-- syscon module, a bunch of misc global system control MMIO registers
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library work;
use work.wishbone_types.all;
entity syscon is
generic (
SIG_VALUE : std_ulogic_vector(63 downto 0) := x"f00daa5500010001";
CLK_FREQ : integer;
HAS_UART : boolean;
HAS_DRAM : boolean;
BRAM_SIZE : integer;
DRAM_SIZE : integer;
DRAM_INIT_SIZE : integer;
HAS_SPI_FLASH : boolean;
SPI_FLASH_OFFSET : integer
);
port (
clk : in std_ulogic;
rst : in std_ulogic;
-- Wishbone ports:
wishbone_in : in wb_io_master_out;
wishbone_out : out wb_io_slave_out;
-- System control ports
dram_at_0 : out std_ulogic;
core_reset : out std_ulogic;
soc_reset : out std_ulogic
);
end entity syscon;
architecture behaviour of syscon is
-- Register address bits
constant SYS_REG_BITS : positive := 3;
-- Register addresses (matches wishbone addr downto 3, ie, 8 bytes per reg)
constant SYS_REG_SIG : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "000";
constant SYS_REG_INFO : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "001";
constant SYS_REG_BRAMINFO : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "010";
constant SYS_REG_DRAMINFO : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "011";
constant SYS_REG_CLKINFO : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "100";
constant SYS_REG_CTRL : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "101";
constant SYS_REG_DRAMINITINFO : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "110";
constant SYS_REG_SPIFLASHINFO : std_ulogic_vector(SYS_REG_BITS-1 downto 0) := "111";
-- Muxed reg read signal
signal reg_out : std_ulogic_vector(63 downto 0);
-- INFO register bits
constant SYS_REG_INFO_HAS_UART : integer := 0;
constant SYS_REG_INFO_HAS_DRAM : integer := 1;
constant SYS_REG_INFO_HAS_BRAM : integer := 2;
constant SYS_REG_INFO_HAS_SPIF : integer := 3;
-- BRAMINFO contains the BRAM size in the bottom 52 bits
-- DRAMINFO contains the DRAM size if any in the bottom 52 bits
-- (both have reserved top bits for future use)
-- CLKINFO contains the CLK frequency is HZ in the bottom 40 bits
-- CTRL register bits
constant SYS_REG_CTRL_BITS : positive := 3;
constant SYS_REG_CTRL_DRAM_AT_0 : integer := 0;
constant SYS_REG_CTRL_CORE_RESET : integer := 1;
constant SYS_REG_CTRL_SOC_RESET : integer := 2;
-- SPI Info register bits
--
-- Top 32-bit is flash offset which is the amount of flash
-- reserved for the FPGA bitfile if any
constant SYS_REG_SPI_INFO_IS_FLASH : integer := 0;
-- Ctrl register
signal reg_ctrl : std_ulogic_vector(SYS_REG_CTRL_BITS-1 downto 0);
signal reg_ctrl_out : std_ulogic_vector(63 downto 0);
-- Others
signal reg_info : std_ulogic_vector(63 downto 0);
signal reg_braminfo : std_ulogic_vector(63 downto 0);
signal reg_draminfo : std_ulogic_vector(63 downto 0);
signal reg_dramiinfo : std_ulogic_vector(63 downto 0);
signal reg_clkinfo : std_ulogic_vector(63 downto 0);
signal reg_spiinfo : std_ulogic_vector(63 downto 0);
signal info_has_dram : std_ulogic;
signal info_has_bram : std_ulogic;
signal info_has_uart : std_ulogic;
signal info_has_spif : std_ulogic;
signal info_clk : std_ulogic_vector(39 downto 0);
signal info_fl_off : std_ulogic_vector(31 downto 0);
-- Wishbone response latch
signal wb_rsp : wb_io_slave_out;
begin
-- Generated output signals
dram_at_0 <= '1' when BRAM_SIZE = 0 else reg_ctrl(SYS_REG_CTRL_DRAM_AT_0);
soc_reset <= reg_ctrl(SYS_REG_CTRL_SOC_RESET);
core_reset <= reg_ctrl(SYS_REG_CTRL_CORE_RESET);
-- Info register is hard wired
info_has_uart <= '1' when HAS_UART else '0';
info_has_dram <= '1' when HAS_DRAM else '0';
info_has_bram <= '1' when BRAM_SIZE /= 0 else '0';
info_has_spif <= '1' when HAS_SPI_FLASH else '0';
info_clk <= std_ulogic_vector(to_unsigned(CLK_FREQ, 40));
reg_info <= (SYS_REG_INFO_HAS_UART => info_has_uart,
SYS_REG_INFO_HAS_DRAM => info_has_dram,
SYS_REG_INFO_HAS_BRAM => info_has_bram,
SYS_REG_INFO_HAS_SPIF => info_has_spif,
others => '0');
reg_braminfo <= x"000" & std_ulogic_vector(to_unsigned(BRAM_SIZE, 52));
reg_draminfo <= x"000" & std_ulogic_vector(to_unsigned(DRAM_SIZE, 52)) when HAS_DRAM
else (others => '0');
reg_dramiinfo <= x"000" & std_ulogic_vector(to_unsigned(DRAM_INIT_SIZE, 52)) when HAS_DRAM
else (others => '0');
reg_clkinfo <= (39 downto 0 => info_clk,
others => '0');
info_fl_off <= std_ulogic_vector(to_unsigned(SPI_FLASH_OFFSET, 32));
reg_spiinfo <= (31 downto 0 => info_fl_off,
others => '0');
-- Control register read composition
reg_ctrl_out <= (63 downto SYS_REG_CTRL_BITS => '0',
SYS_REG_CTRL_BITS-1 downto 0 => reg_ctrl);
-- Wishbone response
wb_rsp.ack <= wishbone_in.cyc and wishbone_in.stb;
with wishbone_in.adr(SYS_REG_BITS+2 downto 3) select reg_out <=
SIG_VALUE when SYS_REG_SIG,
reg_info when SYS_REG_INFO,
reg_braminfo when SYS_REG_BRAMINFO,
reg_draminfo when SYS_REG_DRAMINFO,
reg_dramiinfo when SYS_REG_DRAMINITINFO,
reg_clkinfo when SYS_REG_CLKINFO,
reg_ctrl_out when SYS_REG_CTRL,
reg_spiinfo when SYS_REG_SPIFLASHINFO,
(others => '0') when others;
wb_rsp.dat <= reg_out(63 downto 32) when wishbone_in.adr(2) = '1' else
reg_out(31 downto 0);
wb_rsp.stall <= '0';
-- Wishbone response latch
regs_read: process(clk)
begin
if rising_edge(clk) then
-- Send response from latch
wishbone_out <= wb_rsp;
end if;
end process;
-- Register writes
regs_write: process(clk)
begin
if rising_edge(clk) then
if (rst) then
reg_ctrl <= (others => '0');
else
if wishbone_in.cyc and wishbone_in.stb and wishbone_in.we then
-- Change this if CTRL ever has more than 32 bits
if wishbone_in.adr(SYS_REG_BITS+2 downto 3) = SYS_REG_CTRL and
wishbone_in.adr(2) = '0' then
reg_ctrl(SYS_REG_CTRL_BITS-1 downto 0) <=
wishbone_in.dat(SYS_REG_CTRL_BITS-1 downto 0);
end if;
end if;
-- Reset auto-clear
if reg_ctrl(SYS_REG_CTRL_SOC_RESET) = '1' then
reg_ctrl(SYS_REG_CTRL_SOC_RESET) <= '0';
end if;
if reg_ctrl(SYS_REG_CTRL_CORE_RESET) = '1' then
reg_ctrl(SYS_REG_CTRL_CORE_RESET) <= '0';
end if;
-- If BRAM doesn't exist, force DRAM at 0
if BRAM_SIZE = 0 then
reg_ctrl(SYS_REG_CTRL_DRAM_AT_0) <= '1';
end if;
end if;
end if;
end process;
end architecture behaviour;