AN2584 Freescale Semiconductor / Motorola, AN2584 Datasheet - Page 7

• Manufacturer Part Number: AN2584
• Description: Migrating from the MPC852T to the MPC875
• Manufacturer: Freescale Semiconductor / Motorola

6 New Features for MPC875
The following sections discuss new features of MPC875.
6.1 IMMR[ISB] bits 14:15
The IMMR[ISB] bits 14:15 have new meaning with the MPC875. When IMMR[ISB] bits 14:15 are cleared,
the internal memory map is the same as in previous iterations of PowerQUICC. When IMMR[ISB] 14:15
=10, the registers for the security engine become available.
6.2 Security Engine
The block diagram of the security engine’s internal architecture is shown in Figure 5. The MPC8XX bus
interface module is designed to transfer 32-bit words between the MPC8XX bus and any register inside the
security engine core.
An operation begins with a write of a pointer to the crypto-channel fetch register, which points to a data
packet descriptor. The channel requests the descriptor and decodes the operation to be performed. The
channel then asks the controller to assign crypto execution units and fetch the keys, IVs, and data needed to
perform the specific operation. The controller assigns execution units to the channel and makes requests to
the master interface to satisfy the requests. As data is processed, it is written to the individual executions
unit’s output buffer and then back to system memory by means of the MPC8XX I/F module.
The internal registers for the security engine can be accessed when IMMR [ISB]14:15 = 10. The MPC885
PowerQUICC Family Reference Manual lists details of the registers and their locations in the internal
memory map.
7 Summary
Although the migration from the MPC852T to the MPC875 requires layout and software changes, the
benefits of an additional Fast Ethernet controller, USB1.1, and an internal security engine may warrant the
migration, depending on system requirements.
MOTOROLA
MPC8XX
Freescale Semiconductor, Inc.
Bus I/F
Figure 5. Security Engine Functional Blocks
Migrating from the MPC852T to the MPC875
Unit
For More Information On This Product,
Go to: www.freescale.com
Controller
Crypto-
Channel
DEU
FIFO
FIFO
AESU
New Features for MPC875
MDEU
FIFO
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