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riscv-openocd/src/target/adi_v5_swd.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/***************************************************************************
*
* Copyright (C) 2010 by David Brownell
***************************************************************************/
/**
* @file
* Utilities to support ARM "Serial Wire Debug" (SWD), a low pin-count debug
* link protocol used in cases where JTAG is not wanted. This is coupled to
* recent versions of ARM's "CoreSight" debug framework. This specific code
* is a transport level interface, with "target/arm_adi_v5.[hc]" code
* understanding operation semantics, shared with the JTAG transport.
*
* Single DAP and multidrop-SWD support.
*
* for details, see "ARM IHI 0031A"
* ARM Debug Interface v5 Architecture Specification
* especially section 5.3 for SWD protocol
* and "ARM IHI 0074C" ARM Debug Interface Architecture Specification ADIv6.0
*
* On many chips (most current Cortex-M3 parts) SWD is a run-time alternative
* to JTAG. Boards may support one or both. There are also SWD-only chips,
* (using SW-DP not SWJ-DP).
*
* Even boards that also support JTAG can benefit from SWD support, because
* usually there's no way to access the SWO trace view mechanism in JTAG mode.
* That is, trace access may require SWD support.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "arm.h"
#include "arm_adi_v5.h"
#include <helper/time_support.h>
#include <transport/transport.h>
#include <jtag/interface.h>
#include <jtag/swd.h>
/* for debug, set do_sync to true to force synchronous transfers */
static bool do_sync;
static struct adiv5_dap *swd_multidrop_selected_dap;
static bool swd_multidrop_in_swd_state;
static int swd_queue_dp_write_inner(struct adiv5_dap *dap, unsigned int reg,
uint32_t data);
static int swd_send_sequence(struct adiv5_dap *dap, enum swd_special_seq seq)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
return swd->switch_seq(seq);
}
static void swd_finish_read(struct adiv5_dap *dap)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
if (dap->last_read) {
swd->read_reg(swd_cmd(true, false, DP_RDBUFF), dap->last_read, 0);
dap->last_read = NULL;
}
}
static void swd_clear_sticky_errors(struct adiv5_dap *dap)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
swd->write_reg(swd_cmd(false, false, DP_ABORT),
STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
}
static int swd_run_inner(struct adiv5_dap *dap)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
return swd->run();
}
static inline int check_sync(struct adiv5_dap *dap)
{
return do_sync ? swd_run_inner(dap) : ERROR_OK;
}
/** Select the DP register bank */
static int swd_queue_dp_bankselect(struct adiv5_dap *dap, unsigned int reg)
{
/* Only register address 0 (ADIv6 only) and 4 are banked. */
if (is_adiv6(dap) ? (reg & 0xf) > 4 : (reg & 0xf) != 4)
return ERROR_OK;
uint32_t sel = (reg >> 4) & DP_SELECT_DPBANK;
/* ADIv6 ensures DPBANKSEL = 0 after line reset */
if ((dap->select_valid || (is_adiv6(dap) && dap->select_dpbanksel_valid))
&& (sel == (dap->select & DP_SELECT_DPBANK)))
return ERROR_OK;
/* Use the AP part of dap->select regardless of dap->select_valid:
* if !dap->select_valid
* dap->select contains a speculative value likely going to be used
* in the following swd_queue_ap_bankselect() */
sel |= (uint32_t)(dap->select & SELECT_AP_MASK);
LOG_DEBUG_IO("DP BANK SELECT: %" PRIx32, sel);
/* dap->select cache gets updated in the following call */
return swd_queue_dp_write_inner(dap, DP_SELECT, sel);
}
static int swd_queue_dp_read_inner(struct adiv5_dap *dap, unsigned int reg,
uint32_t *data)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
int retval = swd_queue_dp_bankselect(dap, reg);
if (retval != ERROR_OK)
return retval;
swd->read_reg(swd_cmd(true, false, reg), data, 0);
return check_sync(dap);
}
static int swd_queue_dp_write_inner(struct adiv5_dap *dap, unsigned int reg,
uint32_t data)
{
int retval = ERROR_OK;
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
swd_finish_read(dap);
if (reg == DP_SELECT) {
dap->select = data | (dap->select & (0xffffffffull << 32));
swd->write_reg(swd_cmd(false, false, reg), data, 0);
retval = check_sync(dap);
dap->select_valid = (retval == ERROR_OK);
dap->select_dpbanksel_valid = dap->select_valid;
return retval;
}
if (reg == DP_SELECT1)
dap->select = ((uint64_t)data << 32) | (dap->select & 0xffffffffull);
/* DP_ABORT write is not banked.
* Prevent writing DP_SELECT before as it would fail on locked up DP */
if (reg != DP_ABORT)
retval = swd_queue_dp_bankselect(dap, reg);
if (retval == ERROR_OK) {
swd->write_reg(swd_cmd(false, false, reg), data, 0);
retval = check_sync(dap);
}
if (reg == DP_SELECT1)
dap->select1_valid = (retval == ERROR_OK);
return retval;
}
static int swd_multidrop_select_inner(struct adiv5_dap *dap, uint32_t *dpidr_ptr,
uint32_t *dlpidr_ptr, bool clear_sticky)
{
int retval;
uint32_t dpidr, dlpidr;
assert(dap_is_multidrop(dap));
/* Send JTAG_TO_DORMANT and DORMANT_TO_SWD just once
* and then use shorter LINE_RESET until communication fails */
if (!swd_multidrop_in_swd_state) {
swd_send_sequence(dap, JTAG_TO_DORMANT);
swd_send_sequence(dap, DORMANT_TO_SWD);
} else {
swd_send_sequence(dap, LINE_RESET);
}
/*
* Zero dap->select and set dap->select_dpbanksel_valid
* to skip the write to DP_SELECT before DPIDR read, avoiding
* the protocol error.
* Clear the other validity flags because the rest of the DP
* SELECT and SELECT1 registers is unknown after line reset.
*/
dap->select = 0;
dap->select_dpbanksel_valid = true;
dap->select_valid = false;
dap->select1_valid = false;
retval = swd_queue_dp_write_inner(dap, DP_TARGETSEL, dap->multidrop_targetsel);
if (retval != ERROR_OK)
return retval;
retval = swd_queue_dp_read_inner(dap, DP_DPIDR, &dpidr);
if (retval != ERROR_OK)
return retval;
if (clear_sticky) {
/* Clear all sticky errors (including ORUN) */
swd_clear_sticky_errors(dap);
} else {
/* Ideally just clear ORUN flag which is set by reset */
retval = swd_queue_dp_write_inner(dap, DP_ABORT, ORUNERRCLR);
if (retval != ERROR_OK)
return retval;
}
retval = swd_queue_dp_read_inner(dap, DP_DLPIDR, &dlpidr);
if (retval != ERROR_OK)
return retval;
retval = swd_run_inner(dap);
if (retval != ERROR_OK)
return retval;
if ((dpidr & DP_DPIDR_VERSION_MASK) < (2UL << DP_DPIDR_VERSION_SHIFT)) {
LOG_INFO("Read DPIDR 0x%08" PRIx32
" has version < 2. A non multidrop capable device connected?",
dpidr);
return ERROR_FAIL;
}
/* TODO: check TARGETID if DLIPDR is same for more than one DP */
uint32_t expected_dlpidr = DP_DLPIDR_PROTVSN |
(dap->multidrop_targetsel & DP_TARGETSEL_INSTANCEID_MASK);
if (dlpidr != expected_dlpidr) {
LOG_INFO("Read incorrect DLPIDR 0x%08" PRIx32
" (possibly CTRL/STAT value)",
dlpidr);
return ERROR_FAIL;
}
LOG_DEBUG_IO("Selected DP_TARGETSEL 0x%08" PRIx32, dap->multidrop_targetsel);
swd_multidrop_selected_dap = dap;
swd_multidrop_in_swd_state = true;
if (dpidr_ptr)
*dpidr_ptr = dpidr;
if (dlpidr_ptr)
*dlpidr_ptr = dlpidr;
return retval;
}
static int swd_multidrop_select(struct adiv5_dap *dap)
{
if (!dap_is_multidrop(dap))
return ERROR_OK;
if (swd_multidrop_selected_dap == dap)
return ERROR_OK;
int retval = ERROR_OK;
for (unsigned int retry = 0; ; retry++) {
bool clear_sticky = retry > 0;
retval = swd_multidrop_select_inner(dap, NULL, NULL, clear_sticky);
if (retval == ERROR_OK)
break;
swd_multidrop_selected_dap = NULL;
if (retry > 3) {
LOG_ERROR("Failed to select multidrop %s", adiv5_dap_name(dap));
dap->do_reconnect = true;
return retval;
}
LOG_DEBUG("Failed to select multidrop %s, retrying...",
adiv5_dap_name(dap));
}
dap->do_reconnect = false;
return retval;
}
static int swd_connect_multidrop(struct adiv5_dap *dap)
{
int retval;
uint32_t dpidr = 0xdeadbeef;
uint32_t dlpidr = 0xdeadbeef;
int64_t timeout = timeval_ms() + 500;
do {
/* Do not make any assumptions about SWD state in case of reconnect */
if (dap->do_reconnect)
swd_multidrop_in_swd_state = false;
/* Clear link state, including the SELECT cache. */
dap->do_reconnect = false;
dap_invalidate_cache(dap);
swd_multidrop_selected_dap = NULL;
retval = swd_multidrop_select_inner(dap, &dpidr, &dlpidr, true);
if (retval == ERROR_OK)
break;
swd_multidrop_in_swd_state = false;
alive_sleep(1);
} while (timeval_ms() < timeout);
if (retval != ERROR_OK) {
swd_multidrop_selected_dap = NULL;
LOG_ERROR("Failed to connect multidrop %s", adiv5_dap_name(dap));
return retval;
}
swd_multidrop_in_swd_state = true;
LOG_INFO("SWD DPIDR 0x%08" PRIx32 ", DLPIDR 0x%08" PRIx32,
dpidr, dlpidr);
return retval;
}
static int swd_connect_single(struct adiv5_dap *dap)
{
int retval;
uint32_t dpidr = 0xdeadbeef;
int64_t timeout = timeval_ms() + 500;
do {
if (dap->switch_through_dormant) {
swd_send_sequence(dap, JTAG_TO_DORMANT);
swd_send_sequence(dap, DORMANT_TO_SWD);
} else {
swd_send_sequence(dap, JTAG_TO_SWD);
}
/* Clear link state, including the SELECT cache. */
dap->do_reconnect = false;
dap_invalidate_cache(dap);
/* The sequences to enter in SWD (JTAG_TO_SWD and DORMANT_TO_SWD) end
* with a SWD line reset sequence (50 clk with SWDIO high).
* From ARM IHI 0031F ADIv5.2 and ARM IHI 0074C ADIv6.0,
* chapter B4.3.3 "Connection and line reset sequence":
* - DPv3 (ADIv6) only: line reset sets DP_SELECT_DPBANK to zero;
* - read of DP_DPIDR takes the connection out of reset;
* - write of DP_TARGETSEL keeps the connection in reset;
* - other accesses return protocol error (SWDIO not driven by target).
*
* dap_invalidate_cache() sets dap->select to zero and all validity
* flags to invalid. Set dap->select_dpbanksel_valid only
* to skip the write to DP_SELECT, avoiding the protocol error.
* Read DP_DPIDR to get out of reset.
*/
dap->select_dpbanksel_valid = true;
retval = swd_queue_dp_read_inner(dap, DP_DPIDR, &dpidr);
if (retval == ERROR_OK) {
retval = swd_run_inner(dap);
if (retval == ERROR_OK)
break;
}
alive_sleep(1);
dap->switch_through_dormant = !dap->switch_through_dormant;
} while (timeval_ms() < timeout);
if (retval != ERROR_OK) {
LOG_ERROR("Error connecting DP: cannot read IDR");
return retval;
}
LOG_INFO("SWD DPIDR 0x%08" PRIx32, dpidr);
do {
dap->do_reconnect = false;
/* force clear all sticky faults */
swd_clear_sticky_errors(dap);
retval = swd_run_inner(dap);
if (retval != ERROR_WAIT)
break;
alive_sleep(10);
} while (timeval_ms() < timeout);
return retval;
}
static int swd_pre_connect(struct adiv5_dap *dap)
{
swd_multidrop_in_swd_state = false;
return ERROR_OK;
}
static int swd_connect(struct adiv5_dap *dap)
{
int status;
/* FIXME validate transport config ... is the
* configured DAP present (check IDCODE)?
*/
/* Check if we should reset srst already when connecting, but not if reconnecting. */
if (!dap->do_reconnect) {
enum reset_types jtag_reset_config = jtag_get_reset_config();
if (jtag_reset_config & RESET_CNCT_UNDER_SRST) {
if (jtag_reset_config & RESET_SRST_NO_GATING)
adapter_assert_reset();
else
LOG_WARNING("\'srst_nogate\' reset_config option is required");
}
}
if (dap_is_multidrop(dap))
status = swd_connect_multidrop(dap);
else
status = swd_connect_single(dap);
/* IHI 0031E B4.3.2:
* "A WAIT response must not be issued to the ...
* ... writes to the ABORT register"
* swd_clear_sticky_errors() writes to the ABORT register only.
*
* Unfortunately at least Microchip SAMD51/E53/E54 returns WAIT
* in a corner case. Just try if ABORT resolves the problem.
*/
if (status == ERROR_WAIT) {
LOG_WARNING("Connecting DP: stalled AP operation, issuing ABORT");
dap->do_reconnect = false;
status = swd_queue_dp_write_inner(dap, DP_ABORT,
DAPABORT | STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR);
if (status == ERROR_OK)
status = swd_run_inner(dap);
}
if (status == ERROR_OK)
status = dap_dp_init(dap);
return status;
}
static int swd_check_reconnect(struct adiv5_dap *dap)
{
if (dap->do_reconnect)
return swd_connect(dap);
return ERROR_OK;
}
static int swd_queue_ap_abort(struct adiv5_dap *dap, uint8_t *ack)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
/* TODO: Send DAPABORT in swd_multidrop_select_inner()
* in the case the multidrop dap is not selected?
* swd_queue_ap_abort() is not currently used anyway...
*/
int retval = swd_multidrop_select(dap);
if (retval != ERROR_OK)
return retval;
swd->write_reg(swd_cmd(false, false, DP_ABORT),
DAPABORT | STKCMPCLR | STKERRCLR | WDERRCLR | ORUNERRCLR, 0);
return check_sync(dap);
}
static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
uint32_t *data)
{
int retval = swd_check_reconnect(dap);
if (retval != ERROR_OK)
return retval;
retval = swd_multidrop_select(dap);
if (retval != ERROR_OK)
return retval;
return swd_queue_dp_read_inner(dap, reg, data);
}
static int swd_queue_dp_write(struct adiv5_dap *dap, unsigned reg,
uint32_t data)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
int retval = swd_check_reconnect(dap);
if (retval != ERROR_OK)
return retval;
retval = swd_multidrop_select(dap);
if (retval != ERROR_OK)
return retval;
return swd_queue_dp_write_inner(dap, reg, data);
}
/** Select the AP register bank */
static int swd_queue_ap_bankselect(struct adiv5_ap *ap, unsigned reg)
{
int retval;
struct adiv5_dap *dap = ap->dap;
uint64_t sel;
if (is_adiv6(dap))
sel = ap->ap_num | (reg & 0x00000FF0);
else
sel = (ap->ap_num << 24) | (reg & ADIV5_DP_SELECT_APBANK);
uint64_t sel_diff = (sel ^ dap->select) & SELECT_AP_MASK;
bool set_select = !dap->select_valid || (sel_diff & 0xffffffffull);
bool set_select1 = is_adiv6(dap) && dap->asize > 32
&& (!dap->select1_valid
|| sel_diff & (0xffffffffull << 32));
if (set_select && set_select1) {
/* Prepare DP bank for DP_SELECT1 now to save one write */
sel |= (DP_SELECT1 & 0x000000f0) >> 4;
} else {
/* Use the DP part of dap->select regardless of dap->select_valid:
* if !dap->select_valid
* dap->select contains a speculative value likely going to be used
* in the following swd_queue_dp_bankselect().
* Moreover dap->select_valid should never be false here as a DP bank
* is always selected before selecting an AP bank */
sel |= dap->select & DP_SELECT_DPBANK;
}
if (set_select) {
LOG_DEBUG_IO("AP BANK SELECT: %" PRIx32, (uint32_t)sel);
retval = swd_queue_dp_write(dap, DP_SELECT, (uint32_t)sel);
if (retval != ERROR_OK)
return retval;
}
if (set_select1) {
LOG_DEBUG_IO("AP BANK SELECT1: %" PRIx32, (uint32_t)(sel >> 32));
retval = swd_queue_dp_write(dap, DP_SELECT1, (uint32_t)(sel >> 32));
if (retval != ERROR_OK)
return retval;
}
return ERROR_OK;
}
static int swd_queue_ap_read(struct adiv5_ap *ap, unsigned reg,
uint32_t *data)
{
struct adiv5_dap *dap = ap->dap;
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
int retval = swd_check_reconnect(dap);
if (retval != ERROR_OK)
return retval;
retval = swd_multidrop_select(dap);
if (retval != ERROR_OK)
return retval;
retval = swd_queue_ap_bankselect(ap, reg);
if (retval != ERROR_OK)
return retval;
swd->read_reg(swd_cmd(true, true, reg), dap->last_read, ap->memaccess_tck);
dap->last_read = data;
return check_sync(dap);
}
static int swd_queue_ap_write(struct adiv5_ap *ap, unsigned reg,
uint32_t data)
{
struct adiv5_dap *dap = ap->dap;
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
assert(swd);
int retval = swd_check_reconnect(dap);
if (retval != ERROR_OK)
return retval;
retval = swd_multidrop_select(dap);
if (retval != ERROR_OK)
return retval;
swd_finish_read(dap);
retval = swd_queue_ap_bankselect(ap, reg);
if (retval != ERROR_OK)
return retval;
swd->write_reg(swd_cmd(false, true, reg), data, ap->memaccess_tck);
return check_sync(dap);
}
/** Executes all queued DAP operations. */
static int swd_run(struct adiv5_dap *dap)
{
int retval = swd_multidrop_select(dap);
if (retval != ERROR_OK)
return retval;
swd_finish_read(dap);
retval = swd_run_inner(dap);
if (retval != ERROR_OK) {
/* fault response */
dap->do_reconnect = true;
}
return retval;
}
/** Put the SWJ-DP back to JTAG mode */
static void swd_quit(struct adiv5_dap *dap)
{
const struct swd_driver *swd = adiv5_dap_swd_driver(dap);
static bool done;
/* There is no difference if the sequence is sent at the last
* or the first swd_quit() call, send it just once */
if (done)
return;
done = true;
if (dap_is_multidrop(dap)) {
/* Emit the switch seq to dormant state regardless the state mirrored
* in swd_multidrop_in_swd_state. Doing so ensures robust operation
* in the case the variable is out of sync.
* Sending SWD_TO_DORMANT makes no change if the DP is already dormant. */
swd->switch_seq(SWD_TO_DORMANT);
swd_multidrop_in_swd_state = false;
/* Revisit!
* Leaving DPs in dormant state was tested and offers some safety
* against DPs mismatch in case of unintentional use of non-multidrop SWD.
* To put SWJ-DPs to power-on state issue
* swd->switch_seq(DORMANT_TO_JTAG);
*/
} else {
if (dap->switch_through_dormant) {
swd->switch_seq(SWD_TO_DORMANT);
swd->switch_seq(DORMANT_TO_JTAG);
} else {
swd->switch_seq(SWD_TO_JTAG);
}
}
/* flush the queue to shift out the sequence before exit */
swd->run();
}
const struct dap_ops swd_dap_ops = {
.pre_connect_init = swd_pre_connect,
.connect = swd_connect,
.send_sequence = swd_send_sequence,
.queue_dp_read = swd_queue_dp_read,
.queue_dp_write = swd_queue_dp_write,
.queue_ap_read = swd_queue_ap_read,
.queue_ap_write = swd_queue_ap_write,
.queue_ap_abort = swd_queue_ap_abort,
.run = swd_run,
.quit = swd_quit,
};
static const struct command_registration swd_commands[] = {
{
/*
* Set up SWD and JTAG targets identically, unless/until
* infrastructure improves ... meanwhile, ignore all
* JTAG-specific stuff like IR length for SWD.
*
* REVISIT can we verify "just one SWD DAP" here/early?
*/
.name = "newdap",
.handler = handle_jtag_newtap,
.mode = COMMAND_CONFIG,
.help = "declare a new SWD DAP",
.usage = "basename dap_type ['-irlen' count] "
"['-enable'|'-disable'] "
"['-expected_id' number] "
"['-ignore-version'] "
"['-ignore-bypass'] "
"['-ircapture' number] "
"['-ir-bypass' number] "
"['-mask' number]",
},
COMMAND_REGISTRATION_DONE
};
static const struct command_registration swd_handlers[] = {
{
.name = "swd",
.mode = COMMAND_ANY,
.help = "SWD command group",
.chain = swd_commands,
.usage = "",
},
COMMAND_REGISTRATION_DONE
};
static int swd_select(struct command_context *ctx)
{
/* FIXME: only place where global 'adapter_driver' is still needed */
extern struct adapter_driver *adapter_driver;
const struct swd_driver *swd = adapter_driver->swd_ops;
int retval;
retval = register_commands(ctx, NULL, swd_handlers);
if (retval != ERROR_OK)
return retval;
/* be sure driver is in SWD mode; start
* with hardware default TRN (1), it can be changed later
*/
if (!swd || !swd->read_reg || !swd->write_reg || !swd->init) {
LOG_DEBUG("no SWD driver?");
return ERROR_FAIL;
}
retval = swd->init();
if (retval != ERROR_OK) {
LOG_DEBUG("can't init SWD driver");
return retval;
}
return retval;
}
static int swd_init(struct command_context *ctx)
{
/* nothing done here, SWD is initialized
* together with the DAP */
return ERROR_OK;
}
static struct transport swd_transport = {
.name = "swd",
.select = swd_select,
.init = swd_init,
};
static void swd_constructor(void) __attribute__((constructor));
static void swd_constructor(void)
{
transport_register(&swd_transport);
}
/** Returns true if the current debug session
* is using SWD as its transport.
*/
bool transport_is_swd(void)
{
return get_current_transport() == &swd_transport;
}
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