93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
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/***************************************************************************
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*
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* Copyright (C) 2010 by David Brownell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the
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* Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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***************************************************************************/
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/**
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* @file
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* This file implements SWD transport support for cores implementing
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the ARM Debug Interface version 5 (ADIv5).
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "arm.h"
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#include "arm_adi_v5.h"
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#include <helper/time_support.h>
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/*
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* This represents the bits which must be sent out on TMS/SWDIO to
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* switch a DAP implemented using an SWJ-DP module into SWD mode.
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* These bits are stored (and transmitted) LSB-first.
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*
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* See the DAP-Lite specification, section 2.2.5 for information
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* about making the debug link select SWD or JTAG. (Similar info
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* is in a few other ARM documents.)
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*/
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static const uint8_t jtag2swd_bitseq[] = {
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/* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
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* putting both JTAG and SWD logic into reset state.
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*/
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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/* Switching sequence enables SWD and disables JTAG
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* NOTE: bits in the DP's IDCODE may expose the need for
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* an old/deprecated sequence (0xb6 0xed).
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*/
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0x9e, 0xe7,
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/* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
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* putting both JTAG and SWD logic into reset state.
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*/
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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};
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/**
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* Put the debug link into SWD mode, if the target supports it.
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* The link's initial mode may be either JTAG (for example,
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* with SWJ-DP after reset) or SWD.
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*
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* @param target Enters SWD mode (if possible).
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*
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* Note that targets using the JTAG-DP do not support SWD, and that
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* some targets which could otherwise support it may have have been
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* configured to disable SWD signaling
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*
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* @return ERROR_OK or else a fault code.
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*/
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int dap_to_swd(struct target *target)
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{
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int retval;
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LOG_DEBUG("Enter SWD mode");
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/* REVISIT it's nasty to need to make calls to a "jtag"
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* subsystem if the link isn't in JTAG mode...
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*/
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retval = jtag_add_tms_seq(8 * sizeof(jtag2swd_bitseq),
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jtag2swd_bitseq, TAP_INVALID);
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if (retval == ERROR_OK)
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retval = jtag_execute_queue();
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/* REVISIT set up the DAP's ops vector for SWD mode. */
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return retval;
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}
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