cores/usb: Output a Start-Of-Frame strobe

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

cores/usb/rtl/usb.v

@@ -60,6 +60,9 @@ module usb #(
 	// IRQ
 	output wire irq,
 
+	// SOF indication
+	output wire sof,
+
 	// Common
 	input  wire clk,
 	input  wire rst
@@ -157,7 +160,7 @@ module usb #(
 
 	// Out-of-band conditions
 	wire oob_se0;
-	wire oob_sop;
+	wire oob_sof;
 
 	reg  [19:0] timeout_suspend;	//  3 ms with no activity
 	reg  [19:0] timeout_reset;		// 10 ms SE0
@@ -165,6 +168,9 @@ module usb #(
 	reg  rst_usb_l;
 	reg  suspend;
 
+	// Start-Of-Frame indication
+	reg  sof_ind;
+
 	// USB core logic reset
 	wire rst_usb;
 
@@ -553,14 +559,14 @@ module usb #(
 
 	// Detect some conditions for triggers
 	assign oob_se0 = !phy_rx_dp && !phy_rx_dn;
-	assign oob_sop = rxpkt_start & rxpkt_is_sof;
+	assign oob_sof = rxpkt_start & rxpkt_is_sof;
 
 	// Suspend timeout counter
 	always @(posedge clk)
 		if (rst_usb)
 			timeout_suspend <= 20'ha3280;
 		else
-			timeout_suspend <= oob_sop ? 20'ha3280 : (timeout_suspend - timeout_suspend[19]);
+			timeout_suspend <= oob_sof ? 20'ha3280 : (timeout_suspend - timeout_suspend[19]);
 
 	always @(posedge clk)
 		if (rst_usb)
@@ -599,4 +605,13 @@ module usb #(
 		else
 			pad_pu <= cr_pu_ena;
 
+
+	// Misc
+	// ----
+
+	always @(posedge clk)
+		sof_ind <= rxpkt_start & rxpkt_is_sof;
+
+	assign sof = sof_ind;
+
 endmodule // usb