From 8d22db83560d782c2f9e43e7359d7f616a3f4bb0 Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Fri, 6 Oct 2023 08:24:19 -0600
Subject: rtl/cache: split token.sv out of cache_control.vs

---
 rtl/cache/token.sv | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 rtl/cache/token.sv

(limited to 'rtl/cache/token.sv')

diff --git a/rtl/cache/token.sv b/rtl/cache/token.sv
new file mode 100644
index 0000000..cb3e59d
--- /dev/null
+++ b/rtl/cache/token.sv
@@ -0,0 +1,57 @@
+`include "cache/defs.sv"
+
+module cache_token
+#(parameter TOKEN_AT_RESET=0)
+(
+	input  logic       clk,
+	                   rst_n,
+
+	input  addr_tag    core_tag,
+	input  addr_index  core_index,
+
+	input  ring_token  in_token,			// input del token
+	input  logic       in_token_valid,		// se está recibiendo el token
+
+	output ring_token  out_token,			// output del token
+	output logic       out_token_valid,		// se está enviando el token
+
+	input  logic       send,
+	                   lock_line,
+	                   unlock_line,
+	output logic       locked,
+	                   may_send
+);
+
+	logic may_send_if_token_held;
+
+	// Solo se puede iniciar un request si se tiene el token y el token es
+	// válido
+	assign may_send = may_send_if_token_held && in_token_valid;
+	assign may_send_if_token_held
+	     = (!in_token.e2.valid || in_token.e2.index != core_index || in_token.e2.tag != core_tag)
+	    && (!in_token.e1.valid || in_token.e1.index != core_index || in_token.e1.tag != core_tag)
+	    && (!in_token.e0.valid || in_token.e0.index != core_index || in_token.e0.tag != core_tag);
+
+	always_ff @(posedge clk or negedge rst_n)
+		if (!rst_n) begin
+			out_token <= {($bits(out_token)){1'b0}};
+			out_token_valid <= TOKEN_AT_RESET;
+
+			locked <= 0;
+		end else begin
+			out_token.e0.tag <= core_tag;
+			out_token.e0.index <= core_index;
+			out_token.e0.valid <= may_send_if_token_held && (send || locked) && !unlock_line;
+
+			out_token.e2 <= in_token.e1;
+			out_token.e1 <= in_token.e0;
+			out_token_valid <= in_token_valid;
+
+			if (lock_line)
+				locked <= 1;
+
+			if (unlock_line)
+				locked <= 0;
+		end
+
+endmodule
-- 
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