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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—Expansion Bus
Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
710
Order Number: 306262-004US
Register Name:
EXP_CNFG1
Hex Offset Address:
0XC4000024
Reset Hex Value:
0x00000000
Register
Description:
Configuration Register #1
Access: Read/Write.
31
20 19 18 17 16 15 14 13 12 11 10 9
8
7
2
1
0
MPI_EN
(Reserved)
SMII S
O
U
R
CE
SYNC
NPE-C SMII
NPE-
B SMII
NP
E-
A SMII
(R
eserv
ed)
NP
E-C
E
RR_EN
N
PE-
B
E
R
R
_
EN
NP
E-
A E
RR_EN
(R
eserv
ed)
EX
P_
BY
TE_
S
W
A
P_
E
N
FORCE
_
B
Y
TE
_
S
W
A
P
BY
TE_SW
A
P_EN
(Reserved)
SW_ INT1
SW_ INT0
Table 231.
Expansion Bus Configuration Register 1-Bit Definition (Sheet 1 of 3)
Bit
Name
Description
31
MPI_EN
0 = DDR transactions are routed through the AHB
1 = DDR transactions are routed through the MPI port. This bit
should always be set when configuring the DDR during boot-up.
When this bit is set, the performance between the Intel XScale
®
Processor and DDR is increased.
30:20
(Reserved)
(Reserved)
19
SMII SOURCE SYNC
0 = SMII mode for NPE-A, NPE-B, NPE-C does not operate in
source synchronous mode
1 = Reserved
This bit must be configured during boot-up. Set to 0 for the
IXP45X/IXP46X network processors.
Note:
For transactions initiated by the Intel XScale
®
Processor, the selection between address or data
coherency is controlled by a software-programmable, P-attribute bit in the Intel
®
IXP4XX Product
Line Memory Management Unit (MMU) and the BYTE_SWAP_EN bit. The BYTE_SWAP_EN bit will be
from Expansion bus controller Configuration Register 1, Bit 8. This bit will reset to 0.
The default endian conversion method for IXP45X/IXP46X network processors is address coherency.
This was selected to enable backward compatible with the Intel
®
IXP425 processor.
The BYTE_SWAP_EN bit is an enable bit that enables data coherency to be performed, based on the
P-attribute bit.
When the bit is 0, address coherency is always performed.
When the bit is 1, the type of coherency depends on the P-attribute bit.
The P-attribute bit is associated with each 1-Mbyte page. The P-attribute bit is output, from the Intel
XScale processor, with any store or load access associated with that page.
Note:
When enabling SMII mode for the NPE’s during boot-up, the NPE’s will need to be reset in software
to ensure a clean transition into SMII mode. Software must execute the following code when
entering SMII mode:
1.
Write the Expansion EXP_UNIT_FUSE_RESET register to turn ON the reset for the NPE's.
2.
If the PCI interface is not used, the PCI RCOMP bit of the EXP_UNIT_FUSE_RESET register must be
set to a ‘1’. If the PCI interface is used, the PCI RCOMP bit must be left unchanged at logic ‘0’.
3.
Read the SMII_RCOMP_CSR register, set bit 16 to ‘1’, and write value back to SMII_RCOMP_CSR
register.
4.
Write the EXP_SMIIDLL register to enable the DLL.
5.
Write the Expansion EXP_CNFG1 register to turn on SMII mode for the appropriate NPE's (SMII
mode for NPE-B must be enabled for SMII mode to work on NPE-A or NPE-C)
6.
Read the Expansion EXP_CNFG1 register to ensure previous write has occurred
7.
Wait at least 1000 ns
8.
Write the Expansion EXP_UNIT_FUSE_RESET register to turn OFF the reset for the NPE's.
9.
Resume normal boot-up
10.
Wait at least 12ms before starting Ethernet traffic on ports that have SMII enabled, since it takes 12
ms for the SMII pins to stabilize.