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Intel 8255x 10/100 Mbps Ethernet Controller Family Open Source Software Developer Manual 43
Host Software Interface
3. Write zeros to the last Dword in this area. This can be done before or after step 2.
4. Write the Dump Statistical Counters or Dump and Reset Statistical Counters command into the
CUC field in the SCB.
5. Wait for the device to dump the content of the statistical counters into the allocated memory
area. The dump is followed by the device writing a completion status into the last Dword in
this area. Software should check this Dword before processing the counters. A value of A005h
indicates the Dump Statistical Counters command has completed. A value of A007h indicates
the Dump and Reset Statistical Counters command has completed.
There should be no interrupts from the device after the completion of this operation. Also, no
changes in the CU status or RU status fields should result after operation completion.
6.3.3 PORT Interface
The Port interface allows software to perform certain control functions on the device. Unlike action
commands, port commands do not require access to the SCB. To initiate a port command, software
should write the appropriate Dword (described below) to the Port register (offset 08h) in the CSR.
Port commands automatically generate an internal selective or complete software reset, depending
on the command. The Dword written as part of a Port command should include:
• 16-byte aligned address value on the AD31:AD4 data bus pins.
• Port function selection code on AD3:AD0
The port Dword may be written as a 32-bit entity, two 16-bit entities, or 4 8-bit entities. In the latter
case, the device accepts only the port command after the high byte (offset Bh) is written; therefore,
the high byte should be written last. Four different port commands are supported in the 82557 and
82558 devices. The 82559 and later generation controllers support an additional command, Dump
Wake-up.
Table 18. Port Register Location
Bits 31:16 (Upper Word) Bits 15:0 (Lower Word) Offset
SCB Command Word SCB Status Word Base + 0h
SCB General Pointer Base + 4h
PORT Base + 8h
Table 19. Port Selection Function
Function Pointer Field (Bits 31:4) Opcode (Bits 3:0)
Software Reset Don't care 0000
Self-test Self-test results pointer (16 byte alignment) 0001
Selective Reset Don't care 0010
Dump Dump area pointer (16 byte alignment) 0011
Dump Wake-up Dump area pointer (16 byte alignment) 0111