s6ddrphy: read path OK in simulation

tb/s6ddrphy/gtkwave.sav

@@ -0,0 +1,45 @@
+[timestart] 0
+[size] 1741 771
+[pos] -1 -1
+*-14.000000 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
+[treeopen] tb_s6ddrphy.
+[treeopen] tb_s6ddrphy.dut.
+[treeopen] tb_s6ddrphy.dut.gen_dq[0].
+@28
+tb_s6ddrphy.dut.sys_clk
+tb_s6ddrphy.dut.clk2x_270
+tb_s6ddrphy.dut.clk4x_wr
+tb_s6ddrphy.dut.clk4x_wr_strb
+@22
+tb_s6ddrphy.dut.dfi_address_p0[12:0]
+tb_s6ddrphy.dut.dfi_address_p1[12:0]
+@200
+-
+@22
+tb_s6ddrphy.dut.sd_a[12:0]
+@28
+tb_s6ddrphy.dut.sd_clk_out_p
+@22
+tb_s6ddrphy.dut.sd_dm[3:0]
+tb_s6ddrphy.dut.sd_dq[31:0]
+tb_s6ddrphy.dut.sd_dqs[3:0]
+@200
+-
+@28
+tb_s6ddrphy.dut.dfi_wrdata_en_p1
+@22
+tb_s6ddrphy.dut.dfi_wrdata_mask_p0[7:0]
+tb_s6ddrphy.dut.dfi_wrdata_mask_p1[7:0]
+tb_s6ddrphy.dut.dfi_wrdata_p0[63:0]
+tb_s6ddrphy.dut.dfi_wrdata_p1[63:0]
+@200
+-
+@29
+tb_s6ddrphy.dut.dfi_rddata_en_p0
+@22
+tb_s6ddrphy.dut.dfi_rddata_w0[63:0]
+tb_s6ddrphy.dut.dfi_rddata_w1[63:0]
+@28
+tb_s6ddrphy.dut.dfi_rddata_valid_w0
+[pattern_trace] 1
+[pattern_trace] 0

tb/s6ddrphy/tb_s6ddrphy.v

@@ -58,6 +58,13 @@ reg dfi_wrdata_en_p1 = 0;
 reg [7:0] dfi_wrdata_mask_p1 = 0;
 reg [63:0] dfi_wrdata_p1 = 0;
 
+reg dfi_rddata_en_p0 = 0;
+reg dfi_rddata_en_p1 = 0;
+
+wire [31:0] sd_dq;
+reg [31:0] dq_tb = 32'hzzzzzzzz;
+assign sd_dq = dq_tb;
+
 s6ddrphy #(
 	.NUM_AD(13),
 	.NUM_BA(2),
@@ -83,37 +90,76 @@ s6ddrphy #(
 	.dfi_wrdata_en_p1(dfi_wrdata_en_p1),
 	.dfi_wrdata_mask_p1(dfi_wrdata_mask_p1),
 	.dfi_wrdata_p1(dfi_wrdata_p1),
-	.sd_dq(),
+	.sd_dq(sd_dq),
 	.sd_dm(),
-	.sd_dqs()
+	.sd_dqs(),
+	
+	.dfi_rddata_en_p0(dfi_rddata_en_p0),
+	.dfi_rddata_en_p1(dfi_rddata_en_p1),
+	.dfi_rddata_w0(),
+	.dfi_rddata_w1(),
+	.dfi_rddata_valid_w0(),
+	.dfi_rddata_valid_w1()
 );
 
+`define TEST_SIMPLE_CMD
+`define TEST_WRITE
+`define TEST_READ
+
 initial begin
 	$dumpfile("s6ddrphy.vcd");
 	$dumpvars(3, dut);
+
+`ifdef TEST_SIMPLE_CMD
 	#13;
-	
-	/*dfi_address_p0 <= 13'h1aba;
+	dfi_address_p0 <= 13'h1aba;
 	dfi_address_p1 <= 13'h1234;
 	#12;
 	dfi_address_p0 <= 0;
 	dfi_address_p1 <= 0;
-	#60;*/
-	
-	dfi_address_p0 <= 13'h0dea;
+	#59;
+`endif
+
+`ifdef TEST_WRITE
+	#13;
 	dfi_address_p1 <= 13'h0dbe;
+	#12;
+	dfi_address_p1 <= 0;
+	dfi_wrdata_en_p1 <= 1;
+	dfi_wrdata_mask_p0 <= 8'h12;
+	dfi_wrdata_mask_p1 <= 8'h34;
 	dfi_wrdata_p0 <= 64'hcafebabeabadface;
 	dfi_wrdata_p1 <= 64'h0123456789abcdef;
-	dfi_wrdata_en_p0 <= 1'b1;
-	dfi_wrdata_en_p1 <= 1'b1;
 	#12;
-	dfi_address_p0 <= 0;
-	dfi_address_p1 <= 0;
+	dfi_wrdata_en_p1 <= 0;
+	dfi_wrdata_mask_p0 <= 0;
+	dfi_wrdata_mask_p1 <= 0;
 	dfi_wrdata_p0 <= 64'd0;
 	dfi_wrdata_p1 <= 64'd0;
-	dfi_wrdata_en_p0 <= 1'b0;
-	dfi_wrdata_en_p1 <= 1'b0;
+	#59;
+`endif
+
+`ifdef TEST_READ
+	#13;
+	dfi_address_p0 <= 13'h1234;
+	#12;
+	dfi_address_p0 <= 0;
+	dfi_rddata_en_p0 <= 1;
+	#12;
+	dfi_rddata_en_p0 <= 0;
+	#15.5;
+	dq_tb <= 32'h12345678;
+	#3;
+	dq_tb <= 32'hdeadbeef;
+	#3;
+	dq_tb <= 32'hcafebabe;
+	#3;
+	dq_tb <= 32'habadface;
+	#3;
+	dq_tb <= 32'hzzzzzzzz;
 	#60;
+`endif
+	
 	$finish;
 end
 

verilog/s6ddrphy/s6ddrphy.v

@@ -1,6 +1,21 @@
 /*
- * 1:2 DDR PHY for Spartan-6
+ * 1:2 frequency-ratio DDR PHY for Spartan-6
  *
+ ************* DATAPATH SIGNALS ***********
+ * Assert dfi_wrdata_en and present the data 
+ * on dfi_wrdata_mask/dfi_wrdata one cycle after
+ * a write command. 
+ *
+ * Assert dfi_rddata_en one cycle after a read
+ * command. The data will come back on dfi_rddata
+ * 3 cycles later, along with the assertion of
+ * dfi_rddata_valid.
+ *
+ * This PHY only supports CAS Latency 3.
+ * Read commands must be sent on phase 0.
+ * Write commands must be sent on phase 1.
+ *
+ ************* DETAILED TIMING ************
  * Command path:
  *   posedge sys_clk             + 1
  *   posedge clk2x_270           + 0.375
@@ -17,8 +32,6 @@
  *   posedge clk2x_270           + 0.375
  *   negedge clk2x_270 [oddr]    + 0.125
  * DQS OE latency                1.5 cycles
- *
- * Data read path:
  */
 module s6ddrphy #(
 	parameter NUM_AD = 0,
@@ -309,7 +322,7 @@ generate
 			.CLK1(1'b0),
 			.IOCE(clk4x_rd_strb),
 			.RST(1'b0),
-			.CLKDIV(clk),
+			.CLKDIV(sys_clk),
 			.SHIFTIN(),
 			.BITSLIP(1'b0),
 			.FABRICOUT(),
@@ -377,25 +390,22 @@ endgenerate
  * DQ/DQS/DM control
  */
 
-reg r_dfi_wrdata_en_p0;
 reg r_dfi_wrdata_en_p1;
-
-always @(posedge sys_clk) begin
-	r_dfi_wrdata_en_p0 <= dfi_wrdata_en_p0;
+always @(posedge sys_clk)
 	r_dfi_wrdata_en_p1 <= dfi_wrdata_en_p1;
-end
 
-reg r2_dfi_wrdata_en_p0;
 reg r2_dfi_wrdata_en_p1;
-
-always @(posedge clk2x_270) begin
-	r2_dfi_wrdata_en_p0 <= r_dfi_wrdata_en_p0;
+always @(posedge clk2x_270)
 	r2_dfi_wrdata_en_p1 <= r_dfi_wrdata_en_p1;
-end
 
-assign drive_dqs = r2_dfi_wrdata_en_p0 | r2_dfi_wrdata_en_p1;
-assign drive_dq = dfi_wrdata_en_p0 | dfi_wrdata_en_p1;
+assign drive_dqs = r2_dfi_wrdata_en_p1;
+assign drive_dq = dfi_wrdata_en_p1;
 
-// TODO: dfi_rddata_valid_w0/1?
+wire rddata_valid;
+reg [3:0] rddata_sr;
+assign dfi_rddata_valid_w0 = rddata_sr[0];
+assign dfi_rddata_valid_w1 = rddata_sr[0];
+always @(posedge sys_clk)
+	rddata_sr <= {dfi_rddata_en_p0, rddata_sr[3:1]};
 
 endmodule