DP83867CS datasheet(26/114 Pages) TI1

26 / 114 page

DP83867CS, DP83867IS, DP83867E

SNLS504 – OCTOBER 2015

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9.4.2.1 Extended Address Space Access

The DP83867 SMI function supports read/write access to the extended register set using registers REGCR

(0x000Dh) and ADDAR (0x000Eh) and the MDIO Manageable Device (MMD) indirect method defined in

IEEE802.3ah Draft for clause 22 for accessing the clause 45 extended register set.

The standard register set, MDIO registers 0 to 31, is accessed using the normal direct-MDIO access or the

indirect method, except for register REGCR (0x000Dh) and ADDAR (0x000Eh) which is accessed only using the

normal MDIO transaction. The SMI function will ignore indirect accesses to these registers.

REGCR (0x000Dh) is the MDIO Manageable MMD access control. In general, register REGCR(4:0) is the device

address DEVAD that directs any accesses of ADDAR (0x000Eh) register to the appropriate MMD.

The DP83867 supports one MMD device address. The vendor-specific device address DEVAD[4:0] = "11111" is

used for general MMD register accesses.

All accesses through registers REGCR and ADDAR must use the correct DEVAD. Transactions with other

DEVAD are ignored. REGCR[15:14] holds the access function: address (00), data with no post increment (01),

data with post increment on read and writes (10) and data with post increment on writes only (11).

•

ADDAR is the address/data MMD register. ADDAR is used in conjunction with REGCR to provide the access

to the extended register set. If register REGCR[15:1] is 00, then ADDAR holds the address of the extended

address space register. Otherwise, ADDAR holds the data as indicated by the contents of its address

address register. This address register must always be initialized in order to access any of the registers within

the extended register set.

•

When REGCR[15:14] is set to 01, accesses to register ADDAR access the register within the extended

•

When REGCR[15:14] is set to 10, access to register ADDAR access the register within the extended register

set selected by the value in the address register. After that access is complete, for both reads and writes, the

value in the address register is incremented.

•

When REGCR[15:14] is set to 11, access to register ADDAR access the register within the extended register

set selected by the value in the address register. After that access is complete, for write accesses only, the

value in the address register is incremented. For read accesses, the value of the address register remains

unchanged.

The following sections describe how to perform operations on the extended register set using register REGCR

and ADDAR. The descriptions use the device address for general MMD register accesses (DEVAD[4:0] =

"11111").

9.4.2.2 Write Address Operation

1. Write the value 0x001F (address function field = 00, DEVAD = 31) to register REGCR.

2. Write the desired register address to register ADDAR.

Subsequent writes to register ADDAR (step 2) continue to write the address register.

9.4.2.3 Read Address Operation

To read the address register:

1. Write the value 0x001F (address function field = 00, DEVAD = 31) to register REGCR.

2. Read the register address from register ADDAR.

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