        (unsigned int) 0);            // NextED       //设置批量入端点的TD     //用于接收数据的TD     AT91F_CreateGenTd(        (unsigned int) &genTd[2],   // TD Address        0,                          // Data Toggle        TD_DELAY_INT,               // DelayInterrupt        TD_IN,                      // Direction        1,                          // Buffer Rounding        (unsigned int) pData,       // Current Buffer Pointer        (unsigned int) &genTd[3],   // Next TD        512);                       // Buffer Length         //用于接收CSW的TD     AT91F_CreateGenTd(        (unsigned int) &genTd[3],   // TD Address        0,                          // Data Toggle        TD_DELAY_INT,               // DelayInterrupt        TD_IN,                      // Direction        1,                          // Buffer Rounding        (unsigned int) pCsw,        // Current Buffer Pointer        (unsigned int) &genTd[4],   // Next TD        64);                        // Buffer Length         AT91F_CreateGenTd(        (unsigned int) &genTd[4],   // TD Address        0,                          // Data Toggle        TD_DELAY_INT,               // DelayInterrupt        TD_IN,                      // Direction        1,                          // Buffer Rounding        0x0,                        // Current Buffer Pointer        (unsigned int) 0,           // Next TD        0x0);                       // Buffer Length         //调用底层接口把数据发送出去     ohciBulkXfer(&bulkEd[0]);         usbRunCmd(USB_CMD_TYPE_BULK_READ, 3);         return 0; }