OvmfPkg/LsiScsiDxe: Process the SCSI Request Packet

OvmfPkg/LsiScsiDxe: Process the SCSI Request Packet

This is the second part of LsiScsiPassThru(). LsiScsiProcessRequest() is
added to translate the SCSI Request Packet into the LSI 53C895A
commands. This function utilizes the so-called Script buffer to transmit
a series of commands to the chip and then polls the DMA Status (DSTAT)
register until the Scripts Interrupt Instruction Received (SIR) bit
sets. Once the script is done, the SCSI Request Packet will be modified
to reflect the result of the script. The Cumulative SCSI Byte Count
(CSBC) register is fetched before and after the script to calculate the
transferred bytes and update InTransferLength/OutTransferLength if
necessary.

v3:
  - Set DStat, SIst0, and SIst1 to 0 before using them
  - Amend the if statements for the DMA data instruction and add the
    assertions for the data direction
  - Also set SenseDataLength to 0 on the error path
  - Fix typos and amend comments
  - Amend the error handling of the calculation of transferred bytes
v2:
  - Use the BITx macros for the most of LSI_* constants
  - Fix a typo: contorller => controller
  - Add SeaBIOS lsi-scsi driver as one of the references of the script
  - Cast the result of sizeof to UINT32 for the instructions of the
    script
  - Drop the backslashes
  - Replace LSI_SCSI_DMA_ADDR_LOW with LSI_SCSI_DMA_ADDR since we
    already removed DUAL_ADDRESS_CYCLE
  - Add more comments for the script
  - Fix the check of the script size at the end of the script
  - Always set SenseDataLength to 0 to avoid the caller to access
    SenseData
  - Improve the error handling in LsiScsiProcessRequest()

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Gary Lin <glin@suse.com>
Message-Id: <20200717061130.8881-11-glin@suse.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>