It turns out the Chisel C++ backend can't emit correct initialization
code for a 128 bit wide NastiROM. Rather than trying to fix Chisel, I'm
just going to hack up the backup memory port Verilog harness a bit more
to make it work.
Note that the backup memory port Verilog already couldn't take arbitrary
parameters for MIF_*, so it's not like we're losing any flexibility
here.
We need this to work for our chip, and it's not been tested in a long
time in upstream -- it didn't even used to build since the Nasti
conversion. This makes a few changes:
* Rather than calling the backup memory port parameters MEM_*, it calls
them MIF_* (to match the MIT* paramater objects). A new name was
necessary because the Nasti stuff is now dumped as MEM_*, which has
similar names but incompatible values.
* p(MIFDataBits) was changed back to 128, as otherwise the backup
memory port doesn't work (it only send half a TileLink transaction).
64 also causes readmemh to bail out, but changing the elf2hex parameters
works around that.
* A configuration was added that enabled the backup memory port in the
tester. While this is kind of an awkward way to do it, I want to
make sure I can start testing this regularly and this makes it easy to
integrate.
We're building a chip with 8 memory channels. Since this will require a
complicated test setup we want to also be able to bring up the chip with fewer
memory channels. This commit adds a SCR that controls the number of active
memory channels on a chip. Toggling this SCR will scramble memory and drop
Nasti messages, so it's only possible to change while the chip is booting.
By default this just adds a 1-bit SCR, which essentially no extra logic.
When multiple memory channel configurations are enabled at elaboration time, a
NastiMemoryInterconnect is generated for each channel configuration. The
number of outstanding misses is increased to coorespond to the maximum number
of banks per memory channel (added as a parameter), which I believe is
necessary to avoid deadlock in the memory system.
A configuration is added that supports 8 memory channels but has only 1 enabled
by default.
* DMA frontend-backend communication tunneled over TileLink/AXI
* Split MMIO and Mem requests in l1tol2net instead of in AXI interconnect
* Don't make NIOMSHRs configurable. Fixed at 1.
* Connect accelerator-internal CSRs into the CSR file
* Make mtvec register configurable and writeable
* Outermost TL parameters should have the width set to be the same as the
MIF data width.
* Broadcast Hub and Narrower, which use different sets of TL parameters
should use the proper set of parameters at each interface
