
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
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Caching RPDRs reduces the number of host bus accesses that the RMAC
makes.
Each cache is managed independently. The elements of the cache are
consumed one at a time as they are needed by the RMAC. The RPDR small
buffer cache is reloaded when it is empty and the RMAC requires a new small
buffer RPDR. The large buffer RPDR cache is reloaded when it is empty and the
RMAC requires a new large buffer RPDR. When reloading either of the caches,
the appropriate cache controller will read up to six new elements. The cache
controller may read fewer than six elements if there are fewer than six new
elements available, or the read pointer index is within six elements of the end of
the free queue. If the read pointer is near the end of the free queue, the cache
controller reads only to the end of the queue and does not start reading from the
top of the queue until the next time a reload is required. To do so would require
two host memory transactions and would be of no benefit.
8.5 PCI Controller
The General-Purpose Peripheral Component Interconnect Controller block
(GPIC) provides a 32-bit Master and Target interface core which contains all the
required control functions for Peripheral Component Interconnect (PCI) Bus
Revision 2.1 interfacing. Communications between the PCI bus and other
FREEDM-32P32 blocks can be made through either an internal
asynchronous16-bit bus or through one of two synchronous FIFO interfaces.
One of the FIFO interfaces is dedicated to servicing the Receive DMA Controller
block (RMAC) and the other to the Transmit DMA Controller block (TMAC).
The GPIC supports a 32-bit PCI bus operating at up to 33 MHz and bridges
between the timing domain of the DMA controllers (SYSCLK) and the timing
domain of the PCI bus (PCICLK). By itself, the GPIC does not generate any PCI
bus accesses. All transactions on the bus are initiated by another PCI bus
master or by the core device. The GPIC transforms each access to and from the
PCI bus to the intended target or initiator in the core device. Except for the
configuration space registers and parity generating/checking, the GPIC performs
no operations on the data.
The GPIC is made up of four sections: master state machine, a target state
machine, internal microprocessor bus interface and error/bus controller. The
target and master blocks operate independent of each other. The error/bus
control block monitors the control signals from the target and master blocks to
determine the state of the PCI I/O pads. This block also generates and/or
checks parity for all data going to or coming from the PCI bus. The internal
microprocessor bus interface block contains configuration and status registers
together with the production test logic for the GPIC block.