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- /***************************************************************************
- *
- * Copyright (C) 2010 by David Brownell
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the
- * Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- ***************************************************************************/
-
- /**
- * @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 support only.
- *
- * for details, see "ARM IHI 0031A"
- * ARM Debug Interface v5 Architecture Specification
- * especially section 5.3 for SWD protocol
- *
- * 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>
-
- /* YUK! - but this is currently a global.... */
- extern struct jtag_interface *jtag_interface;
-
- static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
- uint32_t *data)
- {
- /* REVISIT status return vs ack ... */
- const struct swd_driver *swd = jtag_interface->swd;
- assert(swd);
-
- return swd->read_reg(swd_cmd(true, false, reg), data);
- }
-
- static int swd_queue_idcode_read(struct adiv5_dap *dap,
- uint8_t *ack, uint32_t *data)
- {
- int status = swd_queue_dp_read(dap, DP_IDCODE, data);
- if (status < 0)
- return status;
- *ack = status;
- /* ?? */
- return ERROR_OK;
- }
-
- static int (swd_queue_dp_write)(struct adiv5_dap *dap, unsigned reg,
- uint32_t data)
- {
- /* REVISIT status return vs ack ... */
- const struct swd_driver *swd = jtag_interface->swd;
- assert(swd);
-
- return swd->write_reg(swd_cmd(false, false, reg), data);
- }
-
-
- static int (swd_queue_ap_read)(struct adiv5_dap *dap, unsigned reg,
- uint32_t *data)
- {
- /* REVISIT APSEL ... */
- /* REVISIT status return ... */
- const struct swd_driver *swd = jtag_interface->swd;
- assert(swd);
-
- return swd->read_reg(swd_cmd(true, true, reg), data);
- }
-
- static int (swd_queue_ap_write)(struct adiv5_dap *dap, unsigned reg,
- uint32_t data)
- {
- /* REVISIT APSEL ... */
- /* REVISIT status return ... */
- const struct swd_driver *swd = jtag_interface->swd;
- assert(swd);
-
- return swd->write_reg(swd_cmd(false, true, reg), data);
- }
-
- static int (swd_queue_ap_abort)(struct adiv5_dap *dap, uint8_t *ack)
- {
- return ERROR_FAIL;
- }
-
- /** Executes all queued DAP operations. */
- static int swd_run(struct adiv5_dap *dap)
- {
- /* for now the SWD interface hard-wires a zero-size queue. */
-
- /* FIXME but we still need to check and scrub
- * any hardware errors ...
- */
- return ERROR_OK;
- }
-
- const struct dap_ops swd_dap_ops = {
- .is_swd = true,
-
- .queue_idcode_read = swd_queue_idcode_read,
- .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,
- };
-
- /*
- * This represents the bits which must be sent out on TMS/SWDIO to
- * switch a DAP implemented using an SWJ-DP module into SWD mode.
- * These bits are stored (and transmitted) LSB-first.
- *
- * See the DAP-Lite specification, section 2.2.5 for information
- * about making the debug link select SWD or JTAG. (Similar info
- * is in a few other ARM documents.)
- */
- static const uint8_t jtag2swd_bitseq[] = {
- /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
- * putting both JTAG and SWD logic into reset state.
- */
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- /* Switching sequence enables SWD and disables JTAG
- * NOTE: bits in the DP's IDCODE may expose the need for
- * an old/obsolete/deprecated sequence (0xb6 0xed).
- */
- 0x9e, 0xe7,
- /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
- * putting both JTAG and SWD logic into reset state.
- */
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- };
-
- /**
- * Put the debug link into SWD mode, if the target supports it.
- * The link's initial mode may be either JTAG (for example,
- * with SWJ-DP after reset) or SWD.
- *
- * @param target Enters SWD mode (if possible).
- *
- * Note that targets using the JTAG-DP do not support SWD, and that
- * some targets which could otherwise support it may have have been
- * configured to disable SWD signaling
- *
- * @return ERROR_OK or else a fault code.
- */
- int dap_to_swd(struct target *target)
- {
- struct arm *arm = target_to_arm(target);
- int retval;
-
- LOG_DEBUG("Enter SWD mode");
-
- /* REVISIT it's ugly to need to make calls to a "jtag"
- * subsystem if the link may not be in JTAG mode...
- */
-
- retval = jtag_add_tms_seq(8 * sizeof(jtag2swd_bitseq),
- jtag2swd_bitseq, TAP_INVALID);
- if (retval == ERROR_OK)
- retval = jtag_execute_queue();
-
- /* set up the DAP's ops vector for SWD mode. */
- arm->dap->ops = &swd_dap_ops;
-
- return retval;
- }
-
- COMMAND_HANDLER(handle_swd_wcr)
- {
- int retval;
- struct target *target = get_current_target(CMD_CTX);
- struct arm *arm = target_to_arm(target);
- struct adiv5_dap *dap = arm->dap;
- uint32_t wcr;
- unsigned trn, scale = 0;
-
- switch (CMD_ARGC) {
- /* no-args: just dump state */
- case 0:
- /*retval = swd_queue_dp_read(dap, DP_WCR, &wcr); */
- retval = dap_queue_dp_read(dap, DP_WCR, &wcr);
- if (retval == ERROR_OK)
- dap->ops->run(dap);
- if (retval != ERROR_OK) {
- LOG_ERROR("can't read WCR?");
- return retval;
- }
-
- command_print(CMD_CTX,
- "turnaround=%" PRIu32 ", prescale=%" PRIu32,
- WCR_TO_TRN(wcr),
- WCR_TO_PRESCALE(wcr));
- return ERROR_OK;
-
- case 2: /* TRN and prescale */
- COMMAND_PARSE_NUMBER(uint, CMD_ARGV[1], scale);
- if (scale > 7) {
- LOG_ERROR("prescale %d is too big", scale);
- return ERROR_FAIL;
- }
- /* FALL THROUGH */
-
- case 1: /* TRN only */
- COMMAND_PARSE_NUMBER(uint, CMD_ARGV[0], trn);
- if (trn < 1 || trn > 4) {
- LOG_ERROR("turnaround %d is invalid", trn);
- return ERROR_FAIL;
- }
-
- wcr = ((trn - 1) << 8) | scale;
- /* FIXME
- * write WCR ...
- * then, re-init adapter with new TRN
- */
- LOG_ERROR("can't yet modify WCR");
- return ERROR_FAIL;
-
- default: /* too many arguments */
- return ERROR_COMMAND_SYNTAX_ERROR;
- }
- }
-
- 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",
- .jim_handler = jim_jtag_newtap,
- .mode = COMMAND_CONFIG,
- .help = "declare a new SWD DAP"
- },
- {
- .name = "wcr",
- .handler = handle_swd_wcr,
- .mode = COMMAND_ANY,
- .help = "display or update DAP's WCR register",
- .usage = "turnaround (1..4), prescale (0..7)",
- },
-
- /* REVISIT -- add a command for SWV trace on/off */
- COMMAND_REGISTRATION_DONE
- };
-
- static const struct command_registration swd_handlers[] = {
- {
- .name = "swd",
- .mode = COMMAND_ANY,
- .help = "SWD command group",
- .chain = swd_commands,
- },
- COMMAND_REGISTRATION_DONE
- };
-
- static int swd_select(struct command_context *ctx)
- {
- int retval;
-
- retval = register_commands(ctx, NULL, swd_handlers);
-
- if (retval != ERROR_OK)
- return retval;
-
- const struct swd_driver *swd = jtag_interface->swd;
-
- /* 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(1);
- if (retval != ERROR_OK) {
- LOG_DEBUG("can't init SWD driver");
- return retval;
- }
-
- /* force DAP into SWD mode (not JTAG) */
- /*retval = dap_to_swd(target);*/
-
- if (ctx->current_target) {
- /* force DAP into SWD mode (not JTAG) */
- struct target *target = get_current_target(ctx);
- retval = dap_to_swd(target);
- }
-
- return retval;
- }
-
- static int swd_init(struct command_context *ctx)
- {
- struct target *target = get_current_target(ctx);
- struct arm *arm = target_to_arm(target);
- struct adiv5_dap *dap = arm->dap;
- uint32_t idcode;
- int status;
-
- /* Force the DAP's ops vector for SWD mode.
- * messy - is there a better way? */
- arm->dap->ops = &swd_dap_ops;
-
- /* FIXME validate transport config ... is the
- * configured DAP present (check IDCODE)?
- * Is *only* one DAP configured?
- *
- * MUST READ IDCODE
- */
-
- /* Note, debugport_init() does setup too */
-
- uint8_t ack;
-
- status = swd_queue_idcode_read(dap, &ack, &idcode);
-
- if (status == ERROR_OK)
- LOG_INFO("SWD IDCODE %#8.8" PRIx32, idcode);
-
- return status;
-
- }
-
- 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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