Commit Graph

6 Commits (master)

Author SHA1 Message Date
Anton Blanchard b5accb78b2 wishbone_bram_wrapper ram_addr_bits is 1 bit off
log2ceil() returns the number of bits required to store a value, so we
need to pass in memory_size-1, not memory_size.

Every other user of log2ceil() gets this right.

Signed-off-by: Anton Blanchard <>
2 years ago
Paul Mackerras ca4eb46aea Make wishbone addresses be in units of doublewords or words
This makes the 64-bit wishbone buses have the address expressed in
units of doublewords (64 bits), and similarly for the 32-bit buses the
address is in units of words (32 bits).  This is to comply with the
wishbone spec.  Previously the addresses on the wishbone buses were in
units of bytes regardless of the bus data width, which is not correct
and caused problems with interfacing with externally-generated logic.

Signed-off-by: Paul Mackerras <>
3 years ago
Anton Blanchard bc0f7cf236 Rename 'do' signal to avoid verilator System Verilog warning
Experimenting with using ghdl to do VHDL to Verilog conversion (instead
of ghdl+yosys), verilator complains that a signal is a SystemVerilog

%Error: microwatt.v:15013:18: Unexpected 'do': 'do' is a SystemVerilog keyword misused as an identifier.
        ... Suggest modify the Verilog-2001 code to avoid SV keywords, or use `begin_keywords or --language.

We could probably make this go away by disabling SystemVerilog, but
it's easy to rename the signal in question. Rename di at the same

Signed-off-by: Anton Blanchard <>
3 years ago
Anton Blanchard 488c30fe91 Add log2ceil and use it in bram code
We might want a non power of 2 amount of RAM in order to fit into an
FPGA, so create log2ceil and use it when calculating the number of
memory bits.

Signed-off-by: Anton Blanchard <>
4 years ago
Benjamin Herrenschmidt 336f0e0690 ram: Ack stores early
Stores only need a single cycle, so we can ack them early if there
isn't an older ack already in the pipeline

Signed-off-by: Benjamin Herrenschmidt <>
5 years ago
Benjamin Herrenschmidt 8e0389b973 ram: Rework main RAM interface
This replaces the simple_ram_behavioural and mw_soc_memory modules
with a common wishbone_bram_wrapper.vhdl that interfaces the
pipelined WB with a lower-level RAM module, along with an FPGA
and a sim variants of the latter.

Signed-off-by: Benjamin Herrenschmidt <>
5 years ago