This adds a divider unit, connected to the core in much the same way
that the multiplier unit is connected. The division algorithm is
very simple-minded, taking 64 clock cycles for any division (even
32-bit division instructions).
The decoding is simplified by making use of regularities in the
instruction encoding for div* and mod* instructions. Instead of
having PPC_* encodings from the first-stage decoder for each of the
different div* and mod* instructions, we now just have PPC_DIV and
PPC_MOD, and the inputs to the divider that indicate what sort of
division operation to do are derived from instruction word bits.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This adds a debug module off the DMI (debug) bus which can act as a
wishbone master to generate read and write cycles.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds a simple bus that can be mastered from an external
system via JTAG, which will be used to hookup various debug
modules.
It's loosely based on the RiscV model (hence the DMI name).
The module currently only supports hooking up to a Xilinx BSCANE2
but it shouldn't be too hard to adapt it to support different TAPs
if necessary.
The JTAG protocol proper is not exactly the RiscV one at this point,
though I might still change it.
This comes with some sim variants of Xilinx BSCANE2 and BUFG and a
test bench.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
(And rename it to mw_soc_memory).
This makes soc.vhdl simpler and provides the same interface as
the simulated memory, which will help when sharing soc.vhdl
with sim later
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This will be useful when we start needing different toplevels for
different boards.
We keep the reset and clock generators in the toplevel as they will
eventually be taken over by litedram when we integrate it, and they
are more likely to change on different system types.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds support for the Digilane Cmod A7-35.
I had to use the MMCM because the clock (12 MHz) is below the PLL
minimum of 19 MHz.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
The old reset code was overly complicated and never worked properly.
Replace it with a simpler sequence that uses a couple of shift registers
to assert resets:
- Wait a number of external clock cycles before removing reset from
the PLL.
- After the PLL locks and the external reset button isn't pressed,
wait a number of PLL clock cycles before removing reset from the SOC.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
The decode2 stage was spaghetti code and needed cleaning up.
Create a series of functions to pull fields from a ppc instruction
and also a series of helpers to extract values for the execution
units.
As suggested by Paul, we should pass all signals to the execution
units and only set the valid signal conditionally, which should
use less resources.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
The synth target can be used to analyze the core after synthesis
without running P&R. Currently, the only edalize backends that
support synthesis without P&R are vivado and icestorm, and icestorm
needs yosys built with verific support to parse vhdl.
To run synthesis only for a part, run
fusesoc run --target=synth --tool=vivado microwatt --part=<part>
where part is a valid Xilinx part such as xc7a100tcsg324-1
Anton Blanchard
Paul Mackerras