Execution Units
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
26-41
Overflows and underflow caused by reading or writing the DEU FIFOs are reflected in the DEU
Interrupt Status Register.
26.4.3 Advanced Encryption Standard Execution Unit (AESU)
In typical operation, the AESU is used through channel-controlled access, which means that most
reads and writes of AESU registers are directed by the SEC channels. Driver software performs
core processor-controlled register accesses only on a few registers for initial configuration and
error handling.
This EU includes an ICV checking feature, that is, it can generate an integrity check value (ICV)
and compare it to another supplied ICV. The pass/fail result of this ICV check can be returned to
the core processor either via interrupt by a writeback of EU status fields into core processor
memory, but not by both methods at once.
To signal the ICV checking result by status writeback, turn on either the IWSE bit or AWSE bit
in the Channel Configuration Register (see Section 26.5.5.1, Channel Configuration Registers
for Channels 1–4 (CCR[1–4]), on page 26-89), and mask the ICE bit in the Interrupt Mask
Register (Section 26.4.3.7, AESU Interrupt Mask Register, on page 26-43). In this case the
normal done signaling (by interrupt or writeback) is undisturbed.
To signal the ICV checking result by interrupt, unmask the ICE bit in the Interrupt Mask Register
and turn off the IWSE and AWSE bits in the Channel Configuration Register. If there is no ICV
mismatch, then the normal done signalling (by interrupt or writeback) occurs. When there is an
ICV mismatch, there is an error interrupt generated to the core processor, but no done interrupt or
writeback.
The following subsections include general descriptions of the AESU registers and structures.
Section 26.5, Programming Model, on page 26-66 provides a detailed description of each
register and associated register fields.
26.4.3.1 AESU Mode Register
The AESU Mode Register contains 7 fields used to program the AESU. The Mode Register is
cleared when the AESU is reset or reinitialized. Setting a reserved mode bit generates a data
error. If the Mode Register is modified during processing, a context error is generated.
In most networking applications, the decryption of an AES protected packet is performed as a
single operation. However, if circumstances require that the decryption of a message be split
across multiple descriptors, the AESU allows the user to save the decrypt key and the active AES
context to memory for later reuse. This eliminates the internal AESU processing overhead
associated with regenerating the decryption key schedule (~12 AESU clock cycles for the first
block of data decrypted).
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...