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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.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
***************************************************************************/
/**
* @file
* This file implements SWD transport support for cores implementing
the ARM Debug Interface version 5 (ADIv5).
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "arm.h"
#include "arm_adi_v5.h"
#include <helper/time_support.h>
/*
* 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/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)
{
int retval;
LOG_DEBUG("Enter SWD mode");
/* REVISIT it's nasty to need to make calls to a "jtag"
* subsystem if the link isn't in JTAG mode...
*/
retval = jtag_add_tms_seq(8 * sizeof(jtag2swd_bitseq),
jtag2swd_bitseq, TAP_INVALID);
if (retval == ERROR_OK)
retval = jtag_execute_queue();
/* REVISIT set up the DAP's ops vector for SWD mode. */
return retval;
}
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