PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
10.6.2 Interrupt Driven Error/Status Reporting
The interrupt logic has several layers. The top layer of the interrupt logic, the
Master Interrupt Register, indicates from which block the interrupt came. Once
the block is determined the processor can access the appropriate block to
determine the interrupt cause.
10.6.2.1
TC Layer Interrupts
The TC layer sources 4 different interrupts that are reported through a FIFO
structure. As each interrupt occurs it is placed into a FIFO along with a Link
Identifier to uniquely identify the link. The error conditions reported through this
structure include HEC Errors, Loss of Cell Delineation (LCD) state change, Out of
Cell Delineation (OCD) state change, and Receive Link FIFO overflow. To
determine the actual states of LCD and OCD it is necessary to query the
individual link status. If this FIFO overflows, it is necessary to query the status of
all links in order to retrieve accurate state information.
10.6.2.2
IMA Interrupts
The IMA sub-layer sources four interrupts: RIPP_INTR, TIMA_INTR,
RDAT_INTR, and ICP_CELL_AVL. The RIPP_INTR indicates that either a status
change or an error occurred on an IMA group. The RIPP Interrupt status FIFO
contains the groups that have enabled conditions active. The RIPP Interrupt
status FIFO is managed so that each group will only ever have a single entry in
the FIFO. To facilitate interrupt processing, a RIPP command is provided to
gather all interrupts and status for a group and all of the links within the group in
one snapshot.
TIMA_INTR provides information that a link FIFO has overflowed. During normal
operations, this will only happen when: (1) the TIMA is misconfigured or (2) the
rate difference between the clocks in an IMA group is greater than the maximum
tolerance. To determine which link has experienced a problem, the TIMA Link
FIFO Overflow Status registers should be read.
RDAT_INTR indicates either: (1) that cells were dropped due to Any-
PHY/UTOPIA congestion or (2) that TC group cells were dropped due to FIFO
overflow. To determine the cause of the interrupt, the RDAT Master Interrupt
register should be read.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
90
PMC [ PMC-SIERRA, INC ]
