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Add pause functionality to FIFO modules
Signed-off-by: Alex Forencich <[email protected]>
1 parent e308c95 commit 62c2148

13 files changed

+492
-48
lines changed

‎rtl/axis_async_fifo.v

+128-23
Original file line numberDiff line numberDiff line change
@@ -80,7 +80,11 @@ module axis_async_fifo #
8080
// Drop incoming frames when full
8181
// When set, s_axis_tready is always asserted
8282
// Requires FRAME_FIFO and DROP_OVERSIZE_FRAME set
83-
parameter DROP_WHEN_FULL = 0
83+
parameter DROP_WHEN_FULL = 0,
84+
// Enable pause request input
85+
parameter PAUSE_ENABLE = 0,
86+
// Pause between frames
87+
parameter FRAME_PAUSE = FRAME_FIFO
8488
)
8589
(
8690
/*
@@ -111,6 +115,14 @@ module axis_async_fifo #
111115
output wire [DEST_WIDTH-1:0] m_axis_tdest,
112116
output wire [USER_WIDTH-1:0] m_axis_tuser,
113117

118+
/*
119+
* Pause
120+
*/
121+
input wire s_pause_req,
122+
output wire s_pause_ack,
123+
input wire m_pause_req,
124+
output wire m_pause_ack,
125+
114126
/*
115127
* Status
116128
*/
@@ -291,6 +303,7 @@ endgenerate
291303

292304
wire [WIDTH-1:0] m_axis = m_axis_pipe_reg[RAM_PIPELINE+1-1];
293305

306+
wire m_axis_tready_pipe;
294307
wire m_axis_tvalid_pipe = m_axis_tvalid_pipe_reg[RAM_PIPELINE+1-1];
295308

296309
wire [DATA_WIDTH-1:0] m_axis_tdata_pipe = m_axis[DATA_WIDTH-1:0];
@@ -300,6 +313,16 @@ wire [ID_WIDTH-1:0] m_axis_tid_pipe = ID_ENABLE ? m_axis[ID_OFFSET +: ID
300313
wire [DEST_WIDTH-1:0] m_axis_tdest_pipe = DEST_ENABLE ? m_axis[DEST_OFFSET +: DEST_WIDTH] : {DEST_WIDTH{1'b0}};
301314
wire [USER_WIDTH-1:0] m_axis_tuser_pipe = USER_ENABLE ? (m_terminate_frame_reg ? USER_BAD_FRAME_VALUE : m_axis[USER_OFFSET +: USER_WIDTH]) : {USER_WIDTH{1'b0}};
302315

316+
wire m_axis_tready_out;
317+
wire m_axis_tvalid_out;
318+
319+
wire [DATA_WIDTH-1:0] m_axis_tdata_out;
320+
wire [KEEP_WIDTH-1:0] m_axis_tkeep_out;
321+
wire m_axis_tlast_out;
322+
wire [ID_WIDTH-1:0] m_axis_tid_out;
323+
wire [DEST_WIDTH-1:0] m_axis_tdest_out;
324+
wire [USER_WIDTH-1:0] m_axis_tuser_out;
325+
303326
wire pipe_ready;
304327

305328
assign s_status_depth = (KEEP_ENABLE && KEEP_WIDTH > 1) ? {s_depth_reg, {$clog2(KEEP_WIDTH){1'b0}}} : s_depth_reg;
@@ -574,22 +597,22 @@ end
574597
integer j;
575598

576599
always @(posedge m_clk) begin
577-
if (OUTPUT_FIFO_ENABLE || m_axis_tready) begin
600+
if (m_axis_tready_pipe) begin
578601
// output ready; invalidate stage
579602
m_axis_tvalid_pipe_reg[RAM_PIPELINE+1-1] <= 1'b0;
580603
m_terminate_frame_reg <= 1'b0;
581604
end
582605

583606
for (j = RAM_PIPELINE+1-1; j > 0; j = j - 1) begin
584-
if (OUTPUT_FIFO_ENABLE || m_axis_tready || ((~m_axis_tvalid_pipe_reg) >> j)) begin
607+
if (m_axis_tready_pipe || ((~m_axis_tvalid_pipe_reg) >> j)) begin
585608
// output ready or bubble in pipeline; transfer down pipeline
586609
m_axis_tvalid_pipe_reg[j] <= m_axis_tvalid_pipe_reg[j-1];
587610
m_axis_pipe_reg[j] <= m_axis_pipe_reg[j-1];
588611
m_axis_tvalid_pipe_reg[j-1] <= 1'b0;
589612
end
590613
end
591614

592-
if (OUTPUT_FIFO_ENABLE || m_axis_tready || ~m_axis_tvalid_pipe_reg) begin
615+
if (m_axis_tready_pipe || ~m_axis_tvalid_pipe_reg) begin
593616
// output ready or bubble in pipeline; read new data from FIFO
594617
m_axis_tvalid_pipe_reg[0] <= 1'b0;
595618
m_axis_pipe_reg[0] <= mem[rd_ptr_reg[ADDR_WIDTH-1:0]];
@@ -604,14 +627,14 @@ always @(posedge m_clk) begin
604627

605628
if (m_axis_tvalid_pipe && LAST_ENABLE) begin
606629
// track output frame status
607-
if (m_axis_tlast_pipe && (OUTPUT_FIFO_ENABLE || m_axis_tready)) begin
630+
if (m_axis_tlast_pipe && m_axis_tready_pipe) begin
608631
m_frame_reg <= 1'b0;
609632
end else begin
610633
m_frame_reg <= 1'b1;
611634
end
612635
end
613636

614-
if (m_drop_frame_reg && (OUTPUT_FIFO_ENABLE ? pipe_ready : m_axis_tready || !m_axis_tvalid_pipe) && LAST_ENABLE) begin
637+
if (m_drop_frame_reg && (OUTPUT_FIFO_ENABLE ? pipe_ready : m_axis_tready_pipe || !m_axis_tvalid_pipe) && LAST_ENABLE) begin
615638
// terminate frame
616639
// (only for frame transfers interrupted by source reset)
617640
m_axis_tvalid_pipe_reg[RAM_PIPELINE+1-1] <= 1'b1;
@@ -662,16 +685,17 @@ if (!OUTPUT_FIFO_ENABLE) begin
662685

663686
assign pipe_ready = 1'b1;
664687

665-
assign m_axis_tvalid = m_axis_tvalid_pipe;
688+
assign m_axis_tready_pipe = m_axis_tready_out;
689+
assign m_axis_tvalid_out = m_axis_tvalid_pipe;
666690

667-
assign m_axis_tdata = m_axis_tdata_pipe;
668-
assign m_axis_tkeep = m_axis_tkeep_pipe;
669-
assign m_axis_tlast = m_axis_tlast_pipe;
670-
assign m_axis_tid = m_axis_tid_pipe;
671-
assign m_axis_tdest = m_axis_tdest_pipe;
672-
assign m_axis_tuser = m_axis_tuser_pipe;
691+
assign m_axis_tdata_out = m_axis_tdata_pipe;
692+
assign m_axis_tkeep_out = m_axis_tkeep_pipe;
693+
assign m_axis_tlast_out = m_axis_tlast_pipe;
694+
assign m_axis_tid_out = m_axis_tid_pipe;
695+
assign m_axis_tdest_out = m_axis_tdest_pipe;
696+
assign m_axis_tuser_out = m_axis_tuser_pipe;
673697

674-
end else begin
698+
end else begin : output_fifo
675699

676700
// output datapath logic
677701
reg [DATA_WIDTH-1:0] m_axis_tdata_reg = {DATA_WIDTH{1'b0}};
@@ -704,16 +728,18 @@ end else begin
704728

705729
assign pipe_ready = !out_fifo_half_full_reg;
706730

707-
assign m_axis_tdata = m_axis_tdata_reg;
708-
assign m_axis_tkeep = KEEP_ENABLE ? m_axis_tkeep_reg : {KEEP_WIDTH{1'b1}};
709-
assign m_axis_tvalid = m_axis_tvalid_reg;
710-
assign m_axis_tlast = LAST_ENABLE ? m_axis_tlast_reg : 1'b1;
711-
assign m_axis_tid = ID_ENABLE ? m_axis_tid_reg : {ID_WIDTH{1'b0}};
712-
assign m_axis_tdest = DEST_ENABLE ? m_axis_tdest_reg : {DEST_WIDTH{1'b0}};
713-
assign m_axis_tuser = USER_ENABLE ? m_axis_tuser_reg : {USER_WIDTH{1'b0}};
731+
assign m_axis_tready_pipe = 1'b1;
732+
733+
assign m_axis_tdata_out = m_axis_tdata_reg;
734+
assign m_axis_tkeep_out = KEEP_ENABLE ? m_axis_tkeep_reg : {KEEP_WIDTH{1'b1}};
735+
assign m_axis_tvalid_out = m_axis_tvalid_reg;
736+
assign m_axis_tlast_out = LAST_ENABLE ? m_axis_tlast_reg : 1'b1;
737+
assign m_axis_tid_out = ID_ENABLE ? m_axis_tid_reg : {ID_WIDTH{1'b0}};
738+
assign m_axis_tdest_out = DEST_ENABLE ? m_axis_tdest_reg : {DEST_WIDTH{1'b0}};
739+
assign m_axis_tuser_out = USER_ENABLE ? m_axis_tuser_reg : {USER_WIDTH{1'b0}};
714740

715741
always @(posedge m_clk) begin
716-
m_axis_tvalid_reg <= m_axis_tvalid_reg && !m_axis_tready;
742+
m_axis_tvalid_reg <= m_axis_tvalid_reg && !m_axis_tready_out;
717743

718744
out_fifo_half_full_reg <= $unsigned(out_fifo_wr_ptr_reg - out_fifo_rd_ptr_reg) >= 2**(OUTPUT_FIFO_ADDR_WIDTH-1);
719745

@@ -727,7 +753,7 @@ end else begin
727753
out_fifo_wr_ptr_reg <= out_fifo_wr_ptr_reg + 1;
728754
end
729755

730-
if (!out_fifo_empty && (!m_axis_tvalid_reg || m_axis_tready)) begin
756+
if (!out_fifo_empty && (!m_axis_tvalid_reg || m_axis_tready_out)) begin
731757
m_axis_tdata_reg <= out_fifo_tdata[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
732758
m_axis_tkeep_reg <= out_fifo_tkeep[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
733759
m_axis_tvalid_reg <= 1'b1;
@@ -747,6 +773,85 @@ end else begin
747773

748774
end
749775

776+
if (PAUSE_ENABLE) begin : pause
777+
778+
// Pause logic
779+
reg pause_reg = 1'b0;
780+
reg pause_frame_reg = 1'b0;
781+
782+
reg s_pause_req_sync1_reg;
783+
reg s_pause_req_sync2_reg;
784+
reg s_pause_req_sync3_reg;
785+
reg s_pause_ack_sync1_reg;
786+
reg s_pause_ack_sync2_reg;
787+
reg s_pause_ack_sync3_reg;
788+
789+
always @(posedge s_clk) begin
790+
s_pause_req_sync1_reg <= s_pause_req;
791+
s_pause_ack_sync2_reg <= s_pause_ack_sync1_reg;
792+
s_pause_ack_sync3_reg <= s_pause_ack_sync2_reg;
793+
end
794+
795+
always @(posedge m_clk) begin
796+
s_pause_req_sync2_reg <= s_pause_req_sync1_reg;
797+
s_pause_req_sync3_reg <= s_pause_req_sync2_reg;
798+
s_pause_ack_sync1_reg <= pause_reg;
799+
end
800+
801+
assign m_axis_tready_out = m_axis_tready && !pause_reg;
802+
assign m_axis_tvalid = m_axis_tvalid_out && !pause_reg;
803+
804+
assign m_axis_tdata = m_axis_tdata_out;
805+
assign m_axis_tkeep = m_axis_tkeep_out;
806+
assign m_axis_tlast = m_axis_tlast_out;
807+
assign m_axis_tid = m_axis_tid_out;
808+
assign m_axis_tdest = m_axis_tdest_out;
809+
assign m_axis_tuser = m_axis_tuser_out;
810+
811+
assign s_pause_ack = s_pause_ack_sync3_reg;
812+
assign m_pause_ack = pause_reg;
813+
814+
always @(posedge m_clk) begin
815+
if (FRAME_PAUSE) begin
816+
if (m_axis_tvalid && m_axis_tready) begin
817+
if (m_axis_tlast) begin
818+
pause_frame_reg <= 1'b0;
819+
pause_reg <= m_pause_req || s_pause_req_sync3_reg;
820+
end else begin
821+
pause_frame_reg <= 1'b1;
822+
end
823+
end else begin
824+
if (!pause_frame_reg) begin
825+
pause_reg <= m_pause_req || s_pause_req_sync3_reg;
826+
end
827+
end
828+
end else begin
829+
pause_reg <= m_pause_req || s_pause_req_sync3_reg;
830+
end
831+
832+
if (m_rst) begin
833+
pause_frame_reg <= 1'b0;
834+
pause_reg <= 1'b0;
835+
end
836+
end
837+
838+
end else begin
839+
840+
assign m_axis_tready_out = m_axis_tready;
841+
assign m_axis_tvalid = m_axis_tvalid_out;
842+
843+
assign m_axis_tdata = m_axis_tdata_out;
844+
assign m_axis_tkeep = m_axis_tkeep_out;
845+
assign m_axis_tlast = m_axis_tlast_out;
846+
assign m_axis_tid = m_axis_tid_out;
847+
assign m_axis_tdest = m_axis_tdest_out;
848+
assign m_axis_tuser = m_axis_tuser_out;
849+
850+
assign s_pause_ack = 1'b0;
851+
assign m_pause_ack = 1'b0;
852+
853+
end
854+
750855
endgenerate
751856

752857
endmodule

‎rtl/axis_async_fifo_adapter.v

+21-2
Original file line numberDiff line numberDiff line change
@@ -85,7 +85,11 @@ module axis_async_fifo_adapter #
8585
// Drop incoming frames when full
8686
// When set, s_axis_tready is always asserted
8787
// Requires FRAME_FIFO and DROP_OVERSIZE_FRAME set
88-
parameter DROP_WHEN_FULL = 0
88+
parameter DROP_WHEN_FULL = 0,
89+
// Enable pause request input
90+
parameter PAUSE_ENABLE = 0,
91+
// Pause between frames
92+
parameter FRAME_PAUSE = FRAME_FIFO
8993
)
9094
(
9195
/*
@@ -116,6 +120,14 @@ module axis_async_fifo_adapter #
116120
output wire [DEST_WIDTH-1:0] m_axis_tdest,
117121
output wire [USER_WIDTH-1:0] m_axis_tuser,
118122

123+
/*
124+
* Pause
125+
*/
126+
input wire s_pause_req,
127+
output wire s_pause_ack,
128+
input wire m_pause_req,
129+
output wire m_pause_ack,
130+
119131
/*
120132
* Status
121133
*/
@@ -255,7 +267,9 @@ axis_async_fifo #(
255267
.USER_BAD_FRAME_MASK(USER_BAD_FRAME_MASK),
256268
.DROP_OVERSIZE_FRAME(DROP_OVERSIZE_FRAME),
257269
.DROP_BAD_FRAME(DROP_BAD_FRAME),
258-
.DROP_WHEN_FULL(DROP_WHEN_FULL)
270+
.DROP_WHEN_FULL(DROP_WHEN_FULL),
271+
.PAUSE_ENABLE(PAUSE_ENABLE),
272+
.FRAME_PAUSE(FRAME_PAUSE)
259273
)
260274
fifo_inst (
261275
// AXI input
@@ -280,6 +294,11 @@ fifo_inst (
280294
.m_axis_tid(post_fifo_axis_tid),
281295
.m_axis_tdest(post_fifo_axis_tdest),
282296
.m_axis_tuser(post_fifo_axis_tuser),
297+
// Pause
298+
.s_pause_req(s_pause_req),
299+
.s_pause_ack(s_pause_ack),
300+
.m_pause_req(m_pause_req),
301+
.m_pause_ack(m_pause_ack),
283302
// Status
284303
.s_status_depth(s_status_depth),
285304
.s_status_depth_commit(s_status_depth_commit),

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