1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * This program is free software; you can redistribute it and/or modify *
9 * it under the terms of the GNU General Public License as published by *
10 * the Free Software Foundation; either version 2 of the License, or *
11 * (at your option) any later version. *
13 * This program is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16 * GNU General Public License for more details. *
18 * You should have received a copy of the GNU General Public License *
19 * along with this program; if not, write to the *
20 * Free Software Foundation, Inc., *
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *
22 ***************************************************************************/
29 #include <jtag/interface.h>
30 #include <jtag/commands.h>
33 * Function bitbang_stableclocks
34 * issues a number of clock cycles while staying in a stable state.
35 * Because the TMS value required to stay in the RESET state is a 1, whereas
36 * the TMS value required to stay in any of the other stable states is a 0,
37 * this function checks the current stable state to decide on the value of TMS
40 static void bitbang_stableclocks(int num_cycles
);
42 struct bitbang_interface
*bitbang_interface
;
44 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
46 * Set this to 1 and str912 reset halt will fail.
48 * If someone can submit a patch with an explanation it will be greatly
49 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
50 * clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
51 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
52 * state". With hardware there is no such thing as *while* in a state. There
53 * are only edges. So clk => 0 is in fact a very subtle state transition that
54 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
56 * For "reset halt" the last thing that happens before srst is asserted
57 * is that the breakpoint is set up. If DCLK is not wiggled one last
58 * time before the reset, then the breakpoint is not set up and
59 * "reset halt" will fail to halt.
62 #define CLOCK_IDLE() 0
64 /* The bitbang driver leaves the TCK 0 when in idle */
65 static void bitbang_end_state(tap_state_t state
)
67 if (tap_is_state_stable(state
))
68 tap_set_end_state(state
);
70 LOG_ERROR("BUG: %i is not a valid end state", state
);
75 static void bitbang_state_move(int skip
)
78 uint8_t tms_scan
= tap_get_tms_path(tap_get_state(), tap_get_end_state());
79 int tms_count
= tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
81 for (i
= skip
; i
< tms_count
; i
++) {
82 tms
= (tms_scan
>> i
) & 1;
83 bitbang_interface
->write(0, tms
, 0);
84 bitbang_interface
->write(1, tms
, 0);
86 bitbang_interface
->write(CLOCK_IDLE(), tms
, 0);
88 tap_set_state(tap_get_end_state());
92 * Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
93 * (or SWD) state machine.
95 static int bitbang_execute_tms(struct jtag_command
*cmd
)
97 unsigned num_bits
= cmd
->cmd
.tms
->num_bits
;
98 const uint8_t *bits
= cmd
->cmd
.tms
->bits
;
100 DEBUG_JTAG_IO("TMS: %d bits", num_bits
);
103 for (unsigned i
= 0; i
< num_bits
; i
++) {
104 tms
= ((bits
[i
/8] >> (i
% 8)) & 1);
105 bitbang_interface
->write(0, tms
, 0);
106 bitbang_interface
->write(1, tms
, 0);
108 bitbang_interface
->write(CLOCK_IDLE(), tms
, 0);
113 static void bitbang_path_move(struct pathmove_command
*cmd
)
115 int num_states
= cmd
->num_states
;
121 if (tap_state_transition(tap_get_state(), false) == cmd
->path
[state_count
])
123 else if (tap_state_transition(tap_get_state(), true) == cmd
->path
[state_count
])
126 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition",
127 tap_state_name(tap_get_state()),
128 tap_state_name(cmd
->path
[state_count
]));
132 bitbang_interface
->write(0, tms
, 0);
133 bitbang_interface
->write(1, tms
, 0);
135 tap_set_state(cmd
->path
[state_count
]);
140 bitbang_interface
->write(CLOCK_IDLE(), tms
, 0);
142 tap_set_end_state(tap_get_state());
145 static void bitbang_runtest(int num_cycles
)
149 tap_state_t saved_end_state
= tap_get_end_state();
151 /* only do a state_move when we're not already in IDLE */
152 if (tap_get_state() != TAP_IDLE
) {
153 bitbang_end_state(TAP_IDLE
);
154 bitbang_state_move(0);
157 /* execute num_cycles */
158 for (i
= 0; i
< num_cycles
; i
++) {
159 bitbang_interface
->write(0, 0, 0);
160 bitbang_interface
->write(1, 0, 0);
162 bitbang_interface
->write(CLOCK_IDLE(), 0, 0);
164 /* finish in end_state */
165 bitbang_end_state(saved_end_state
);
166 if (tap_get_state() != tap_get_end_state())
167 bitbang_state_move(0);
170 static void bitbang_stableclocks(int num_cycles
)
172 int tms
= (tap_get_state() == TAP_RESET
? 1 : 0);
175 /* send num_cycles clocks onto the cable */
176 for (i
= 0; i
< num_cycles
; i
++) {
177 bitbang_interface
->write(1, tms
, 0);
178 bitbang_interface
->write(0, tms
, 0);
182 static void bitbang_scan(bool ir_scan
, enum scan_type type
, uint8_t *buffer
, int scan_size
)
184 tap_state_t saved_end_state
= tap_get_end_state();
188 (tap_get_state() == TAP_DRSHIFT
)) ||
189 (ir_scan
&& (tap_get_state() == TAP_IRSHIFT
)))) {
191 bitbang_end_state(TAP_IRSHIFT
);
193 bitbang_end_state(TAP_DRSHIFT
);
195 bitbang_state_move(0);
196 bitbang_end_state(saved_end_state
);
199 for (bit_cnt
= 0; bit_cnt
< scan_size
; bit_cnt
++) {
201 int tms
= (bit_cnt
== scan_size
-1) ? 1 : 0;
203 int bytec
= bit_cnt
/8;
204 int bcval
= 1 << (bit_cnt
% 8);
206 /* if we're just reading the scan, but don't care about the output
207 * default to outputting 'low', this also makes valgrind traces more readable,
208 * as it removes the dependency on an uninitialised value
211 if ((type
!= SCAN_IN
) && (buffer
[bytec
] & bcval
))
214 bitbang_interface
->write(0, tms
, tdi
);
216 if (type
!= SCAN_OUT
)
217 val
= bitbang_interface
->read();
219 bitbang_interface
->write(1, tms
, tdi
);
221 if (type
!= SCAN_OUT
) {
223 buffer
[bytec
] |= bcval
;
225 buffer
[bytec
] &= ~bcval
;
229 if (tap_get_state() != tap_get_end_state()) {
230 /* we *KNOW* the above loop transitioned out of
231 * the shift state, so we skip the first state
232 * and move directly to the end state.
234 bitbang_state_move(1);
238 int bitbang_execute_queue(void)
240 struct jtag_command
*cmd
= jtag_command_queue
; /* currently processed command */
246 if (!bitbang_interface
) {
247 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
251 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
252 * that wasn't handled by a caller-provided error handler
256 if (bitbang_interface
->blink
)
257 bitbang_interface
->blink(1);
262 #ifdef _DEBUG_JTAG_IO_
263 LOG_DEBUG("reset trst: %i srst %i",
264 cmd
->cmd
.reset
->trst
,
265 cmd
->cmd
.reset
->srst
);
267 if ((cmd
->cmd
.reset
->trst
== 1) ||
268 (cmd
->cmd
.reset
->srst
&& (jtag_get_reset_config() & RESET_SRST_PULLS_TRST
)))
269 tap_set_state(TAP_RESET
);
270 bitbang_interface
->reset(cmd
->cmd
.reset
->trst
, cmd
->cmd
.reset
->srst
);
273 #ifdef _DEBUG_JTAG_IO_
274 LOG_DEBUG("runtest %i cycles, end in %s",
275 cmd
->cmd
.runtest
->num_cycles
,
276 tap_state_name(cmd
->cmd
.runtest
->end_state
));
278 bitbang_end_state(cmd
->cmd
.runtest
->end_state
);
279 bitbang_runtest(cmd
->cmd
.runtest
->num_cycles
);
282 case JTAG_STABLECLOCKS
:
283 /* this is only allowed while in a stable state. A check for a stable
284 * state was done in jtag_add_clocks()
286 bitbang_stableclocks(cmd
->cmd
.stableclocks
->num_cycles
);
290 #ifdef _DEBUG_JTAG_IO_
291 LOG_DEBUG("statemove end in %s",
292 tap_state_name(cmd
->cmd
.statemove
->end_state
));
294 bitbang_end_state(cmd
->cmd
.statemove
->end_state
);
295 bitbang_state_move(0);
298 #ifdef _DEBUG_JTAG_IO_
299 LOG_DEBUG("pathmove: %i states, end in %s",
300 cmd
->cmd
.pathmove
->num_states
,
301 tap_state_name(cmd
->cmd
.pathmove
->path
[cmd
->cmd
.pathmove
->num_states
- 1]));
303 bitbang_path_move(cmd
->cmd
.pathmove
);
306 #ifdef _DEBUG_JTAG_IO_
307 LOG_DEBUG("%s scan end in %s",
308 (cmd
->cmd
.scan
->ir_scan
) ? "IR" : "DR",
309 tap_state_name(cmd
->cmd
.scan
->end_state
));
311 bitbang_end_state(cmd
->cmd
.scan
->end_state
);
312 scan_size
= jtag_build_buffer(cmd
->cmd
.scan
, &buffer
);
313 type
= jtag_scan_type(cmd
->cmd
.scan
);
314 bitbang_scan(cmd
->cmd
.scan
->ir_scan
, type
, buffer
, scan_size
);
315 if (jtag_read_buffer(buffer
, cmd
->cmd
.scan
) != ERROR_OK
)
316 retval
= ERROR_JTAG_QUEUE_FAILED
;
321 #ifdef _DEBUG_JTAG_IO_
322 LOG_DEBUG("sleep %" PRIi32
, cmd
->cmd
.sleep
->us
);
324 jtag_sleep(cmd
->cmd
.sleep
->us
);
327 retval
= bitbang_execute_tms(cmd
);
330 LOG_ERROR("BUG: unknown JTAG command type encountered");
335 if (bitbang_interface
->blink
)
336 bitbang_interface
->blink(0);
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