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riscv-openocd/src/jtag/bitbang.c

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/***************************************************************************
* Copyright (C) 2005 by Dominic Rath *
* Dominic.Rath@gmx.de *
* *
* Copyright (C) 2007,2008 Øyvind Harboe *
* oyvind.harboe@zylin.com *
* *
* 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. *
***************************************************************************/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "bitbang.h"
#include "jtag.h"
/**
* Function bitbang_stableclocks
* issues a number of clock cycles while staying in a stable state.
* Because the TMS value required to stay in the RESET state is a 1, whereas
* the TMS value required to stay in any of the other stable states is a 0,
* this function checks the current stable state to decide on the value of TMS
* to use.
*/
static void bitbang_stableclocks(int num_cycles);
bitbang_interface_t *bitbang_interface;
/* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
*
* Set this to 1 and str912 reset halt will fail.
*
* If someone can submit a patch with an explanation it will be greatly
* appreciated, but as far as I can tell (ØH) DCLK is generated upon
* clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
* The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
* state". With hardware there is no such thing as *while* in a state. There
* are only edges. So clk => 0 is in fact a very subtle state transition that
* happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
*
* For "reset halt" the last thing that happens before srst is asserted
* is that the breakpoint is set up. If DCLK is not wiggled one last
* time before the reset, then the breakpoint is not set up and
* "reset halt" will fail to halt.
*
*/
#define CLOCK_IDLE() 0
/* The bitbang driver leaves the TCK 0 when in idle */
static void bitbang_end_state(tap_state_t state)
{
if (tap_is_state_stable(state))
tap_set_end_state(state);
else
{
LOG_ERROR("BUG: %i is not a valid end state", state);
exit(-1);
}
}
static void bitbang_state_move(int skip)
{
int i=0, tms=0;
u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
for (i = skip; i < tms_count; i++)
{
tms = (tms_scan >> i) & 1;
bitbang_interface->write(0, tms, 0);
bitbang_interface->write(1, tms, 0);
}
bitbang_interface->write(CLOCK_IDLE(), tms, 0);
tap_set_state(tap_get_end_state());
}
static void bitbang_path_move(pathmove_command_t *cmd)
{
int num_states = cmd->num_states;
int state_count;
int tms = 0;
state_count = 0;
while (num_states)
{
if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
{
tms = 0;
}
else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
{
tms = 1;
}
else
{
LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
exit(-1);
}
bitbang_interface->write(0, tms, 0);
bitbang_interface->write(1, tms, 0);
tap_set_state(cmd->path[state_count]);
state_count++;
num_states--;
}
bitbang_interface->write(CLOCK_IDLE(), tms, 0);
tap_set_end_state(tap_get_state());
}
static void bitbang_runtest(int num_cycles)
{
int i;
tap_state_t saved_end_state = tap_get_end_state();
/* only do a state_move when we're not already in IDLE */
if (tap_get_state() != TAP_IDLE)
{
bitbang_end_state(TAP_IDLE);
bitbang_state_move(0);
}
/* execute num_cycles */
for (i = 0; i < num_cycles; i++)
{
bitbang_interface->write(0, 0, 0);
bitbang_interface->write(1, 0, 0);
}
bitbang_interface->write(CLOCK_IDLE(), 0, 0);
/* finish in end_state */
bitbang_end_state(saved_end_state);
if (tap_get_state() != tap_get_end_state())
bitbang_state_move(0);
}
static void bitbang_stableclocks(int num_cycles)
{
int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
int i;
/* send num_cycles clocks onto the cable */
for (i = 0; i < num_cycles; i++)
{
bitbang_interface->write(1, tms, 0);
bitbang_interface->write(0, tms, 0);
}
}
static void bitbang_scan(bool 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(0);
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;
}
}
if (tap_get_state() != tap_get_end_state())
{
/* we *KNOW* the above loop transitioned out of
* the shift state, so we skip the first state
* and move directly to the end state.
*/
bitbang_state_move(1);
}
}
int bitbang_execute_queue(void)
{
jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
int scan_size;
enum scan_type type;
u8 *buffer;
int retval;
if (!bitbang_interface)
{
LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
exit(-1);
}
/* return ERROR_OK, unless a jtag_read_buffer returns a failed check
* that wasn't handled by a caller-provided error handler
*/
retval = ERROR_OK;
if(bitbang_interface->blink)
bitbang_interface->blink(1);
while (cmd)
{
switch (cmd->type)
{
case JTAG_RESET:
#ifdef _DEBUG_JTAG_IO_
LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
#endif
if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
{
tap_set_state(TAP_RESET);
}
bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
break;
case JTAG_RUNTEST:
#ifdef _DEBUG_JTAG_IO_
LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
#endif
if (cmd->cmd.runtest->end_state != TAP_INVALID)
bitbang_end_state(cmd->cmd.runtest->end_state);
bitbang_runtest(cmd->cmd.runtest->num_cycles);
break;
case JTAG_STABLECLOCKS:
/* this is only allowed while in a stable state. A check for a stable
* state was done in jtag_add_clocks()
*/
bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
break;
case JTAG_STATEMOVE:
#ifdef _DEBUG_JTAG_IO_
LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
#endif
if (cmd->cmd.statemove->end_state != TAP_INVALID)
bitbang_end_state(cmd->cmd.statemove->end_state);
bitbang_state_move(0);
break;
case JTAG_PATHMOVE:
#ifdef _DEBUG_JTAG_IO_
LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
#endif
bitbang_path_move(cmd->cmd.pathmove);
break;
case JTAG_SCAN:
#ifdef _DEBUG_JTAG_IO_
LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
#endif
if (cmd->cmd.scan->end_state != TAP_INVALID)
bitbang_end_state(cmd->cmd.scan->end_state);
scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
type = jtag_scan_type(cmd->cmd.scan);
bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
retval = ERROR_JTAG_QUEUE_FAILED;
if (buffer)
free(buffer);
break;
case JTAG_SLEEP:
#ifdef _DEBUG_JTAG_IO_
LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
#endif
jtag_sleep(cmd->cmd.sleep->us);
break;
default:
LOG_ERROR("BUG: unknown JTAG command type encountered");
exit(-1);
}
cmd = cmd->next;
}
if(bitbang_interface->blink)
bitbang_interface->blink(0);
return retval;
}
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