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hw/reqrsp: Add generic reqrsp-like interface cut and mux
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‎Bender.yml‎

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# reqrsp_interface
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- files:
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# Level 0
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- hw/reqrsp_interface/src/generic_reqrsp_cut.sv
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- hw/reqrsp_interface/src/generic_reqrsp_mux.sv
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- hw/reqrsp_interface/src/reqrsp_pkg.sv
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# Level 1
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- hw/reqrsp_interface/src/reqrsp_intf.sv

‎hw/reqrsp_interface/include/reqrsp_interface/assign.svh‎

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// Author: Florian Zaruba <[email protected]>
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// Author: Fabian Schuiki <[email protected]>
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// Author: Luca Colagrande <[email protected]>
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// Macros to assign reqrsp Interfaces and Structs
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`ifndef REQRSP_ASSIGN_SVH_
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`define REQRSP_ASSIGN_SVH_
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// Tie off a generic reqrsp-like interface
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`define REQRSP_TIE_OFF_REQ(__if) \
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assign ``__if``.q = '0; \
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assign ``__if``.q_valid = 1'b0; \
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assign ``__if``.p_ready = 1'b0;
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`define REQRSP_TIE_OFF_RSP(__if) \
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assign ``__if``.p = '0; \
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assign ``__if``.p_valid = 1'b0; \
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assign ``__if``.q_ready = 1'b0;
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// Assign an reqrsp handshake.
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`define REQRSP_ASSIGN_VALID(__opt_as, __dst, __src, __chan) \
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__opt_as ``__dst``.``__chan``_valid = ``__src``.``__chan``_valid;

‎hw/reqrsp_interface/include/reqrsp_interface/typedef.svh‎

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logic error; \
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} __rsp_chan_t;
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`define GENERIC_REQRSP_REQ_STRUCT(__req_chan_t) \
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struct packed { \
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__req_chan_t q; \
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logic q_valid; \
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logic p_ready; \
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}
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`define GENERIC_REQRSP_RSP_STRUCT(__rsp_chan_t) \
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struct packed { \
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__rsp_chan_t p; \
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logic p_valid; \
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logic q_ready; \
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}
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`define REQRSP_TYPEDEF_REQ_T(__req_t, __req_chan_t) \
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typedef struct packed { \
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__req_chan_t q; \
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logic q_valid; \
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logic p_ready; \
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} __req_t;
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typedef `GENERIC_REQRSP_REQ_STRUCT(__req_chan_t) __req_t;
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`define REQRSP_TYPEDEF_RSP_T(__rsp_t, __rsp_chan_t) \
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typedef struct packed { \
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__rsp_chan_t p; \
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logic p_valid; \
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logic q_ready; \
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} __rsp_t;
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typedef `GENERIC_REQRSP_RSP_STRUCT(__rsp_chan_t) __rsp_t;
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`define REQRSP_TYPEDEF_ALL(__name, __addr_t, __data_t, __strb_t, __user_t) \
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`REQRSP_TYPEDEF_REQ_CHAN_T(__name``_req_chan_t, __addr_t, __data_t, __strb_t, __user_t) \
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`REQRSP_TYPEDEF_RSP_CHAN_T(__name``_rsp_chan_t, __data_t) \
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`REQRSP_TYPEDEF_REQ_T(__name``_req_t, __name``_req_chan_t) \
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`REQRSP_TYPEDEF_RSP_T(__name``_rsp_t, __name``_rsp_chan_t)
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`define GENERIC_REQRSP_TYPEDEF_ALL(__name, __req_chan_t, __rsp_chan_t) \
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`REQRSP_TYPEDEF_REQ_T(__name``_req_t, __req_chan_t) \
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`REQRSP_TYPEDEF_RSP_T(__name``_rsp_t, __rsp_chan_t)
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`endif

‎hw/reqrsp_interface/src/generic_reqrsp_cut.sv‎

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// Copyright 2025 ETH Zurich and University of Bologna.
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// Solderpad Hardware License, Version 0.51, see LICENSE for details.
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// SPDX-License-Identifier: SHL-0.51
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// Author: Luca Colagrande <[email protected]>
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`include "reqrsp_interface/typedef.svh"
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/// Cut all combinatorial paths through a generic `reqrsp`-like interface.
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module generic_reqrsp_cut #(
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/// Request type.
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parameter type req_chan_t = logic,
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/// Response type.
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parameter type rsp_chan_t = logic,
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/// Bypass request channel.
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parameter bit BypassReq = 0,
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/// Bypass Response channel.
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parameter bit BypassRsp = 0,
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/// Derived parameters *do not override*
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localparam type req_t = `GENERIC_REQRSP_REQ_STRUCT(req_chan_t),
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localparam type rsp_t = `GENERIC_REQRSP_RSP_STRUCT(rsp_chan_t)
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) (
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input logic clk_i,
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input logic rst_ni,
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input req_t slv_req_i,
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output rsp_t slv_rsp_o,
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output req_t mst_req_o,
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input rsp_t mst_rsp_i
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);
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spill_register #(
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.T (req_chan_t),
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.Bypass(BypassReq)
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) i_spill_register_q (
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.clk_i,
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.rst_ni,
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.valid_i(slv_req_i.q_valid),
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.ready_o(slv_rsp_o.q_ready),
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.data_i (slv_req_i.q),
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.valid_o(mst_req_o.q_valid),
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.ready_i(mst_rsp_i.q_ready),
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.data_o (mst_req_o.q)
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);
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spill_register #(
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.T (rsp_chan_t),
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.Bypass(BypassRsp)
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) i_spill_register_p (
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.clk_i,
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.rst_ni,
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.valid_i(mst_rsp_i.p_valid),
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.ready_o(mst_req_o.p_ready),
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.data_i (mst_rsp_i.p),
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.valid_o(slv_rsp_o.p_valid),
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.ready_i(slv_req_i.p_ready),
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.data_o (slv_rsp_o.p)
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);
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endmodule

‎hw/reqrsp_interface/src/generic_reqrsp_mux.sv‎

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// Copyright 2025 ETH Zurich and University of Bologna.
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// Solderpad Hardware License, Version 0.51, see LICENSE for details.
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// SPDX-License-Identifier: SHL-0.51
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// Author: Luca Colagrande <[email protected]>
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`include "reqrsp_interface/typedef.svh"
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/// Multiplex multiple generic `reqrsp`-like ports onto one, based on arbitration.
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module generic_reqrsp_mux #(
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/// Number of input ports.
12+
parameter int unsigned NrPorts = 2,
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/// Request channel type.
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parameter type req_chan_t = logic,
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/// Response channel type.
16+
parameter type rsp_chan_t = logic,
17+
/// Amount of outstanding responses. Determines the FIFO size.
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parameter int unsigned RspDepth = 8,
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/// Cut timing paths on the request path. Incurs a cycle additional latency.
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/// Registers are inserted at the slave side.
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parameter bit [NrPorts-1:0] RegisterReq = '0,
22+
/// Externally provide routing information for responses. Can be used when
23+
/// storing response routes externally, e.g. as a source tag passed along a
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/// pipeline, i.e. when RspDepth == 0.
25+
parameter bit ExtRspRoute = 1'b0,
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/// Dependent parameters *do not override*
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/// Width of the arbitrated index.
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localparam int unsigned IdxWidth = cf_math_pkg::idx_width(NrPorts),
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localparam type req_t = `GENERIC_REQRSP_REQ_STRUCT(req_chan_t),
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localparam type rsp_t = `GENERIC_REQRSP_RSP_STRUCT(rsp_chan_t)
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) (
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input logic clk_i,
33+
input logic rst_ni,
34+
input req_t [NrPorts-1:0] slv_req_i,
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output rsp_t [NrPorts-1:0] slv_rsp_o,
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output req_t mst_req_o,
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input rsp_t mst_rsp_i,
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// Route responses should follow when using external routing.
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input logic [IdxWidth-1:0] rsp_route_i,
40+
// Request port select by the arbitration logic.
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output logic [IdxWidth-1:0] idx_o
42+
);
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logic [NrPorts-1:0] req_valid_masked, req_ready_masked;
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logic [IdxWidth-1:0] idx, idx_rsp;
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logic full;
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req_chan_t [NrPorts-1:0] req_payload_q;
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logic [NrPorts-1:0] req_valid_q, req_ready_q;
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// Unforunately we need this signal otherwise the simulator complains about
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// multiple driven signals, because some other signals are driven from an
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// `always_comb` block.
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logic [NrPorts-1:0] slv_rsp_q_ready;
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// Optionally cut the incoming paths
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for (genvar i = 0; i < NrPorts; i++) begin : gen_cuts
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spill_register #(
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.T (req_chan_t),
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.Bypass (!RegisterReq[i])
61+
) i_spill_register_req (
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.clk_i,
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.rst_ni,
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.valid_i (slv_req_i[i].q_valid),
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.ready_o (slv_rsp_q_ready[i]),
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.data_i (slv_req_i[i].q),
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.valid_o (req_valid_q[i]),
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.ready_i (req_ready_masked[i]),
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.data_o (req_payload_q[i])
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);
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end
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73+
// We need to silence the handshake in case the fifo is full and we can't
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// accept more transactions.
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for (genvar i = 0; i < NrPorts; i++) begin : gen_req_valid_masked
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assign req_valid_masked[i] = req_valid_q[i] & ~full;
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assign req_ready_masked[i] = req_ready_q[i] & ~full;
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end
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80+
/// Arbitrate requests
81+
rr_arb_tree #(
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.NumIn (NrPorts),
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.DataType (req_chan_t),
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.AxiVldRdy (1'b1),
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.LockIn (1'b1)
86+
) i_q_mux (
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.clk_i,
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.rst_ni,
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.flush_i (1'b0),
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.rr_i ('0),
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.req_i (req_valid_masked),
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.gnt_o (req_ready_q),
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.data_i (req_payload_q),
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.gnt_i (mst_rsp_i.q_ready),
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.req_o (mst_req_o.q_valid),
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.data_o (mst_req_o.q),
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.idx_o (idx_o)
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);
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// De-generate version does not need a fifo. We always know where to route
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// back the responses.
102+
if (NrPorts == 1) begin : gen_single_port
103+
assign idx_rsp = 0;
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assign full = 1'b0;
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end else begin : gen_multi_port
106+
if (ExtRspRoute) begin : gen_no_rsp_fifo
107+
// Alternatively select route based on externally provided information.
108+
assign idx_rsp = rsp_route_i;
109+
assign full = 1'b0;
110+
end else begin : gen_rsp_fifo
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// For the "normal" case we need to save the arbitration decision. We do so
112+
// by converting the handshake into a binary signal which we save for
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// response routing.
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onehot_to_bin #(
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.ONEHOT_WIDTH (NrPorts)
116+
) i_onehot_to_bin (
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.onehot (req_valid_q & req_ready_q),
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.bin (idx)
119+
);
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// Save the arbitration decision.
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fifo_v3 #(
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.DATA_WIDTH (IdxWidth),
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.DEPTH (RspDepth)
124+
) i_rsp_fifo (
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.clk_i,
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.rst_ni,
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.flush_i (1'b0),
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.testmode_i (1'b0),
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.full_o (full),
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.empty_o (),
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.usage_o (),
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.data_i (idx),
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.push_i (mst_req_o.q_valid & mst_rsp_i.q_ready),
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.data_o (idx_rsp),
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.pop_i (mst_req_o.p_ready & mst_rsp_i.p_valid)
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);
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end
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end
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// Output Mux
141+
always_comb begin
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for (int i = 0; i < NrPorts; i++) begin
143+
slv_rsp_o[i].p_valid = '0;
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slv_rsp_o[i].q_ready = slv_rsp_q_ready[i];
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slv_rsp_o[i].p = mst_rsp_i.p;
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end
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slv_rsp_o[idx_rsp].p_valid = mst_rsp_i.p_valid;
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end
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assign mst_req_o.p_ready = slv_req_i[idx_rsp].p_ready;
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endmodule

‎hw/reqrsp_interface/src/reqrsp_cut.sv‎

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@@ -38,32 +38,18 @@ module reqrsp_cut #(
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3939
`REQRSP_TYPEDEF_ALL(reqrsp, addr_t, data_t, strb_t, user_t)
4040

41-
spill_register #(
42-
.T (reqrsp_req_chan_t),
43-
.Bypass ( BypassReq )
44-
) i_spill_register_q (
45-
.clk_i,
46-
.rst_ni,
47-
.valid_i (slv_req_i.q_valid) ,
48-
.ready_o (slv_rsp_o.q_ready) ,
49-
.data_i (slv_req_i.q),
50-
.valid_o (mst_req_o.q_valid),
51-
.ready_i (mst_rsp_i.q_ready),
52-
.data_o (mst_req_o.q)
53-
);
54-
55-
spill_register #(
56-
.T (reqrsp_rsp_chan_t),
57-
.Bypass ( BypassRsp )
58-
) i_spill_register_p (
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generic_reqrsp_cut #(
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.req_chan_t(reqrsp_req_chan_t),
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.rsp_chan_t(reqrsp_rsp_chan_t),
44+
.BypassReq (BypassReq),
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.BypassRsp (BypassRsp)
46+
) i_generic_reqrsp_cut (
5947
.clk_i,
6048
.rst_ni,
61-
.valid_i (mst_rsp_i.p_valid) ,
62-
.ready_o (mst_req_o.p_ready) ,
63-
.data_i (mst_rsp_i.p),
64-
.valid_o (slv_rsp_o.p_valid),
65-
.ready_i (slv_req_i.p_ready),
66-
.data_o (slv_rsp_o.p)
49+
.slv_req_i (slv_req_i),
50+
.slv_rsp_o (slv_rsp_o),
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.mst_req_o (mst_req_o),
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.mst_rsp_i (mst_rsp_i)
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);
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endmodule

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