add round-robin distributor

Bender.yml

@@ -8,6 +8,7 @@ package:
     - "Manuel Eggimann <[email protected]>"
     - "Stefan Mach <[email protected]>"
     - "Wolfgang Roenninger <[email protected]>"
+    - "Thomas Benz <[email protected]>"
 
 dependencies:
   common_verification: { git: "https://github.com/pulp-platform/common_verification.git", version: 0.2.0 }
@@ -44,6 +45,7 @@ sources:
   - src/plru_tree.sv
   - src/popcount.sv
   - src/rr_arb_tree.sv
+  - src/rr_distributor.sv
   - src/rstgen_bypass.sv
   - src/serial_deglitch.sv
   - src/shift_reg.sv

ci/install-verilator.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 set -e
-ROOT=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+ROOT=$(cd "$(dirname "${BASH_SOURCE[0]:-${(%):-%x}}")/.." && pwd)
 cd $ROOT/tmp
 
 if [ -z ${NUM_JOBS} ]; then

src/rr_distributor.sv

@@ -0,0 +1,93 @@
+// Copyright 2019 ETH Zurich and University of Bologna.
+// Copyright and related rights are licensed under the Solderpad Hardware
+// License, Version 0.51 (the "License"); you may not use this file except in
+// compliance with the License.  You may obtain a copy of the License at
+// http://solderpad.org/licenses/SHL-0.51. Unless required by applicable law
+// or agreed to in writing, software, hardware and materials distributed under
+// this License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations under the License.
+//
+// Author: Thomas Benz <[email protected]>, ETH Zurich
+// Date: 12.01.2021
+// Description: round robin distributor
+
+/// The rr_distributor forwards requests to individual outputs in a round robin fashion.
+module rr_distributor # (
+    /// Number of outputs to distribute to.
+    parameter int unsigned NumOut    = 1,
+    /// Data width of the payload in bits. Not needed if `data_t` is overwritten.
+    parameter int unsigned Width     = 1,
+    /// Data type of the payload, can be overwritten with a custom type. Only use of `Width`.
+    parameter type         data_t    = logic [Width-1:0],
+    /// Setting StrictRR enforces a strict round-robin distribution
+    /// If set to 1'b1, the rr_distributor will distribute the requests to the next output
+    ///   in line, irrespective if this output is ready or not, irrespective if another
+    ///   output could accept the request. The transaction will wait until the next one in
+    ///   line accepts the handshake.
+    /// If set to 1'b0, the rr_distributor will step through the outputs if one is ready
+    ///   but the current one is not. This can reduce wait time for the input.
+    ///   **THIS IS NOT COMPLIANT AS IT MAY DE-ASSERT VALID WITHOUT A PROPER HANDSHAKE**
+    parameter bit          StrictRR  = 1'b1,
+    /// Dependent parameter, do **not** overwrite.
+    /// Width of the selected index
+    parameter int unsigned IdxWidth  = cf_math_pkg::idx_width(NumOut),
+    /// Dependent parameter, do **not** overwrite.
+    /// type of the selected index
+    parameter type         idx_t     = logic [IdxWidth-1:0]
+) (
+    input  logic               clk_i,
+    input  logic               rst_ni,
+    // input stream
+    input  logic               valid_i,
+    output logic               ready_o,
+    input  data_t              payload_i,
+    // output stream
+    output logic  [NumOut-1:0] valid_o,
+    input  logic  [NumOut-1:0] ready_i,
+    output data_t [NumOut-1:0] payload_o,
+    output idx_t               sel_o
+);
+
+    if (NumOut == 1) begin : gen_bypass
+        assign valid_o[0] = valid_i;
+        assign ready_o    = ready_i[0];
+        assign sel_o      = 1'b0;
+    end else begin : gen_arb
+
+        idx_t rr_d, rr_q;
+        logic one_ready;
+
+        always_comb begin : rr_next
+            rr_d = rr_q;
+            if (valid_i && ( ready_i[rr_q] || (one_ready && !StrictRR))) begin
+                if (rr_q == idx_t'(NumOut - 1)) begin
+                    rr_d = '0;
+                end else begin
+                    rr_d = rr_q + 1'b1;
+                end
+            end
+        end
+
+        assign one_ready = |ready_i;
+
+        always_comb begin : proc_arbitration
+            valid_o = '0;
+            valid_o[rr_q] = valid_i;
+        end
+        assign ready_o = ready_i[rr_q];
+
+        always_ff @(posedge clk_i or negedge rst_ni) begin : proc_prio_regs
+            if(~rst_ni) begin
+                rr_q <= 0;
+            end else begin
+                rr_q <= rr_d;
+            end
+        end
+
+        assign sel_o = rr_q;
+    end
+
+    assign payload_o = {{NumOut}{payload_i}};
+
+endmodule : rr_distributor

src_files.yml

@@ -27,6 +27,7 @@ common_cells_all:
     - src/plru_tree.sv
     - src/popcount.sv
     - src/rr_arb_tree.sv
+    - src/rr_distributor.sv
     - src/rstgen_bypass.sv
     - src/serial_deglitch.sv
     - src/shift_reg.sv