MPC8280 datasheet(1174/1386 Pages) FREESCALE

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Inverse Multiplexing for ATM (IMA)

MPC8280 PowerQUICC II Family Reference Manual, Rev. 1

34-28

Freescale Semiconductor

Table 34-7 describes the IGTSTATE bit fields.

34.4.4.1.3

Transmit Group Order Table

The transmit group order table defines the order of the links in the round-robin distribution of cells to the

links of the IMA group. The table consists of an array of bytes ordered from first link to last link, with each

byte providing the PHY address of its associated link. The end of the table is indicated by an entry

programmed to 0x1F.

This table alone defines the order of cell distribution. It is the responsibility of software to program the

LID of the links in the IMA Link Table entries, and to program the group order table such that its order

corresponds to the order of increasing LIDs within the group.

The format of a transmit group order table entry is shown in Figure 34-16.

Table 34-8 describes the format of a transmit group order table entry.

Table 34-7. IGTSTATE Field Descriptions

Bits

Name

Description

TSTF

TRL stuff flag. Microcode-managed parameter. Indicates that the next ICP cell on the TRL will

be part of a stuff event. Initialize to zero at group startup.

TIMSTF

TRL imminent stuff flag. Microcode-managed parameter. Indicates that an upcoming stuff

event will be signalled in the next ICP of the TRL (via LSI=001). Initialize to zero at group

startup.

GTE

Go to end flag - TRL has requested 2 times before round robin distribution has completed or

link will underrun and is still due a cell from round robin distribution. Microcode managed

parameter initialize to 0. Used for optional TRL Service Latency enhancement only.

TRQS

TRL Request - TRL has requested therefore 1 round robin distribution of cells and is yet to be

completed. Microcode managed parameter initialize to 0. Used for optional TRL Service

Latency enhancement only.

ELX

Early exit flag. Microcode-managed parameter. Initialize to zero at group startup.

5—

Reserved

ICH

ICP change holdoff. Microcode-managed parameter. Initialize to zero at group startup.

ICPCA

ICP change allowed flag. Microcode-managed parameter. See description of IGTCNTL[ICPC].

Field

—

PHY ADDRESS

Figure 34-16. Transmit Group Order Table Entry

Table 34-8. Transmit Group Order Table Entry Field Descriptions

Bits

Name

Description

0–2

—

Reserved

3–7

PHY

ADDRESS

PHY address (Up to 31 PHYs[0–30]) of the link transmitting in this position in the round-robin.

A value of 0x1F in this field indicates the end of the group order table.

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