The design is backward-compatible in functionality for users
who don't want to use DRP. That is, on power on, the XADC will
scan the supply and temperature and store them in CSRs.
If drp_enable is set, the scanning stops, and the XADC is now
controlled by the DRP bus.
Wher drp_enable is reset, the XADC may return to an auto-sample
mode, but only if the internal registers are configured to do this.
If you return to drp_enable without, for example, turning on
the continuous sequence and setting which channels to check,
the results will be unpredictable (mostly either it'll scan just
once and stop, or it'll not scan all the channels, depending on
the register settings).
At this point, the backward compatibility was confirmed in testing,
the DRP API is still a work in progress as the application this
is being developed for needs to support fun stuff like real time
sampling of signals to a buffer.
Down the road, this block may have to be modified again to support an
output FIFO, so we're not railing the CPU trying to do real time
sampling of ADC data. This will probably be added as a True/False flag
of some sort in the parameter list, because the FIFO will be expensive
as far as BRAM goes to implement and applications that don't need the
FIFO buffer can probably use that BRAM for better things.
This fixes some formatting errors with the timer documentation, such as
the lack of a space between the first and second sentences. It also
fixes some grammar for documentation of various fields.
Signed-off-by: Sean Cross <sean@xobs.io>
The ReStructured Text used was not properly formatted, resulting in
confusing and broken output. This corrects the output and lets it
format correctly when using sphinx.
Signed-off-by: Sean Cross <sean@xobs.io>
If clocks and multipliers are planned well, we can have
a zero-error solution for clocks. Suggest to change < to <= in
margin comparison loop, so that a "perfect" solution is allowed
to converge.
Various development boards' LiteDRAM ports may have native data
widths of either 64 (nexys4ddr), 128 (versa5g), or 256 (trellis)
bits. Add Rocket variants configured with mem_axi ports of matching
data widths, so that a point to point connection between the CPU's
memory port and LiteDRAM can be accomplished without any additional
data width conversion gateware.
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Enforce the condition that csr_alignment be either 32 or 64 when
requested explicitly when initializing SoCCore().
Additionally, if a CPU is specified, enforce that csr_alignment be
equal to the native CPU word size (currently either 32 or 64), and
warn the caller if an alignment value *higher* than the CPU native
word size was explicitly requested.
In conclusion, if a CPU is specified, then csr_alignment should be
assumed to equal 8*sizeof(unsigned long).
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Since the PLIC is internal to Rocket, access its registers
directly via pointer dereference, rather than through the
LiteX CSR Bus accessors (which assume subregister slicing,
and are therefore inappropriate for registers NOT accessed
over the LiteX CSR Bus).
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Since csr_data_width=64 has probably never worked properly, remove
it as one of the possible options (to be fixed and re-added later).
Add csr_data_width=16, which has been tested and does work.
Additionally, ensure csr_data_width <= csr_alignment (we should not
attempt to create (sub)registers larger than the CPU's native word
size or XLen).
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Additional sdc/qsf commands can be added from the design like:
platform.sdc_additional_commands.append("create_clock ...")
platform.sdc_additional_commands.append("set_false_path ...")
The SPI mode is actually mode3, since the output value is updated on the
falling edge of CLK and the input value is updated on the rising edge.
This also clarifies some of the documentation based on experience with
the core.
Signed-off-by: Sean Cross <sean@xobs.io>
It was necessary to add drp_locked CSR for reading LOCK signal from
MMCM. Additionally, input signal RESET from MMCM was not driven by
any signal to do a proper reset of MMCM module thus it was impossible
to perform entirely correct dynamic clock reconfiguration.
Enable SDRAM to be initialized when csr_data_width > 8 bits.
Currently, csr_data_width up to 32 bits is supported.
Read leveling tested with csr_data_width [8, 16, 32] on the
ecp5-versa5g and trellisboard (using yosys/trellis/nextpnr),
and on the nexys4ddr (using Vivado).
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
With high speed link (10gbps XGMII ethernet for example), stream data_width is generally
> 8-bit which make header/data un-aligned on bytes boundaries. The change allows the
Packetizer/Depacketizer to work on stream with a data_width > 8-bit.
Rocket variants can be configured with axi port data widths that
are multiples of the native word size (64 bits in our case). In
the future, we will add variants with mem_axi data width > 64 bit,
to match the native data width of the LiteDRAM controller on
various development boards (e.g., 128 bits on the ecp5versa, and
256 bits on the trellisboard).
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Connect Rocket's dedicated port for cached RAM accesses (mem_axi)
directly to the LiteDRAM data port, bypassing the shared LiteX
(Wishbone) bus.
When both Rocket's mem_axi and LiteDRAM's port have the same data
width, use a native point-to-point AXI connection.
Otherwise, convert both ends to Wishbone, and use the Wishbone
data width converter to bridge the gap.
FIXME: In the future, this part should be replaced with a native
AXI data width converter!
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Before;
```
ValueError: Memory region conflict between rom and main_ram
```
After;
```
ValueError: Memory region conflict between rom (<SoCMemRegion 0x10000000 0x10000 cached>) and main_ram (<SoCMemRegion 0x0 0x20000000 cached>)
```
Fixes#296.
When timing requirements are strict, allow the build process to fail upon
failure to meet timing. This facilitates running the build process from a
loop, repeatedly, until a "lucky" p&r solution is found, e.g.:
while true; do
litex/boards/targets/versa_ecp5.py --gateware-toolchain trellis \
--sys-clk-freq=60e06 --cpu-type rocket --cpu-variant linux \
--with-ethernet --yosys-nowidelut \
--nextpnr-timingstrict
if [ "$?" == "0" ]; then
echo "Success" | mail -s "Build Succeeded" your@email.here
break
fi
done
This augments commit #683e0668, which unconditionally forced p&r to
succeed, regardless of whether timing was met, via '--timing-allow-fail'.
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Python does not have native OrderedSet and we need to be able to preserve the order of the sources
for some backends (Verilator for instance), so use list instead of set.
The total size of RAM (main_mem) can be expected to vary significantly,
and often exceed the size needed for MMIO allocations by a large margin.
As such, place Rocket's MMIO (io regions) below 0x8000_0000, and start
the RAM (main_mem) at 0x8000_0000, with nothing above it to limit its
future growth.
Also, bump the pre-built Rocket verilog submodule to an updated version,
which also comes with matching changes to the way MMIO and RAM accesses
are mapped and routed to their respective AXI interfaces.
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
The shadow_base parameter has always been difficult to apprehend, replace it with
io_regions (uncached regions) defined user or the CPU.
The equivalent of a shadow_base parameter of 0x80000000 in the old API is:
io_regions = {0x80000000: 0x80000000} # origin, length
It's still possible to use shadow_base with retro-compat, but user is encouraged
to update and features will be removed in the future.
Both the SoC and get_csr_header() have independently set defaults
for the value of 'shadow_base'. If the SoC's value was modified,
ensure that get_csr_header() uses the modified value instead of
its own default.
Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
Passing '-nowidelut' to yosys' synth_ecp5 command improves area utilization
to the point where a (linux variant) rocket-chip based design will fit on a
versa_ecp5 board. Usually '-nowidelut' incurs a timing penalty, but that is
then mitigated by using DSP inference (enabled by default from yosys commit
8474c5b3).
Off by default, this flag can be enabled by adding '--yosys-nowidelut=True'
to the litex/boards/targets/versa_ecp5.py command line.
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Doing actions on register read is generally not a good design practice (it's
better to do separate register write to trigger actions) but in some very
specific cases being able to know that register has been read can solve cases
that are difficult to do with the recommended practives and that can justify
doing an exception.
This commit add a we signal to CSR, CSRStatus and this allow the logic to know
when the CSR, CSRStatus is read.
For example a standalone controller with no exposed CSRs (probably not
a very useful configuration but I really don't like python backtraces)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
With the new ModuleDoc class, we can inherit `ModuleDoc` and
automatically get module-level documentation.
This patch also corrects a typo in `timer` that causes an error in
sphinx.
Signed-off-by: Sean Cross <sean@xobs.io>
It is important to be able to document modules other than CSRs.
This patch adds ModuleDoc and AutoDoc, both of which can be used
together to document modules.
ModuleDoc can be used to transform the __doc__ string of a class into a
reference-manual section. Alternately, it can be used to add additional
sections to a module.
AutoDoc is used to gather all submodule ModuleDoc objects in order to
traverse the tree of documentation.
Signed-off-by: Sean Cross <sean@xobs.io>
Mainline Linux expects it to be loaded at the physical address of 0x0.
Change the MAIN_RAM base address to 0x0 and update exception vector
during the booting process.
Currently section '.rodata' of the LiteX BIOS doesn't fit in the 'rom'
region if mor1kx is used with EthernetSoC. Increase the integrated ROM
size from 0x8000 to 0x10000 in EthernetSoC.
With this change, we will now generate csr.h and sdram_phy.h, which
will be needed by the initialization code running on the host CPU.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Document the various fields present in the SPI flash bitbang interface.
This adds documentation for the Single and DualQuad modules.
Signed-off-by: Sean Cross <sean@xobs.io>
Add `name` and `description` as optional arguments to the various
EventSource types. These default to `None`, so this should be a
backwards-compatible change.
Use the same trick as CSRs, where we default the `name` to be the
instantiated object name as read from the Migen `get_obj_var_name()`
call.
Signed-off-by: Sean Cross <sean@xobs.io>
bunnie
Florent Kermarrec
Sean Cross
Tim 'mithro' Ansell
Giammarco Zacheo
Gabriel Somlo
Arnaud Durand
Konrad Beckmann
Miodrag Milanovic
Pawel Czarnecki
Ilia Sergachev
Vamsi K Vytla
fb@frank-buss.de
Jan Kowalewski
Martin Cornil
Benjamin Herrenschmidt
Filip Kokosinski