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oh/elink/hdl/etx_io.v
Andreas Olofsson d275406aa6 Reset timing optimization
- holding rx in reset state until tx is done
- removing reset from all pipeline registers
- removing reset from oddr/iddr
- the idea is to keep things quiet not to block in lots of places. The only real block needed is in the FIFO to keep "noise" from propagating past the link. The link should be kept in a safe reset state until the rx fram is stable and the clock is running so that the pipe can be cleaned out.
2015-10-08 10:34:59 -04:00

291 lines
7.8 KiB
Verilog

`include "elink_constants.v"
module etx_io (/*AUTOARG*/
// Outputs
txo_lclk_p, txo_lclk_n, txo_frame_p, txo_frame_n, txo_data_p,
txo_data_n, tx_io_wait, tx_wr_wait, tx_rd_wait,
// Inputs
reset, tx_lclk, tx_lclk90, txi_wr_wait_p, txi_wr_wait_n,
txi_rd_wait_p, txi_rd_wait_n, tx_packet, tx_access, tx_burst
);
parameter IOSTD_ELINK = "LVDS_25";
parameter PW = 104;
parameter ETYPE = 1;//0=parallella
//1=ephycard
//###########
//# reset, clocks
//##########
input reset; //sync reset for io
input tx_lclk; //fast clock for io
input tx_lclk90; //fast 90deg shifted lclk
//###########
//# eLink pins
//###########
output txo_lclk_p, txo_lclk_n; // tx clock output
output txo_frame_p, txo_frame_n; // tx frame signal
output [7:0] txo_data_p, txo_data_n; // tx data (dual data rate)
input txi_wr_wait_p,txi_wr_wait_n; // tx write pushback
input txi_rd_wait_p, txi_rd_wait_n; // tx read pushback
//#############
//# Fabric interface
//#############
input [PW-1:0] tx_packet;
input tx_access;
input tx_burst;
output tx_io_wait;
output tx_wr_wait;
output tx_rd_wait;
//############
//# REGS
//############
reg [7:0] tx_pointer;
reg [15:0] tx_data16;
reg tx_access_reg;
reg tx_frame;
reg tx_io_wait_reg;
reg [PW-1:0] tx_packet_reg;
reg [63:0] tx_double;
reg [2:0] tx_state_reg;
reg [2:0] tx_state;
//############
//# WIRES
//############
wire new_tran;
wire access;
wire write;
wire [1:0] datamode;
wire [3:0] ctrlmode;
wire [31:0] dstaddr;
wire [31:0] data;
wire [31:0] srcaddr;
wire [7:0] txo_data;
wire txo_frame;
wire txo_lclk90;
reg tx_io_wait;
//#############################
//# Transmit state machine
//#############################
`define IDLE 3'b000
`define CYCLE1 3'b001
`define CYCLE2 3'b010
`define CYCLE3 3'b011
`define CYCLE4 3'b100
`define CYCLE5 3'b101
`define CYCLE6 3'b110
`define CYCLE7 3'b111
always @ (posedge tx_lclk)
if(reset)
tx_state[2:0] <= `IDLE;
else
case (tx_state[2:0])
`IDLE : tx_state[2:0] <= tx_access ? `CYCLE1 : `IDLE;
`CYCLE1 : tx_state[2:0] <= `CYCLE2;
`CYCLE2 : tx_state[2:0] <= `CYCLE3;
`CYCLE3 : tx_state[2:0] <= `CYCLE4;
`CYCLE4 : tx_state[2:0] <= `CYCLE5;
`CYCLE5 : tx_state[2:0] <= `CYCLE6;
`CYCLE6 : tx_state[2:0] <= `CYCLE7;
`CYCLE7 : tx_state[2:0] <= tx_burst ? `CYCLE4 : `IDLE;
endcase // case (tx_state)
assign tx_new_frame = (tx_state[2:0]==`CYCLE1);
//Creating wait pulse for slow clock domain
always @ (posedge tx_lclk)
if(reset | ~tx_access)
tx_io_wait <= 1'b0;
else if ((tx_state[2:0] ==`CYCLE4) & ~tx_burst)
tx_io_wait <= 1'b1;
else if (tx_state[2:0]==`CYCLE7)
tx_io_wait <= 1'b0;
//Create frame signal for output
always @ (posedge tx_lclk)
begin
tx_state_reg[2:0] <= tx_state[2:0];
tx_frame <= |(tx_state_reg[2:0]);
end
//#############################
//# 2 CYCLE PACKET PIPELINE
//#############################
always @ (posedge tx_lclk)
if (tx_access)
tx_packet_reg[PW-1:0] <= tx_packet[PW-1:0];
packet2emesh p2e (.access_out (access),
.write_out (write),
.datamode_out (datamode[1:0]),
.ctrlmode_out (ctrlmode[3:0]),
.dstaddr_out (dstaddr[31:0]),
.data_out (data[31:0]),
.srcaddr_out (srcaddr[31:0]),
.packet_in (tx_packet_reg[PW-1:0]));
always @ (posedge tx_lclk)
if (tx_new_frame)
tx_double[63:0] <= {16'b0,//16
~write,7'b0,ctrlmode[3:0],//12
dstaddr[31:0],datamode[1:0],write,access};//36
else if(tx_state[2:0]==`CYCLE4)
tx_double[63:0] <= {data[31:0],srcaddr[31:0]};
//#############################
//# SELECTING DATA FOR TRANSMIT
//#############################
always @ (posedge tx_lclk)
case(tx_state_reg[2:0])
//Cycle1
3'b001: tx_data16[15:0] <= tx_double[47:32];
//Cycle2
3'b010: tx_data16[15:0] <= tx_double[31:16];
//Cycle3
3'b011: tx_data16[15:0] <= tx_double[15:0];
//Cycle4
3'b100: tx_data16[15:0] <= tx_double[63:48];
//Cycle5
3'b101: tx_data16[15:0] <= tx_double[47:32];
//Cycle6
3'b110: tx_data16[15:0] <= tx_double[31:16];
//Cycle7
3'b111: tx_data16[15:0] <= tx_double[15:0];
default tx_data16[15:0] <= 16'b0;
endcase // case (tx_state[2:0])
//#############################
//# ODDR DRIVERS
//#############################
//DATA
genvar i;
generate for(i=0; i<8; i=i+1)
begin : gen_oddr
ODDR #(.DDR_CLK_EDGE ("SAME_EDGE"))
oddr_data (
.Q (txo_data[i]),
.C (tx_lclk),
.CE (1'b1),
.D1 (tx_data16[i+8]),
.D2 (tx_data16[i]),
.R (1'b0),
.S (1'b0)
);
end
endgenerate
//FRAME
ODDR #(.DDR_CLK_EDGE ("SAME_EDGE"), .SRTYPE ("SYNC"))
oddr_frame (
.Q (txo_frame),
.C (tx_lclk),
.CE (1'b1),
.D1 (tx_frame),
.D2 (tx_frame),
.R (1'b0), //reset
.S (1'b0)
);
//LCLK
ODDR #(.DDR_CLK_EDGE ("SAME_EDGE"))
oddr_lclk (
.Q (txo_lclk90),
.C (tx_lclk90),
.CE (1'b1),
.D1 (1'b1),
.D2 (1'b0),
.R (1'b0),//should be no reason to reset clock, static input
.S (1'b0)
);
//##############################
//# OUTPUT BUFFERS
//##############################
OBUFDS obufds_data[7:0] (
.O (txo_data_p[7:0]),
.OB (txo_data_n[7:0]),
.I (txo_data[7:0])
);
OBUFDS obufds_frame ( .O (txo_frame_p),
.OB (txo_frame_n),
.I (txo_frame)
);
OBUFDS obufds_lclk ( .O (txo_lclk_p),
.OB (txo_lclk_n),
.I (txo_lclk90)
);
//################################
//# Wait Input Buffers
//################################
generate
if(ETYPE==1)
begin
assign tx_wr_wait = txi_wr_wait_p;
end
else if (ETYPE==0)
begin
IBUFDS
#(.DIFF_TERM ("TRUE"), // Differential termination
.IOSTANDARD (IOSTD_ELINK))
ibufds_wrwait
(.I (txi_wr_wait_p),
.IB (txi_wr_wait_n),
.O (tx_wr_wait));
end
endgenerate
//TODO: Come up with cleaner defines for this
//Parallella and other platforms...
`ifdef TODO
IBUFDS
#(.DIFF_TERM ("TRUE"), // Differential termination
.IOSTANDARD (IOSTD_ELINK))
ibufds_rdwait
(.I (txi_rd_wait_p),
.IB (txi_rd_wait_n),
.O (tx_rd_wait));
`else
//On Parallella this signal comes in single-ended
assign tx_rd_wait = txi_rd_wait_p;
`endif
endmodule // etx_io
// Local Variables:
// verilog-library-directories:("." "../../emesh/hdl")
// End:
/*
Copyright (C) 2014 Adapteva, Inc.
Contributed by Andreas Olofsson <andreas@adapteva.com>
Contributed by Gunnar Hillerstrom
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program (see the file COPYING). If not, see
<http://www.gnu.org/licenses/>.
*/