design/sys/iop/niu/rtl/niu_smx_sm_req_datareq.v

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// OpenSPARC T2 Processor File: niu_smx_sm_req_datareq.v
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module niu_smx_sm_req_datareq(
/*AUTOARG*/
   // Outputs
   rst_cmdflag, datareq_busy, datareq_idle, datareq, dreq_cs,
   // Inputs
   clk, reset_l, cmdflag, cmdflag_data, early_cmdflag_n,
   early_cmdflag_data_n, dv_pad_done, cfg_pad_wait
   );

input           clk;
input           reset_l;

        // cmdreq if
input           cmdflag;
input [4:0]     cmdflag_data;
input           early_cmdflag_n;
input [4:0]     early_cmdflag_data_n;
output          rst_cmdflag;
output          datareq_busy;
output          datareq_idle;

        // dmc if
output          datareq;

        // dv if
input           dv_pad_done;
input           cfg_pad_wait;

output [2:0]    dreq_cs;

reg rst_cmdflag_n;
wire rst_cmdflag= rst_cmdflag_n;

parameter s0= 3'h0,
          s1= 3'h1,
          s2= 3'h2,
          s3= 3'h3,
          s4= 3'h4,
          s5= 3'h5;

reg datareq_n, datareq;
reg [2:0] dreq_ns, dreq_cs;
wire datareq_busy= (!(dreq_cs==s0)|| cmdflag);
wire datareq_idle= (dreq_cs==s0);

always @(posedge clk)begin
  if(!reset_l) begin
    datareq<= `SMX_PD  1'b0;
    dreq_cs<= `SMX_PD  s0;
  end
  else begin
    datareq<= `SMX_PD  datareq_n;
    dreq_cs<= `SMX_PD  dreq_ns;
  end
end

reg ld_cmdflag_data_n;
reg [4:0] cmdflag_data_r;
always @(posedge clk)begin
  if(ld_cmdflag_data_n) cmdflag_data_r<= `SMX_PD  (cmdflag)? cmdflag_data :
                                             early_cmdflag_data_n;
end

always @(/*AUTOSENSE*/cfg_pad_wait or cmdflag or cmdflag_data
         or cmdflag_data_r or dreq_cs or dv_pad_done
         or early_cmdflag_data_n or early_cmdflag_n) begin
  datareq_n= 1'b0;
  ld_cmdflag_data_n= 1'b0;
  rst_cmdflag_n= 1'b0;
  dreq_ns= dreq_cs;
  case(dreq_cs)
    s0: begin
          if(cmdflag || early_cmdflag_n) begin // wait for flag
            datareq_n= (cmdflag)? cmdflag_data[0] : early_cmdflag_data_n[0];
            ld_cmdflag_data_n= 1'b1;
            rst_cmdflag_n= cmdflag; // clear flag for next
            dreq_ns= s1;
          end
        end
    s1: begin
          datareq_n= cmdflag_data_r[1];
          dreq_ns= s2;
        end
    s2: begin
          datareq_n= cmdflag_data_r[2];
          dreq_ns= s3;
        end
    s3: begin
          datareq_n= cmdflag_data_r[3];
          dreq_ns= ((&cmdflag_data_r[3:0]) | ~cfg_pad_wait)?
                                ((cmdflag_data_r[4])? s5 : s0): s4;
        end
    s4: begin // wait dv done pad;
                // only for pad case in case client
                // pack lastline (which needs pad)
                // with next line (no gap)
                // (despite datareq issues gap at pad,
                // no guarantee client return with same gap)
          if(dv_pad_done) begin
            dreq_ns= s0;
          end
        end
    s5: begin // eop dummy state
          dreq_ns= s0;
        end
  endcase
end

endmodule