Freescale Semiconductor MPC8260 - Manual (Page 1146)

Inverse Multiplexing for ATM (IMA)
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
33-44 Freescale Semiconductor
Table 33-18 describes the ITINTSTAT bit fields.
33.4.5.2 IMA Link Receive Table Entry
Table 33-18. ITINTSTAT Field Descriptions
Bits Name Description
0-3 — Reserved, initialize to zero.
4 PTQO Persistent transmit queue overflow. Set when a transmit queue overflow occurs for two cells in
a row. Further transmit queue overflow events are masked when this bit is set, in order to avoid
a ’flood’ of interrupts. This bit can be used to distinguish a temporary overflow condition (which
could be caused by a rate differential between the TRL and non-TRL link which was out of
compensatable range), or a persistent overflow condition (which could be caused by a more
permanent condition, such as a failure of this link’s PHY device).
Initialize to zero at link startup.
5 TQO Transmit queue overflow. Set when a transmit queue overflow occurs; cleared when a cell is
successfully transmitted. As this bit is set or cleared on a cell-by-cell basis, it may no longer be
set when software reads it if the overflow condition was only temporary. PTQO should be used
instead to distinguish between persistent or temporary underrun conditions.
6 PTQU Persistent transmit queue underrun. Set when a transmit queue underrun occurs for two cells
in a row. Further transmit queue underrun events are masked when this bit is set, in order to
avoid a ’flood’ of interrupts. This bit can be used to distinguish a temporary underrun condition
(which could be caused by a rate differential between the TRL and non-TRL link which was out
of compensatable range), or a persistent underrun condition (which could be caused by a more
permanent condition, such as a TRL failure).
Initialize to zero at link startup.
7 TQU Transmit queue underrun. Set when a transmit queue underrun occurs; cleared when a cell is
successfully transmitted. As this bit is set or cleared on a cell-by-cell basis, it may no longer be
set when software reads it if the underrun condition was only temporary. PTQU should be used
instead to distinguish between persistent or temporary underrun conditions.
Initialize to zero at link startup.
Table 33-19. IMA Link Receive Table Entry
1
Offset Name Width Description
0x00 ILRCNTL Hword IMA link receive control parameters.
0x02 ILRSTATE Hword IMA link receive state. Microcode-managed parameter. Initialize to
0x0040 at link startup.
0x04 ILID Byte IMA link ID. Formatted per the Cell ID and Link ID field of an ICP cell.
Bit 0: 1 (indicating ICP cell)
Bits 1-2: Program to zero
Bits 3-7: Program to validated LID for this link
[Note: This value is only used by microcode to validate incoming ICP
cells for this link, it is not used to determine round-robin transmission
order. That function is performed by the group order table.]
0x05 RMCTR Byte Receive M counter. Microcode-managed parameter.
0x06 LRIFSN Byte Receive IFSN counter. Microcode-managed parameter.