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microwatt/fpga/top-nexys-video.vhdl

310 lines
8.7 KiB
VHDL

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library unisim;
use unisim.vcomponents.all;
library work;
use work.wishbone_types.all;
entity toplevel is
generic (
MEMORY_SIZE : integer := 16384;
RAM_INIT_FILE : string := "firmware.hex";
RESET_LOW : boolean := true;
CLK_FREQUENCY : positive := 100000000;
HAS_FPU : boolean := true;
fetch1: Implement a simple branch target cache This implements a cache in fetch1, where each entry stores the address of a simple branch instruction (b or bc) and the target of the branch. When fetching sequentially, if the address being fetched matches the cache entry, then fetching will be redirected to the branch target. The cache has 1024 entries and is direct-mapped, i.e. indexed by bits 11..2 of the NIA. The bus from execute1 now carries information about taken and not-taken simple branches, which fetch1 uses to update the cache. The cache entry is updated for both taken and not-taken branches, with the valid bit being set if the branch was taken and cleared if the branch was not taken. If fetching is redirected to the branch target then that goes down the pipe as a predicted-taken branch, and decode1 does not do any static branch prediction. If fetching is not redirected, then the next instruction goes down the pipe as normal and decode1 does its static branch prediction. In order to make timing, the lookup of the cache is pipelined, so on each cycle the cache entry for the current NIA + 8 is read. This means that after a redirect (from decode1 or execute1), only the third and subsequent sequentially-fetched instructions will be able to be predicted. This improves the coremark value on the Arty A7-100 from about 180 to about 190 (more than 5%). The BTC is optional. Builds for the Artix 7 35-T part have it off by default because the extra ~1420 LUTs it takes mean that the design doesn't fit on the Arty A7-35 board. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
HAS_BTC : boolean := true;
USE_LITEDRAM : boolean := false;
NO_BRAM : boolean := false;
DISABLE_FLATTEN_CORE : boolean := false;
SPI_FLASH_OFFSET : integer := 10485760;
SPI_FLASH_DEF_CKDV : natural := 1;
SPI_FLASH_DEF_QUAD : boolean := true;
LOG_LENGTH : natural := 2048;
UART_IS_16550 : boolean := true
);
port(
ext_clk : in std_ulogic;
ext_rst : in std_ulogic;
-- UART0 signals:
uart_main_tx : out std_ulogic;
uart_main_rx : in std_ulogic;
-- LEDs
led0 : out std_logic;
led1 : out std_logic;
-- SPI
spi_flash_cs_n : out std_ulogic;
spi_flash_mosi : inout std_ulogic;
spi_flash_miso : inout std_ulogic;
spi_flash_wp_n : inout std_ulogic;
spi_flash_hold_n : inout std_ulogic;
-- DRAM wires
ddram_a : out std_logic_vector(14 downto 0);
ddram_ba : out std_logic_vector(2 downto 0);
ddram_ras_n : out std_logic;
ddram_cas_n : out std_logic;
ddram_we_n : out std_logic;
ddram_dm : out std_logic_vector(1 downto 0);
ddram_dq : inout std_logic_vector(15 downto 0);
ddram_dqs_p : inout std_logic_vector(1 downto 0);
ddram_dqs_n : inout std_logic_vector(1 downto 0);
ddram_clk_p : out std_logic;
ddram_clk_n : out std_logic;
ddram_cke : out std_logic;
ddram_odt : out std_logic;
ddram_reset_n : out std_logic
);
end entity toplevel;
architecture behaviour of toplevel is
-- Reset signals:
signal soc_rst : std_ulogic;
signal pll_rst : std_ulogic;
-- Internal clock signals:
signal system_clk : std_ulogic;
signal system_clk_locked : std_ulogic;
-- DRAM main data wishbone connection
signal wb_dram_in : wishbone_master_out;
signal wb_dram_out : wishbone_slave_out;
-- DRAM control wishbone connection
signal wb_ext_io_in : wb_io_master_out;
signal wb_ext_io_out : wb_io_slave_out;
signal wb_ext_is_dram_csr : std_ulogic;
signal wb_ext_is_dram_init : std_ulogic;
-- Control/status
signal core_alt_reset : std_ulogic;
-- SPI flash
signal spi_sck : std_ulogic;
signal spi_cs_n : std_ulogic;
signal spi_sdat_o : std_ulogic_vector(3 downto 0);
signal spi_sdat_oe : std_ulogic_vector(3 downto 0);
signal spi_sdat_i : std_ulogic_vector(3 downto 0);
-- Fixup various memory sizes based on generics
function get_bram_size return natural is
begin
if USE_LITEDRAM and NO_BRAM then
return 0;
else
return MEMORY_SIZE;
end if;
end function;
function get_payload_size return natural is
begin
if USE_LITEDRAM and NO_BRAM then
return MEMORY_SIZE;
else
return 0;
end if;
end function;
constant BRAM_SIZE : natural := get_bram_size;
constant PAYLOAD_SIZE : natural := get_payload_size;
begin
-- Main SoC
soc0: entity work.soc
generic map(
MEMORY_SIZE => BRAM_SIZE,
RAM_INIT_FILE => RAM_INIT_FILE,
SIM => false,
CLK_FREQ => CLK_FREQUENCY,
HAS_FPU => HAS_FPU,
fetch1: Implement a simple branch target cache This implements a cache in fetch1, where each entry stores the address of a simple branch instruction (b or bc) and the target of the branch. When fetching sequentially, if the address being fetched matches the cache entry, then fetching will be redirected to the branch target. The cache has 1024 entries and is direct-mapped, i.e. indexed by bits 11..2 of the NIA. The bus from execute1 now carries information about taken and not-taken simple branches, which fetch1 uses to update the cache. The cache entry is updated for both taken and not-taken branches, with the valid bit being set if the branch was taken and cleared if the branch was not taken. If fetching is redirected to the branch target then that goes down the pipe as a predicted-taken branch, and decode1 does not do any static branch prediction. If fetching is not redirected, then the next instruction goes down the pipe as normal and decode1 does its static branch prediction. In order to make timing, the lookup of the cache is pipelined, so on each cycle the cache entry for the current NIA + 8 is read. This means that after a redirect (from decode1 or execute1), only the third and subsequent sequentially-fetched instructions will be able to be predicted. This improves the coremark value on the Arty A7-100 from about 180 to about 190 (more than 5%). The BTC is optional. Builds for the Artix 7 35-T part have it off by default because the extra ~1420 LUTs it takes mean that the design doesn't fit on the Arty A7-35 board. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
HAS_BTC => HAS_BTC,
HAS_DRAM => USE_LITEDRAM,
DRAM_SIZE => 512 * 1024 * 1024,
DRAM_INIT_SIZE => PAYLOAD_SIZE,
DISABLE_FLATTEN_CORE => DISABLE_FLATTEN_CORE,
HAS_SPI_FLASH => true,
SPI_FLASH_DLINES => 4,
SPI_FLASH_OFFSET => SPI_FLASH_OFFSET,
SPI_FLASH_DEF_CKDV => SPI_FLASH_DEF_CKDV,
SPI_FLASH_DEF_QUAD => SPI_FLASH_DEF_QUAD,
LOG_LENGTH => LOG_LENGTH,
UART0_IS_16550 => UART_IS_16550
)
port map (
-- System signals
system_clk => system_clk,
rst => soc_rst,
-- UART signals
uart0_txd => uart_main_tx,
uart0_rxd => uart_main_rx,
-- SPI signals
spi_flash_sck => spi_sck,
spi_flash_cs_n => spi_cs_n,
spi_flash_sdat_o => spi_sdat_o,
spi_flash_sdat_oe => spi_sdat_oe,
spi_flash_sdat_i => spi_sdat_i,
-- DRAM wishbone
wb_dram_in => wb_dram_in,
wb_dram_out => wb_dram_out,
wb_ext_io_in => wb_ext_io_in,
wb_ext_io_out => wb_ext_io_out,
wb_ext_is_dram_csr => wb_ext_is_dram_csr,
wb_ext_is_dram_init => wb_ext_is_dram_init,
alt_reset => core_alt_reset
);
-- SPI Flash. The SPI clk needs to be fed through the STARTUPE2
-- primitive of the FPGA as it's not a normal pin
--
spi_flash_cs_n <= spi_cs_n;
spi_flash_mosi <= spi_sdat_o(0) when spi_sdat_oe(0) = '1' else 'Z';
spi_flash_miso <= spi_sdat_o(1) when spi_sdat_oe(1) = '1' else 'Z';
spi_flash_wp_n <= spi_sdat_o(2) when spi_sdat_oe(2) = '1' else 'Z';
spi_flash_hold_n <= spi_sdat_o(3) when spi_sdat_oe(3) = '1' else 'Z';
spi_sdat_i(0) <= spi_flash_mosi;
spi_sdat_i(1) <= spi_flash_miso;
spi_sdat_i(2) <= spi_flash_wp_n;
spi_sdat_i(3) <= spi_flash_hold_n;
STARTUPE2_INST: STARTUPE2
port map (
CLK => '0',
GSR => '0',
GTS => '0',
KEYCLEARB => '0',
PACK => '0',
USRCCLKO => spi_sck,
USRCCLKTS => '0',
USRDONEO => '1',
USRDONETS => '0'
);
nodram: if not USE_LITEDRAM generate
signal ddram_clk_dummy : 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,
rst_out => soc_rst
);
clkgen: entity work.clock_generator
generic map(
CLK_INPUT_HZ => 100000000,
CLK_OUTPUT_HZ => CLK_FREQUENCY
)
port map(
ext_clk => ext_clk,
pll_rst_in => pll_rst,
pll_clk_out => system_clk,
pll_locked_out => system_clk_locked
);
led0 <= '1';
led1 <= not soc_rst;
core_alt_reset <= '0';
-- Vivado barfs on those differential signals if left
-- unconnected. So instanciate a diff. buffer and feed
-- it a constant '0'.
dummy_dram_clk: OBUFDS
port map (
O => ddram_clk_p,
OB => ddram_clk_n,
I => ddram_clk_dummy
);
ddram_clk_dummy <= '0';
end generate;
has_dram: if USE_LITEDRAM generate
signal dram_init_done : std_ulogic;
signal dram_init_error : std_ulogic;
signal dram_sys_rst : std_ulogic;
begin
-- Eventually dig out the frequency from the generator
-- but for now, assert it's 100Mhz
assert CLK_FREQUENCY = 100000000;
reset_controller: entity work.soc_reset
generic map(
RESET_LOW => RESET_LOW,
PLL_RESET_BITS => 18,
SOC_RESET_BITS => 1
)
port map(
ext_clk => ext_clk,
pll_clk => system_clk,
pll_locked_in => '1',
ext_rst_in => ext_rst,
pll_rst_out => pll_rst,
rst_out => open
);
dram: entity work.litedram_wrapper
generic map(
DRAM_ABITS => 25,
DRAM_ALINES => 15,
DRAM_DLINES => 16,
DRAM_PORT_WIDTH => 128,
PAYLOAD_FILE => RAM_INIT_FILE,
PAYLOAD_SIZE => PAYLOAD_SIZE
)
port map(
clk_in => ext_clk,
rst => pll_rst,
system_clk => system_clk,
system_reset => soc_rst,
core_alt_reset => core_alt_reset,
pll_locked => system_clk_locked,
wb_in => wb_dram_in,
wb_out => wb_dram_out,
wb_ctrl_in => wb_ext_io_in,
wb_ctrl_out => wb_ext_io_out,
wb_ctrl_is_csr => wb_ext_is_dram_csr,
wb_ctrl_is_init => wb_ext_is_dram_init,
init_done => dram_init_done,
init_error => dram_init_error,
ddram_a => ddram_a,
ddram_ba => ddram_ba,
ddram_ras_n => ddram_ras_n,
ddram_cas_n => ddram_cas_n,
ddram_we_n => ddram_we_n,
ddram_cs_n => open,
ddram_dm => ddram_dm,
ddram_dq => ddram_dq,
ddram_dqs_p => ddram_dqs_p,
ddram_dqs_n => ddram_dqs_n,
ddram_clk_p => ddram_clk_p,
ddram_clk_n => ddram_clk_n,
ddram_cke => ddram_cke,
ddram_odt => ddram_odt,
ddram_reset_n => ddram_reset_n
);
led0 <= dram_init_done and not dram_init_error;
led1 <= dram_init_error; -- Make it blink ?
end generate;
end architecture behaviour;