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⚠️ remove redundant JTAG reset signal (TRST) #928

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merged 6 commits into from
Jun 18, 2024
Merged

⚠️ remove redundant JTAG reset signal (TRST) #928

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66f09a2
[top] remove JTAG reset signal
stnolting Jun 17, 2024
7f9a982
[sw] cleanup OpenOCD config file
stnolting Jun 17, 2024
1429ada
[docs] update JTAG signal list
stnolting Jun 17, 2024
ed78af8
[rtl] DTM: remove JTAG TRST
stnolting Jun 17, 2024
d2ff283
[rtl] cleanup debug module code
stnolting Jun 17, 2024
305182b
[changelog] add v1.10.0.1
stnolting Jun 17, 2024
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -29,6 +29,7 @@ mimpid = 0x01040312 -> Version 01.04.03.12 -> v1.4.3.12

| Date | Version | Comment | Ticket |
|:----:|:-------:|:--------|:------:|
| 17.05.2024 | 1.10.0.1 | :warning: remove (optional and redundant) JTAG reset signal `jtag_trst_i` | [#928](https://github.com/stnolting/neorv32/pull/928) |
| 16.05.2024 | [**:rocket:1.10.0**](https://github.com/stnolting/neorv32/releases/tag/v1.10.0) | **New release** | |
| 15.06.2024 | 1.9.9.9 | :sparkles: add pre-configured example project for Eclipse IDE | [#926](https://github.com/stnolting/neorv32/pull/926) |
| 14.06.2024 | 1.9.9.8 | minor rtl edits/cleanups; increase bootloader's auto-boot timeout from 8s to 10s | [#925](https://github.com/stnolting/neorv32/pull/925) |
Expand Down
6 changes: 5 additions & 1 deletion docs/datasheet/on_chip_debugger.adoc
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Expand Up @@ -81,7 +81,6 @@ External JTAG access is provided by the following top-level ports:
[options="header",grid="rows"]
|=======================
| Name | Width | Direction | Description
| `jtag_trst_i` | 1 | in | TAP reset (low-active); this signal is optional, make sure to pull it **high** if not used
| `jtag_tck_i` | 1 | in | serial clock
| `jtag_tdi_i` | 1 | in | serial data input
| `jtag_tdo_o` | 1 | out | serial data output
Expand All @@ -94,6 +93,11 @@ All JTAG signals are synchronized to the processor's clock domain. Hence, no add
However, this constraints the maximal JTAG clock frequency (`jtag_tck_i`) to be less than or equal to **1/5** of the processor
clock frequency (`clk_i`).

.JTAG TAP Reset
[NOTE]
The NEORV32 JTAG TAP does not provide a dedicated reset signal ("TRST"). However, the missing TRST is not a problem,
since JTAG-level resets can be triggered using with TMS signaling.

.Maintaining JTAG Chain
[NOTE]
If the on-chip debugger is disabled the JTAG serial input `jtag_tdi_i` is directly
Expand Down
1 change: 0 additions & 1 deletion docs/datasheet/soc.adoc
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Expand Up @@ -80,7 +80,6 @@ Some interfaces (like the TWI and the 1-Wire bus) require tri-state drivers in t
| `clk_i` | 1 | in | none | global clock line, all registers triggering on rising edge
| `rstn_i` | 1 | in | none | global reset, asynchronous, **low-active**
5+^| **JTAG Access Port for <<_on_chip_debugger_ocd>>**
| `jtag_trst_i` | 1 | in | `'H'` | TAP reset, low-active (optional)
| `jtag_tck_i` | 1 | in | `'L'` | serial clock
| `jtag_tdi_i` | 1 | in | `'L'` | serial data input
| `jtag_tdo_o` | 1 | out | - | serial data output
Expand Down
14 changes: 7 additions & 7 deletions docs/userguide/debugging_with_ocd.adoc
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Expand Up @@ -10,7 +10,7 @@ RISC-V _GNU debugger_ `gdb`.
.TLDR
[TIP]
You can start a pre-configured debug session (using default `main.elf` as executable and
`target extended-remote localhost:3333` as gdb connection configuration) by using the **gdb** makefile target
`target extended-remote localhost:3333` as GDB connection configuration) by using the **GDB** makefile target
(i.e. `make gdb`).

.OCD Hardware Implementation
Expand Down Expand Up @@ -39,17 +39,17 @@ also use a FTDI-based adapter like the "FT2232H-56Q Mini Module", which is a sim
[cols="^3,^2,^2"]
[options="header",grid="rows"]
|=======================
| NEORV32 top signal | JTAG signal | FTDI port
| NEORV32 top signal | JTAG signal | Default FTDI port
| `jtag_tck_i` | TCK | D0
| `jtag_tdi_i` | TDI | D1
| `jtag_tdo_o` | TDO | D2
| `jtag_tms_i` | TMS | D3
| `jtag_trst_i` | TRST | D4
|=======================

[TIP]
The low-active JTAG tap reset `jtag_trst_i` signals is _optional_ as a reset can also be triggered via the TAP controller
issuing special commands. If `jtag_trst_i` is not connected make sure to pull the signal _high_.
.JTAG TAP Reset
[NOTE]
The NEORV32 JTAG TAP does not provide a dedicated reset signal ("TRST"). However, the missing TRST is not a problem,
since JTAG-level resets can be triggered using with TMS signaling.


:sectnums:
Expand Down Expand Up @@ -239,7 +239,7 @@ instruction. Whenever execution reaches this instruction, debug mode is entered
instruction at this address to maintain original program behavior. +
+
When debugging programs executed from ROM _hardware-assisted_ breakpoints using the core's trigger module have to be used.
See section <<_hardware_breakpoints>> for more information.
See section <<_hardware_breakpoints>> for more information.

Now execute `c` (= continue). The CPU will resume operation until it hits the break-point.
By this we can move from one counter increment to another.
Expand Down
64 changes: 32 additions & 32 deletions rtl/core/neorv32_debug_dm.vhd
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Expand Up @@ -213,7 +213,7 @@ begin
dm_ctrl.pbuf_en <= '0';
dm_ctrl.illegal_cmd <= '0';
dm_ctrl.illegal_state <= '0';
dm_ctrl.cmderr <= "000";
dm_ctrl.cmderr <= (others => '0');
elsif rising_edge(clk_i) then
if (dm_reg.dmcontrol_dmactive = '0') then -- DM reset / DM disabled
dm_ctrl.state <= CMD_IDLE;
Expand All @@ -223,7 +223,7 @@ begin
--
dm_ctrl.illegal_cmd <= '0';
dm_ctrl.illegal_state <= '0';
dm_ctrl.cmderr <= "000";
dm_ctrl.cmderr <= (others => '0');
else -- DM active

-- defaults --
Expand Down Expand Up @@ -416,8 +416,8 @@ begin
dm_reg.halt_req <= dmi_req_i.data(31); -- haltreq (-/w): write 1 to request halt; has to be cleared again by debugger
dm_reg.resume_req <= dmi_req_i.data(30); -- resumereq (-/w1): write 1 to request resume; auto-clears
dm_reg.reset_ack <= dmi_req_i.data(28); -- ackhavereset (-/w1): write 1 to ACK reset; auto-clears
dm_reg.dmcontrol_ndmreset <= dmi_req_i.data(01); -- ndmreset (r/w): SoC reset when high
dm_reg.dmcontrol_dmactive <= dmi_req_i.data(00); -- dmactive (r/w): DM reset when low
dm_reg.dmcontrol_ndmreset <= dmi_req_i.data(1); -- ndmreset (r/w): SoC reset when high
dm_reg.dmcontrol_dmactive <= dmi_req_i.data(0); -- dmactive (r/w): DM reset when low
end if;

-- write abstract command --
Expand All @@ -430,7 +430,7 @@ begin
-- write abstract command autoexec --
if (dmi_req_i.addr = addr_abstractauto_c) then
if (dm_ctrl.busy = '0') then -- idle and no errors yet
dm_reg.abstractauto_autoexecdata <= dmi_req_i.data(00);
dm_reg.abstractauto_autoexecdata <= dmi_req_i.data(0);
dm_reg.abstractauto_autoexecprogbuf(0) <= dmi_req_i.data(16);
dm_reg.abstractauto_autoexecprogbuf(1) <= dmi_req_i.data(17);
end if;
Expand Down Expand Up @@ -529,13 +529,13 @@ begin
dmi_rsp_o.data(12) <= dm_reg.dmcontrol_ndmreset; -- anyunavail (r/-): there is only one hart that is unavailable during reset
dmi_rsp_o.data(11) <= not dm_ctrl.hart_halted; -- allrunning (r/-): there is only one hart that can be RUNNING or HALTED
dmi_rsp_o.data(10) <= not dm_ctrl.hart_halted; -- anyrunning (r/-): there is only one hart that can be RUNNING or HALTED
dmi_rsp_o.data(09) <= dm_ctrl.hart_halted; -- allhalted (r/-): there is only one hart that can be RUNNING or HALTED
dmi_rsp_o.data(08) <= dm_ctrl.hart_halted; -- anyhalted (r/-): there is only one hart that can be RUNNING or HALTED
dmi_rsp_o.data(07) <= '1'; -- authenticated (r/-): authentication passed since there is no authentication
dmi_rsp_o.data(06) <= '0'; -- authbusy (r/-): always ready since there is no authentication
dmi_rsp_o.data(05) <= '0'; -- hasresethaltreq (r/-): halt-on-reset not implemented
dmi_rsp_o.data(04) <= '0'; -- confstrptrvalid (r/-): no configuration string available
dmi_rsp_o.data(03 downto 00) <= dm_version_c; -- version (r/-): DM spec. version
dmi_rsp_o.data(9) <= dm_ctrl.hart_halted; -- allhalted (r/-): there is only one hart that can be RUNNING or HALTED
dmi_rsp_o.data(8) <= dm_ctrl.hart_halted; -- anyhalted (r/-): there is only one hart that can be RUNNING or HALTED
dmi_rsp_o.data(7) <= '1'; -- authenticated (r/-): authentication passed since there is no authentication
dmi_rsp_o.data(6) <= '0'; -- authbusy (r/-): always ready since there is no authentication
dmi_rsp_o.data(5) <= '0'; -- hasresethaltreq (r/-): halt-on-reset not implemented
dmi_rsp_o.data(4) <= '0'; -- confstrptrvalid (r/-): no configuration string available
dmi_rsp_o.data(3 downto 0) <= dm_version_c; -- version (r/-): DM spec. version

-- debug module control --
when addr_dmcontrol_c =>
Expand All @@ -546,12 +546,12 @@ begin
dmi_rsp_o.data(27) <= '0'; -- reserved (r/-)
dmi_rsp_o.data(26) <= '0'; -- hasel (r/-) - only a single hart can be selected at once
dmi_rsp_o.data(25 downto 16) <= (others => '0'); -- hartsello (r/-) - there is only one hart
dmi_rsp_o.data(15 downto 06) <= (others => '0'); -- hartselhi (r/-) - there is only one hart
dmi_rsp_o.data(05 downto 04) <= (others => '0'); -- reserved (r/-)
dmi_rsp_o.data(03) <= '0'; -- setresethaltreq (-/w1): halt-on-reset request - halt-on-reset not implemented
dmi_rsp_o.data(02) <= '0'; -- clrresethaltreq (-/w1): halt-on-reset ack - halt-on-reset not implemented
dmi_rsp_o.data(01) <= dm_reg.dmcontrol_ndmreset; -- ndmreset (r/w): soc reset
dmi_rsp_o.data(00) <= dm_reg.dmcontrol_dmactive; -- dmactive (r/w): DM reset
dmi_rsp_o.data(15 downto 6) <= (others => '0'); -- hartselhi (r/-) - there is only one hart
dmi_rsp_o.data(5 downto 4) <= (others => '0'); -- reserved (r/-)
dmi_rsp_o.data(3) <= '0'; -- setresethaltreq (-/w1): halt-on-reset request - halt-on-reset not implemented
dmi_rsp_o.data(2) <= '0'; -- clrresethaltreq (-/w1): halt-on-reset ack - halt-on-reset not implemented
dmi_rsp_o.data(1) <= dm_reg.dmcontrol_ndmreset; -- ndmreset (r/w): soc reset
dmi_rsp_o.data(0) <= dm_reg.dmcontrol_dmactive; -- dmactive (r/w): DM reset

-- hart info --
when addr_hartinfo_c =>
Expand All @@ -560,31 +560,31 @@ begin
dmi_rsp_o.data(19 downto 17) <= (others => '0'); -- reserved (r/-)
dmi_rsp_o.data(16) <= dataaccess_c; -- dataaccess (r/-): 1: data registers are memory-mapped, 0: data registers are CSR-mapped
dmi_rsp_o.data(15 downto 12) <= datasize_c; -- datasize (r/-): number data registers in memory/CSR space
dmi_rsp_o.data(11 downto 00) <= dataaddr_c(11 downto 0); -- dataaddr (r/-): data registers base address (memory/CSR)
dmi_rsp_o.data(11 downto 0) <= dataaddr_c(11 downto 0); -- dataaddr (r/-): data registers base address (memory/CSR)

-- abstract control and status --
when addr_abstractcs_c =>
dmi_rsp_o.data(31 downto 24) <= (others => '0'); -- reserved (r/-)
dmi_rsp_o.data(28 downto 24) <= "00010"; -- progbufsize (r/-): number of words in program buffer = 2
dmi_rsp_o.data(12) <= dm_ctrl.busy; -- busy (r/-): abstract command in progress (1) / idle (0)
dmi_rsp_o.data(11) <= '1'; -- relaxedpriv (r/-): PMP rules are ignored when in debug-mode
dmi_rsp_o.data(10 downto 08) <= dm_ctrl.cmderr; -- cmderr (r/w1c): any error during execution?
dmi_rsp_o.data(07 downto 04) <= (others => '0'); -- reserved (r/-)
dmi_rsp_o.data(03 downto 00) <= "0001"; -- datacount (r/-): number of implemented data registers = 1
dmi_rsp_o.data(10 downto 8) <= dm_ctrl.cmderr; -- cmderr (r/w1c): any error during execution?
dmi_rsp_o.data(7 downto 4) <= (others => '0'); -- reserved (r/-)
dmi_rsp_o.data(3 downto 0) <= "0001"; -- datacount (r/-): number of implemented data registers = 1

-- abstract command (-/w) --
when addr_command_c =>
dmi_rsp_o.data <= (others => '0'); -- register is write-only
-- -- abstract command (-/w) --
-- when addr_command_c =>
-- dmi_rsp_o.data <= (others => '0'); -- register is write-only

-- abstract command autoexec (r/w) --
when addr_abstractauto_c =>
dmi_rsp_o.data(00) <= dm_reg.abstractauto_autoexecdata; -- autoexecdata(0): read/write access to data0 triggers execution of program buffer
dmi_rsp_o.data(0) <= dm_reg.abstractauto_autoexecdata; -- autoexecdata(0): read/write access to data0 triggers execution of program buffer
dmi_rsp_o.data(16) <= dm_reg.abstractauto_autoexecprogbuf(0); -- autoexecprogbuf(0): read/write access to progbuf0 triggers execution of program buffer
dmi_rsp_o.data(17) <= dm_reg.abstractauto_autoexecprogbuf(1); -- autoexecprogbuf(1): read/write access to progbuf1 triggers execution of program buffer

-- next debug module (r/-) --
when addr_nextdm_c =>
dmi_rsp_o.data <= (others => '0'); -- this is the only DM
-- -- next debug module (r/-) --
-- when addr_nextdm_c =>
-- dmi_rsp_o.data <= (others => '0'); -- this is the only DM

-- abstract data 0 (r/w) --
when addr_data0_c =>
Expand All @@ -596,9 +596,9 @@ begin
when addr_progbuf1_c =>
if (LEGACY_MODE = true) then dmi_rsp_o.data <= dm_reg.progbuf(1); else dmi_rsp_o.data <= (others => '0'); end if; -- program buffer 1

-- system bus access control and status (r/-) --
when addr_sbcs_c =>
dmi_rsp_o.data <= (others => '0'); -- system bus access not implemented
-- -- system bus access control and status (r/-) --
-- when addr_sbcs_c =>
-- dmi_rsp_o.data <= (others => '0'); -- system bus access not implemented

-- halt summary 0 (r/-) --
when addr_haltsum0_c =>
Expand Down
49 changes: 17 additions & 32 deletions rtl/core/neorv32_debug_dtm.vhd
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Expand Up @@ -22,17 +22,16 @@ entity neorv32_debug_dtm is
);
port (
-- global control --
clk_i : in std_ulogic; -- global clock line
rstn_i : in std_ulogic; -- global reset line, low-active
clk_i : in std_ulogic; -- global clock line
rstn_i : in std_ulogic; -- global reset line, low-active
-- jtag connection --
jtag_trst_i : in std_ulogic;
jtag_tck_i : in std_ulogic;
jtag_tdi_i : in std_ulogic;
jtag_tdo_o : out std_ulogic;
jtag_tms_i : in std_ulogic;
jtag_tck_i : in std_ulogic;
jtag_tdi_i : in std_ulogic;
jtag_tdo_o : out std_ulogic;
jtag_tms_i : in std_ulogic;
-- debug module interface (DMI) --
dmi_req_o : out dmi_req_t; -- request
dmi_rsp_i : in dmi_rsp_t -- response
dmi_req_o : out dmi_req_t; -- request
dmi_rsp_i : in dmi_rsp_t -- response
);
end neorv32_debug_dtm;

Expand All @@ -51,16 +50,9 @@ architecture neorv32_debug_dtm_rtl of neorv32_debug_dtm is
-- tap JTAG signal synchronizer --
type tap_sync_t is record
-- internal --
trst_ff : std_ulogic_vector(2 downto 0);
tck_ff : std_ulogic_vector(2 downto 0);
tdi_ff : std_ulogic_vector(2 downto 0);
tms_ff : std_ulogic_vector(2 downto 0);
tck_ff, tdi_ff, tms_ff : std_ulogic_vector(2 downto 0);
-- external --
trst : std_ulogic;
tck_rising : std_ulogic;
tck_falling : std_ulogic;
tdi : std_ulogic;
tms : std_ulogic;
tck_rising, tck_falling, tdi, tms: std_ulogic;
end record;
signal tap_sync : tap_sync_t;

Expand Down Expand Up @@ -106,21 +98,16 @@ begin
tap_synchronizer: process(rstn_i, clk_i)
begin
if (rstn_i = '0') then
tap_sync.trst_ff <= (others => '0');
tap_sync.tck_ff <= (others => '0');
tap_sync.tdi_ff <= (others => '0');
tap_sync.tms_ff <= (others => '0');
tap_sync.tck_ff <= (others => '0');
tap_sync.tdi_ff <= (others => '0');
tap_sync.tms_ff <= (others => '0');
elsif rising_edge(clk_i) then
tap_sync.trst_ff <= tap_sync.trst_ff(1 downto 0) & jtag_trst_i;
tap_sync.tck_ff <= tap_sync.tck_ff( 1 downto 0) & jtag_tck_i;
tap_sync.tdi_ff <= tap_sync.tdi_ff( 1 downto 0) & jtag_tdi_i;
tap_sync.tms_ff <= tap_sync.tms_ff( 1 downto 0) & jtag_tms_i;
tap_sync.tck_ff <= tap_sync.tck_ff(1 downto 0) & jtag_tck_i;
tap_sync.tdi_ff <= tap_sync.tdi_ff(1 downto 0) & jtag_tdi_i;
tap_sync.tms_ff <= tap_sync.tms_ff(1 downto 0) & jtag_tms_i;
end if;
end process tap_synchronizer;

-- JTAG reset --
tap_sync.trst <= '0' when (tap_sync.trst_ff(2 downto 1) = "00") else '1';

-- JTAG clock edge --
tap_sync.tck_rising <= '1' when (tap_sync.tck_ff(2 downto 1) = "01") else '0';
tap_sync.tck_falling <= '1' when (tap_sync.tck_ff(2 downto 1) = "10") else '0';
Expand All @@ -139,9 +126,7 @@ begin
if (rstn_i = '0') then
tap_ctrl_state <= LOGIC_RESET;
elsif rising_edge(clk_i) then
if (tap_sync.trst = '0') then -- reset
tap_ctrl_state <= LOGIC_RESET;
elsif (tap_sync.tck_rising = '1') then -- clock pulse (evaluate TMS on the rising edge of TCK)
if (tap_sync.tck_rising = '1') then -- clock pulse (evaluate TMS on the rising edge of TCK)
case tap_ctrl_state is -- JTAG state machine
when LOGIC_RESET => if (tap_sync.tms = '0') then tap_ctrl_state <= RUN_IDLE; else tap_ctrl_state <= LOGIC_RESET; end if;
when RUN_IDLE => if (tap_sync.tms = '0') then tap_ctrl_state <= RUN_IDLE; else tap_ctrl_state <= DR_SCAN; end if;
Expand Down
3 changes: 1 addition & 2 deletions rtl/core/neorv32_package.vhd
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Expand Up @@ -29,7 +29,7 @@ package neorv32_package is

-- Architecture Constants -----------------------------------------------------------------
-- -------------------------------------------------------------------------------------------
constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01100000"; -- hardware version
constant hw_version_c : std_ulogic_vector(31 downto 0) := x"01100001"; -- hardware version
constant archid_c : natural := 19; -- official RISC-V architecture ID
constant XLEN : natural := 32; -- native data path width

Expand Down Expand Up @@ -809,7 +809,6 @@ package neorv32_package is
clk_i : in std_ulogic;
rstn_i : in std_ulogic;
-- JTAG on-chip debugger interface --
jtag_trst_i : in std_ulogic := 'H';
jtag_tck_i : in std_ulogic := 'L';
jtag_tdi_i : in std_ulogic := 'L';
jtag_tdo_o : out std_ulogic;
Expand Down
18 changes: 8 additions & 10 deletions rtl/core/neorv32_top.vhd
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Expand Up @@ -139,7 +139,6 @@ entity neorv32_top is
rstn_i : in std_ulogic; -- global reset, low-active, async

-- JTAG on-chip debugger interface (available if ON_CHIP_DEBUGGER_EN = true) --
jtag_trst_i : in std_ulogic := 'H'; -- low-active TAP reset (optional)
jtag_tck_i : in std_ulogic := 'L'; -- serial clock
jtag_tdi_i : in std_ulogic := 'L'; -- serial data input
jtag_tdo_o : out std_ulogic; -- serial data output
Expand Down Expand Up @@ -1640,15 +1639,14 @@ begin
IDCODE_MANID => JEDEC_ID
)
port map (
clk_i => clk_i,
rstn_i => rstn_ext,
jtag_trst_i => jtag_trst_i,
jtag_tck_i => jtag_tck_i,
jtag_tdi_i => jtag_tdi_i,
jtag_tdo_o => jtag_tdo_o,
jtag_tms_i => jtag_tms_i,
dmi_req_o => dmi_req,
dmi_rsp_i => dmi_rsp
clk_i => clk_i,
rstn_i => rstn_ext,
jtag_tck_i => jtag_tck_i,
jtag_tdi_i => jtag_tdi_i,
jtag_tdo_o => jtag_tdo_o,
jtag_tms_i => jtag_tms_i,
dmi_req_o => dmi_req,
dmi_rsp_i => dmi_rsp
);

-- On-Chip Debugger - Debug Module (DM) ---------------------------------------------------
Expand Down
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