From 2757659d3a47fce776291f45274d0b6157de6e8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Vejn=C3=A1r?= <avakar@ratatanek.cz>
Date: Sun, 9 Jun 2013 10:56:27 +0200
Subject: [PATCH] Added usb_ep helper.

---
 usb_ep.v | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
 create mode 100644 usb_ep.v

diff --git a/usb_ep.v b/usb_ep.v
new file mode 100644
index 0000000..faf1fbc
--- /dev/null
+++ b/usb_ep.v
@@ -0,0 +1,120 @@
+module usb_ep(
+    input clk,
+
+    input direction_in,
+    input setup,
+    input success,
+    input[6:0] cnt,
+
+    output reg toggle,
+    output reg[1:0] handshake,
+    output bank,
+    output in_data_valid,
+
+    input ctrl_dir_in,
+    output reg[15:0] ctrl_rd_data,
+    input[15:0] ctrl_wr_data,
+    input ctrl_wr_strobe
+    );
+
+localparam
+    hs_ack = 2'b00,
+    hs_none = 2'b01,
+    hs_nak = 2'b10,
+    hs_stall = 2'b11;
+
+reg ep_setup;
+reg ep_out_full;
+reg ep_in_full;
+reg ep_out_stall;
+reg ep_in_stall;
+reg ep_out_toggle;
+reg ep_in_toggle;
+reg[6:0] ep_in_cnt;
+reg[6:0] ep_out_cnt;
+
+assign bank = 1'b0;
+assign in_data_valid = (cnt != ep_in_cnt);
+
+always @(*) begin
+    if (!direction_in && setup)
+        toggle = 1'b0;
+    else if (ep_setup)
+        toggle = 1'b1;
+    else if (direction_in)
+        toggle = ep_in_toggle;
+    else
+        toggle = ep_out_toggle;
+end
+
+always @(*) begin
+    if (direction_in) begin
+        if (!ep_in_stall && !ep_setup && ep_in_full) begin
+            handshake = hs_ack;
+        end else if (!ep_setup && ep_in_stall) begin
+            handshake = hs_stall;
+        end else begin
+            handshake = hs_nak;
+        end
+    end else begin
+        if (setup || (!ep_out_stall && !ep_setup && !ep_out_full)) begin
+            handshake = hs_ack;
+        end else if (!ep_setup && ep_out_stall) begin
+            handshake = hs_stall;
+        end else begin
+            handshake = hs_nak;
+        end
+    end
+end
+
+always @(*) begin
+    if (ctrl_dir_in)
+        ctrl_rd_data = { 1'b0, ep_in_full,  ep_in_cnt,  2'b0, ep_in_toggle,  ep_in_stall,  1'b0, ep_setup, 1'b0, ep_in_full  };
+    else
+        ctrl_rd_data = { 1'b0, ep_out_full, ep_out_cnt, 2'b0, ep_out_toggle, ep_out_stall, 1'b0, ep_setup, 1'b0, ep_out_full };
+end
+
+always @(posedge clk) begin
+    if (success) begin
+        if (direction_in) begin
+            ep_in_toggle <= !ep_in_toggle;
+            ep_in_full <= 1'b0;
+        end else begin
+            if (setup)
+                ep_setup <= 1'b1;
+
+            ep_out_toggle <= !ep_out_toggle;
+            ep_out_full <= 1'b1;
+            ep_out_cnt <= cnt;
+        end
+    end
+
+    if (ctrl_wr_strobe && ctrl_dir_in) begin
+        ep_in_cnt <= ctrl_wr_data[14:8];
+        if (ctrl_wr_data[7])
+            ep_in_toggle <= 1'b0;
+        if (ctrl_wr_data[6])
+            ep_in_toggle <= 1'b1;
+        ep_in_stall <= ctrl_wr_data[4];
+        if (ctrl_wr_data[15] || ctrl_wr_data[1])
+            ep_in_full <= 1'b0;
+        if (ctrl_wr_data[14] || ctrl_wr_data[0])
+            ep_in_full <= 1'b1;
+    end
+
+    if (ctrl_wr_strobe && !ctrl_dir_in) begin
+        if (ctrl_wr_data[7])
+            ep_out_toggle <= 1'b0;
+        if (ctrl_wr_data[6])
+            ep_out_toggle <= 1'b1;
+        ep_out_stall <= ctrl_wr_data[4];
+        if (ctrl_wr_data[3])
+            ep_setup <= 1'b0;
+        if (ctrl_wr_data[15] || ctrl_wr_data[1])
+            ep_out_full <= 1'b0;
+        if (ctrl_wr_data[14] || ctrl_wr_data[0])
+            ep_out_full <= 1'b1;
+    end
+end
+
+endmodule