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eth: Push CRC computation logic towards input in 64-bit XGMII RX module

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Signed-off-by: Alex Forencich <alex@alexforencich.com>
This commit is contained in:
Alex Forencich
2025-10-05 19:10:30 -07:00
parent ae53b5d286
commit f6bfd0d097
1 changed files with 40 additions and 52 deletions
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90
src/eth/rtl/taxi_axis_xgmii_rx_64.sv
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@@ -106,10 +106,8 @@ localparam [1:0]
logic [1:0] state_reg = STATE_IDLE, state_next;
// datapath control signals
logic reset_crc;
logic lanes_swapped_reg = 1'b0;
logic lanes_swapped_d1_reg = 1'b0;
logic [31:0] swap_rxd_reg = 32'd0;
logic [3:0] swap_rxc_reg = 4'd0;
logic [3:0] swap_rxc_term_reg = 4'd0;
@@ -174,14 +172,14 @@ wire [31:0] crc_state;
wire [7:0] crc_valid;
logic [7:0] crc_valid_reg = '0;
assign crc_valid[7] = crc_state == ~32'h2144df1c;
assign crc_valid[6] = crc_state == ~32'hc622f71d;
assign crc_valid[5] = crc_state == ~32'hb1c2a1a3;
assign crc_valid[4] = crc_state == ~32'h9d6cdf7e;
assign crc_valid[3] = crc_state == ~32'h6522df69;
assign crc_valid[2] = crc_state == ~32'he60914ae;
assign crc_valid[1] = crc_state == ~32'he38a6876;
assign crc_valid[0] = crc_state == ~32'h6b87b1ec;
assign crc_valid[7] = crc_state_reg == ~32'h2144df1c;
assign crc_valid[6] = crc_state_reg == ~32'hc622f71d;
assign crc_valid[5] = crc_state_reg == ~32'hb1c2a1a3;
assign crc_valid[4] = crc_state_reg == ~32'h9d6cdf7e;
assign crc_valid[3] = crc_state_reg == ~32'h6522df69;
assign crc_valid[2] = crc_state_reg == ~32'he60914ae;
assign crc_valid[1] = crc_state_reg == ~32'he38a6876;
assign crc_valid[0] = crc_state_reg == ~32'h6b87b1ec;
logic [4+16-1:0] last_ts_reg = '0;
logic [4+16-1:0] ts_inc_reg = '0;
@@ -216,6 +214,15 @@ assign stat_rx_err_bad_block = stat_rx_err_bad_block_reg;
assign stat_rx_err_framing = stat_rx_err_framing_reg;
assign stat_rx_err_preamble = stat_rx_err_preamble_reg;
// Mask input data
wire [DATA_W-1:0] xgmii_rxd_masked;
wire [CTRL_W-1:0] xgmii_term;
for (genvar n = 0; n < CTRL_W; n = n + 1) begin
assign xgmii_rxd_masked[n*8 +: 8] = (n > 0 && xgmii_rxc[n]) ? 8'd0 : xgmii_rxd[n*8 +: 8];
assign xgmii_term[n] = xgmii_rxc[n] && (xgmii_rxd[n*8 +: 8] == XGMII_TERM);
end
taxi_lfsr #(
.LFSR_W(32),
.LFSR_POLY(32'h4c11db7),
@@ -227,26 +234,15 @@ taxi_lfsr #(
.DATA_OUT_EN(1'b0)
)
eth_crc (
.data_in(xgmii_rxd_d0_reg),
.data_in(xgmii_start_swap_reg ? {xgmii_rxd_masked[63:32], 32'd0} : xgmii_rxd_masked),
.state_in(crc_state_reg),
.data_out(),
.state_out(crc_state)
);
// Mask input data
wire [DATA_W-1:0] xgmii_rxd_masked;
wire [CTRL_W-1:0] xgmii_term;
for (genvar n = 0; n < CTRL_W; n = n + 1) begin
assign xgmii_rxd_masked[n*8 +: 8] = (n > 0 && xgmii_rxc[n]) ? 8'd0 : xgmii_rxd[n*8 +: 8];
assign xgmii_term[n] = xgmii_rxc[n] && (xgmii_rxd[n*8 +: 8] == XGMII_TERM);
end
always_comb begin
state_next = STATE_IDLE;
reset_crc = 1'b0;
frame_oversize_next = frame_oversize_reg;
pre_ok_next = pre_ok_reg;
hdr_ptr_next = hdr_ptr_reg;
@@ -327,8 +323,6 @@ always_comb begin
case (state_reg)
STATE_IDLE: begin
// idle state - wait for packet
reset_crc = 1'b1;
frame_oversize_next = 1'b0;
frame_len_next = 16'(CTRL_W);
{frame_len_lim_cyc_next, frame_len_lim_last_next} = cfg_rx_max_pkt_len;
@@ -339,8 +333,6 @@ always_comb begin
if (xgmii_start_d1_reg && cfg_rx_enable) begin
// start condition
reset_crc = 1'b0;
stat_rx_byte_next = 4'(CTRL_W);
state_next = STATE_PAYLOAD;
end else begin
@@ -378,6 +370,7 @@ always_comb begin
// control or error characters in packet
m_axis_rx_tlast_next = 1'b1;
m_axis_rx_tuser_next = 1'b1;
stat_rx_pkt_bad_next = 1'b1;
stat_rx_pkt_len_next = frame_len_next;
stat_rx_pkt_ucast_next = !is_mcast_reg;
@@ -389,17 +382,17 @@ always_comb begin
stat_rx_err_preamble_next = !pre_ok_reg;
stat_rx_pkt_fragment_next = frame_len_next[15:6] == 0;
stat_rx_pkt_jabber_next = frame_oversize_next;
reset_crc = 1'b1;
state_next = STATE_IDLE;
end else if (term_first_cycle_reg) begin
// end this cycle
m_axis_rx_tkeep_next = {KEEP_W{1'b1}} >> 3'(CTRL_W-4-term_lane_reg);
m_axis_rx_tlast_next = 1'b1;
if ((term_lane_reg == 0 && crc_valid_reg[7]) ||
(term_lane_reg == 1 && crc_valid[0]) ||
(term_lane_reg == 2 && crc_valid[1]) ||
(term_lane_reg == 3 && crc_valid[2]) ||
(term_lane_reg == 4 && crc_valid[3])) begin
if ((term_lane_reg == 0 && (lanes_swapped_d1_reg ? crc_valid_reg[3] : crc_valid_reg[7])) ||
(term_lane_reg == 1 && (lanes_swapped_d1_reg ? crc_valid_reg[4] : crc_valid[0])) ||
(term_lane_reg == 2 && (lanes_swapped_d1_reg ? crc_valid_reg[5] : crc_valid[1])) ||
(term_lane_reg == 3 && (lanes_swapped_d1_reg ? crc_valid_reg[6] : crc_valid[2])) ||
(term_lane_reg == 4 && (lanes_swapped_d1_reg ? crc_valid_reg[7] : crc_valid[3]))) begin
// CRC valid
if (frame_oversize_next) begin
// too long
@@ -417,6 +410,7 @@ always_comb begin
stat_rx_pkt_bad_next = 1'b1;
stat_rx_err_bad_fcs_next = 1'b1;
end
stat_rx_pkt_len_next = frame_len_next;
stat_rx_pkt_ucast_next = !is_mcast_reg;
stat_rx_pkt_mcast_next = is_mcast_reg && !is_bcast_reg;
@@ -424,7 +418,7 @@ always_comb begin
stat_rx_pkt_vlan_next = is_8021q_reg;
stat_rx_err_oversize_next = frame_oversize_next;
stat_rx_err_preamble_next = !pre_ok_reg;
reset_crc = 1'b1;
state_next = STATE_IDLE;
end else if (term_present_reg) begin
// need extra cycle
@@ -441,11 +435,9 @@ always_comb begin
m_axis_rx_tlast_next = 1'b1;
m_axis_rx_tuser_next = 1'b0;
reset_crc = 1'b1;
if ((term_lane_d0_reg == 5 && crc_valid_reg[4]) ||
(term_lane_d0_reg == 6 && crc_valid_reg[5]) ||
(term_lane_d0_reg == 7 && crc_valid_reg[6])) begin
if ((term_lane_d0_reg == 5 && (lanes_swapped_d1_reg ? crc_valid_reg[0] : crc_valid_reg[4])) ||
(term_lane_d0_reg == 6 && (lanes_swapped_d1_reg ? crc_valid_reg[1] : crc_valid_reg[5])) ||
(term_lane_d0_reg == 7 && (lanes_swapped_d1_reg ? crc_valid_reg[2] : crc_valid_reg[6]))) begin
// CRC valid
if (frame_oversize_reg) begin
// too long
@@ -474,8 +466,6 @@ always_comb begin
if (xgmii_start_d1_reg && cfg_rx_enable) begin
// start condition
reset_crc = 1'b0;
state_next = STATE_PAYLOAD;
end else begin
state_next = STATE_IDLE;
@@ -547,11 +537,7 @@ always_ff @(posedge clk) begin
// lane swapping and termination character detection
if (lanes_swapped_reg) begin
if (swap_rxc_term_reg != 0 || xgmii_term[0]) begin
xgmii_rxd_d0_reg <= {32'd0, swap_rxd_reg};
end else begin
xgmii_rxd_d0_reg <= {xgmii_rxd_masked[31:0], swap_rxd_reg};
end
term_present_reg <= 1'b0;
term_first_cycle_reg <= 1'b0;
@@ -585,17 +571,22 @@ always_ff @(posedge clk) begin
end
// start control character detection
crc_state_reg <= crc_state;
if (xgmii_rxc[0] && xgmii_rxd[7:0] == XGMII_START) begin
lanes_swapped_reg <= 1'b0;
xgmii_start_d0_reg <= 1'b1;
xgmii_rxd_d0_reg <= xgmii_rxd_masked;
crc_state_reg <= 32'hffffffff;
framing_error_reg <= xgmii_rxc[7:1] != 0;
end else if (xgmii_rxc[4] && xgmii_rxd[39:32] == XGMII_START) begin
lanes_swapped_reg <= 1'b1;
xgmii_start_swap_reg <= 1'b1;
crc_state_reg <= ~32'h6dd90a9d;
framing_error_reg <= xgmii_rxc[7:5] != 0;
end
@@ -617,15 +608,11 @@ always_ff @(posedge clk) begin
end
end
lanes_swapped_d1_reg <= lanes_swapped_reg;
term_lane_d0_reg <= term_lane_reg;
framing_error_d0_reg <= framing_error_reg;
if (reset_crc) begin
crc_state_reg <= '1;
end else begin
crc_state_reg <= crc_state;
end
crc_valid_reg <= crc_valid;
xgmii_rxd_d1_reg <= xgmii_rxd_d0_reg;
@@ -663,6 +650,7 @@ always_ff @(posedge clk) begin
xgmii_start_d1_reg <= 1'b0;
lanes_swapped_reg <= 1'b0;
lanes_swapped_d1_reg <= 1'b0;
end
end