at91_sdcard源码分析(5)-中断处理

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中断处理的执行代码在MCI_Handler函数中：
//------------------------------------------------------------------------------/// Processes pending events on the given MCI driver./// \param pMci  Pointer to a MCI driver instance.//------------------------------------------------------------------------------void MCI_Handler(Mci *pMci){    AT91S_MCI *pMciHw = pMci->pMciHw;    MciCmd *pCommand = pMci->pCommand;    unsigned int status;    unsigned char i;    #if defined(at91rm9200)    unsigned int mciCr, mciSdcr, mciMr, mciDtor;    #endif    SANITY_CHECK(pMci);    SANITY_CHECK(pMciHw);    SANITY_CHECK(pCommand);// Read the status register//读取状态寄存器    status = READ_MCI(pMciHw, MCI_SR) & READ_MCI(pMciHw, MCI_IMR);    // TRACE_DEBUG("status %x\n\r", status);    // Check if an error has occured    if ((status & STATUS_ERRORS) != 0) {//传输有错误发生        // Check error code        if ((status & STATUS_ERRORS) == AT91C_MCI_RTOE) {//命令发送超时            pCommand->status = MCI_STATUS_NORESPONSE;        }        // if the command is SEND_OP_COND the CRC error flag is always present        // (cf : R3 response)        else if (((status & STATUS_ERRORS) != AT91C_MCI_RCRCE)                  || ((pCommand->cmd != SDCARD_APP_OP_COND_CMD)                      && (pCommand->cmd != MMC_SEND_OP_COND_CMD))) {            pCommand->status = MCI_STATUS_ERROR;        }    }    // Check if a transfer has been completed    if (((status & AT91C_MCI_CMDRDY) != 0)        || ((status & AT91C_MCI_ENDRX) != 0)        || ((status & AT91C_MCI_RXBUFF) != 0)        || ((status & AT91C_MCI_ENDTX) != 0)        || ((status & AT91C_MCI_BLKE) != 0)        || ((status & AT91C_MCI_RTOE) != 0)) {        if (((status & AT91C_MCI_ENDRX) != 0)            || ((status & AT91C_MCI_RXBUFF) != 0)            || ((status & AT91C_MCI_ENDTX) != 0)) {            MCI_Enable(pMci, DISABLE);        }        /// On AT91RM9200-EK, if stop transmission, software reset MCI.        #if defined(at91rm9200)        if ((pCommand->cmd & AT91C_MCI_TRCMD_STOP) != 0) {            mciMr = READ_MCI(pMciHw, MCI_MR);            mciSdcr = READ_MCI(pMciHw, MCI_SDCR);            mciDtor = READ_MCI(pMciHw, MCI_DTOR);            WRITE_MCI(pMciHw, MCI_CR, AT91C_MCI_SWRST);            // TRACE_DEBUG("reset MCI\n\r");            WRITE_MCI(pMciHw, MCI_CR, AT91C_MCI_MCIDIS | AT91C_MCI_PWSDIS);            WRITE_MCI(pMciHw, MCI_MR, mciMr);            WRITE_MCI(pMciHw, MCI_SDCR, mciSdcr);            WRITE_MCI(pMciHw, MCI_DTOR, mciDtor);        }        #endif        // If no error occured, the transfer is successful        if (pCommand->status == MCI_STATUS_PENDING) {//在命令发送前设置了这个值            pCommand->status = 0;  //说明命令发送成功。        }#if 0        if ((status & AT91C_MCI_CMDRDY) != 0)            TRACE_DEBUG_WP(".");        if ((status & AT91C_MCI_ENDRX) != 0)            TRACE_DEBUG_WP("<");        if ((status & AT91C_MCI_ENDTX) != 0)            TRACE_DEBUG_WP("-");        if ((status & AT91C_MCI_BLKE) != 0)            TRACE_DEBUG_WP(">");        TRACE_DEBUG_WP("\n\r");#endif        // Store the card response in the provided buffer        if (pCommand->pResp) {//发送前设置了此变量            unsigned char resSize;            //判断接收的数据的大小            switch (pCommand->resType) {                case 1:                resSize = 1;                break;                case 2:                resSize = 4;                break;                case 3:                resSize = 1;                break;                case 4:                resSize = 1;                break;                case 5:                resSize = 1;                break;                case 6:                resSize = 1;                break;                case 7:                resSize = 1;                break;                default:                resSize = 0;                break;            }            for (i=0; i < resSize; i++) { //读取接收的数据                pCommand->pResp[i] = READ_MCI(pMciHw, MCI_RSPR[0]);            }        }        // Disable interrupts        WRITE_MCI(pMciHw, MCI_IDR, READ_MCI(pMciHw, MCI_IMR));        // Release the semaphore        pMci->semaphore++;  //释放信号量        // Invoke the callback associated with the current command (if any)        if (pCommand->callback) {//如果设置了callback，则调用它            (pCommand->callback)(pCommand->status, pCommand);        }    }}
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