User guide

Chapter 17: Testbench and Design Example 17–9
Chaining DMA Design Examples
December 2013 Altera Corporation Cyclone V Hard IP for PCI Express
User Guide
■ altpcierd_dma_dt—This module arbitrates PCI Express packets issued by the
submodules altpcierd_dma_prg_reg, altpcierd_read_dma_requester,
altpcierd_write_dma_requester and altpcierd_dma_descriptor.
■ altpcierd_dma_prg_reg—This module contains the chaining DMA control
registers which get programmed by the software application or BFM driver.
■ altpcierd_dma_descriptor—This module retrieves the DMA read or write
descriptor from the BFM shared memory, and stores it in a descriptor FIFO.
This module issues upstream PCI Express TLPs of type Mrd.
■ altpcierd_read_dma_requester, altpcierd_read_dma_requester_128—For each
descriptor located in the altpcierd_descriptor FIFO, this module transfers data
from the BFM shared memory to the Endpoint memory by issuing MRd PCI
Express transaction layer packets. altpcierd_read_dma_requester is used with
the 64-bit Avalon-ST IP core. altpcierd_read_dma_requester_128 is used with
the 128-bit Avalon-ST IP core.
■ altpcierd_write_dma_requester, altpcierd_write_dma_requester_128—For
each descriptor located in the altpcierd_descriptor FIFO, this module transfers
data from the Endpoint memory to the BFM shared memory by issuing MWr
PCI Express transaction layer packets. altpcierd_write_dma_requester is used
with the 64-bit Avalon-ST IP core. altpcierd_write_dma_requester_128 is used
with the 128-bit Avalon-ST IP core.ls
■ altpcierd_cpld_rx_buffer—This modules monitors the available space of the
RX Buffer; It prevents RX Buffer overflow by arbitrating memory read request
issued by the Application Layer.
■ altpcierd_cplerr_lmi—This module transfers the err_desc_func0 from the
Application Layer to the Hard IP block using the LMI interface. It also retimes
the
cpl_er r bits from the Application Layer to the Hard IP block.
■ altpcierd_tl_cfg_sample—This module demultiplexes the Configuration Space
signals from the
tl_cfg_ctl bus from the Hard IP block and synchronizes this
information, along with the
tl_cfg_sts bus to the user clock ( pld_clk )
domain.
Design Example BAR/Address Map
The design example maps received memory transactions to either the target memory
block or the control register block based on which BAR the transaction matches. There
are multiple BARs that map to each of these blocks to maximize interoperability with
different variation files. Table 17–1 shows the mapping.
Table 17–1. Design Example BAR Map
Memory BAR Mapping
32-bit BAR0
32-bit BAR1
64-bit BAR1:0
Maps to 32 KByte target memory block. Use the rc_slave module to bypass the chaining DMA.
32-bit BAR2
32-bit BAR3
64-bit BAR3:2
Maps to DMA Read and DMA write control and status registers, a minimum of 256 bytes.