From 98d493f9c80f356cdbc2669150d772e451c3b80e Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Sat, 28 Oct 2023 02:29:46 -0600
Subject: platform: implement support for disabling CPUs

---
 rtl/core/core.sv | 99 +++++++++++++++++++++-----------------------------------
 1 file changed, 37 insertions(+), 62 deletions(-)

(limited to 'rtl/core/core.sv')

diff --git a/rtl/core/core.sv b/rtl/core/core.sv
index 3b87298..ce51a71 100644
--- a/rtl/core/core.sv
+++ b/rtl/core/core.sv
@@ -1,6 +1,8 @@
 `include "core/uarch.sv"
+`include "config.sv"
 
 module core
+#(parameter ID=0)
 (
 	input  logic      clk,
 	                  rst_n,
@@ -23,72 +25,45 @@ module core
 	input  logic      avl_irq
 );
 
-	logic ex_fail, ex_lock, start, ready, write;
+	generate
+		if (ID < `CONFIG_CPUS) begin: enable
+			ptr addr;
+			word data_wr;
+			logic start, write;
+			logic[3:0] data_be;
 
-	logic[3:0] data_be;
-	logic[29:0] addr;
-	logic[31:0] data_rd, data_wr;
+			arm810 cpu
+			(
+				.irq(avl_irq),
+				.halt(cpu_halt),
+				.halted(cpu_halted),
+				.bus_addr(addr),
+				.bus_data_rd(data_rd),
+				.bus_data_wr(data_wr),
+				.bus_data_be(data_be),
+				.bus_ready(ready),
+				.bus_write(write),
+				.bus_start(start),
+				.bus_ex_fail(ex_fail),
+				.bus_ex_lock(ex_lock),
+				.*
+			);
 
-	enum int unsigned
-	{
-		IDLE,
-		WAIT
-	} state;
+			word data_rd;
+			logic ex_fail, ex_lock, ready;
 
-	arm810 cpu
-	(
-		.irq(avl_irq),
-		.halt(cpu_halt),
-		.halted(cpu_halted),
-		.bus_addr(addr),
-		.bus_data_rd(data_rd),
-		.bus_data_wr(data_wr),
-		.bus_data_be(data_be),
-		.bus_ready(ready),
-		.bus_write(write),
-		.bus_start(start),
-		.bus_ex_fail(ex_fail),
-		.bus_ex_lock(ex_lock),
-		.*
-	);
+			bus_master master
+			(
+				.*
+			);
+		end else begin
+			assign cpu_halted = 1;
+			assign breakpoint = 0;
 
-	assign data_rd = avl_readdata;
-	assign ex_fail = |avl_response;
-
-	always_comb
-		unique case(state)
-			IDLE: ready = 0;
-			WAIT: ready = !avl_waitrequest;
-		endcase
-
-	always_ff @(posedge clk or negedge rst_n)
-		/* P. 16:
-		 * A host must make no assumption about the assertion state of
-		 * waitrequest when the host is idle: waitrequest may be high or
-		 * low, depending on system properties. When waitrequest is asserted,
-		 * host control signals to the agent must remain constant except for
-		 * beginbursttransfer.
-		 */
-		if(!rst_n) begin
-			state <= IDLE;
-			avl_lock <= 0;
-			avl_read <= 0;
-			avl_write <= 0;
-			avl_address <= 0;
-			avl_writedata <= 0;
-			avl_byteenable <= 0;
-		end else if((state == IDLE || !avl_waitrequest) && start) begin
-			state <= WAIT;
-			avl_lock <= ex_lock;
-			avl_read <= ~write;
-			avl_write <= write;
-			avl_address <= {addr, 2'b00};
-			avl_writedata <= data_wr;
-			avl_byteenable <= write ? data_be : 4'b1111;
-		end else if(state == WAIT && !avl_waitrequest) begin
-			state <= IDLE;
-			avl_read <= 0;
-			avl_write <= 0;
+			assign avl_lock = 0;
+			assign avl_read = 0;
+			assign avl_write = 0;
 		end
+	endgenerate
 
 endmodule
-- 
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