Commit 3ef9beb5 authored by David Brownell's avatar David Brownell
Browse files

ADIv5 DAP ops switching to JTAG or SWD modes



Define two new DAP operations which use the new jtag_add_tms_seq()
calls to put the DAP's transport into either SWD or JTAG mode, when
the hardware allows.

Tested with the Stellaris 'Recovering a "Locked" Device' procedure,
which loops five times over both of these.

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
parent 8c9b52e8
......@@ -1716,3 +1716,116 @@ DAP_COMMAND_HANDLER(dap_apid_command)
return retval;
}
/*
* 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;
}
/**
* This represents the bits which must be sent out on TMS/SWDIO to
* switch a DAP implemented using an SWJ-DP module into JTAG mode.
* These bits are stored (and transmitted) LSB-first.
*
* These bits are stored (and transmitted) LSB-first.
*/
static const uint8_t swd2jtag_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 equence disables SWD and enables JTAG
* NOTE: bits in the DP's IDCODE can expose the need for
* the old/deprecated sequence (0xae 0xde).
*/
0x3c, 0xe7,
/* At least 50 TCK/SWCLK cycles with TMS/SWDIO high,
* putting both JTAG and SWD logic into reset state.
* NOTE: some docs say "at least 5".
*/
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
};
/** Put the debug link into JTAG mode, if the target supports it.
* The link's initial mode may be either SWD or JTAG.
*
* @param target Enters JTAG mode (if possible).
*
* Note that targets implemented with SW-DP do not support JTAG, and
* that some targets which could otherwise support it may have been
* configured to disable JTAG signaling
*
* @return ERROR_OK or else a fault code.
*/
int dap_to_jtag(struct target *target)
{
int retval;
LOG_DEBUG("Enter JTAG 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(swd2jtag_bitseq),
swd2jtag_bitseq, TAP_RESET);
if (retval == ERROR_OK)
retval = jtag_execute_queue();
/* REVISIT set up the DAP's ops vector for JTAG mode. */
return retval;
}
......@@ -235,4 +235,12 @@ DAP_COMMAND_HANDLER(dap_memaccess_command);
DAP_COMMAND_HANDLER(dap_apsel_command);
DAP_COMMAND_HANDLER(dap_apid_command);
struct target;
/* Put debug link into SWD mode */
int dap_to_swd(struct target *target);
/* Put debug link into JTAG mode */
int dap_to_jtag(struct target *target);
#endif
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment