msdbot.c

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/***************************************************************************/
#include "em_usb.h"
#include "msdbot.h"

#define TIMEOUT_1SEC       1000
#define TIMEOUT_2SEC       2000
#define DEFAULT_TIMEOUT    TIMEOUT_2SEC

/* Bulk endpoint "handles". */
static USBH_Ep_TypeDef *epOut = NULL;
static USBH_Ep_TypeDef *epIn  = NULL;

/* Bulk transfer timeout scale factor. */
static int timeoutFactor;

/* CSW buffer. */
STATIC_UBUF(csw, CSW_LEN);
static MSDBOT_CSW_TypeDef *pCsw = (MSDBOT_CSW_TypeDef*) csw;

/* Function prototypes. */
static bool CswMeaningful(MSDBOT_CBW_TypeDef *pCbw);
static bool CswValid(MSDBOT_CBW_TypeDef *pCbw);
static void ResetRecovery(void);

/***************************************************************************/
int MSDBOT_Init(USBH_Ep_TypeDef *out, USBH_Ep_TypeDef *in)
{
  /* Check if typedef's are properly packed. */

  if ((sizeof(MSDBOT_CBW_TypeDef) != CBW_LEN) ||
      (sizeof(MSDBOT_CSW_TypeDef) != CSW_LEN))
  {
    DEBUG_USB_API_PUTS("\nMSDBOT_Init(), typedef size error");
    EFM_ASSERT(false);
    return MSDBOT_INIT_ERROR;
  }

  /* Keep a local copy of bulk IN/OUT endpoint handles. */
  epOut = out;
  epIn  = in;

  /* Transfer timeouts are scaled according to device bus speed. */
  if (epIn->parentDevice->speed == PORT_FULL_SPEED)
    timeoutFactor = 512;
  else
    timeoutFactor = 64;

  return MSDBOT_STATUS_OK;
}

/***************************************************************************/
int MSDBOT_Xfer(void* cbw, void* data)
{
  uint32_t           len;
  int                timeout, result, direction, retVal;
  MSDBOT_CBW_TypeDef *pCbw = (MSDBOT_CBW_TypeDef*) cbw;

  /* Send CBW. */
  result = USBH_WriteB(epOut, cbw, CBW_LEN, DEFAULT_TIMEOUT);

  if (result != CBW_LEN)
  {
    ResetRecovery();
    return MSDBOT_XFER_ERROR;
  }

  retVal    = 0;
  direction = pCbw->Direction;
  len       = pCbw->dCBWDataTransferLength;

  /* Send/receive data (optional phase). */
  if (len)
  {
    timeout = DEFAULT_TIMEOUT + (len / timeoutFactor);

    if (direction)
      result = USBH_ReadB(epIn, data, len, timeout);
    else
      result = USBH_WriteB(epOut, data, len, timeout);

    retVal = result;

    if (result == USB_STATUS_EP_STALLED)
    {
      if (direction)
        USBH_UnStallEpB(epIn);
      else
        USBH_UnStallEpB(epOut);
    }

    else if (result <= 0)
    {
      ResetRecovery();
      return MSDBOT_XFER_ERROR;
    }
  }

  /* Retrieve CSW. */
  result = USBH_ReadB(epIn, csw, CSW_LEN, DEFAULT_TIMEOUT);

  if (result != CSW_LEN)
  {
    if (result == USB_STATUS_EP_STALLED)
    {
      if (direction)
        USBH_UnStallEpB(epIn);
      else
        USBH_UnStallEpB(epOut);

      result = USBH_ReadB(epIn, csw, CSW_LEN, DEFAULT_TIMEOUT);

      if (result != CSW_LEN)
      {
        ResetRecovery();
        return MSDBOT_XFER_ERROR;
      }
    }
    else
    {
      ResetRecovery();
      return MSDBOT_XFER_ERROR;
    }
  }

  if (CswValid(pCbw) && CswMeaningful(pCbw))
  {
    if (pCsw->bCSWStatus == USB_CLASS_MSD_CSW_CMDPASSED)
    {
      return retVal;
    }
    return MSDBOT_CMD_FAILED;
  }

  ResetRecovery();
  return MSDBOT_XFER_ERROR;
}

/***************************************************************************/
static bool CswMeaningful(MSDBOT_CBW_TypeDef *cbw)
{
  if (((pCsw->bCSWStatus == USB_CLASS_MSD_CSW_CMDPASSED) ||
       (pCsw->bCSWStatus == USB_CLASS_MSD_CSW_CMDFAILED)) &&
      (pCsw->dCSWDataResidue <= cbw->dCBWDataTransferLength))
    return true;

  return false;
}

/***************************************************************************/
static bool CswValid(MSDBOT_CBW_TypeDef *cbw)
{
  if ((pCsw->dCSWSignature == CSW_SIGNATURE) &&
      (pCsw->dCSWTag == cbw->dCBWTag))
    return true;

  return false;
}

/***************************************************************************/
static void ResetRecovery(void)
{
  USBH_ControlMsgB(&epIn->parentDevice->ep0,
                   USB_SETUP_DIR_H2D | USB_SETUP_RECIPIENT_INTERFACE |
                   USB_SETUP_TYPE_CLASS_MASK,             /* bmRequestType */
                   USB_MSD_BOTRESET,                      /* bRequest      */
                   0,                                     /* wValue        */
                   0,                                     /* wIndex        */
                   0,                                     /* wLength       */
                   NULL,                                  /* void* data    */
                   TIMEOUT_1SEC);                         /* int timeout   */

  USBH_UnStallEpB(epIn);
  USBH_UnStallEpB(epOut);
}