Western Digital T13/2132-D - Manual (Page 81)

June 23, 2010 T13/2132-D Revision 3
Working Draft Enhanced Disk Drive - 4 (EDD-4) 69
8.28 Security Protocol Commands (FN 51h)
The purpose of this function is to support the Trusted Computing feature set (see ACS-2), the SECURITY
PROTOCOL IN command (see SPC-4), and the SECURITY PROTOCOL OUT command (see SPC-4).
Entry
AH 51h
AL Flags
Bit Description
7 Direction
0 = Send data to the device
1 = Receive data from the device
6:0 Reserved
CX Security Protocol Specific
Specifies data which varies based on the Security Protocol ID. (See ACS-2 or SPC-4)
DH Security Protocol ID
Specifies which security protocol is to be used. (See ACS-2 or SPC-4)
DL BIOS device number
ES:BX QWord-aligned pointer to data buffer in memory (see table 33)
Exit
Carry Clear Function completed without error
AH Shall be cleared to zero
AL Shall be set to the status of the last INT 13h operation
ES:BX Shall be set to the QWord-aligned pointer to data buffer in memory (see table
33)
Carry Set Function completed with an error
AH Shall be set to the error code
ES:BX Shall be set to the QWord-aligned pointer to data buffer in memory (see table
33)
Table 33 — Data Buffer for Security Protocol Commands
Offset Type Description
00h DWord Length (bytes) of the Payload Data
On Entry:
If the Direction bit is set to one, then this field contains the number
of bytes to be sent to the device. If Direction bit is cleared to zero,
then this field contains the expected number of bytes to be received
from the device, and the buffer shall be large enough to
accommodate this number, plus 8 bytes.
On Exit:
If the Direction bit is cleared to zero, this field contains the actual
number of bytes received from the device
04h DWord Reserved
08h..(Length of Payload Data+8) Byte Payload Data
The content of this data depends on the selected Security Protocol.