platform: implement support for disabling CPUs

2 files changed, 111 insertions, 62 deletions

diff --git a/rtl/core/bus_master.sv b/rtl/core/bus_master.sv
new file mode 100644
index 0000000..39c4893
--- /dev/null
+++ b/rtl/core/bus_master.sv
@@ -0,0 +1,74 @@
+`include "core/uarch.sv"
+
+module bus_master
+(
+	input  logic      clk,
+	                  rst_n,
+
+	output word       avl_address,
+	output logic      avl_read,
+	                  avl_write,
+	                  avl_lock,
+	input  word       avl_readdata,
+	output word       avl_writedata,
+	input  logic      avl_waitrequest,
+	input  logic[1:0] avl_response,
+	output logic[3:0] avl_byteenable,
+
+	input  logic      start,
+	                  write,
+	                  ex_lock,
+	input  ptr        addr,
+	input  logic[3:0] data_be,
+	input  word       data_wr,
+	output logic      ready,
+	                  ex_fail,
+	output word       data_rd
+);
+
+	enum int unsigned
+	{
+		IDLE,
+		WAIT
+	} state;
+
+	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;
+		end
+
+endmodule
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