//
// Copyright 2018 Ettus Research, A National Instruments Company
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
// Module: axis_switch
// Description:
// Implementation of a M-input, N-output AXI-Stream switch.
// One of the M input ports is allocated based on the s_axis_alloc signal
// and the packet on that port is sent to one of the N output ports based
// on the tdest signal
module axis_switch #(
parameter DATA_W = 64, // tdata width
parameter DEST_W = 1, // Output tdest width
parameter IN_PORTS = 3, // Number of input ports
parameter OUT_PORTS = 3, // Number of output ports
parameter PIPELINE = 1, // Instantiate output pipeline stage?
parameter ALLOC_W = (IN_PORTS == 1) ? 1 : $clog2(IN_PORTS) //PRIVATE
) (
// Clocks and resets
input wire clk, // Switch clock
input wire reset, // Reset
// Input ports
input wire [(DATA_W*IN_PORTS)-1:0] s_axis_tdata, // Input data
input wire [((DEST_W+$clog2(OUT_PORTS))*IN_PORTS)-1:0] s_axis_tdest, // Input destination
input wire [IN_PORTS-1:0] s_axis_tlast, // Input EOP (last)
input wire [IN_PORTS-1:0] s_axis_tvalid, // Input valid
output wire [IN_PORTS-1:0] s_axis_tready, // Input ready
input wire [ALLOC_W-1:0] s_axis_alloc, // Input port allocation for switch
// Output ports
output wire [(DATA_W*OUT_PORTS)-1:0] m_axis_tdata, // Output data
output wire [(DEST_W*OUT_PORTS)-1:0] m_axis_tdest, // Output destination
output wire [OUT_PORTS-1:0] m_axis_tlast, // Output EOP (last)
output wire [OUT_PORTS-1:0] m_axis_tvalid, // Output valid
input wire [OUT_PORTS-1:0] m_axis_tready // Output ready
);
// PRIVATE: Vivado synthesizer workaround (cannot be localparam)
localparam CLOG2_IN_PORTS = $clog2(IN_PORTS);
localparam CLOG2_OUT_PORTS = $clog2(OUT_PORTS);
//---------------------------------------------------------
// Flatten/unflatten and pipeline
//---------------------------------------------------------
wire [DATA_W-1:0] i_tdata [0:IN_PORTS-1];
wire [DEST_W+$clog2(OUT_PORTS)-1:0] i_tdest [0:IN_PORTS-1];
wire i_tlast [0:IN_PORTS-1];
wire [IN_PORTS-1:0] i_tvalid;
wire [IN_PORTS-1:0] i_tready;
wire [ALLOC_W-1:0] i_alloc;
wire [DATA_W-1:0] o_tdata [0:OUT_PORTS-1];
wire [DEST_W-1:0] o_tdest [0:OUT_PORTS-1];
wire o_tlast [0:OUT_PORTS-1];
wire [OUT_PORTS-1:0] o_tvalid;
wire [OUT_PORTS-1:0] o_tready;
genvar i, o;
generate
for (i = 0; i < IN_PORTS; i = i + 1) begin: in_ports
assign i_tdata [i] = s_axis_tdata [(i*DATA_W)+:DATA_W];
assign i_tdest [i] = s_axis_tdest [(i*(DEST_W+CLOG2_OUT_PORTS))+:(DEST_W+CLOG2_OUT_PORTS)];
assign i_tlast [i] = s_axis_tlast [i];
assign i_tvalid [i] = s_axis_tvalid[i];
assign s_axis_tready[i] = i_tready [i];
end
assign i_alloc = s_axis_alloc; //i_alloc has to be delay matched to valid
for (o = 0; o < OUT_PORTS; o = o + 1) begin
if (PIPELINE == 1) begin
axi_fifo_flop2 #(.WIDTH(DEST_W+1+DATA_W)) out_pipe_i (
.clk(clk), .reset(reset), .clear(1'b0),
.i_tdata({o_tdest[o], o_tlast[o], o_tdata[o]}),
.i_tvalid(o_tvalid[o]), .i_tready(o_tready[o]),
.o_tdata({m_axis_tdest[(o*DEST_W)+:DEST_W], m_axis_tlast[o], m_axis_tdata[(o*DATA_W)+:DATA_W]}),
.o_tvalid(m_axis_tvalid[o]), .o_tready(m_axis_tready[o]),
.space(), .occupied()
);
end else begin
assign m_axis_tdata [(o*DATA_W)+:DATA_W] = o_tdata [o];
assign m_axis_tdest [(o*DEST_W)+:DEST_W] = o_tdest [o];
assign m_axis_tlast [o] = o_tlast [o];
assign m_axis_tvalid[o] = o_tvalid [o];
assign o_tready [o] = m_axis_tready[o];
end
end
endgenerate
//---------------------------------------------------------
// Allocator
//---------------------------------------------------------
// The "chosen" input port will drive this bus
wire [DATA_W-1:0] master_tdata;
wire [DEST_W+$clog2(OUT_PORTS)-1:0] master_tdest;
wire master_tlast;
wire master_tvalid;
wire master_tready;
generate if (IN_PORTS > 1) begin
reg [IN_PORTS-1:0] ialloc_oh;
reg [$clog2(IN_PORTS)-1:0] alloc_reg;
always @(posedge clk) begin
if (reset) begin
ialloc_oh <= {IN_PORTS{1'b0}};
end else begin
if (ialloc_oh == {IN_PORTS{1'b0}}) begin
if (|i_tvalid) begin
ialloc_oh[i_alloc] <= 1'b1;
alloc_reg <= i_alloc;
end
end else begin
if(master_tready & master_tvalid & master_tlast)
ialloc_oh <= {IN_PORTS{1'b0}};
end
end
end
assign master_tdata = i_tdata[alloc_reg];
assign master_tdest = i_tdest[alloc_reg];
assign master_tlast = i_tlast[alloc_reg];
assign master_tvalid = |(i_tvalid & ialloc_oh);
assign i_tready = i_tvalid & ialloc_oh & {IN_PORTS{master_tready}};
end else begin
// Special case: One input port
assign master_tdata = i_tdata[0];
assign master_tdest = i_tdest[0];
assign master_tlast = i_tlast[0];
assign master_tvalid = i_tvalid[0];
assign i_tready[0] = master_tready;
end endgenerate
//---------------------------------------------------------
// Router
//---------------------------------------------------------
generate if (OUT_PORTS > 1) begin
reg [OUT_PORTS-1:0] odst_oh;
always @(posedge clk) begin
if (reset) begin
odst_oh <= {OUT_PORTS{1'b0}};
end else begin
if (odst_oh == {OUT_PORTS{1'b0}}) begin
if (master_tvalid)
odst_oh[master_tdest[CLOG2_OUT_PORTS-1:0]] <= 1'b1;
end else begin
if(master_tready & master_tvalid & master_tlast)
odst_oh <= {OUT_PORTS{1'b0}};
end
end
end
assign master_tready = |(o_tready & odst_oh);
assign o_tvalid = {OUT_PORTS{master_tvalid}} & odst_oh;
end else begin
// Special case: One output port
assign master_tready = o_tready[0];
assign o_tvalid[0] = master_tvalid;
end endgenerate
generate for (o = 0; o < OUT_PORTS; o = o + 1) begin
assign o_tdata[o] = master_tdata;
assign o_tdest[o] = master_tdest[DEST_W+CLOG2_OUT_PORTS-1:CLOG2_OUT_PORTS];
assign o_tlast[o] = master_tlast;
end endgenerate
endmodule