BCM5722 Programmer’s Guide
10/15/07
Broadcom Corporation
Page 211 Broadcom Vendor-Specific Capabilities Document 5722-PG101-R
REGISTER DATA REGISTER (OFFSET 0X80)
The Register Data register is used to access registers in the BCM5722 Ethernet controller. If this register is written to, the
underlying register is also written. If this register is read, the current value of the underlying register is also read.
MEMORY WINDOW DATA REGISTER (OFFSET 0X84)
The Memory Window Data register is normally used to access locations in the local memory when the 32 KB memory window
provided by the BCM5722 Ethernet controller is not accessible through memory mapped I/O. An example of this state is
during the preboot execution environment when a 64-KB memory mapping is not available, and all accesses to the device
must be done through PCI Configuration space.
This register combined with the Memory Window Base Address register (see “Memory Window Base Address Register
(Offset 0x7C)” on page 210) provides an indirect method to access the entire local memory address space. If this register is
written to, the underlying memory location is also written. If this register is read, the current value of the underlying memory
location is also read.
Table 132: Register Data Register (Offset 0x80)
Bit Field Description Init Access
31:0 Register Data Register data at the location pointed to by the Register
Base Address Register.
0 on hard
reset
R/W
Table 133: Memory Window Data Register (Offset 0x84)
Bit Field Description Init Access
31:0 Memory Window Data Memory value at the location pointed to by the Memory
Window Base Address Register.
XR/W
Note: Programmers should take special care not to read from the Memory Window Data register if the value of
the Memory Window Base Address register (see “Memory Window Base Address Register (Offset 0x7C)” on
page 210) is not set to a valid local memory address. Doing so causes the BCM5722 Ethernet controller to hang.
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