Split FPGA toplevel from soc

This will be useful when we start needing different toplevels for
different boards.

We keep the reset and clock generators in the toplevel as they will
eventually be taken over by litedram when we integrate it, and they
are more likely to change on different system types.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

fpga/soc.vhdl

@@ -1,6 +1,3 @@
--- The Potato Processor - SoC design for the Arty FPGA board
--- (c) Kristian Klomsten Skordal 2016 <kristian.skordal@wafflemail.net>
-
 library ieee;
 use ieee.std_logic_1164.all;
 use ieee.math_real.all;
@@ -11,31 +8,23 @@ use work.wishbone_types.all;
 
 -- 0x00000000: Main memory (1 MB)
 -- 0xc0002000: UART0 (for host communication)
-entity toplevel is
+entity soc is
 	generic (
-		MEMORY_SIZE   : positive := 524288;
+	    MEMORY_SIZE   : positive;
-		RAM_INIT_FILE : string   := "firmware.hex";
+	    RAM_INIT_FILE : string;
-		RESET_LOW : boolean := true
+	    RESET_LOW     : boolean
 	);
 	port(
-		ext_clk   : in  std_logic;
+	    rst          : in  std_ulogic;
-		ext_rst   : in  std_logic;
+	    system_clk   : in  std_logic;
-		
-		-- UART0 signals:
-		uart0_txd : out std_logic;
-		uart0_rxd : in  std_logic
-	);
-end entity toplevel;
-
-architecture behaviour of toplevel is
 
-	-- Reset signals:
+	    -- UART0 signals:
-	signal rst : std_ulogic;
+	    uart0_txd    : out std_logic;
-	signal pll_rst_n : std_ulogic;
+	    uart0_rxd    : in  std_logic
+	);
+end entity soc;
 
-	-- Internal clock signals:
+architecture behaviour of soc is
-	signal system_clk : std_ulogic;
-	signal system_clk_locked : std_ulogic;
 
 	-- wishbone signals:
 	signal wishbone_proc_out: wishbone_master_out;
@@ -79,13 +68,9 @@ architecture behaviour of toplevel is
 	-- Interconnect address decoder state:
 	signal intercon_busy : boolean := false;
 
-	-- disable for now
-	signal gpio_pins : std_logic_vector(11 downto 0);
-	signal uart1_txd : std_logic;
-	signal uart1_rxd : std_logic;
 begin
 
-	address_decoder: process(system_clk)
+    address_decoder: process(system_clk)
 	begin
 		if rising_edge(system_clk) then
 			if rst = '1' then
@@ -139,27 +124,6 @@ begin
 		end case;
 	end process processor_intercon;
 
-	reset_controller: entity work.soc_reset
-		generic map(
-			RESET_LOW => RESET_LOW
-		)
-		port map(
-			ext_clk => ext_clk,
-			pll_clk => system_clk,
-			pll_locked_in => system_clk_locked,
-			ext_rst_in => ext_rst,
-			pll_rst_out => pll_rst_n,
-			rst_out => rst
-		);
-
-	clkgen: entity work.clock_generator
-		port map(
-			ext_clk => ext_clk,
-			pll_rst_in => pll_rst_n,
-			pll_clk_out => system_clk,
-			pll_locked_out => system_clk_locked
-		);
-
 	processor: entity work.core
 		port map(
 			clk => system_clk,

fpga/toplevel.vhdl

@@ -0,0 +1,67 @@
+library ieee;
+use ieee.std_logic_1164.all;
+
+entity toplevel is
+    generic (
+	MEMORY_SIZE   : positive := 524288;
+	RAM_INIT_FILE : string   := "firmware.hex";
+	RESET_LOW     : boolean := true
+	);
+    port(
+	ext_clk   : in  std_ulogic;
+	ext_rst   : in  std_ulogic;
+
+	-- UART0 signals:
+	uart0_txd : out std_ulogic;
+	uart0_rxd : in  std_ulogic
+	);
+end entity toplevel;
+
+architecture behaviour of toplevel is
+
+    -- Reset signals:
+    signal soc_rst : std_ulogic;
+    signal pll_rst_n : std_ulogic;
+
+    -- Internal clock signals:
+    signal system_clk : std_ulogic;
+    signal system_clk_locked : std_ulogic;
+
+begin
+
+    reset_controller: entity work.soc_reset
+	generic map(
+	    RESET_LOW => RESET_LOW
+	    )
+	port map(
+	    ext_clk => ext_clk,
+	    pll_clk => system_clk,
+	    pll_locked_in => system_clk_locked,
+	    ext_rst_in => ext_rst,
+	    pll_rst_out => pll_rst_n,
+	    rst_out => soc_rst
+	    );
+
+    clkgen: entity work.clock_generator
+	port map(
+	    ext_clk => ext_clk,
+	    pll_rst_in => pll_rst_n,
+	    pll_clk_out => system_clk,
+	    pll_locked_out => system_clk_locked
+	    );
+
+    -- Main SoC
+    soc0: entity work.soc
+	generic map(
+	    MEMORY_SIZE   => MEMORY_SIZE,
+	    RAM_INIT_FILE => RAM_INIT_FILE,
+	    RESET_LOW     => RESET_LOW
+	    )
+	port map (
+	    system_clk        => system_clk,
+	    rst               => soc_rst,
+	    uart0_txd         => uart0_txd,
+	    uart0_rxd         => uart0_rxd
+	    );
+
+end architecture behaviour;

microwatt.core

@@ -36,7 +36,8 @@ filesets:
       - fpga/soc_reset.vhdl
       - fpga/pp_soc_uart.vhd
       - fpga/pp_utilities.vhd
-      - fpga/toplevel.vhd
+      - fpga/soc.vhdl
+      - fpga/toplevel.vhdl
       - fpga/firmware.hex : {copyto : firmware.hex, file_type : user}
     file_type : vhdlSource-2008