CONFIG_USBD_SERIAL
  Enable the generic serial function driver.

CONFIG_USBD_SERIAL_VENDORID
  Specify the USB Device Vendor ID for the serial function driver. The
  top level Vendor ID will be used if this is not specified.

CONFIG_USBD_SERIAL_PRODUCTID
  Specify the USB Device Product ID for the serial function driver.
  The top level Vendor ID will be used if this is not specified.

CONFIG_USBD_SERIAL_CDC
  Enable CDC mode. This configures the network driver to support the
  ACM model specified in the USB Class Definitions.

CONFIG_USBD_SERIAL_OUT_ENDPOINT
  Specify the preferred OUT (received data) endpoint number. This is a
  number from 0-15 and must be allowed by the bus interface device.

  Some devices such as the SA-1110 and Linkup L7205/L7210 will override
  this selection with a fixed address.

CONFIG_USBD_SERIAL_IN_ENDPOINT
  Specify the preferred IN (transmit data) endpoint number. This is a
  number from 0-15 and must be allowed by the bus interface device.

  Some devices such as the SA-1110 and Linkup L7205/L7210 will
  override this selection with a fixed address.

CONFIG_USBD_SERIAL_INT_ENDPOINT
  Specify the preferred INT (interrupt) endpoint number. This is a
  number from 0-15 and must be allowed by the bus interface device.

  Some devices such as the SA-1110 and Linkup L7205/L7210 will
  override this selection with a fixed address.

CONFIG_USBD_SERIAL_IN_PKTSIZE
  Specify the preferred INT (interrupt) endpoint number. This is a
  number from 0-15 and must be allowed by the bus interface device.

  Some devices such as the Linkup L7205/L7210 may override this value
  with a lower maximum value (such as 32).

CONFIG_USBD_SERIAL_OUT_PKTSIZE
  Specify the maximum packet size for the OUT endpoint. This allowable
  values are normally 16, 32 and 64. Some bus interface devices may
  not support all values.

  Some devices such as the Linkup L7205/L7210 may override this value
  with a lower maximum value (such as 32).

CONFIG_USBD_SERIAL_INT_PKTSIZE
  Specify the maximum packet size for the INT endpoint. This allowable
  values are normally 8 and 16. Some bus interface devices may not
  support all values.

  Some devices such as the L7205/L7210 may override this value with a
  fixed value. Others such as the SA-1110 do not allow an interrupt
  value.

CONFIG_USBD_SERIAL_SAFE
  Enable optional Safe Encapsulation layer for the serial driver.

CONFIG_USBD_SERIAL_SAFE_DEFAULT
  Set Secure option default value.

CONFIG_USBD_SERIAL_SAFE_PADDED
  Force all Secure mode packets to be padded to the full packetsize.