Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 2/14/2023
Public

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16.5.8.1.1. Suspend

To suspend data transfer, perform the following steps:
  1. Check if the SDIO card supports the SUSPEND/RESUME protocol by reading the SBS bit in the CCCR at offset 0x08 of the card.
  2. Check if the data transfer for the required function number is in process. The function number that is currently active is reflected in the function select bits (FSx) of the CCCR, bits 3:0 at offset 0x0D of the card.
    Note: If the bus status bit (BS), bit 0 at address 0xC, is 1, only the function number given by the FSx bits is valid.
  3. To suspend the transfer, set the bus release bit (BR), bit 2 at address 0xC, to 1.
  4. Poll the BR and BS bits of the CCCR at offset 0x0C of the card until they are set to 0. The BS bit is 1 when the currently‑selected function is using the data bus. The BR bit remains 1 until the bus release is complete. When the BR and BS bits are 0, the data transfer from the selected function is suspended.
  5. During a read‑data transfer, the controller can be waiting for the data from the card. If the data transfer is a read from a card, the controller must be informed after the successful completion of the SUSPEND command. The controller then resets the data state machine and comes out of the wait state. To accomplish this, set the abort read data bit (abort_read_data) in the ctrl register to 1.
  6. Wait for data completion, by polling until the dto bit is set to 1 in the rintsts register. To determine the number of pending bytes to transfer, read the transferred CIU card byte count (tcbcnt) register of the controller. Subtract this value from the total transfer size. You use this number to resume the transfer properly.