Motorola PowerQUICC II MPC8280 Series Reference Manual page 1238

IMA Programming Model
tables. The IMA group transmit table entries are 16 bytes long. The IMA group receive
table entries are 64 bytes long. However, there is no need to reserve memory space in
DPRAM for 8 receive IMA groups if less than 8 IMA groups are required. To conserve
memory space used by these tables, it is best to add groups starting from group zero. Note
also that group number is independent of the assignment of IMA ID.
34.4.4.1 IMA Group Transmit Table Entry
Table 34-5. IMA Group Transmit Table Entry
Offset Name
0x00 IGTCNTL
0x01 IGTSTATE
0x02 TGRPORDER
0x04 TVPHYNUM
0x05 TIFSN
0x06 TMCTR
0x07 TRLSTFCNT
0x08 TICPPTR
0x0A TM
0x0B TRLSTFN
34-28
Freescale Semiconductor, Inc.
Width
Byte IMA group transmit control parameters.
Byte IMA group transmit state. Microcode-managed parameter. Must be
initialized to zero at group start-up.
Hword Offset of transmit group order table in DPRAM. Can be changed on the fly.
Byte Transmit Virtual PHY number. Maps this IMA transmit group to a virtual
PHY number for the purpose of selecting an ATM pace controller (APC)
table number for this IMA group. Note that this parameter must be unique;
it must not conflict with the PHY number of any non-IMA PHYs or with the
TVPHYNUM of any other IMA group.
If there are any PHY numbers which will never be used in a system (i.e. the
actual PHY with the address does not exist), then TVPHYNUM should be
selected from one of these PHYs. If no such PHY numbers are available
(i.e. the multi-PHY interface consists of the full 31 PHYs), then select
TVPHYNUM from one of the PHY numbers of the PHYs within this IMA
group.
Byte Transmit IMA Frame Sequence Number (IFSN). Microcode-managed
parameter. Increments each time an IMA frame is transmitted, cycling from
0 through 255. Should be initialized to zero at group start-up.
Byte Transmit IMA M counter. Microcode-managed parameter. Tracks IMA
frame boundaries. Increments once per round-robin distribution of cells to
the transmit queues, cycling from 0 through M. Initialize to zero at group
startup.
Byte TRL stuff frame counter. Microcode-managed parameter. Controls required
stuffing on the TRL. Decrements each time an ICP cell is sent on the TRL,
cycling from TRLSTFN through 0. A TRL stuff event occurs when it reaches
zero. Initialize to the value of TRLSTFN at group start-up.
Hword Offset of transmit ICP cell payload template area in DPRAM. Must be
64-byte aligned. This parameter and the associated template area may only
be changed when IGCNTL[ICPC]=IGTSTATE[ICPCA].
After changing TICPPTR, IGCNTL[ICPC] must be toggled.
Byte Transmit IMA frame size. Program to 31, 63, 127, or 255 for frame sizes (M)
of 32, 64, 128, or 256, respectively.
Byte TRL stuff frame number. Defines the number of IMA frames sent between
TRL stuff events.
For ITC operation IGTCNT[CTC] = 0, program TRLSTFN = 2048/M. For
CTC operation IGTCNT[CTC] = 1, program TRLSTFN = (2048/M) – 1.
Refer to Section 34.4.4.1.1, "IMA Group Transmit Control (IGTCNTL)."
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