SEC Lite Descriptors
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
49-3
Figure 49-3
shows the two sub fields of OP_n.
OP_n EU_SELECT values of ‘no EU selected’ or ‘reserved EU’ will result in an ‘unrecognized header
error’ condition during processing of the descriptor header. Also, the primary EU selected by the OP_n
EU_SELECT field may only be DEU or AESU when a valid secondary EU is selected. For this case, all
other values of OP_n EU_SELECT will result in an ‘Unrecognized header’ error condition. The full range
of permissible EU_SELECT values is shown in
Table 49-2
.
24–27
DESC_TYPE Descriptor Type—Each type of descriptor determines the following attributes for the corresponding
data length/pointer pairs: the direction of the data flow; which EU is associated with the data; and
which internal EU address is used.
Table 49-3
lists the valid types of descriptors.
28–29
—
Reserved. Set to zero
30
ST
Snoop type—Selects which of the two types of available snoop modes applies to the descriptor.
0 Snoop output data mode.
1 Snoop input data mode.
In snoop input data mode, while the bus transaction to write data into the input FIFO of the primary
EU is in progress, the secondary EU (always MDEU) will snoop the same data into its input FIFO.
In snoop output data mode, the secondary EU (always MDEU) will snoop data into its input FIFO
during the bus transaction to read data out of the output FIFO of the primary EU.
Note:
When snooping is not performed, this bit is ignored by the SEC Lite crypto-channel.
31
DN
DONE_NOTIFICATION_FLAG—Done Notification Flag.
Setting this bit indicates whether to perform notification upon completion of this descriptor. The
notification can take the form of an interrupt or modified header write back or both depending upon
the state of the INTERRUPT_ENABLE and WRITEBACK_ENABLE control bits in Control Register.
0 Do not signal DONE upon completion of this descriptor (unless globally programmed to do so via
the Master Control Register.)
1 Signal DONE upon completion of this descriptor
Note:
The SEC Lite can be programmed to perform DONE notification upon completion of each
descriptor, upon completion of any descriptor, or completion of a chain of descriptors. This bit
provides for the second case.
0
3
4
11
OP_
n
EU_SELECT
MODE_DATA
Figure 49-3. OP_
n
sub fields
Table 49-2. EU_SELECT Values
Value
EU Select
0000
No EU selected.
0001
Reserved EU
0010
DEU
0011
MDEU
Table 49-1. Header Bit Definitions (continued)
Bits
Name
Description
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