Single stepping does not work for arm1136 on the parport adapter.
Looking at ft2232 vs. bitbang, I see a big difference in how
these drivers exist the scan operation. (Hope I got this one right... :-)
The bitbang driver manually wiggles it's way to TAP_xRPAUSE,
then does a 7 clock transition to the end state.
The ft2232 driver does a 7 clock transition *directly* from
TAP_xRSHIFT. (I hope I figured this out correctly from the code,
I'm not terribly familiar with ft2232 code).
The ARM11 is finicky about the precise paths taken, so
this *could* explain why ft2232 happens to work(since
ARM11 support happened to be developed on that adapter).
#if 0 /* keeping old hex stuff for awhile, for reference */
/* RESET IDLE DRSHIFT
DRPAUSE IRSHIFT IRPAUSE */
{ 0x7f, 0x00, 0x17,
0x0a, 0x1b, 0x16 }, /* RESET */
{ 0x7f, 0x00, 0x25,
0x05, 0x2b, 0x0b }, /* IDLE */
{ 0x7f, 0x31, 0x00,
0x01, 0x0f, 0x2f }, /* DRSHIFT */
{ 0x7f, 0x30, 0x20,
0x17, 0x1e, 0x2f }, /* DRPAUSE */
{ 0x7f, 0x31, 0x07,
0x17, 0x00, 0x01 }, /* IRSHIFT */
{ 0x7f, 0x30, 0x1c,
0x17, 0x20, 0x2f } /* IRPAUSE */
#endif
The ft2232 will move
if ( ( ir_scan && (tap_get_end_state() == TAP_IRSHIFT) )
|| ( !ir_scan && (tap_get_end_state() == TAP_DRSHIFT) ) )
{
if (type == SCAN_IO)
{
/* Clock Data Bits In and Out LSB First */
BUFFER_ADD = 0x3b;
/* LOG_DEBUG("added TDI bits (io) %i", bits_left - 1);
*/
}
else if (type == SCAN_OUT)
{
/* Clock Data Bits Out on -ve Clock Edge LSB First (no
Read) */
BUFFER_ADD = 0x1b;
/* LOG_DEBUG("added TDI bits (o)"); */
}
else if (type == SCAN_IN)
{
/* Clock Data Bits In on +ve Clock Edge LSB First (no
Write) */
BUFFER_ADD = 0x2a;
/* LOG_DEBUG("added TDI bits (i %i)", bits_left - 1); */
}
BUFFER_ADD = 0x0;
BUFFER_ADD = last_bit;
}
else
{
/* move from Shift-IR/DR to end state */
if (type != SCAN_OUT)
{
/* Clock Data to TMS/CS Pin with Read */
BUFFER_ADD = 0x6b;
/* LOG_DEBUG("added TMS scan (read)"); */
}
else
{
/* Clock Data to TMS/CS Pin (no Read) */
BUFFER_ADD = 0x4b;
/* LOG_DEBUG("added TMS scan (no read)"); */
}
BUFFER_ADD = 0x6; /* scan 7 bits */
BUFFER_ADD = tap_get_tms_path( tap_get_state(),
tap_get_end_state()
) | (last_bit << 7);
tap_set_state( tap_get_end_state() );
}
static void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer,
int scan_size)
{
tap_state_t saved_end_state = tap_get_end_state();
int bit_cnt;
if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan &&
(tap_get_state() == TAP_IRSHIFT))))
{
if (ir_scan)
bitbang_end_state(TAP_IRSHIFT);
else
bitbang_end_state(TAP_DRSHIFT);
bitbang_state_move();
bitbang_end_state(saved_end_state);
}
for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
{
int val=0;
int tms=(bit_cnt==scan_size-1) ? 1 : 0;
int tdi;
int bytec=bit_cnt/8;
int bcval=1<<(bit_cnt % 8);
/* if we're just reading the scan, but don't care about the
output
* default to outputting 'low', this also makes valgrind traces
more readable,
* as it removes the dependency on an uninitialised value
*/
tdi=0;
if ((type != SCAN_IN) && (buffer[bytec] & bcval))
tdi=1;
bitbang_interface->write(0, tms, tdi);
if (type!=SCAN_OUT)
val=bitbang_interface->read();
bitbang_interface->write(1, tms, tdi);
if (type != SCAN_OUT)
{
if (val)
buffer[bytec] |= bcval;
else
buffer[bytec] &= ~bcval;
}
}
/* TAP_DRSHIFT & TAP_IRSHIFT are illegal end states, so we always
transition to the pause
* state which is a legal stable state from which statemove will work.
*
* Exit1 -> Pause
*/
bitbang_interface->write(0, 0, 0);
bitbang_interface->write(1, 0, 0);
bitbang_interface->write(CLOCK_IDLE(), 0, 0);
if (ir_scan)
tap_set_state(TAP_IRPAUSE);
else
tap_set_state(TAP_DRPAUSE);
if (tap_get_state() != tap_get_end_state())
bitbang_state_move();
}
--
Øyvind Harboe
Embedded software and hardware consulting services
http://consulting.zylin.com
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