cores
/
microwatt
mirror of https://github.com/antonblanchard/microwatt
3
1
Fork 1
Code Issues Projects Releases Wiki Activity
Browse Source

dmi_dtm_ecp5: Use ECP5 JTAGG for DMI 

This uses the JTAGG primitive which is similar to BSCANE2.
The LUT4 delay approach came from Florian and Greg in
https://github.com/enjoy-digital/litex/pull/1087

Has been tested on an OrangeCrab with 48MHz sysclk
FT232H up to 30MHz (though libusb/urjtag is by far the bottleneck vs
the JTAG clock)

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
pull/346/head
Matt Johnston 1 year ago
parent
eb20195a10
commit
3775650df3
2 changed files with 299 additions and 0 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 1
      Makefile
  2. 298
      dmi_dtm_ecp5.vhdl

1
Makefile
Unescape View File

@ -192,6 +192,7 @@ ECP_FLASH_OFFSET=0x80000 @@ -192,6 +192,7 @@ ECP_FLASH_OFFSET=0x80000
toplevel=fpga/top-orangecrab0.2.vhdl
litedram_target=orangecrab-85-0.2
soc_extra_v += litesdcard/generated/lattice/litesdcard_core.v
dmi_dtm=dmi_dtm_ecp5.vhdl
endif

# ECP5-EVN

298
dmi_dtm_ecp5.vhdl
Unescape View File

@ -0,0 +1,298 @@ @@ -0,0 +1,298 @@
library ieee;
use ieee.std_logic_1164.all;
use ieee.math_real.all;

library work;
use work.wishbone_types.all;

entity dmi_dtm is
generic(ABITS : INTEGER:=8;
DBITS : INTEGER:=64);

port(sys_clk : in std_ulogic;
sys_reset : in std_ulogic;
dmi_addr : out std_ulogic_vector(ABITS - 1 downto 0);
dmi_din : in std_ulogic_vector(DBITS - 1 downto 0);
dmi_dout : out std_ulogic_vector(DBITS - 1 downto 0);
dmi_req : out std_ulogic;
dmi_wr : out std_ulogic;
dmi_ack : in std_ulogic
-- dmi_err : in std_ulogic TODO: Add error response
);
end entity dmi_dtm;

architecture behaviour of dmi_dtm is
-- Signals coming out of the JTAGG block
signal jtag_reset_n : std_ulogic;
signal tdi : std_ulogic;
signal tdo : std_ulogic;
signal tck : std_ulogic;
signal jce1 : std_ulogic;
signal jshift : std_ulogic;
signal update : std_ulogic;

-- signals to match dmi_dtb_xilinx
signal jtag_reset : std_ulogic;
signal capture : std_ulogic;
signal jtag_clk : std_ulogic;
signal sel : std_ulogic;
signal shift : std_ulogic;

-- delays
signal jce1_d : std_ulogic;
constant TCK_DELAY : INTEGER := 8;
signal tck_d : std_ulogic_vector(TCK_DELAY+1 downto 1);

-- ** JTAG clock domain **

-- Shift register
signal shiftr : std_ulogic_vector(ABITS + DBITS + 1 downto 0);

-- Latched request
signal request : std_ulogic_vector(ABITS + DBITS + 1 downto 0);

-- A request is present
signal jtag_req : std_ulogic;

-- Synchronizer for jtag_rsp (sys clk -> jtag_clk)
signal dmi_ack_0 : std_ulogic;
signal dmi_ack_1 : std_ulogic;

-- ** sys clock domain **

-- Synchronizer for jtag_req (jtag clk -> sys clk)
signal jtag_req_0 : std_ulogic;
signal jtag_req_1 : std_ulogic;

-- ** combination signals
signal jtag_bsy : std_ulogic;
signal op_valid : std_ulogic;
signal rsp_op : std_ulogic_vector(1 downto 0);

-- ** Constants **
constant DMI_REQ_NOP : std_ulogic_vector(1 downto 0) := "00";
constant DMI_REQ_RD : std_ulogic_vector(1 downto 0) := "01";
constant DMI_REQ_WR : std_ulogic_vector(1 downto 0) := "10";
constant DMI_RSP_OK : std_ulogic_vector(1 downto 0) := "00";
constant DMI_RSP_BSY : std_ulogic_vector(1 downto 0) := "11";

attribute ASYNC_REG : string;
attribute ASYNC_REG of jtag_req_0: signal is "TRUE";
attribute ASYNC_REG of jtag_req_1: signal is "TRUE";
attribute ASYNC_REG of dmi_ack_0: signal is "TRUE";
attribute ASYNC_REG of dmi_ack_1: signal is "TRUE";

-- ECP5 JTAGG
component JTAGG is
generic (
ER1 : string := "ENABLED";
ER2 : string := "ENABLED"
);
port(
JTDO1 : in std_ulogic;
JTDO2 : in std_ulogic;
JTDI : out std_ulogic;
JTCK : out std_ulogic;
JRTI1 : out std_ulogic;
JRTI2 : out std_ulogic;
JSHIFT : out std_ulogic;
JUPDATE : out std_ulogic;
JRSTN : out std_ulogic;
JCE1 : out std_ulogic;
JCE2 : out std_ulogic
);
end component;

component LUT4 is
generic (
INIT : std_logic_vector
);
port(
A : in STD_ULOGIC;
B : in STD_ULOGIC;
C : in STD_ULOGIC;
D : in STD_ULOGIC;
Z : out STD_ULOGIC
);
end component;

begin

jtag: JTAGG
generic map(
ER2 => "DISABLED"
)
port map (
JTDO1 => tdo,
JTDO2 => '0',
JTDI => tdi,
JTCK => tck,
JRTI1 => open,
JRTI2 => open,
JSHIFT => jshift,
JUPDATE => update,
JRSTN => jtag_reset_n,
JCE1 => jce1,
JCE2 => open
);

-- JRTI1 looks like it could be connected to SEL, but
-- in practise JRTI1 is only high briefly, not for the duration
-- of the transmission. possibly mw_debug could be modified.
-- The ecp5 is probably the only jtag device anyway.
sel <= '1';

-- TDI needs to align with TCK, we use LUT delays here.
-- From https://github.com/enjoy-digital/litex/pull/1087
tck_d(1) <= tck;
del: for i in 1 to TCK_DELAY generate
attribute keep : boolean;
attribute keep of l: label is true;
begin
l: LUT4
generic map(
INIT => b"0000_0000_0000_0010"
)
port map (
A => tck_d(i),
B => '0', C => '0', D => '0',
Z => tck_d(i+1)
);
end generate;
jtag_clk <= tck_d(TCK_DELAY+1);

-- capture signal
jce1_sync : process(jtag_clk)
begin
if rising_edge(jtag_clk) then
jce1_d <= jce1;
capture <= jce1 and not jce1_d;
end if;
end process;

-- latch the shift signal, otherwise
-- we miss the last shift in
-- (maybe because we are delaying tck?)
shift_sync : process(jtag_clk)
begin
if (sys_reset = '1') then
shift <= '0';
elsif rising_edge(jtag_clk) then
shift <= jshift;
end if;
end process;

jtag_reset <= not jtag_reset_n;

-- dmi_req synchronization
dmi_req_sync : process(sys_clk)
begin
-- sys_reset is synchronous
if rising_edge(sys_clk) then
if (sys_reset = '1') then
jtag_req_0 <= '0';
jtag_req_1 <= '0';
else
jtag_req_0 <= jtag_req;
jtag_req_1 <= jtag_req_0;
end if;
end if;
end process;
dmi_req <= jtag_req_1;

-- dmi_ack synchronization
dmi_ack_sync: process(jtag_clk, jtag_reset)
begin
-- jtag_reset is async (see comments)
if jtag_reset = '1' then
dmi_ack_0 <= '0';
dmi_ack_1 <= '0';
elsif rising_edge(jtag_clk) then
dmi_ack_0 <= dmi_ack;
dmi_ack_1 <= dmi_ack_0;
end if;
end process;
-- jtag_bsy indicates whether we can start a new request, we can when
-- we aren't already processing one (jtag_req) and the synchronized ack
-- of the previous one is 0.
--
jtag_bsy <= jtag_req or dmi_ack_1;

-- decode request type in shift register
with shiftr(1 downto 0) select op_valid <=
'1' when DMI_REQ_RD,
'1' when DMI_REQ_WR,
'0' when others;

-- encode response op
rsp_op <= DMI_RSP_BSY when jtag_bsy = '1' else DMI_RSP_OK;

-- Some DMI out signals are directly driven from the request register
dmi_addr <= request(ABITS + DBITS + 1 downto DBITS + 2);
dmi_dout <= request(DBITS + 1 downto 2);
dmi_wr <= '1' when request(1 downto 0) = DMI_REQ_WR else '0';

-- TDO is wired to shift register bit 0
tdo <= shiftr(0);

-- Main state machine. Handles shift registers, request latch and
-- jtag_req latch. Could be split into 3 processes but it's probably
-- not worthwhile.
--
shifter: process(jtag_clk, jtag_reset, sys_reset)
begin
if jtag_reset = '1' or sys_reset = '1' then
shiftr <= (others => '0');
jtag_req <= '0';
request <= (others => '0');
elsif rising_edge(jtag_clk) then

-- Handle jtag "commands" when sel is 1
if sel = '1' then
-- Shift state, rotate the register
if shift = '1' then
shiftr <= tdi & shiftr(ABITS + DBITS + 1 downto 1);
end if;

-- Update state (trigger)
--
-- Latch the request if we aren't already processing one and
-- it has a valid command opcode.
--
if update = '1' and op_valid = '1' then
if jtag_bsy = '0' then
request <= shiftr;
jtag_req <= '1';
end if;
-- Set the shift register "op" to "busy". This will prevent
-- us from re-starting the command on the next update if
-- the command completes before that.
shiftr(1 downto 0) <= DMI_RSP_BSY;
end if;

-- Request completion.
--
-- Capture the response data for reads and clear request flag.
--
-- Note: We clear req (and thus dmi_req) here which relies on tck
-- ticking and sel set. This means we are stuck with dmi_req up if
-- the jtag interface stops. Slaves must be resilient to this.
--
if jtag_req = '1' and dmi_ack_1 = '1' then
jtag_req <= '0';
if request(1 downto 0) = DMI_REQ_RD then
request(DBITS + 1 downto 2) <= dmi_din;
end if;
end if;

-- Capture state, grab latch content with updated status
if capture = '1' then
shiftr <= request(ABITS + DBITS + 1 downto 2) & rsp_op;
end if;

end if;
end if;
end process;
end architecture behaviour;

Write Preview
Loading…
Cancel
Save