IOBUF support #1148

mkurc-ant · 2019-11-12T14:16:10Z

This PR adds support for IOBUF to SymbiFlow.

With this PR the flow of SymbiFlow changes a bit. Upon sysnthesis the design is written to a JSON file. Then, the file is processed by the split_inouts.py utility which splits inout ports into separate inputs and outputs. After processing, the design is written to another JSON file which is then converted to EBLIF using Yosys.

This processing should be moved to a Yosys plugin in the future.

Each top-level inout port of the design is split into one input and one output port. Port names are given in the following way: inout A -> input A_$inp and output A_$out.

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

…w in CMake build system. Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

…longer required. Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

mkurc-ant · 2019-11-18T13:52:58Z

I'm still having issues with making Yosys infer IOBUFs from assign statements though. For such a design:

inout wire pin

...

wire pin_i;
wire pin_o;
wire pin_t;

assign pin_i = pin;
assign pin = (pin_t == 1'b1) ? pin_o : 1'bz;

In some cases I end up with an OBUFT-like cell for the 3-state output and the input taken directly from the pin (not through any buffer). In other cases I have a properly connected IOBUF cell but after optimization its output gets disconnected (a bug?).

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

litghost · 2019-11-18T16:48:35Z

I'm still having issues with making Yosys infer IOBUFs from assign statements though. For such a design:

I know I suggested the iobufmap to begin with, but if we simply require the IOBUF explicitly, would your script do the right thing?

common/cmake/devices.cmake

litghost · 2019-11-18T17:17:26Z

common/cmake/devices.cmake

+      OUTPUT ${OUT_JSON}
+      DEPENDS ${OUT_JSON_SYNTH} ${QUIET_CMD} ${QUIET_CMD_TARGET} ${SPLIT_INOUTS} ${PYTHON3} ${PYTHON3_TARGET} simplejson
+      COMMAND
+        ${CMAKE_COMMAND} -E env PYTHONPATH=${PRJXRAY_DIR}:${symbiflow-arch-defs_SOURCE_DIR}/utils ${PYTHON3} ${SPLIT_INOUTS} -i ${OUT_JSON_SYNTH} -o ${OUT_JSON}


What is PRJXRAY_DIR required here? It seems weird to have a 7-series specific thing in the (in theory) generic CMake function?

Upon review of split_inouts, it doesn't seem to use PRJXRAY at all? So you should just be able to drop the path?

Right, It ended up here as a mistake. Removed.

litghost · 2019-11-18T17:19:27Z

utils/split_inouts.py

+# =============================================================================
+
+
+def find_and_split_inout_ports(design, module_name):


litghost · 2019-11-18T17:19:59Z

utils/split_inouts.py

+
+def get_nets(bits):
+    """
+    Returns a set of numbers corresponding to net indices.


This function is very weird. Can you provide some doctest examples?

Added docstring and doctest.

litghost · 2019-11-18T17:20:24Z

utils/split_inouts.py

+        if "top" in attrs and attrs["top"] == 1:
+            return name
+
+    return None


Should throw an exception rather than return None?

Added throwing an exception.

utils/split_inouts.py

litghost

This is looking really good! Comments added

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

probot-autolabeler bot added lang-verilog Issue uses (or requires) Verilog language. lang-xml Issues uses (or requires) XML language. type-vpr labels Nov 12, 2019

mkurc-ant force-pushed the vpr_iobuf_support branch from 4c1e098 to 7784fb8 Compare November 13, 2019 15:00

probot-autolabeler bot added arch-artix7 arch-ice40 Issue related to the iCE40 architecture description. arch-test type-utils Issues is related to the scripts inside the repo. lang-python Issue uses (or requires) Python language. labels Nov 13, 2019

mkurc-ant added 8 commits November 14, 2019 13:10

Initial IOBUF techmap + minitest.

4f89ad6

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Support for Yosys -> JSON -> processing -> JSON -> Yosys -> EBLIF flo…

a7b0052

…w in CMake build system. Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Added an utility script for splitting inout ports to inputs and outputs.

073abc1

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Integrated split_inouts.py with the build system.

bcffc8f

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Initial model of the IOBUF_VPR + techmap modification.

3697ffc

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Fixed arch to pass through T, fixed minitest pcf file.

959500b

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Modified vpr_io_place.py to support EBLIF with splitted inout nets.

4feee51

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Added fasm features.

fb6a3a4

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

mkurc-ant force-pushed the vpr_iobuf_support branch from 8b8bd85 to fb6a3a4 Compare November 14, 2019 12:11

mkurc-ant added 4 commits November 14, 2019 14:36

Fixed lint error, adapted iobuf test to the ROI-less graph.

fc68188

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Fixed the net split and the techmap so changing cell port def. is no …

f2d9179

…longer required. Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Fixed bugs in split_inouts.py

9d23d61

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Added (acutally fixed) inference of IOBUF in fasm2bels.

b233ffe

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

mkurc-ant changed the title ~~[WIP] IOBUF support~~ IOBUF support Nov 15, 2019

mkurc-ant added 2 commits November 15, 2019 16:58

Fixed comment in test code.

a256f0b

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Code formatting.

35e48e9

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

mkurc-ant requested a review from litghost November 18, 2019 13:46

Fixed a bug in split_inouts.py

750f7b1

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

litghost reviewed Nov 18, 2019

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mkurc-ant added 2 commits November 19, 2019 12:31

A working I2C scan test.

c7463d2

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

Addressed review comments.

48531d3

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

probot-autolabeler bot added the type-docs Issue is related to documentation. label Nov 19, 2019

litghost merged commit eff035a into f4pga:master Nov 19, 2019

mkurc-ant deleted the vpr_iobuf_support branch November 20, 2019 09:25

mkurc-ant mentioned this pull request Nov 20, 2019

Inference of 3-state IOBUFs in Yosys #1161

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IOBUF support #1148

IOBUF support #1148

mkurc-ant commented Nov 12, 2019 •

edited

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litghost commented Nov 18, 2019

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		# =============================================================================


		def find_and_split_inout_ports(design, module_name):

IOBUF support #1148

IOBUF support #1148

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mkurc-ant commented Nov 12, 2019 • edited

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mkurc-ant commented Nov 12, 2019 •

edited