DP83821 datasheet(35/86 Pages) NSC

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4.0 Register Set (Continued)

4.1.3 Configuration Revision ID Register

This register stores the silicon revision number, revision number of software interface specification and lets the

configuration software know that it is an Ethernet controller in the class of network controllers.

4.1.4 Configuration Latency Timer Register

This register gives status and controls such miscellaneous functions as BIST, Latency timer and Cache line size.

DP83821 Bus Master Operations:

Based on cache line size, the DP83821 will use the following PCI commands for bus mastered transfers:

0110 - Mem Read

Single dword read transfers

1110 - Mem Read Line

Read More than 1 dword but not across a cacheline boundary

1100 - Mem Read Multiple

Read transfers that cross a cacheline boundary

0111 - Mem Write

Writes that do not exactly overwrite 1 or more cachelines

1111 - Mem Write Invalidate Writes that exactly overwrite 1 or more cachelines

Tag: CFGRID

Size: 32 bits

Hard Reset: 02000000h

Offset: 08h

Access: Read Only

Soft Reset: Unchanged

bit

tag

description

usage

31-24

BASECL

Base Class

Returns 02h which specifies a network controller.

23-16

SUBCL

Sub Class

Returns 00h which specifies an Ethernet controller.

15-8

PROGIF

Programming IF

Returns 00h which specifies the first release of the DP83821.

7-0

REVID

Silicon Revision

Returns 00h which specifies the silicon revision.

Tag: CFGLAT

Size: 32 bits

Hard Reset: 00000000h

Offset: 0Ch

Access: Read Write

Soft Reset: Unchanged

bit

tag

description

usage

BISTCAP

BIST Capable

Reads will always return 0.

BISTEN

BIST Enable

Reads will return a 0, writes are ignored.

29-16

Reserved

Reads will return a 0, writes are ignored.

15-8

LAT

Latency Timer

Set by software to the number of PCI clocks that DP83821 may hold the

PCI bus.

7-0

CLS

Cache Line Size

Set to the value of the system cache line size in dwords. Acceptable values

are powers of 2 less than or equal to 128. All other values will be

recognized as 0.

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