axi_sim_mem.sv

// Copyright (c) 2020 ETH Zurich and University of Bologna
// SPDX-License-Identifier: SHL-0.51
//
// Authors:
// - Andreas Kurth <akurth@iis.ee.ethz.ch>
// - Samuel Riedel <sriedel@iis.ee.ethz.ch>
// - Michael Rogenmoser <michaero@iis.ee.ethz.ch>
// - Thomas Benz <tbenz@iis.ee.ethz.ch>

`include "axi/typedef.svh"

/// Infinite (Simulation-Only) Memory with AXI Slave Port
///
/// The memory array is named `mem`, and it is *not* initialized or reset.  This makes it possible to
/// load the memory of this module in simulation with an external `$readmem*` command, e.g.,
/// ```sv
/// axi_sim_mem #( ... ) i_sim_mem ( ... );
/// initial begin
///   $readmemh("file_with_memory_addrs_and_data.mem", i_sim_mem.mem);
///   $readmemh("file_with_memory_addrs_and_read_errors.mem", i_sim_mem.rerr);
///   $readmemh("file_with_memory_addrs_and_write_errors.mem", i_sim_mem.werr);
/// end
/// ```
/// `mem` is addressed (or indexed) byte-wise with `AddrWidth`-wide addresses.
///
/// This module does not support atomic operations (ATOPs).
module axi_sim_mem #(
  /// AXI Address Width
  parameter int unsigned AddrWidth = 32'd0,
  /// AXI Data Width
  parameter int unsigned DataWidth = 32'd0,
  /// AXI ID Width
  parameter int unsigned IdWidth = 32'd0,
  /// AXI User Width.
  parameter int unsigned UserWidth = 32'd0,
  /// AXI4 request struct definition
  parameter type axi_req_t = logic,
  /// AXI4 response struct definition
  parameter type axi_rsp_t = logic,
  /// Warn on accesses to uninitialized bytes
  parameter bit WarnUninitialized = 1'b0,
  /// Clear error on access
  parameter bit ClearErrOnAccess = 1'b0,
  /// Application delay (measured after rising clock edge)
  parameter time ApplDelay = 0ps,
  /// Acquisition delay (measured after rising clock edge)
  parameter time AcqDelay = 0ps
) (
  /// Rising-edge clock
  input  logic clk_i,
  /// Active-low reset
  input  logic rst_ni,
  /// AXI4 request struct
  input  axi_req_t axi_req_i,
  /// AXI4 response struct
  output axi_rsp_t axi_rsp_o,
  /// Memory monitor write valid.  All `mon_w_*` outputs are only valid if this signal is high.
  /// A write to the memory is visible on the `mon_w_*` outputs in the clock cycle after it has
  /// happened.
  output logic                 mon_w_valid_o,
  /// Memory monitor write address
  output logic [AddrWidth-1:0] mon_w_addr_o,
  /// Memory monitor write data
  output logic [DataWidth-1:0] mon_w_data_o,
  /// Memory monitor write ID
  output logic [IdWidth-1:0]   mon_w_id_o,
  /// Memory monitor write user
  output logic [UserWidth-1:0] mon_w_user_o,
  /// Memory monitor write beat count
  output axi_pkg::len_t        mon_w_beat_count_o,
  /// Memory monitor write last
  output logic                 mon_w_last_o,
  /// Memory monitor read valid.  All `mon_r_*` outputs are only valid if this signal is high.
  /// A read from the memory is visible on the `mon_w_*` outputs in the clock cycle after it has
  /// happened.
  output logic                 mon_r_valid_o,
  /// Memory monitor read address
  output logic [AddrWidth-1:0] mon_r_addr_o,
  /// Memory monitor read data
  output logic [DataWidth-1:0] mon_r_data_o,
  /// Memory monitor read ID
  output logic [IdWidth-1:0]   mon_r_id_o,
  /// Memory monitor read user
  output logic [UserWidth-1:0] mon_r_user_o,
  /// Memory monitor read beat count
  output axi_pkg::len_t        mon_r_beat_count_o,
  /// Memory monitor read last
  output logic                 mon_r_last_o
);

  localparam int unsigned StrbWidth = DataWidth / 8;
  typedef logic [AddrWidth-1:0] addr_t;
  typedef logic [DataWidth-1:0] data_t;
  typedef logic [IdWidth-1:0]   id_t;
  typedef logic [StrbWidth-1:0] strb_t;
  typedef logic [UserWidth-1:0] user_t;
  `AXI_TYPEDEF_AW_CHAN_T(aw_t, addr_t, id_t, user_t)
  `AXI_TYPEDEF_W_CHAN_T(w_t, data_t, strb_t, user_t)
  `AXI_TYPEDEF_B_CHAN_T(b_t, id_t, user_t)
  `AXI_TYPEDEF_AR_CHAN_T(ar_t, addr_t, id_t, user_t)
  `AXI_TYPEDEF_R_CHAN_T(r_t, data_t, id_t, user_t)

  typedef struct packed {
    logic                 valid;
    logic [AddrWidth-1:0] addr;
    logic [DataWidth-1:0] data;
    logic [IdWidth-1:0]   id;
    logic [UserWidth-1:0] user;
    axi_pkg::len_t        beat_count;
    logic                 last;
  } monitor_t;

  monitor_t mon_w, mon_r;
  logic [7:0]     mem[addr_t];
  axi_pkg::resp_t rerr[addr_t] = '{default: axi_pkg::RESP_OKAY};
  axi_pkg::resp_t werr[addr_t] = '{default: axi_pkg::RESP_OKAY};

  // error happened in write burst
  axi_pkg::resp_t error_happened = axi_pkg::RESP_OKAY;

  initial begin
    automatic ar_t ar_queue[$];
    automatic aw_t aw_queue[$];
    automatic b_t b_queue[$];
    automatic shortint unsigned r_cnt = 0, w_cnt = 0;
    axi_rsp_o = '0;
    // Monitor interface
    mon_w = '0;
    mon_r = '0;
    wait (rst_ni);
    fork
      // AW
      forever begin
        @(posedge clk_i);
        #(ApplDelay);
        axi_rsp_o.aw_ready = 1'b1;
        #(AcqDelay - ApplDelay);
        if (axi_req_i.aw_valid) begin
          automatic aw_t aw = axi_req_i.aw;
          aw_queue.push_back(aw);
        end
      end
      // W
      forever begin
        @(posedge clk_i);
        #(ApplDelay);
        axi_rsp_o.w_ready = 1'b0;
        mon_w = '0;
        if (aw_queue.size() != 0) begin
          axi_rsp_o.w_ready = 1'b1;
          #(AcqDelay - ApplDelay);
          if (axi_req_i.w_valid) begin
            automatic axi_pkg::burst_t burst = aw_queue[0].burst;
            automatic axi_pkg::len_t len = aw_queue[0].len;
            automatic axi_pkg::size_t size = aw_queue[0].size;
            automatic addr_t addr = axi_pkg::beat_addr(aw_queue[0].addr, size, len, burst,
                w_cnt);
            mon_w.valid = 1'b1;
            mon_w.addr = addr;
            mon_w.data = axi_req_i.w.data;
            mon_w.id = aw_queue[0].id;
            mon_w.user = aw_queue[0].user;
            mon_w.beat_count = w_cnt;
            for (shortint unsigned
                i_byte = axi_pkg::beat_lower_byte(addr, size, len, burst, StrbWidth, w_cnt);
                i_byte <= axi_pkg::beat_upper_byte(addr, size, len, burst, StrbWidth, w_cnt);
                i_byte++) begin
              if (axi_req_i.w.strb[i_byte]) begin
                automatic addr_t byte_addr = (addr / StrbWidth) * StrbWidth + i_byte;
                mem[byte_addr] = axi_req_i.w.data[i_byte*8+:8];
                error_happened = axi_pkg::resp_precedence(werr[byte_addr], error_happened);
                if (ClearErrOnAccess)
                  werr[byte_addr] = axi_pkg::RESP_OKAY;
              end
            end
            if (w_cnt == aw_queue[0].len) begin
              automatic b_t b_beat = '0;
              assert (axi_req_i.w.last) else $error("Expected last beat of W burst!");
              b_beat.id = aw_queue[0].id;
              b_beat.resp = error_happened;
              b_queue.push_back(b_beat);
              w_cnt = 0;
              mon_w.last = 1'b1;
              error_happened = axi_pkg::RESP_OKAY;
              void'(aw_queue.pop_front());
            end else begin
              assert (!axi_req_i.w.last) else $error("Did not expect last beat of W burst!");
              w_cnt++;
            end
          end
        end
      end
      // B
      forever begin
        @(posedge clk_i);
        #(ApplDelay);
        axi_rsp_o.b_valid = 1'b0;
        if (b_queue.size() != 0) begin
          axi_rsp_o.b = b_queue[0];
          axi_rsp_o.b_valid = 1'b1;
          #(AcqDelay - ApplDelay);
          if (axi_req_i.b_ready) begin
            void'(b_queue.pop_front());
          end
        end
      end
      // AR
      forever begin
        @(posedge clk_i);
        #(ApplDelay);
        axi_rsp_o.ar_ready = 1'b1;
        #(AcqDelay - ApplDelay);
        if (axi_req_i.ar_valid) begin
          automatic ar_t ar = axi_req_i.ar;
          ar_queue.push_back(ar);
        end
      end
      // R
      forever begin
        @(posedge clk_i);
        #(ApplDelay);
        axi_rsp_o.r_valid = 1'b0;
        mon_r = '0;
        if (ar_queue.size() != 0) begin
          automatic axi_pkg::burst_t burst = ar_queue[0].burst;
          automatic axi_pkg::len_t len = ar_queue[0].len;
          automatic axi_pkg::size_t size = ar_queue[0].size;
          automatic addr_t addr = axi_pkg::beat_addr(ar_queue[0].addr, size, len, burst, r_cnt);
          automatic r_t r_beat = '0;
          automatic data_t r_data = 'x; // compatibility reasons
          r_beat.data = 'x;
          r_beat.id = ar_queue[0].id;
          r_beat.resp = axi_pkg::RESP_OKAY;
          for (shortint unsigned
              i_byte = axi_pkg::beat_lower_byte(addr, size, len, burst, StrbWidth, r_cnt);
              i_byte <= axi_pkg::beat_upper_byte(addr, size, len, burst, StrbWidth, r_cnt);
              i_byte++) begin
            automatic addr_t byte_addr = (addr / StrbWidth) * StrbWidth + i_byte;
            if (!mem.exists(byte_addr)) begin
              if (WarnUninitialized) begin
                $warning("Access to non-initialized byte at address 0x%016x by ID 0x%x.", byte_addr,
                    r_beat.id);
              end
              r_data[i_byte*8+:8] = 'x;
            end else begin
              r_data[i_byte*8+:8] = mem[byte_addr];
            end
            r_beat.resp = axi_pkg::resp_precedence(rerr[byte_addr], r_beat.resp);
            if (ClearErrOnAccess & axi_req_i.r_ready) begin
              rerr[byte_addr] = axi_pkg::RESP_OKAY;
            end
          end
          r_beat.data = r_data;
          if (r_cnt == ar_queue[0].len) begin
            r_beat.last = 1'b1;
            mon_r.last = 1'b1;
          end
          axi_rsp_o.r = r_beat;
          axi_rsp_o.r_valid = 1'b1;
          mon_r.valid = 1'b1;
          mon_r.addr = addr;
          mon_r.data = r_beat.data;
          mon_r.id = r_beat.id;
          mon_r.user = ar_queue[0].user;
          mon_r.beat_count = r_cnt;
          #(AcqDelay - ApplDelay);
          while (!axi_req_i.r_ready) begin
            @(posedge clk_i);
            #(AcqDelay);
            mon_r = '0;
          end
          if (r_beat.last) begin
            r_cnt = 0;
            void'(ar_queue.pop_front());
          end else begin
            r_cnt++;
          end
        end
      end
    join
  end

  // Assign the monitor output in the next clock cycle.  Rationale: We only know whether we are
  // writing until after `AcqDelay`.  This means we could only provide the monitoring output for
  // writes after `AcqDelay` in the same cycle, which is incompatible with ATI timing.  Thus, we
  // provide the monitoring output for writes (and for uniformity also for reads) in the next clock
  // cycle.
  initial begin
    mon_w_valid_o = '0;
    mon_w_addr_o = '0;
    mon_w_data_o = '0;
    mon_w_id_o = '0;
    mon_w_user_o = '0;
    mon_w_beat_count_o = '0;
    mon_w_last_o = '0;
    mon_r_valid_o = '0;
    mon_r_addr_o = '0;
    mon_r_data_o = '0;
    mon_r_id_o = '0;
    mon_r_user_o = '0;
    mon_r_beat_count_o = '0;
    mon_r_last_o = '0;
    wait (rst_ni);
    forever begin
      @(posedge clk_i);
      mon_w_valid_o <= #(ApplDelay) mon_w.valid;
      mon_w_addr_o <= #(ApplDelay) mon_w.addr;
      mon_w_data_o <= #(ApplDelay) mon_w.data;
      mon_w_id_o <= #(ApplDelay) mon_w.id;
      mon_w_user_o <= #(ApplDelay) mon_w.user;
      mon_w_beat_count_o <= #(ApplDelay) mon_w.beat_count;
      mon_w_last_o <= #(ApplDelay) mon_w.last;
      mon_r_valid_o <= #(ApplDelay) mon_r.valid;
      mon_r_addr_o <= #(ApplDelay) mon_r.addr;
      mon_r_data_o <= #(ApplDelay) mon_r.data;
      mon_r_id_o <= #(ApplDelay) mon_r.id;
      mon_r_user_o <= #(ApplDelay) mon_r.user;
      mon_r_beat_count_o <= #(ApplDelay) mon_r.beat_count;
      mon_r_last_o <= #(ApplDelay) mon_r.last;
    end
  end

  // Parameter Assertions
  initial begin
    assert (AddrWidth != 0) else $fatal("AddrWidth must be non-zero!", 1);
    assert (DataWidth != 0) else $fatal("DataWidth must be non-zero!", 1);
    assert (IdWidth != 0) else $fatal("IdWidth must be non-zero!", 1);
    assert (UserWidth != 0) else $fatal("UserWidth must be non-zero!", 1);
  end

endmodule


`include "axi/assign.svh"

/// Interface variant of [`axi_sim_mem`](module.axi_sim_mem).
///
/// See the documentation of the main module for the definition of ports and parameters.
module axi_sim_mem_intf #(
  parameter int unsigned AXI_ADDR_WIDTH = 32'd0,
  parameter int unsigned AXI_DATA_WIDTH = 32'd0,
  parameter int unsigned AXI_ID_WIDTH = 32'd0,
  parameter int unsigned AXI_USER_WIDTH = 32'd0,
  parameter bit WARN_UNINITIALIZED = 1'b0,
  parameter bit ClearErrOnAccess = 1'b0,
  parameter time APPL_DELAY = 0ps,
  parameter time ACQ_DELAY = 0ps
) (
  input  logic                      clk_i,
  input  logic                      rst_ni,
  AXI_BUS.Slave                     axi_slv,
  output logic                      mon_w_valid_o,
  output logic [AXI_ADDR_WIDTH-1:0] mon_w_addr_o,
  output logic [AXI_DATA_WIDTH-1:0] mon_w_data_o,
  output logic [AXI_ID_WIDTH-1:0]   mon_w_id_o,
  output logic [AXI_USER_WIDTH-1:0] mon_w_user_o,
  output axi_pkg::len_t             mon_w_beat_count_o,
  output logic                      mon_w_last_o,
  output logic                      mon_r_valid_o,
  output logic [AXI_ADDR_WIDTH-1:0] mon_r_addr_o,
  output logic [AXI_DATA_WIDTH-1:0] mon_r_data_o,
  output logic [AXI_ID_WIDTH-1:0]   mon_r_id_o,
  output logic [AXI_USER_WIDTH-1:0] mon_r_user_o,
  output axi_pkg::len_t             mon_r_beat_count_o,
  output logic                      mon_r_last_o
);

  typedef logic [AXI_ADDR_WIDTH-1:0]   axi_addr_t;
  typedef logic [AXI_DATA_WIDTH-1:0]   axi_data_t;
  typedef logic [AXI_ID_WIDTH-1:0]     axi_id_t;
  typedef logic [AXI_DATA_WIDTH/8-1:0] axi_strb_t;
  typedef logic [AXI_USER_WIDTH-1:0]   axi_user_t;
  `AXI_TYPEDEF_ALL(axi, axi_addr_t, axi_id_t, axi_data_t, axi_strb_t, axi_user_t)

  axi_req_t   axi_req;
  axi_resp_t  axi_rsp;

  `AXI_ASSIGN_TO_REQ(axi_req, axi_slv)
  `AXI_ASSIGN_FROM_RESP(axi_slv, axi_rsp)

  axi_sim_mem #(
    .AddrWidth          (AXI_ADDR_WIDTH),
    .DataWidth          (AXI_DATA_WIDTH),
    .IdWidth            (AXI_ID_WIDTH),
    .UserWidth          (AXI_USER_WIDTH),
    .axi_req_t          (axi_req_t),
    .axi_rsp_t          (axi_resp_t),
    .WarnUninitialized  (WARN_UNINITIALIZED),
    .ClearErrOnAccess   (ClearErrOnAccess),
    .ApplDelay          (APPL_DELAY),
    .AcqDelay           (ACQ_DELAY)
  ) i_sim_mem (
    .clk_i,
    .rst_ni,
    .axi_req_i (axi_req),
    .axi_rsp_o (axi_rsp),
    .mon_w_valid_o,
    .mon_w_addr_o,
    .mon_w_data_o,
    .mon_w_id_o,
    .mon_w_user_o,
    .mon_w_beat_count_o,
    .mon_w_last_o,
    .mon_r_valid_o,
    .mon_r_addr_o,
    .mon_r_data_o,
    .mon_r_id_o,
    .mon_r_user_o,
    .mon_r_beat_count_o,
    .mon_r_last_o
  );

endmodule