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First pass at an external JTAG port

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The verilator simulation interface uses the remote_bitbang
protocol from openocd. I have a simple implementation for
urjtag too.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
caravel-20210105
Anton Blanchard 4 years ago committed by Anton Blanchard
parent 3f1e2b3a4f
commit 6544dbe94c
6 changed files with 1207 additions and 19 deletions
Show Stats Download Patch File Download Diff File

6
Makefile
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@ -175,7 +175,7 @@ GHDL_IMAGE_GENERICS=-gMEMORY_SIZE=$(MEMORY_SIZE) -gRAM_INIT_FILE=$(RAM_INIT_FILE

clkgen=fpga/clk_gen_ecp5.vhd
toplevel=fpga/top-generic.vhdl
dmi_dtm=dmi_dtm_dummy.vhdl
dmi_dtm=dmi_dtm_jtag.vhdl dmi_dtm_dummy.vhdl

ifeq ($(FPGA_TARGET), verilator)
RESET_LOW=true
@ -197,8 +197,8 @@ microwatt.v: $(synth_files) $(RAM_INIT_FILE)
$(YOSYS) -m $(GHDLSYNTH) -p "ghdl --std=08 --no-formal $(GHDL_IMAGE_GENERICS) $(GHDL_TARGET_GENERICS) $(synth_files) -e toplevel; write_verilog $@"

# Need to investigate why yosys is hitting verilator warnings, and eventually turn on -Wall
microwatt-verilator: microwatt.v verilator/microwatt-verilator.cpp verilator/uart-verilator.c
verilator -O3 -CFLAGS "-DCLK_FREQUENCY=$(CLK_FREQUENCY)" --assert --cc microwatt.v --exe verilator/microwatt-verilator.cpp verilator/uart-verilator.c -o $@ -Iuart16550 -Wno-fatal -Wno-CASEOVERLAP -Wno-UNOPTFLAT #--trace
microwatt-verilator: microwatt.v verilator/microwatt-verilator.cpp verilator/uart-verilator.c verilator/jtag-verilator.c
verilator -O3 -CFLAGS "-DCLK_FREQUENCY=$(CLK_FREQUENCY)" --assert --cc microwatt.v --exe verilator/microwatt-verilator.cpp verilator/uart-verilator.c verilator/jtag-verilator.c -o $@ -Iuart16550 -Ijtag_tap -Wno-fatal -Wno-CASEOVERLAP -Wno-UNOPTFLAT #--trace
make -C obj_dir -f Vmicrowatt.mk
@cp -f obj_dir/microwatt-verilator microwatt-verilator


302
dmi_dtm_jtag.vhdl
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@ -0,0 +1,302 @@
-- JTAG to DMI interface, based on the Xilinx version
--
-- DMI bus
--
-- req : ____/------------\_____
-- addr: xxxx< >xxxxx, based on the Xilinx version
-- dout: xxxx< >xxxxx
-- wr : xxxx< >xxxxx
-- din : xxxxxxxxxxxx< >xxx
-- ack : ____________/------\___
--
-- * addr/dout set along with req, can be latched on same cycle by slave
-- * ack & din remain up until req is dropped by master, the slave must
-- provide a stable output on din on reads during that time.
-- * req remains low at until at least one sysclk after ack seen down.
--
-- JTAG (tck) DMI (sys_clk)
--
-- * jtag_req = 1
-- (jtag_req_0) *
-- (jtag_req_1) -> * dmi_req = 1 >
-- *.../...
-- * dmi_ack = 1 <
-- * (dmi_ack_0)
-- * <- (dmi_ack_1)
-- * jtag_req = 0 (and latch dmi_din)
-- (jtag_req_0) *
-- (jtag_req_1) -> * dmi_req = 0 >
-- * dmi_ack = 0 <
-- * (dmi_ack_0)
-- * <- (dmi_ack_1)
--
-- jtag_req can go back to 1 when jtag_rsp_1 is 0
--
-- Questions/TODO:
-- - I use 2 flip fops for sync, is that enough ?
-- - I treat the jtag_trst as an async reset, is that necessary ?
-- - Dbl check reset situation since we have two different resets
-- each only resetting part of the logic...
-- - Look at optionally removing the synchronizer on the ack path,
-- assuming JTAG is always slow enough that ack will have been
-- stable long enough by the time CAPTURE comes in.
-- - We could avoid the latched request by not shifting while a
-- request is in progress (and force TDO to 1 to return a busy
-- status).
--
-- WARNING: This isn't the real DMI JTAG protocol (at least not yet).
-- a command while busy will be ignored. A response of "11"
-- means the previous command is still going, try again.
-- As such We don't implement the DMI "error" status, and
-- we don't implement DTMCS yet... This may still all change
-- but for now it's easier that way as the real DMI protocol
-- requires for a command to work properly that enough TCK
-- are sent while IDLE and I'm having trouble getting that
-- working with UrJtag and the Xilinx BSCAN2 for now.

library ieee;
use ieee.std_logic_1164.all;
use ieee.math_real.all;

library work;
use work.wishbone_types.all;

entity dmi_dtm_jtag is
generic(ABITS : INTEGER:=8;
DBITS : INTEGER:=32);

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
jtag_tck : in std_ulogic;
jtag_tdi : in std_ulogic;
jtag_tms : in std_ulogic;
jtag_trst : in std_ulogic;
jtag_tdo : out std_ulogic
);
end entity dmi_dtm_jtag;

architecture behaviour of dmi_dtm_jtag is

-- Signals coming out of the JTAG TAP controller
signal capture : std_ulogic;
signal update : std_ulogic;
signal sel : std_ulogic;
signal shift : std_ulogic;
signal tdi : std_ulogic;
signal tdo : std_ulogic;

-- ** 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_tck)
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";

component tap_top port (
-- JTAG pads
tms_pad_i : in std_ulogic;
tck_pad_i : in std_ulogic;
trst_pad_i : in std_ulogic;
tdi_pad_i : in std_ulogic;
tdo_pad_o : out std_ulogic;
tdo_padoe_o : out std_ulogic;

-- TAP states
shift_dr_o : out std_ulogic;
pause_dr_o : out std_ulogic;
update_dr_o : out std_ulogic;
capture_dr_o : out std_ulogic;

-- Select signals for boundary scan or mbist
extest_select_o : out std_ulogic;
sample_preload_select_o : out std_ulogic;
mbist_select_o : out std_ulogic;
debug_select_o : out std_ulogic;

-- TDO signal that is connected to TDI of sub-modules.
tdo_o : out std_ulogic;

-- TDI signals from sub-modules
debug_tdi_i : in std_ulogic;
bs_chain_tdi_i : in std_ulogic;
mbist_tdi_i : in std_ulogic
);
end component;

begin
tap_top0 : tap_top
port map (
tms_pad_i => jtag_tms,
tck_pad_i => jtag_tck,
trst_pad_i => jtag_trst,
tdi_pad_i => jtag_tdi,
tdo_pad_o => jtag_tdo,
tdo_padoe_o => open, -- what to do with this?

shift_dr_o => shift,
pause_dr_o => open, -- what to do with this?
update_dr_o => update,
capture_dr_o => capture,

-- connect boundary scan and mbist?
extest_select_o => open,
sample_preload_select_o => open,
mbist_select_o => open,
debug_select_o => sel,

tdo_o => tdi,
debug_tdi_i => tdo,
bs_chain_tdi_i => '0',
mbist_tdi_i => '0'
);

-- 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_tck, jtag_trst)
begin
-- jtag_trst is async (see comments)
if jtag_trst = '1' then
dmi_ack_0 <= '0';
dmi_ack_1 <= '0';
elsif rising_edge(jtag_tck) 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_tck, jtag_trst, sys_reset)
begin
if jtag_trst = '1' or sys_reset = '1' then
shiftr <= (others => '0');
jtag_req <= '0';
request <= (others => '0');
elsif rising_edge(jtag_tck) 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;

640
jtag_tap/tap_top.v
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@ -0,0 +1,640 @@
//////////////////////////////////////////////////////////////////////
//// ////
//// tap_top.v ////
//// ////
//// ////
//// This file is part of the JTAG Test Access Port (TAP) ////
//// http://www.opencores.org/projects/jtag/ ////
//// ////
//// Author(s): ////
//// Igor Mohor (igorm@opencores.org) ////
//// ////
//// ////
//// All additional information is avaliable in the README.txt ////
//// file. ////
//// ////
//////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2000 - 2003 Authors ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer. ////
//// ////
//// This source file is free software; you can redistribute it ////
//// and/or modify it under the terms of the GNU Lesser General ////
//// Public License as published by the Free Software Foundation; ////
//// either version 2.1 of the License, or (at your option) any ////
//// later version. ////
//// ////
//// This source is distributed in the hope that it will be ////
//// useful, but WITHOUT ANY WARRANTY; without even the implied ////
//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////
//// PURPOSE. See the GNU Lesser General Public License for more ////
//// details. ////
//// ////
//// You should have received a copy of the GNU Lesser General ////
//// Public License along with this source; if not, download it ////
//// from http://www.opencores.org/lgpl.shtml ////
//// ////
//////////////////////////////////////////////////////////////////////
//
// CVS Revision History
//
// $Log: not supported by cvs2svn $
// Revision 1.5 2004/01/18 09:27:39 simons
// Blocking non blocking assignmenst fixed.
//
// Revision 1.4 2004/01/17 17:37:44 mohor
// capture_dr_o added to ports.
//
// Revision 1.3 2004/01/14 13:50:56 mohor
// 5 consecutive TMS=1 causes reset of TAP.
//
// Revision 1.2 2004/01/08 10:29:44 mohor
// Control signals for tdo_pad_o mux are changed to negedge.
//
// Revision 1.1 2003/12/23 14:52:14 mohor
// Directory structure changed. New version of TAP.
//
// Revision 1.10 2003/10/23 18:08:01 mohor
// MBIST chain connection fixed.
//
// Revision 1.9 2003/10/23 16:17:02 mohor
// CRC logic changed.
//
// Revision 1.8 2003/10/21 09:48:31 simons
// Mbist support added.
//
// Revision 1.7 2002/11/06 14:30:10 mohor
// Trst active high. Inverted on higher layer.
//
// Revision 1.6 2002/04/22 12:55:56 mohor
// tdo_padoen_o changed to tdo_padoe_o. Signal is active high.
//
// Revision 1.5 2002/03/26 14:23:38 mohor
// Signal tdo_padoe_o changed back to tdo_padoen_o.
//
// Revision 1.4 2002/03/25 13:16:15 mohor
// tdo_padoen_o changed to tdo_padoe_o. Signal was always active high, just
// not named correctly.
//
// Revision 1.3 2002/03/12 14:30:05 mohor
// Few outputs for boundary scan chain added.
//
// Revision 1.2 2002/03/12 10:31:53 mohor
// tap_top and dbg_top modules are put into two separate modules. tap_top
// contains only tap state machine and related logic. dbg_top contains all
// logic necessery for debugging.
//
// Revision 1.1 2002/03/08 15:28:16 mohor
// Structure changed. Hooks for jtag chain added.
//
//
//
//

// Top module
module tap_top #(parameter
// 0001 version
// 0100100101010001 part number (IQ)
// 00011100001 manufacturer id (flextronics)
// 1 required by standard
IDCODE_VALUE = 32'h149511c3,
IR_LENGTH = 4)
(
// JTAG pads
tms_pad_i,
tck_pad_i,
trst_pad_i,
tdi_pad_i,
tdo_pad_o,
tdo_padoe_o,

// TAP states
shift_dr_o,
pause_dr_o,
update_dr_o,
capture_dr_o,
// Select signals for boundary scan or mbist
extest_select_o,
sample_preload_select_o,
mbist_select_o,
debug_select_o,
// TDO signal that is connected to TDI of sub-modules.
tdo_o,
// TDI signals from sub-modules
debug_tdi_i, // from debug module
bs_chain_tdi_i, // from Boundary Scan Chain
mbist_tdi_i // from Mbist Chain
);


// JTAG pins
input tms_pad_i; // JTAG test mode select pad
input tck_pad_i; // JTAG test clock pad
input trst_pad_i; // JTAG test reset pad
input tdi_pad_i; // JTAG test data input pad
output tdo_pad_o; // JTAG test data output pad
output tdo_padoe_o; // Output enable for JTAG test data output pad

// TAP states
output shift_dr_o;
output pause_dr_o;
output update_dr_o;
output capture_dr_o;

// Select signals for boundary scan or mbist
output extest_select_o;
output sample_preload_select_o;
output mbist_select_o;
output debug_select_o;

// TDO signal that is connected to TDI of sub-modules.
output tdo_o;

// TDI signals from sub-modules
input debug_tdi_i; // from debug module
input bs_chain_tdi_i; // from Boundary Scan Chain
input mbist_tdi_i; // from Mbist Chain

//Internal constants
localparam EXTEST = 4'b0000;
localparam SAMPLE_PRELOAD = 4'b0001;
localparam IDCODE = 4'b0010;
localparam DEBUG = 4'b1000;
localparam MBIST = 4'b1001;
localparam BYPASS = 4'b1111;

// Registers
reg test_logic_reset;
reg run_test_idle;
reg select_dr_scan;
reg capture_dr;
reg shift_dr;
reg exit1_dr;
reg pause_dr;
reg exit2_dr;
reg update_dr;
reg select_ir_scan;
reg capture_ir;
reg shift_ir, shift_ir_neg;
reg exit1_ir;
reg pause_ir;
reg exit2_ir;
reg update_ir;
reg extest_select;
reg sample_preload_select;
reg idcode_select;
reg mbist_select;
reg debug_select;
reg bypass_select;
reg tdo_pad_o;
reg tdo_padoe_o;
reg tms_q1, tms_q2, tms_q3, tms_q4;
wire tms_reset;

assign tdo_o = tdi_pad_i;
assign shift_dr_o = shift_dr;
assign pause_dr_o = pause_dr;
assign update_dr_o = update_dr;
assign capture_dr_o = capture_dr;

assign extest_select_o = extest_select;
assign sample_preload_select_o = sample_preload_select;
assign mbist_select_o = mbist_select;
assign debug_select_o = debug_select;


always @ (posedge tck_pad_i)
begin
tms_q1 <= tms_pad_i;
tms_q2 <= tms_q1;
tms_q3 <= tms_q2;
tms_q4 <= tms_q3;
end


assign tms_reset = tms_q1 & tms_q2 & tms_q3 & tms_q4 & tms_pad_i; // 5 consecutive TMS=1 causes reset


/**********************************************************************************
* *
* TAP State Machine: Fully JTAG compliant *
* *
**********************************************************************************/

// test_logic_reset state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
test_logic_reset<= 1'b1;
else if (tms_reset)
test_logic_reset<= 1'b1;
else
begin
if(tms_pad_i & (test_logic_reset | select_ir_scan))
test_logic_reset<= 1'b1;
else
test_logic_reset<= 1'b0;
end
end

// run_test_idle state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
run_test_idle<= 1'b0;
else if (tms_reset)
run_test_idle<= 1'b0;
else
if(~tms_pad_i & (test_logic_reset | run_test_idle | update_dr | update_ir))
run_test_idle<= 1'b1;
else
run_test_idle<= 1'b0;
end

// select_dr_scan state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
select_dr_scan<= 1'b0;
else if (tms_reset)
select_dr_scan<= 1'b0;
else
if(tms_pad_i & (run_test_idle | update_dr | update_ir))
select_dr_scan<= 1'b1;
else
select_dr_scan<= 1'b0;
end

// capture_dr state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
capture_dr<= 1'b0;
else if (tms_reset)
capture_dr<= 1'b0;
else
if(~tms_pad_i & select_dr_scan)
capture_dr<= 1'b1;
else
capture_dr<= 1'b0;
end

// shift_dr state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
shift_dr<= 1'b0;
else if (tms_reset)
shift_dr<= 1'b0;
else
if(~tms_pad_i & (capture_dr | shift_dr | exit2_dr))
shift_dr<= 1'b1;
else
shift_dr<= 1'b0;
end

// exit1_dr state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
exit1_dr<= 1'b0;
else if (tms_reset)
exit1_dr<= 1'b0;
else
if(tms_pad_i & (capture_dr | shift_dr))
exit1_dr<= 1'b1;
else
exit1_dr<= 1'b0;
end

// pause_dr state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
pause_dr<= 1'b0;
else if (tms_reset)
pause_dr<= 1'b0;
else
if(~tms_pad_i & (exit1_dr | pause_dr))
pause_dr<= 1'b1;
else
pause_dr<= 1'b0;
end

// exit2_dr state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
exit2_dr<= 1'b0;
else if (tms_reset)
exit2_dr<= 1'b0;
else
if(tms_pad_i & pause_dr)
exit2_dr<= 1'b1;
else
exit2_dr<= 1'b0;
end

// update_dr state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
update_dr<= 1'b0;
else if (tms_reset)
update_dr<= 1'b0;
else
if(tms_pad_i & (exit1_dr | exit2_dr))
update_dr<= 1'b1;
else
update_dr<= 1'b0;
end

// select_ir_scan state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
select_ir_scan<= 1'b0;
else if (tms_reset)
select_ir_scan<= 1'b0;
else
if(tms_pad_i & select_dr_scan)
select_ir_scan<= 1'b1;
else
select_ir_scan<= 1'b0;
end

// capture_ir state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
capture_ir<= 1'b0;
else if (tms_reset)
capture_ir<= 1'b0;
else
if(~tms_pad_i & select_ir_scan)
capture_ir<= 1'b1;
else
capture_ir<= 1'b0;
end

// shift_ir state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
shift_ir<= 1'b0;
else if (tms_reset)
shift_ir<= 1'b0;
else
if(~tms_pad_i & (capture_ir | shift_ir | exit2_ir))
shift_ir<= 1'b1;
else
shift_ir<= 1'b0;
end

// exit1_ir state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
exit1_ir<= 1'b0;
else if (tms_reset)
exit1_ir<= 1'b0;
else
if(tms_pad_i & (capture_ir | shift_ir))
exit1_ir<= 1'b1;
else
exit1_ir<= 1'b0;
end

// pause_ir state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
pause_ir<= 1'b0;
else if (tms_reset)
pause_ir<= 1'b0;
else
if(~tms_pad_i & (exit1_ir | pause_ir))
pause_ir<= 1'b1;
else
pause_ir<= 1'b0;
end

// exit2_ir state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
exit2_ir<= 1'b0;
else if (tms_reset)
exit2_ir<= 1'b0;
else
if(tms_pad_i & pause_ir)
exit2_ir<= 1'b1;
else
exit2_ir<= 1'b0;
end

// update_ir state
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
update_ir<= 1'b0;
else if (tms_reset)
update_ir<= 1'b0;
else
if(tms_pad_i & (exit1_ir | exit2_ir))
update_ir<= 1'b1;
else
update_ir<= 1'b0;
end

/**********************************************************************************
* *
* End: TAP State Machine *
* *
**********************************************************************************/



/**********************************************************************************
* *
* jtag_ir: JTAG Instruction Register *
* *
**********************************************************************************/
reg [IR_LENGTH-1:0] jtag_ir; // Instruction register
reg [IR_LENGTH-1:0] latched_jtag_ir, latched_jtag_ir_neg;
reg instruction_tdo;

always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
jtag_ir[IR_LENGTH-1:0] <= {IR_LENGTH{1'b0}};
else if(capture_ir)
jtag_ir <= 4'b0101; // This value is fixed for easier fault detection
else if(shift_ir)
jtag_ir[IR_LENGTH-1:0] <= {tdi_pad_i, jtag_ir[IR_LENGTH-1:1]};
end

always @ (negedge tck_pad_i)
begin
instruction_tdo <= jtag_ir[0];
end
/**********************************************************************************
* *
* End: jtag_ir *
* *
**********************************************************************************/



/**********************************************************************************
* *
* idcode logic *
* *
**********************************************************************************/
reg [31:0] idcode_reg;
reg idcode_tdo;

always @ (posedge tck_pad_i)
begin
if(idcode_select & shift_dr)
idcode_reg <= {tdi_pad_i, idcode_reg[31:1]};
else
idcode_reg <= IDCODE_VALUE;
end

always @ (negedge tck_pad_i)
begin
idcode_tdo <= idcode_reg[0];
end
/**********************************************************************************
* *
* End: idcode logic *
* *
**********************************************************************************/


/**********************************************************************************
* *
* Bypass logic *
* *
**********************************************************************************/
reg bypassed_tdo;
reg bypass_reg;

always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if (trst_pad_i)
bypass_reg<= 1'b0;
else if(shift_dr)
bypass_reg<= tdi_pad_i;
end

always @ (negedge tck_pad_i)
begin
bypassed_tdo <= bypass_reg;
end
/**********************************************************************************
* *
* End: Bypass logic *
* *
**********************************************************************************/


/**********************************************************************************
* *
* Activating Instructions *
* *
**********************************************************************************/
// Updating jtag_ir (Instruction Register)
always @ (posedge tck_pad_i or posedge trst_pad_i)
begin
if(trst_pad_i)
latched_jtag_ir <= IDCODE; // IDCODE selected after reset
else if (tms_reset)
latched_jtag_ir <= IDCODE; // IDCODE selected after reset
else if(update_ir)
latched_jtag_ir <= jtag_ir;
end

/**********************************************************************************
* *
* End: Activating Instructions *
* *
**********************************************************************************/


// Updating jtag_ir (Instruction Register)
always @ (latched_jtag_ir)
begin
extest_select = 1'b0;
sample_preload_select = 1'b0;
idcode_select = 1'b0;
mbist_select = 1'b0;
debug_select = 1'b0;
bypass_select = 1'b0;

case(latched_jtag_ir) /* synthesis parallel_case */
EXTEST: extest_select = 1'b1; // External test
SAMPLE_PRELOAD: sample_preload_select = 1'b1; // Sample preload
IDCODE: idcode_select = 1'b1; // ID Code
MBIST: mbist_select = 1'b1; // Mbist test
DEBUG: debug_select = 1'b1; // Debug
BYPASS: bypass_select = 1'b1; // BYPASS
default: bypass_select = 1'b1; // BYPASS
endcase
end



/**********************************************************************************
* *
* Multiplexing TDO data *
* *
**********************************************************************************/
always @ (shift_ir_neg or exit1_ir or instruction_tdo or latched_jtag_ir_neg or idcode_tdo or
debug_tdi_i or bs_chain_tdi_i or mbist_tdi_i or
bypassed_tdo)
begin
if(shift_ir_neg)
tdo_pad_o = instruction_tdo;
else
begin
case(latched_jtag_ir_neg) // synthesis parallel_case
IDCODE: tdo_pad_o = idcode_tdo; // Reading ID code
DEBUG: tdo_pad_o = debug_tdi_i; // Debug
SAMPLE_PRELOAD: tdo_pad_o = bs_chain_tdi_i; // Sampling/Preloading
EXTEST: tdo_pad_o = bs_chain_tdi_i; // External test
MBIST: tdo_pad_o = mbist_tdi_i; // Mbist test
default: tdo_pad_o = bypassed_tdo; // BYPASS instruction
endcase
end
end


// Tristate control for tdo_pad_o pin
always @ (negedge tck_pad_i)
begin
tdo_padoe_o <= shift_ir | shift_dr | (pause_dr & debug_select);
end
/**********************************************************************************
* *
* End: Multiplexing TDO data *
* *
**********************************************************************************/


always @ (negedge tck_pad_i)
begin
shift_ir_neg <= shift_ir;
latched_jtag_ir_neg <= latched_jtag_ir;
end


endmodule

65
soc.vhdl
Unescape Escape View File

@ -65,7 +65,8 @@ entity soc is
LOG_LENGTH : natural := 512;
HAS_LITEETH : boolean := false;
UART0_IS_16550 : boolean := true;
HAS_UART1 : boolean := false
HAS_UART1 : boolean := false;
HAS_JTAG : boolean := false
);
port(
rst : in std_ulogic;
@ -100,6 +101,13 @@ entity soc is
spi_flash_sdat_oe : out std_ulogic_vector(SPI_FLASH_DLINES-1 downto 0);
spi_flash_sdat_i : in std_ulogic_vector(SPI_FLASH_DLINES-1 downto 0) := (others => '1');

-- JTAG signals
jtag_tck : in std_ulogic := '0';
jtag_tdi : in std_ulogic := '0';
jtag_tms : in std_ulogic := '0';
jtag_trst : in std_ulogic := '0';
jtag_tdo : out std_ulogic;

-- DRAM controller signals
alt_reset : in std_ulogic := '0'
);
@ -840,21 +848,46 @@ begin
end generate;

-- DMI(debug bus) <-> JTAG bridge
dtm: entity work.dmi_dtm
generic map(
ABITS => 8,
DBITS => 64
)
port map(
sys_clk => system_clk,
sys_reset => rst_dtm,
dmi_addr => dmi_addr,
dmi_din => dmi_din,
dmi_dout => dmi_dout,
dmi_req => dmi_req,
dmi_wr => dmi_wr,
dmi_ack => dmi_ack
);
dmi_jtag: if HAS_JTAG generate
dtm: entity work.dmi_dtm_jtag
generic map(
ABITS => 8,
DBITS => 64
)
port map(
sys_clk => system_clk,
sys_reset => rst_dtm,
dmi_addr => dmi_addr,
dmi_din => dmi_din,
dmi_dout => dmi_dout,
dmi_req => dmi_req,
dmi_wr => dmi_wr,
dmi_ack => dmi_ack,
jtag_tck => jtag_tck,
jtag_tdi => jtag_tdi,
jtag_tms => jtag_tms,
jtag_trst => jtag_trst,
jtag_tdo => jtag_tdo
);
end generate;

dmi_xilinx: if not HAS_JTAG generate
dtm: entity work.dmi_dtm
generic map(
ABITS => 8,
DBITS => 64
)
port map(
sys_clk => system_clk,
sys_reset => rst_dtm,
dmi_addr => dmi_addr,
dmi_din => dmi_din,
dmi_dout => dmi_dout,
dmi_req => dmi_req,
dmi_wr => dmi_wr,
dmi_ack => dmi_ack
);
end generate;

-- DMI interconnect
dmi_intercon: process(dmi_addr, dmi_req,

196
verilator/jtag-verilator.c
Unescape Escape View File

@ -0,0 +1,196 @@
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <poll.h>
#include <signal.h>
#include <fcntl.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#undef DEBUG

/* XXX Make that some parameter */
#define TCP_PORT 13245

static int fd = -1;
static int cfd = -1;

static void open_socket(void)
{
struct sockaddr_in addr;
int opt, rc, flags;

if (fd >= 0 || fd < -1)
return;

signal(SIGPIPE, SIG_IGN);
fd = socket(AF_INET, SOCK_STREAM, 0);
if (fd < 0) {
fprintf(stderr, "Failed to open debug socket\r\n");
goto fail;
}

rc = 0;
flags = fcntl(fd, F_GETFL);
if (flags >= 0)
rc = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
if (flags < 0 || rc < 0) {
fprintf(stderr, "Failed to configure debug socket\r\n");
}

memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(TCP_PORT);
addr.sin_addr.s_addr = htonl(INADDR_ANY);
opt = 1;
setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
rc = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
if (rc < 0) {
fprintf(stderr, "Failed to bind debug socket\r\n");
goto fail;
}
rc = listen(fd,1);
if (rc < 0) {
fprintf(stderr, "Failed to listen to debug socket\r\n");
goto fail;
}
#ifdef DEBUG
fprintf(stdout, "Debug socket ready\r\n");
#endif
return;
fail:
if (fd >= 0)
close(fd);
fd = -2;
}

static void check_connection(void)
{
struct sockaddr_in addr;
socklen_t addr_len = sizeof(addr);

cfd = accept(fd, (struct sockaddr *)&addr, &addr_len);
if (cfd < 0)
return;
#ifdef DEBUG
fprintf(stdout, "Debug client connected\r\n");
#endif
}

static bool read_one_byte(char *c)
{
struct pollfd fdset[1];
int rc;

if (fd == -1)
open_socket();
if (fd < 0)
return false;
if (cfd < 0)
check_connection();
if (cfd < 0)
return false;

memset(fdset, 0, sizeof(fdset));
fdset[0].fd = cfd;
fdset[0].events = POLLIN;
rc = poll(fdset, 1, 0);
if (rc <= 0)
return false;
rc = read(cfd, c, 1);
if (rc != 1) {
#ifdef DEBUG
fprintf(stdout, "Debug read error, assuming client disconnected !\r\n");
#endif
close(cfd);
cfd = -1;
return false;
}

#ifdef DEBUG
fprintf(stdout, "Got message: %c\n", *c);
#endif

return true;
}

static void write_one_byte(char c)
{
int rc;

#ifdef DEBUG
fprintf(stdout, "Sending message: %c\r\n", c);
#endif

rc = write(cfd, &c, 1);
if (rc != 1) {
#ifdef DEBUG
fprintf(stdout, "JTAG write error, disconnecting\r\n");
#endif
close(cfd);
cfd = -1;
}
}

struct jtag_in {
uint8_t tck;
uint8_t tms;
uint8_t tdi;
uint8_t trst;
};

static struct jtag_in jtag_in;

struct jtag_in jtag_one_cycle(uint8_t tdo)
{
char c;

if (read_one_byte(&c) == false)
goto out;

// Write request
if ((c >= '0') && (c <= '7')) {
uint8_t val = c - '0';

jtag_in.tck = (val >> 2) & 1;
jtag_in.tms = (val >> 1) & 1;
jtag_in.tdi = (val >> 0) & 1;

goto out;
}

// Reset request
if ((c >= 'r') && (c <= 'u')) {
uint8_t val = c - 'r';

jtag_in.trst = (val >> 1) & 1;
}

switch (c) {
case 'B': // Blink on
case 'b': // Blink off
goto out;

case 'R': // Read request
write_one_byte(tdo + '0');
goto out;

case 'Q': // Quit request
#ifdef DEBUG
fprintf(stdout, "Disconnecting JTAG\r\n");
#endif
close(cfd);
cfd = -1;
goto out;

default:
fprintf(stderr, "Unknown JTAG command %c\r\n", c);
}

out:
return jtag_in;
}

17
verilator/microwatt-verilator.cpp
Unescape Escape View File

@ -46,6 +46,14 @@ void tick(Vmicrowatt *top)
void uart_tx(unsigned char tx);
unsigned char uart_rx(void);

struct jtag_in {
unsigned char tck;
unsigned char tms;
unsigned char tdi;
unsigned char trst;
};
struct jtag_in jtag_one_cycle(uint8_t tdo);

int main(int argc, char **argv)
{
Verilated::commandArgs(argc, argv);
@ -68,10 +76,19 @@ int main(int argc, char **argv)
top->ext_rst = 1;

while(!Verilated::gotFinish()) {
struct jtag_in p;

tick(top);

uart_tx(top->uart0_txd);
top->uart0_rxd = uart_rx();

p = jtag_one_cycle(top->jtag_tdo);

top->jtag_tck = p.tck;
top->jtag_tms = p.tms;
top->jtag_tdi = p.tdi;
top->jtag_trst = p.trst;
}

#if VM_TRACE

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