The DMAC has the requirement that the length of the transfer is aligned to
the widest interface width. E.g. if the widest interface is 256 bit or 32
bytes the length of the transfer needs to be a multiple of 32.
This restriction can be relaxed for the memory mapped interfaces. This is
done by partially ignoring data of a beat from/to the MM interface.
For write access the stb bits are used to mask out bytes that do not
contain valid data.
For read access a full beat is read but part of the data is discarded. This
works fine as long as the read access is side effect free. I.e. this method
should not be used to access data from memory mapped peripherals like a
FIFO.
This means that for example the length alignment requirement of a DMA
configured for a 64-bit memory and a 16-bit streaming interface is now only
2 bytes instead of 8 bytes as before.
Note that the address alignment requirement is not affected by this. The
address still needs to be aligned to the width of the MM interface that it
belongs to.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
For consistent simulation behavior it is recommended to annotate all source
files with a timescale. Add it to those where it is currently missing.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Length of partial transfers are stored in a queue for SW reads.
The presence of partial transfer is indicated by a status bit.
The reporting can be enabled by a control bit.
The progress of any transfer can be followed by a debug register.
Drive the descriptor from the source side to destination
so we can abort consecutive transfers in case TLAST asserts.
For AXIS count the length of the burst and pass that value to the
destination instead the programmed one. This is useful when the
streams aborts early by asserting the TLAST. We want to notify the
destination with the right number of beats received.
For FIFO source interface reuse the same logic due the small footprint
even if the stream does not got interrupted in that case.
For MM source interface wire the burst length from the request side to
destination.
Currently both the source side and the destination side interfaces employ a
beat counter to identify the last beat in a burst.
The burst memory already has an internal last signal on the destination
side. Exporting it allows the destination side interfaces to use it instead
of having to generate their own signal. This allows to eliminate the beat
counters on the destination side and simplify the data path logic.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
There is an implicit dependency between the outgoing data stream and the
incoming response stream. The AXI specification requires that the
corresponding response is not sent before the last beat of data has been
received.
We can take advantage of this and remove the currently explicit dependency
between the data and response paths. This slightly simplifies the design.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The DMAC allows a transfer to be aborted. When a transfer is aborted the
DMAC shuts down as fast as possible while still completing any pending
transactions as required by the protocol specifications of the port. E.g.
for AXI-MM this means to complete all outstanding bursts.
Once the DMAC has entered an idle state a special synchronization signal is
send to all modules. This synchronization signal instructs them to flush
the pipeline and remove any stale data and metadata associated with the
aborted transfer. Once all data has been flushed the DMAC enters the
shutdown state and is ready for the next transfer.
In addition each module has a reset that resets the modules state and is
used at system startup to bring them into a consistent state.
Re-work the shutdown process to instead of flushing the pipeline re-use the
startup reset signal also for shutdown.
To manage the reset signal generation introduce the reset manager module.
It contains a state machine that will assert the reset signals in the
correct order and for the appropriate duration in case of a transfer
shutdown.
The reset signal is asserted in all domains until it has been asserted for
at least 4 clock cycles in the slowest domain. This ensures that the reset
signal is not de-asserted in the faster domains before the slower domains
have had a chance to process the reset signal.
In addition the reset signal is de-asserted in the opposite direction of
the data flow. This ensures that the data sink is ready to receive data
before the data source can start sending data. This simplifies the internal
handshaking.
This approach has multiple advantages.
* Issuing a reset and removing all state takes less time than
explicitly flushing one sample per clock cycle at a time.
* It simplifies the logic in the faster clock domains at the expense of
more complicated logic in the slower control clock domain. This allows
for higher fMax on the data paths.
* Less signals to synchronize from the control domain to the data domains
The implementation of the pause mode has also slightly changed. Pause is
now a simple disable of the data domains. When the transfer is resumed
after a pause the data domains are re-enabled and continue at their
previous state.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
The DMAC currently doesn't support transfers where the length is not a
multiple of the bus width. When generating the wstrb signal we do pretend
though that we do and dynamically generate it based on the LSBs of the
transfer length.
Given that the other parts of the DMA don't support such transfers this is
unnecessary though. So remove it for now and replace it with a constant
expression where wstrb is always fully asserted.
The generated logic for the wstrb signal was quite terrible, so this
improves the timing of the core.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
All the hdl (verilog and vhdl) source files were updated. If a file did not
have any license, it was added into it. Files, which were generated by
a tool (like Matlab) or were took over from other source (like opencores.org),
were unchanged.
New license looks as follows:
Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
Each core or library found in this collection may have its own licensing terms.
The user should keep this in in mind while exploring these cores.
Redistribution and use in source and binary forms,
with or without modification of this file, are permitted under the terms of either
(at the option of the user):
1. The GNU General Public License version 2 as published by the
Free Software Foundation, which can be found in the top level directory, or at:
https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html
OR
2. An ADI specific BSD license as noted in the top level directory, or on-line at:
https://github.com/analogdevicesinc/hdl/blob/dev/LICENSE
Currently the AXI address width of the DMA is always 32-bit. But not all
address spaces are so large that they require 32-bit to address all memory.
Extract the size of the address space that the DMA is connected too and
configure reduce the address size to the minimum required to address the
full address space.
This slightly reduces utilization.
If no mapped address space can be found the default of 32 bits is used for
the address.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Depending on whether the core is configured for AXI4 or AXI3 mode the width
of the awlen/arlen signal is either 8 or 4 bit. At the moment this is only
considered in top-level module and all other modules use 8 bit internally.
This causes warnings about truncated signals in AXI3 mode, to resolve this
forward the width of the signal through the core.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Mark all unused output ports explicitly as explicitly. This makes it clear
that they are left unconnected on purpose and avoids warnings from the
tools about unconnected ports.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Make sure that the address generator behaves correctly when the buswidth is not
64-bit. Also since the source and destination can have different widths add
separate parameters for source and destination address alignment.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
There were a few place in the core where it assumed a 64-bit wide bus. Make this
configurable using parameters. The patch also adds support for having different
DMA bus widths on the source and destination side.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Lars-Peter Clausen
Laszlo Nagy
Istvan Csomortani
Adrian Costina