?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Added OpenJTAG Driver
[openocd.git] / src / jtag / drivers / bitbang.c
blob8a097ca1b165aaac25475ec88090a2b876c656c0
1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
4 * *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
7 * *
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. *
12 * *
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. *
17 * *
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 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
22 ***************************************************************************/
23
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27
28 #include "bitbang.h"
29 #include <jtag/interface.h>
30 #include <jtag/commands.h>
31
32 /**
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
38 * to use.
39 */
40 static void bitbang_stableclocks(int num_cycles);
41
42 struct bitbang_interface *bitbang_interface;
43
44 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
45 *
46 * Set this to 1 and str912 reset halt will fail.
47 *
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. "#&¤"#¤&"#&"#&
55 *
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.
60 *
61 */
62 #define CLOCK_IDLE() 0
63
64 /* The bitbang driver leaves the TCK 0 when in idle */
65 static void bitbang_end_state(tap_state_t state)
66 {
67 if (tap_is_state_stable(state))
68 tap_set_end_state(state);
69 else {
70 LOG_ERROR("BUG: %i is not a valid end state", state);
71 exit(-1);
72 }
73 }
74
75 static void bitbang_state_move(int skip)
76 {
77 int i = 0, tms = 0;
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());
80
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);
85 }
86 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
87
88 tap_set_state(tap_get_end_state());
89 }
90
91 /**
92 * Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
93 * (or SWD) state machine.
94 */
95 static int bitbang_execute_tms(struct jtag_command *cmd)
96 {
97 unsigned num_bits = cmd->cmd.tms->num_bits;
98 const uint8_t *bits = cmd->cmd.tms->bits;
99
100 DEBUG_JTAG_IO("TMS: %d bits", num_bits);
101
102 int tms = 0;
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);
107 }
108 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
109
110 return ERROR_OK;
111 }
112
113 static void bitbang_path_move(struct pathmove_command *cmd)
114 {
115 int num_states = cmd->num_states;
116 int state_count;
117 int tms = 0;
118
119 state_count = 0;
120 while (num_states) {
121 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
122 tms = 0;
123 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
124 tms = 1;
125 else {
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]));
129 exit(-1);
130 }
131
132 bitbang_interface->write(0, tms, 0);
133 bitbang_interface->write(1, tms, 0);
134
135 tap_set_state(cmd->path[state_count]);
136 state_count++;
137 num_states--;
138 }
139
140 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
141
142 tap_set_end_state(tap_get_state());
143 }
144
145 static void bitbang_runtest(int num_cycles)
146 {
147 int i;
148
149 tap_state_t saved_end_state = tap_get_end_state();
150
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);
155 }
156
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);
161 }
162 bitbang_interface->write(CLOCK_IDLE(), 0, 0);
163
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);
168 }
169
170 static void bitbang_stableclocks(int num_cycles)
171 {
172 int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
173 int i;
174
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);
179 }
180 }
181
182 static void bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size)
183 {
184 tap_state_t saved_end_state = tap_get_end_state();
185 int bit_cnt;
186
187 if (!((!ir_scan &&
188 (tap_get_state() == TAP_DRSHIFT)) ||
189 (ir_scan && (tap_get_state() == TAP_IRSHIFT)))) {
190 if (ir_scan)
191 bitbang_end_state(TAP_IRSHIFT);
192 else
193 bitbang_end_state(TAP_DRSHIFT);
194
195 bitbang_state_move(0);
196 bitbang_end_state(saved_end_state);
197 }
198
199 for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++) {
200 int val = 0;
201 int tms = (bit_cnt == scan_size-1) ? 1 : 0;
202 int tdi;
203 int bytec = bit_cnt/8;
204 int bcval = 1 << (bit_cnt % 8);
205
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
209 */
210 tdi = 0;
211 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
212 tdi = 1;
213
214 bitbang_interface->write(0, tms, tdi);
215
216 if (type != SCAN_OUT)
217 val = bitbang_interface->read();
218
219 bitbang_interface->write(1, tms, tdi);
220
221 if (type != SCAN_OUT) {
222 if (val)
223 buffer[bytec] |= bcval;
224 else
225 buffer[bytec] &= ~bcval;
226 }
227 }
228
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.
233 */
234 bitbang_state_move(1);
235 }
236 }
237
238 int bitbang_execute_queue(void)
239 {
240 struct jtag_command *cmd = jtag_command_queue; /* currently processed command */
241 int scan_size;
242 enum scan_type type;
243 uint8_t *buffer;
244 int retval;
245
246 if (!bitbang_interface) {
247 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
248 exit(-1);
249 }
250
251 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
252 * that wasn't handled by a caller-provided error handler
253 */
254 retval = ERROR_OK;
255
256 if (bitbang_interface->blink)
257 bitbang_interface->blink(1);
258
259 while (cmd) {
260 switch (cmd->type) {
261 case JTAG_RESET:
262 #ifdef _DEBUG_JTAG_IO_
263 LOG_DEBUG("reset trst: %i srst %i",
264 cmd->cmd.reset->trst,
265 cmd->cmd.reset->srst);
266 #endif
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);
271 break;
272 case JTAG_RUNTEST:
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));
277 #endif
278 bitbang_end_state(cmd->cmd.runtest->end_state);
279 bitbang_runtest(cmd->cmd.runtest->num_cycles);
280 break;
281
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()
285 */
286 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
287 break;
288
289 case JTAG_TLR_RESET:
290 #ifdef _DEBUG_JTAG_IO_
291 LOG_DEBUG("statemove end in %s",
292 tap_state_name(cmd->cmd.statemove->end_state));
293 #endif
294 bitbang_end_state(cmd->cmd.statemove->end_state);
295 bitbang_state_move(0);
296 break;
297 case JTAG_PATHMOVE:
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]));
302 #endif
303 bitbang_path_move(cmd->cmd.pathmove);
304 break;
305 case JTAG_SCAN:
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));
310 #endif
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;
317 if (buffer)
318 free(buffer);
319 break;
320 case JTAG_SLEEP:
321 #ifdef _DEBUG_JTAG_IO_
322 LOG_DEBUG("sleep %" PRIi32, cmd->cmd.sleep->us);
323 #endif
324 jtag_sleep(cmd->cmd.sleep->us);
325 break;
326 case JTAG_TMS:
327 retval = bitbang_execute_tms(cmd);
328 break;
329 default:
330 LOG_ERROR("BUG: unknown JTAG command type encountered");
331 exit(-1);
332 }
333 cmd = cmd->next;
334 }
335 if (bitbang_interface->blink)
336 bitbang_interface->blink(0);
337
338 return retval;
339 }
Official OpenOCD Mirror