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openocd/src/jtag/drivers/bitbang.c

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/***************************************************************************
* Copyright (C) 2005 by Dominic Rath *
* Dominic.Rath@gmx.de *
* *
* Copyright (C) 2007,2008 Øyvind Harboe *
* oyvind.harboe@zylin.com *
***************************************************************************/
/* 2014-12: Addition of the SWD protocol support is based on the initial work
* by Paul Fertser and modifications by Jean-Christian de Rivaz. */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "bitbang.h"
#include <jtag/interface.h>
#include <jtag/commands.h>
/**
* Function bitbang_stableclocks
* issues a number of clock cycles while staying in a stable state.
* Because the TMS value required to stay in the RESET state is a 1, whereas
* the TMS value required to stay in any of the other stable states is a 0,
* this function checks the current stable state to decide on the value of TMS
* to use.
*/
static int bitbang_stableclocks(int num_cycles);
static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk);
struct bitbang_interface *bitbang_interface;
/* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
*
* Set this to 1 and str912 reset halt will fail.
*
* If someone can submit a patch with an explanation it will be greatly
* appreciated, but as far as I can tell (ØH) DCLK is generated upon
* clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
* The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
* state". With hardware there is no such thing as *while* in a state. There
* are only edges. So clk => 0 is in fact a very subtle state transition that
* happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
*
* For "reset halt" the last thing that happens before srst is asserted
* is that the breakpoint is set up. If DCLK is not wiggled one last
* time before the reset, then the breakpoint is not set up and
* "reset halt" will fail to halt.
*
*/
#define CLOCK_IDLE() 0
/* The bitbang driver leaves the TCK 0 when in idle */
static void bitbang_end_state(tap_state_t state)
{
assert(tap_is_state_stable(state));
tap_set_end_state(state);
}
static int bitbang_state_move(int skip)
{
int i = 0, tms = 0;
uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
for (i = skip; i < tms_count; i++) {
tms = (tms_scan >> i) & 1;
if (bitbang_interface->write(0, tms, 0) != ERROR_OK)
return ERROR_FAIL;
if (bitbang_interface->write(1, tms, 0) != ERROR_OK)
return ERROR_FAIL;
}
if (bitbang_interface->write(CLOCK_IDLE(), tms, 0) != ERROR_OK)
return ERROR_FAIL;
tap_set_state(tap_get_end_state());
return ERROR_OK;
}
/**
* Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
* (or SWD) state machine.
*/
static int bitbang_execute_tms(struct jtag_command *cmd)
{
unsigned num_bits = cmd->cmd.tms->num_bits;
const uint8_t *bits = cmd->cmd.tms->bits;
LOG_DEBUG_IO("TMS: %d bits", num_bits);
int tms = 0;
for (unsigned i = 0; i < num_bits; i++) {
tms = ((bits[i/8] >> (i % 8)) & 1);
if (bitbang_interface->write(0, tms, 0) != ERROR_OK)
return ERROR_FAIL;
if (bitbang_interface->write(1, tms, 0) != ERROR_OK)
return ERROR_FAIL;
}
if (bitbang_interface->write(CLOCK_IDLE(), tms, 0) != ERROR_OK)
return ERROR_FAIL;
return ERROR_OK;
}
static int bitbang_path_move(struct pathmove_command *cmd)
{
int num_states = cmd->num_states;
int state_count;
int tms = 0;
state_count = 0;
while (num_states) {
if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
tms = 0;
else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
tms = 1;
else {
LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition",
tap_state_name(tap_get_state()),
tap_state_name(cmd->path[state_count]));
exit(-1);
}
if (bitbang_interface->write(0, tms, 0) != ERROR_OK)
return ERROR_FAIL;
if (bitbang_interface->write(1, tms, 0) != ERROR_OK)
return ERROR_FAIL;
tap_set_state(cmd->path[state_count]);
state_count++;
num_states--;
}
if (bitbang_interface->write(CLOCK_IDLE(), tms, 0) != ERROR_OK)
return ERROR_FAIL;
tap_set_end_state(tap_get_state());
return ERROR_OK;
}
static int bitbang_runtest(int num_cycles)
{
int i;
tap_state_t saved_end_state = tap_get_end_state();
/* only do a state_move when we're not already in IDLE */
if (tap_get_state() != TAP_IDLE) {
bitbang_end_state(TAP_IDLE);
if (bitbang_state_move(0) != ERROR_OK)
return ERROR_FAIL;
}
/* execute num_cycles */
for (i = 0; i < num_cycles; i++) {
if (bitbang_interface->write(0, 0, 0) != ERROR_OK)
return ERROR_FAIL;
if (bitbang_interface->write(1, 0, 0) != ERROR_OK)
return ERROR_FAIL;
}
if (bitbang_interface->write(CLOCK_IDLE(), 0, 0) != ERROR_OK)
return ERROR_FAIL;
/* finish in end_state */
bitbang_end_state(saved_end_state);
if (tap_get_state() != tap_get_end_state())
if (bitbang_state_move(0) != ERROR_OK)
return ERROR_FAIL;
return ERROR_OK;
}
static int bitbang_stableclocks(int num_cycles)
{
int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
int i;
/* send num_cycles clocks onto the cable */
for (i = 0; i < num_cycles; i++) {
if (bitbang_interface->write(1, tms, 0) != ERROR_OK)
return ERROR_FAIL;
if (bitbang_interface->write(0, tms, 0) != ERROR_OK)
return ERROR_FAIL;
}
return ERROR_OK;
}
static int bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer,
unsigned scan_size)
{
tap_state_t saved_end_state = tap_get_end_state();
unsigned bit_cnt;
if (!((!ir_scan &&
(tap_get_state() == TAP_DRSHIFT)) ||
(ir_scan && (tap_get_state() == TAP_IRSHIFT)))) {
if (ir_scan)
bitbang_end_state(TAP_IRSHIFT);
else
bitbang_end_state(TAP_DRSHIFT);
if (bitbang_state_move(0) != ERROR_OK)
return ERROR_FAIL;
bitbang_end_state(saved_end_state);
}
size_t buffered = 0;
for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++) {
int tms = (bit_cnt == scan_size-1) ? 1 : 0;
int tdi;
int bytec = bit_cnt/8;
int bcval = 1 << (bit_cnt % 8);
/* if we're just reading the scan, but don't care about the output
* default to outputting 'low', this also makes valgrind traces more readable,
* as it removes the dependency on an uninitialised value
*/
tdi = 0;
if ((type != SCAN_IN) && (buffer[bytec] & bcval))
tdi = 1;
if (bitbang_interface->write(0, tms, tdi) != ERROR_OK)
return ERROR_FAIL;
if (type != SCAN_OUT) {
if (bitbang_interface->buf_size) {
if (bitbang_interface->sample() != ERROR_OK)
return ERROR_FAIL;
buffered++;
} else {
switch (bitbang_interface->read()) {
case BB_LOW:
buffer[bytec] &= ~bcval;
break;
case BB_HIGH:
buffer[bytec] |= bcval;
break;
default:
return ERROR_FAIL;
}
}
}
if (bitbang_interface->write(1, tms, tdi) != ERROR_OK)
return ERROR_FAIL;
if (type != SCAN_OUT && bitbang_interface->buf_size &&
(buffered == bitbang_interface->buf_size ||
bit_cnt == scan_size - 1)) {
for (unsigned i = bit_cnt + 1 - buffered; i <= bit_cnt; i++) {
switch (bitbang_interface->read_sample()) {
case BB_LOW:
buffer[i/8] &= ~(1 << (i % 8));
break;
case BB_HIGH:
buffer[i/8] |= 1 << (i % 8);
break;
default:
return ERROR_FAIL;
}
}
buffered = 0;
}
}
if (tap_get_state() != tap_get_end_state()) {
/* we *KNOW* the above loop transitioned out of
* the shift state, so we skip the first state
* and move directly to the end state.
*/
if (bitbang_state_move(1) != ERROR_OK)
return ERROR_FAIL;
}
return ERROR_OK;
}
int bitbang_execute_queue(void)
{
struct jtag_command *cmd = jtag_command_queue; /* currently processed command */
int scan_size;
enum scan_type type;
uint8_t *buffer;
int retval;
if (!bitbang_interface) {
LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
exit(-1);
}
/* return ERROR_OK, unless a jtag_read_buffer returns a failed check
* that wasn't handled by a caller-provided error handler
*/
retval = ERROR_OK;
if (bitbang_interface->blink) {
if (bitbang_interface->blink(1) != ERROR_OK)
return ERROR_FAIL;
}
while (cmd) {
switch (cmd->type) {
case JTAG_RUNTEST:
LOG_DEBUG_IO("runtest %i cycles, end in %s",
cmd->cmd.runtest->num_cycles,
tap_state_name(cmd->cmd.runtest->end_state));
bitbang_end_state(cmd->cmd.runtest->end_state);
if (bitbang_runtest(cmd->cmd.runtest->num_cycles) != ERROR_OK)
return ERROR_FAIL;
break;
case JTAG_STABLECLOCKS:
/* this is only allowed while in a stable state. A check for a stable
* state was done in jtag_add_clocks()
*/
if (bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles) != ERROR_OK)
return ERROR_FAIL;
break;
case JTAG_TLR_RESET:
LOG_DEBUG_IO("statemove end in %s",
tap_state_name(cmd->cmd.statemove->end_state));
bitbang_end_state(cmd->cmd.statemove->end_state);
if (bitbang_state_move(0) != ERROR_OK)
return ERROR_FAIL;
break;
case JTAG_PATHMOVE:
LOG_DEBUG_IO("pathmove: %i states, end in %s",
cmd->cmd.pathmove->num_states,
tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
if (bitbang_path_move(cmd->cmd.pathmove) != ERROR_OK)
return ERROR_FAIL;
break;
case JTAG_SCAN:
bitbang_end_state(cmd->cmd.scan->end_state);
scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
LOG_DEBUG_IO("%s scan %d bits; end in %s",
(cmd->cmd.scan->ir_scan) ? "IR" : "DR",
scan_size,
tap_state_name(cmd->cmd.scan->end_state));
type = jtag_scan_type(cmd->cmd.scan);
if (bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer,
scan_size) != ERROR_OK)
return ERROR_FAIL;
if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
retval = ERROR_JTAG_QUEUE_FAILED;
free(buffer);
break;
case JTAG_SLEEP:
LOG_DEBUG_IO("sleep %" PRIu32, cmd->cmd.sleep->us);
jtag_sleep(cmd->cmd.sleep->us);
break;
case JTAG_TMS:
retval = bitbang_execute_tms(cmd);
break;
default:
LOG_ERROR("BUG: unknown JTAG command type encountered");
exit(-1);
}
cmd = cmd->next;
}
if (bitbang_interface->blink) {
if (bitbang_interface->blink(0) != ERROR_OK)
return ERROR_FAIL;
}
return retval;
}
static int queued_retval;
static int bitbang_swd_init(void)
{
LOG_DEBUG("bitbang_swd_init");
return ERROR_OK;
}
static void bitbang_swd_exchange(bool rnw, uint8_t buf[], unsigned int offset, unsigned int bit_cnt)
{
LOG_DEBUG("bitbang_swd_exchange");
if (bitbang_interface->blink) {
/* FIXME: we should manage errors */
bitbang_interface->blink(1);
}
for (unsigned int i = offset; i < bit_cnt + offset; i++) {
int bytec = i/8;
int bcval = 1 << (i % 8);
int swdio = !rnw && (buf[bytec] & bcval);
bitbang_interface->swd_write(0, swdio);
if (rnw && buf) {
if (bitbang_interface->swdio_read())
buf[bytec] |= bcval;
else
buf[bytec] &= ~bcval;
}
bitbang_interface->swd_write(1, swdio);
}
if (bitbang_interface->blink) {
/* FIXME: we should manage errors */
bitbang_interface->blink(0);
}
}
static int bitbang_swd_switch_seq(enum swd_special_seq seq)
{
LOG_DEBUG("bitbang_swd_switch_seq");
switch (seq) {
case LINE_RESET:
LOG_DEBUG("SWD line reset");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_line_reset, 0, swd_seq_line_reset_len);
break;
case JTAG_TO_SWD:
LOG_DEBUG("JTAG-to-SWD");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_jtag_to_swd, 0, swd_seq_jtag_to_swd_len);
break;
case JTAG_TO_DORMANT:
LOG_DEBUG("JTAG-to-DORMANT");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_jtag_to_dormant, 0, swd_seq_jtag_to_dormant_len);
break;
case SWD_TO_JTAG:
LOG_DEBUG("SWD-to-JTAG");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_swd_to_jtag, 0, swd_seq_swd_to_jtag_len);
break;
case SWD_TO_DORMANT:
LOG_DEBUG("SWD-to-DORMANT");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_swd_to_dormant, 0, swd_seq_swd_to_dormant_len);
break;
case DORMANT_TO_SWD:
LOG_DEBUG("DORMANT-to-SWD");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_dormant_to_swd, 0, swd_seq_dormant_to_swd_len);
break;
case DORMANT_TO_JTAG:
LOG_DEBUG("DORMANT-to-JTAG");
bitbang_swd_exchange(false, (uint8_t *)swd_seq_dormant_to_jtag, 0, swd_seq_dormant_to_jtag_len);
break;
default:
LOG_ERROR("Sequence %d not supported", seq);
return ERROR_FAIL;
}
return ERROR_OK;
}
static void swd_clear_sticky_errors(void)
{
bitbang_swd_write_reg(swd_cmd(false, false, DP_ABORT),
STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
}
static void bitbang_swd_read_reg(uint8_t cmd, uint32_t *value, uint32_t ap_delay_clk)
{
LOG_DEBUG("bitbang_swd_read_reg");
assert(cmd & SWD_CMD_RNW);
if (queued_retval != ERROR_OK) {
LOG_DEBUG("Skip bitbang_swd_read_reg because queued_retval=%d", queued_retval);
return;
}
for (;;) {
uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)];
cmd |= SWD_CMD_START | SWD_CMD_PARK;
bitbang_swd_exchange(false, &cmd, 0, 8);
bitbang_interface->swdio_drive(false);
bitbang_swd_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 32 + 1 + 1);
bitbang_interface->swdio_drive(true);
int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
uint32_t data = buf_get_u32(trn_ack_data_parity_trn, 1 + 3, 32);
int parity = buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 32, 1);
LOG_DEBUG("%s %s read reg %X = %08"PRIx32,
ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
cmd & SWD_CMD_APNDP ? "AP" : "DP",
(cmd & SWD_CMD_A32) >> 1,
data);
if (ack == SWD_ACK_WAIT) {
swd_clear_sticky_errors();
continue;
} else if (ack != SWD_ACK_OK) {
queued_retval = swd_ack_to_error_code(ack);
return;
}
if (parity != parity_u32(data)) {
LOG_ERROR("Wrong parity detected");
queued_retval = ERROR_FAIL;
return;
}
if (value)
*value = data;
if (cmd & SWD_CMD_APNDP)
bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
return;
}
}
static void bitbang_swd_write_reg(uint8_t cmd, uint32_t value, uint32_t ap_delay_clk)
{
LOG_DEBUG("bitbang_swd_write_reg");
assert(!(cmd & SWD_CMD_RNW));
if (queued_retval != ERROR_OK) {
LOG_DEBUG("Skip bitbang_swd_write_reg because queued_retval=%d", queued_retval);
return;
}
/* Devices do not reply to DP_TARGETSEL write cmd, ignore received ack */
bool check_ack = swd_cmd_returns_ack(cmd);
/* init the array to silence scan-build */
uint8_t trn_ack_data_parity_trn[DIV_ROUND_UP(4 + 3 + 32 + 1 + 4, 8)] = {0};
for (;;) {
buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32, value);
buf_set_u32(trn_ack_data_parity_trn, 1 + 3 + 1 + 32, 1, parity_u32(value));
cmd |= SWD_CMD_START | SWD_CMD_PARK;
bitbang_swd_exchange(false, &cmd, 0, 8);
bitbang_interface->swdio_drive(false);
bitbang_swd_exchange(true, trn_ack_data_parity_trn, 0, 1 + 3 + 1);
bitbang_interface->swdio_drive(true);
bitbang_swd_exchange(false, trn_ack_data_parity_trn, 1 + 3 + 1, 32 + 1);
int ack = buf_get_u32(trn_ack_data_parity_trn, 1, 3);
LOG_DEBUG("%s%s %s write reg %X = %08"PRIx32,
check_ack ? "" : "ack ignored ",
ack == SWD_ACK_OK ? "OK" : ack == SWD_ACK_WAIT ? "WAIT" : ack == SWD_ACK_FAULT ? "FAULT" : "JUNK",
cmd & SWD_CMD_APNDP ? "AP" : "DP",
(cmd & SWD_CMD_A32) >> 1,
buf_get_u32(trn_ack_data_parity_trn, 1 + 3 + 1, 32));
if (check_ack) {
if (ack == SWD_ACK_WAIT) {
swd_clear_sticky_errors();
continue;
} else if (ack != SWD_ACK_OK) {
queued_retval = swd_ack_to_error_code(ack);
return;
}
}
if (cmd & SWD_CMD_APNDP)
bitbang_swd_exchange(true, NULL, 0, ap_delay_clk);
return;
}
}
static int bitbang_swd_run_queue(void)
{
LOG_DEBUG("bitbang_swd_run_queue");
/* A transaction must be followed by another transaction or at least 8 idle cycles to
* ensure that data is clocked through the AP. */
bitbang_swd_exchange(true, NULL, 0, 8);
int retval = queued_retval;
queued_retval = ERROR_OK;
LOG_DEBUG("SWD queue return value: %02x", retval);
return retval;
}
const struct swd_driver bitbang_swd = {
.init = bitbang_swd_init,
.switch_seq = bitbang_swd_switch_seq,
.read_reg = bitbang_swd_read_reg,
.write_reg = bitbang_swd_write_reg,
.run = bitbang_swd_run_queue,
};
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