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ft2232: implement TMS sequence command 

Implement the new TMS_SEQ command on FT2232 hardware.
Also, swap a bogus exit() call with a clean failure return.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
David Brownell 2010-02-27 00:12:38 -08:00
parent a3245bd7cd
commit 8c9b52e8b6
1 changed files with 72 additions and 2 deletions
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74
src/jtag/drivers/ft2232.c
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@ -1678,6 +1678,72 @@ static int ft2232_execute_statemove(struct jtag_command *cmd)
return retval;
}
/**
* Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
* (or SWD) state machine.
*/
static int ft2232_execute_tms(struct jtag_command *cmd)
{
int retval = ERROR_OK;
unsigned num_bits = cmd->cmd.tms->num_bits;
const uint8_t *bits = cmd->cmd.tms->bits;
unsigned count;
DEBUG_JTAG_IO("TMS: %d bits", num_bits);
/* only send the maximum buffer size that FT2232C can handle */
count = 3 * DIV_ROUND_UP(num_bits, 4);
if (ft2232_buffer_size + 3*count + 1 > FT2232_BUFFER_SIZE) {
if (ft2232_send_and_recv(first_unsent, cmd) != ERROR_OK)
retval = ERROR_JTAG_QUEUE_FAILED;
require_send = 0;
first_unsent = cmd;
}
/* Shift out in batches of at most 6 bits; there's a report of an
* FT2232 bug in this area, where shifting exactly 7 bits can make
* problems with TMS signaling for the last clock cycle:
*
* http://developer.intra2net.com/mailarchive/html/
* libftdi/2009/msg00292.html
*
* Command 0x4b is: "Clock Data to TMS/CS Pin (no Read)"
*
* Note that pathmoves in JTAG are not often seven bits, so that
* isn't a particularly likely situation outside of "special"
* signaling such as switching between JTAG and SWD modes.
*/
while (num_bits) {
if (num_bits <= 6) {
buffer_write(0x4b);
buffer_write(num_bits - 1);
buffer_write(*bits & 0x3f);
break;
}
/* Yes, this is lazy ... we COULD shift out more data
* bits per operation, but doing it in nybbles is easy
*/
buffer_write(0x4b);
buffer_write(3);
buffer_write(*bits & 0xf);
num_bits -= 4;
count = (num_bits > 4) ? 4 : num_bits;
buffer_write(0x4b);
buffer_write(count - 1);
buffer_write((*bits >> 4) & 0xf);
num_bits -= count;
bits++;
}
require_send = 1;
return retval;
}
static int ft2232_execute_pathmove(struct jtag_command *cmd)
{
int predicted_size = 0;
@ -1830,7 +1896,6 @@ static int ft2232_execute_stableclocks(struct jtag_command *cmd)
static int ft2232_execute_command(struct jtag_command *cmd)
{
int retval;
retval = ERROR_OK;
switch (cmd->type)
{
@ -1841,9 +1906,13 @@ static int ft2232_execute_command(struct jtag_command *cmd)
case JTAG_SCAN: retval = ft2232_execute_scan(cmd); break;
case JTAG_SLEEP: retval = ft2232_execute_sleep(cmd); break;
case JTAG_STABLECLOCKS: retval = ft2232_execute_stableclocks(cmd); break;
case JTAG_TMS:
retval = ft2232_execute_tms(cmd);
break;
default:
LOG_ERROR("BUG: unknown JTAG command type encountered");
exit(-1);
retval = ERROR_JTAG_QUEUE_FAILED;
break;
}
return retval;
}
@ -4108,6 +4177,7 @@ static const struct command_registration ft2232_command_handlers[] = {
struct jtag_interface ft2232_interface = {
.name = "ft2232",
.supported = DEBUG_CAP_TMS_SEQ,
.commands = ft2232_command_handlers,
.init = ft2232_init,