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adding input buffering to bus arbiters to reduce backpressure delay propagation

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This commit is contained in:
Blaise Tine
2020-12-05 17:31:29 -08:00
parent 13a5370254
commit d0f2a3984d
17 changed files with 480 additions and 338 deletions
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128
hw/rtl/VX_io_arb.v
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@@ -14,96 +14,118 @@ module VX_io_arb #(
input wire reset,
// input requests
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0] io_req_valid_in,
input wire [NUM_REQS-1:0][TAG_IN_WIDTH-1:0] io_req_tag_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0][ADDR_WIDTH-1:0] io_req_addr_in,
input wire [NUM_REQS-1:0] io_req_rw_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0][WORD_SIZE-1:0] io_req_byteen_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0][WORD_WIDTH-1:0] io_req_data_in,
output wire [NUM_REQS-1:0] io_req_ready_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0] req_valid_in,
input wire [NUM_REQS-1:0][TAG_IN_WIDTH-1:0] req_tag_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0][ADDR_WIDTH-1:0] req_addr_in,
input wire [NUM_REQS-1:0] req_rw_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0][WORD_SIZE-1:0] req_byteen_in,
input wire [NUM_REQS-1:0][`NUM_THREADS-1:0][WORD_WIDTH-1:0] req_data_in,
output wire [NUM_REQS-1:0] req_ready_in,
// output request
output wire [`NUM_THREADS-1:0] io_req_valid_out,
output wire [TAG_OUT_WIDTH-1:0] io_req_tag_out,
output wire [`NUM_THREADS-1:0][ADDR_WIDTH-1:0] io_req_addr_out,
output wire io_req_rw_out,
output wire [`NUM_THREADS-1:0][WORD_SIZE-1:0] io_req_byteen_out,
output wire [`NUM_THREADS-1:0][WORD_WIDTH-1:0] io_req_data_out,
input wire io_req_ready_out,
output wire [`NUM_THREADS-1:0] req_valid_out,
output wire [TAG_OUT_WIDTH-1:0] req_tag_out,
output wire [`NUM_THREADS-1:0][ADDR_WIDTH-1:0] req_addr_out,
output wire req_rw_out,
output wire [`NUM_THREADS-1:0][WORD_SIZE-1:0] req_byteen_out,
output wire [`NUM_THREADS-1:0][WORD_WIDTH-1:0] req_data_out,
input wire req_ready_out,
// input response
output wire [NUM_REQS-1:0] io_rsp_valid_in,
output wire [NUM_REQS-1:0][TAG_IN_WIDTH-1:0] io_rsp_tag_in,
output wire [NUM_REQS-1:0][WORD_WIDTH-1:0] io_rsp_data_in,
input wire [NUM_REQS-1:0] io_rsp_ready_in,
output wire [NUM_REQS-1:0] rsp_valid_in,
output wire [NUM_REQS-1:0][TAG_IN_WIDTH-1:0] rsp_tag_in,
output wire [NUM_REQS-1:0][WORD_WIDTH-1:0] rsp_data_in,
input wire [NUM_REQS-1:0] rsp_ready_in,
// output response
input wire io_rsp_valid_out,
input wire [TAG_OUT_WIDTH-1:0] io_rsp_tag_out,
input wire [WORD_WIDTH-1:0] io_rsp_data_out,
output wire io_rsp_ready_out
input wire rsp_valid_out,
input wire [TAG_OUT_WIDTH-1:0] rsp_tag_out,
input wire [WORD_WIDTH-1:0] rsp_data_out,
output wire rsp_ready_out
);
localparam DATAW = `NUM_THREADS + TAG_OUT_WIDTH + (`NUM_THREADS * ADDR_WIDTH) + 1 + (`NUM_THREADS * WORD_SIZE) + (`NUM_THREADS * WORD_WIDTH);
if (NUM_REQS > 1) begin
wire [NUM_REQS-1:0] valids;
for (genvar i = 0; i < NUM_REQS; i++) begin
assign valids[i] = (| io_req_valid_in[i]);
assign valids[i] = (| req_valid_in[i]);
end
wire [NUM_REQS-1:0][(`NUM_THREADS + TAG_OUT_WIDTH + (`NUM_THREADS * ADDR_WIDTH) + 1 + (`NUM_THREADS * WORD_SIZE) + (`NUM_THREADS * WORD_WIDTH))-1:0] data_in;
wire [NUM_REQS-1:0][DATAW-1:0] data_in;
for (genvar i = 0; i < NUM_REQS; i++) begin
assign data_in[i] = {io_req_valid_in[i], {io_req_tag_in[i], REQS_BITS'(i)}, io_req_addr_in[i], io_req_rw_in[i], io_req_byteen_in[i], io_req_data_in[i]};
assign data_in[i] = {req_valid_in[i], {req_tag_in[i], REQS_BITS'(i)}, req_addr_in[i], req_rw_in[i], req_byteen_in[i], req_data_in[i]};
end
wire [`NUM_THREADS-1:0] io_req_tmask_out;
wire io_req_valid_out_unqual;
// Inputs buffering
wire [NUM_REQS-1:0] req_valid_in_qual;
wire [NUM_REQS-1:0][DATAW-1:0] req_data_in_qual;
wire [NUM_REQS-1:0] req_ready_in_qual;
for (genvar i = 0; i < NUM_REQS; ++i) begin
VX_skid_buffer #(
.DATAW (DATAW),
.PASSTHRU (NUM_REQS < 4)
) req_buffer (
.clk (clk),
.reset (reset),
.valid_in (valids[i]),
.data_in (data_in[i]),
.ready_in (req_ready_in[i]),
.valid_out (req_valid_in_qual[i]),
.data_out (req_data_in_qual[i]),
.ready_out (req_ready_in_qual[i])
);
end
wire [`NUM_THREADS-1:0] req_tmask_out;
wire req_valid_out_unqual;
VX_stream_arbiter #(
.NUM_REQS(NUM_REQS),
.DATAW(`NUM_THREADS + TAG_OUT_WIDTH + (`NUM_THREADS * ADDR_WIDTH) + 1 + (`NUM_THREADS * WORD_SIZE) + (`NUM_THREADS * WORD_WIDTH)),
.BUFFERED(NUM_REQS >= 4)
.NUM_REQS (NUM_REQS),
.DATAW (DATAW),
.BUFFERED (NUM_REQS >= 4)
) req_arb (
.clk (clk),
.reset (reset),
.valid_in (valids),
.valid_out (io_req_valid_out_unqual),
.data_in (data_in),
.data_out ({io_req_tmask_out, io_req_tag_out, io_req_addr_out, io_req_rw_out, io_req_byteen_out, io_req_data_out}),
.ready_in (io_req_ready_in),
.ready_out (io_req_ready_out)
.valid_in (req_valid_in_qual),
.data_in (req_data_in_qual),
.ready_in (req_ready_in_qual),
.valid_out (req_valid_out_unqual),
.data_out ({req_tmask_out, req_tag_out, req_addr_out, req_rw_out, req_byteen_out, req_data_out}),
.ready_out (req_ready_out)
);
assign io_req_valid_out = {`NUM_THREADS{io_req_valid_out_unqual}} & io_req_tmask_out;
assign req_valid_out = {`NUM_THREADS{req_valid_out_unqual}} & req_tmask_out;
///////////////////////////////////////////////////////////////////////
wire [REQS_BITS-1:0] rsp_sel = io_rsp_tag_out[REQS_BITS-1:0];
wire [REQS_BITS-1:0] rsp_sel = rsp_tag_out[REQS_BITS-1:0];
for (genvar i = 0; i < NUM_REQS; i++) begin
assign io_rsp_valid_in[i] = io_rsp_valid_out && (rsp_sel == REQS_BITS'(i));
assign io_rsp_tag_in[i] = io_rsp_tag_out[REQS_BITS +: TAG_IN_WIDTH];
assign io_rsp_data_in[i] = io_rsp_data_out;
assign rsp_valid_in[i] = rsp_valid_out && (rsp_sel == REQS_BITS'(i));
assign rsp_tag_in[i] = rsp_tag_out[REQS_BITS +: TAG_IN_WIDTH];
assign rsp_data_in[i] = rsp_data_out;
end
assign io_rsp_ready_out = io_rsp_ready_in[rsp_sel];
assign rsp_ready_out = rsp_ready_in[rsp_sel];
end else begin
`UNUSED_VAR (clk)
`UNUSED_VAR (reset)
assign io_req_valid_out = io_req_valid_in;
assign io_req_tag_out = io_req_tag_in;
assign io_req_addr_out = io_req_addr_in;
assign io_req_rw_out = io_req_rw_in;
assign io_req_byteen_out = io_req_byteen_in;
assign io_req_data_out = io_req_data_in;
assign io_req_ready_in = io_req_ready_out;
assign req_valid_out = req_valid_in;
assign req_tag_out = req_tag_in;
assign req_addr_out = req_addr_in;
assign req_rw_out = req_rw_in;
assign req_byteen_out = req_byteen_in;
assign req_data_out = req_data_in;
assign req_ready_in = req_ready_out;
assign io_rsp_valid_in = io_rsp_valid_out;
assign io_rsp_tag_in = io_rsp_tag_out;
assign io_rsp_data_in = io_rsp_data_out;
assign io_rsp_ready_out = io_rsp_ready_in;
assign rsp_valid_in = rsp_valid_out;
assign rsp_tag_in = rsp_tag_out;
assign rsp_data_in = rsp_data_out;
assign rsp_ready_out = rsp_ready_in;
end