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microwatt/fpga/toplevel.vhd

220 lines
6.6 KiB
VHDL

-- 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;
library work;
use work.wishbone_types.all;
-- 0x00000000: Main memory (1 MB)
-- 0xc0002000: UART0 (for host communication)
entity toplevel is
generic (
MEMORY_SIZE : positive := 524288;
RAM_INIT_FILE : string := "firmware.hex");
port(
clk : in std_logic;
reset_n : 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:
signal reset : std_logic;
-- Internal clock signals:
signal system_clk : std_logic;
signal timer_clk : std_logic;
signal system_clk_locked : std_logic;
-- wishbone signals:
signal wishbone_proc_out: wishbone_master_out;
signal wishbone_proc_in: wishbone_slave_out;
-- Processor signals:
signal processor_adr_out : std_logic_vector(63 downto 0);
signal processor_sel_out : std_logic_vector(7 downto 0);
signal processor_cyc_out : std_logic;
signal processor_stb_out : std_logic;
signal processor_we_out : std_logic;
signal processor_dat_out : std_logic_vector(63 downto 0);
signal processor_dat_in : std_logic_vector(63 downto 0);
signal processor_ack_in : std_logic;
-- UART0 signals:
signal uart0_adr_in : std_logic_vector(11 downto 0);
signal uart0_dat_in : std_logic_vector( 7 downto 0);
signal uart0_dat_out : std_logic_vector( 7 downto 0);
signal uart0_cyc_in : std_logic;
signal uart0_stb_in : std_logic;
signal uart0_we_in : std_logic;
signal uart0_ack_out : std_logic;
-- Main memory signals:
signal main_memory_adr_in : std_logic_vector(positive(ceil(log2(real(MEMORY_SIZE))))-1 downto 0);
signal main_memory_dat_in : std_logic_vector(63 downto 0);
signal main_memory_dat_out : std_logic_vector(63 downto 0);
signal main_memory_cyc_in : std_logic;
signal main_memory_stb_in : std_logic;
signal main_memory_sel_in : std_logic_vector(7 downto 0);
signal main_memory_we_in : std_logic;
signal main_memory_ack_out : std_logic;
-- Selected peripheral on the interconnect:
type intercon_peripheral_type is (
PERIPHERAL_UART0, PERIPHERAL_MAIN_MEMORY, PERIPHERAL_ERROR,
PERIPHERAL_NONE);
signal intercon_peripheral : intercon_peripheral_type := PERIPHERAL_NONE;
-- 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)
begin
if rising_edge(system_clk) then
if reset = '1' then
intercon_peripheral <= PERIPHERAL_NONE;
intercon_busy <= false;
else
if not intercon_busy then
if processor_cyc_out = '1' then
intercon_busy <= true;
if processor_adr_out(31 downto 24) = x"00" then -- Main memory space
intercon_peripheral <= PERIPHERAL_MAIN_MEMORY;
elsif processor_adr_out(31 downto 24) = x"c0" then -- Peripheral memory space
case processor_adr_out(15 downto 12) is
when x"2" =>
intercon_peripheral <= PERIPHERAL_UART0;
when others => -- Invalid address - delegated to the error peripheral
intercon_peripheral <= PERIPHERAL_ERROR;
end case;
else
intercon_peripheral <= PERIPHERAL_ERROR;
end if;
else
intercon_peripheral <= PERIPHERAL_NONE;
end if;
else
if processor_cyc_out = '0' then
intercon_busy <= false;
intercon_peripheral <= PERIPHERAL_NONE;
end if;
end if;
end if;
end if;
end process address_decoder;
processor_intercon: process(all)
begin
case intercon_peripheral is
when PERIPHERAL_UART0 =>
processor_ack_in <= uart0_ack_out;
processor_dat_in <= x"00000000000000" & uart0_dat_out;
when PERIPHERAL_MAIN_MEMORY =>
processor_ack_in <= main_memory_ack_out;
processor_dat_in <= main_memory_dat_out;
when PERIPHERAL_NONE =>
processor_ack_in <= '0';
processor_dat_in <= (others => '0');
when others =>
processor_ack_in <= '0';
processor_dat_in <= (others => '0');
end case;
end process processor_intercon;
reset_controller: entity work.pp_soc_reset
port map(
clk => system_clk,
reset_n => reset_n,
reset_out => reset,
system_clk => system_clk,
system_clk_locked => system_clk_locked
);
clkgen: entity work.clock_generator
port map(
clk => clk,
resetn => reset_n,
system_clk => system_clk,
locked => system_clk_locked
);
processor: entity work.core
port map(
clk => system_clk,
rst => reset,
wishbone_out => wishbone_proc_out,
wishbone_in => wishbone_proc_in
);
processor_adr_out <= wishbone_proc_out.adr;
processor_dat_out <= wishbone_proc_out.dat;
processor_sel_out <= wishbone_proc_out.sel;
processor_cyc_out <= wishbone_proc_out.cyc;
processor_stb_out <= wishbone_proc_out.stb;
processor_we_out <= wishbone_proc_out.we;
wishbone_proc_in.dat <= processor_dat_in;
wishbone_proc_in.ack <= processor_ack_in;
uart0: entity work.pp_soc_uart
generic map(
FIFO_DEPTH => 32
) port map(
clk => system_clk,
reset => reset,
txd => uart0_txd,
rxd => uart0_rxd,
wb_adr_in => uart0_adr_in,
wb_dat_in => uart0_dat_in,
wb_dat_out => uart0_dat_out,
wb_cyc_in => uart0_cyc_in,
wb_stb_in => uart0_stb_in,
wb_we_in => uart0_we_in,
wb_ack_out => uart0_ack_out
);
uart0_adr_in <= processor_adr_out(uart0_adr_in'range);
uart0_dat_in <= processor_dat_out(7 downto 0);
uart0_we_in <= processor_we_out;
uart0_cyc_in <= processor_cyc_out when intercon_peripheral = PERIPHERAL_UART0 else '0';
uart0_stb_in <= processor_stb_out when intercon_peripheral = PERIPHERAL_UART0 else '0';
main_memory: entity work.pp_soc_memory
generic map(
MEMORY_SIZE => MEMORY_SIZE,
RAM_INIT_FILE => RAM_INIT_FILE
) port map(
clk => system_clk,
reset => reset,
wb_adr_in => main_memory_adr_in,
wb_dat_in => main_memory_dat_in,
wb_dat_out => main_memory_dat_out,
wb_cyc_in => main_memory_cyc_in,
wb_stb_in => main_memory_stb_in,
wb_sel_in => main_memory_sel_in,
wb_we_in => main_memory_we_in,
wb_ack_out => main_memory_ack_out
);
main_memory_adr_in <= processor_adr_out(main_memory_adr_in'range);
main_memory_dat_in <= processor_dat_out;
main_memory_we_in <= processor_we_out;
main_memory_sel_in <= processor_sel_out;
main_memory_cyc_in <= processor_cyc_out when intercon_peripheral = PERIPHERAL_MAIN_MEMORY else '0';
main_memory_stb_in <= processor_stb_out when intercon_peripheral = PERIPHERAL_MAIN_MEMORY else '0';
end architecture behaviour;