39f38572c541d07c3866a96ad34802289d65b681
[openocd.git] / src / target / adi_v5_swd.c
1 /***************************************************************************
2 *
3 * Copyright (C) 2010 by David Brownell
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the
17 * Free Software Foundation, Inc.,
18 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 ***************************************************************************/
20
21 /**
22 * @file
23 * Utilities to support ARM "Serial Wire Debug" (SWD), a low pin-count debug
24 * link protocol used in cases where JTAG is not wanted. This is coupled to
25 * recent versions of ARM's "CoreSight" debug framework. This specific code
26 * is a transport level interface, with "target/arm_adi_v5.[hc]" code
27 * understanding operation semantics, shared with the JTAG transport.
28 *
29 * Single-DAP support only.
30 *
31 * for details, see "ARM IHI 0031A"
32 * ARM Debug Interface v5 Architecture Specification
33 * especially section 5.3 for SWD protocol
34 *
35 * On many chips (most current Cortex-M3 parts) SWD is a run-time alternative
36 * to JTAG. Boards may support one or both. There are also SWD-only chips,
37 * (using SW-DP not SWJ-DP).
38 *
39 * Even boards that also support JTAG can benefit from SWD support, because
40 * usually there's no way to access the SWO trace view mechanism in JTAG mode.
41 * That is, trace access may require SWD support.
42 *
43 */
44
45 #ifdef HAVE_CONFIG_H
46 #include "config.h"
47 #endif
48
49 #include "arm.h"
50 #include "arm_adi_v5.h"
51 #include <helper/time_support.h>
52
53 #include <jtag/transport.h>
54 #include <jtag/interface.h>
55
56 #include <jtag/swd.h>
57
58
59
60 static int swd_queue_dp_read(struct adiv5_dap *dap, unsigned reg,
61 uint32_t *data)
62 {
63 // REVISIT status return vs ack ...
64 return swd->read_reg(swd_cmd(true, false, reg), data);
65 }
66
67 static int swd_queue_idcode_read(struct adiv5_dap *dap,
68 uint8_t *ack, uint32_t *data)
69 {
70 int status = swd_queue_dp_read(dap, DP_IDCODE, data);
71 if (status < 0)
72 return status;
73 *ack = status;
74 // ??
75 return ERROR_OK;
76 }
77
78 static int (swd_queue_dp_write)(struct adiv5_dap *dap, unsigned reg,
79 uint32_t data)
80 {
81 // REVISIT status return vs ack ...
82 return swd->write_reg(swd_cmd(false, false, reg), data);
83 }
84
85
86 static int (swd_queue_ap_read)(struct adiv5_dap *dap, unsigned reg,
87 uint32_t *data)
88 {
89 // REVISIT APSEL ...
90 // REVISIT status return ...
91 return swd->read_reg(swd_cmd(true, true, reg), data);
92 }
93
94 static int (swd_queue_ap_write)(struct adiv5_dap *dap, unsigned reg,
95 uint32_t data)
96 {
97 // REVISIT APSEL ...
98 // REVISIT status return ...
99 return swd->write_reg(swd_cmd(false, true, reg), data);
100 }
101
102 static int (swd_queue_ap_abort)(struct adiv5_dap *dap, uint8_t *ack)
103 {
104 return ERROR_FAIL;
105 }
106
107 /** Executes all queued DAP operations. */
108 static int swd_run(struct adiv5_dap *dap)
109 {
110 /* for now the SWD interface hard-wires a zero-size queue. */
111
112 /* FIXME but we still need to check and scrub
113 * any hardware errors ...
114 */
115 return ERROR_OK;
116 }
117
118 const struct dap_ops swd_dap_ops = {
119 .is_swd = true,
120
121 .queue_idcode_read = swd_queue_idcode_read,
122 .queue_dp_read = swd_queue_dp_read,
123 .queue_dp_write = swd_queue_dp_write,
124 .queue_ap_read = swd_queue_ap_read,
125 .queue_ap_write = swd_queue_ap_write,
126 .queue_ap_abort = swd_queue_ap_abort,
127 .run = swd_run,
128 };
129
130 /*
131 * This represents the bits which must be sent out on TMS/SWDIO to
132 * switch a DAP implemented using an SWJ-DP module into SWD mode.
133 * These bits are stored (and transmitted) LSB-first.
134 *
135 * See the DAP-Lite specification, section 2.2.5 for information
136 * about making the debug link select SWD or JTAG. (Similar info
137 * is in a few other ARM documents.)
138 */
139 static const uint8_t jtag2swd_bitseq[] = {
140 /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
141 * putting both JTAG and SWD logic into reset state.
142 */
143 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
144 /* Switching sequence enables SWD and disables JTAG
145 * NOTE: bits in the DP's IDCODE may expose the need for
146 * an old/obsolete/deprecated sequence (0xb6 0xed).
147 */
148 0x9e, 0xe7,
149 /* More than 50 TCK/SWCLK cycles with TMS/SWDIO high,
150 * putting both JTAG and SWD logic into reset state.
151 */
152 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
153 };
154
155 /**
156 * Put the debug link into SWD mode, if the target supports it.
157 * The link's initial mode may be either JTAG (for example,
158 * with SWJ-DP after reset) or SWD.
159 *
160 * @param target Enters SWD mode (if possible).
161 *
162 * Note that targets using the JTAG-DP do not support SWD, and that
163 * some targets which could otherwise support it may have have been
164 * configured to disable SWD signaling
165 *
166 * @return ERROR_OK or else a fault code.
167 */
168 int dap_to_swd(struct target *target)
169 {
170 struct arm *arm = target_to_arm(target);
171 int retval;
172
173 LOG_DEBUG("Enter SWD mode");
174
175 /* REVISIT it's ugly to need to make calls to a "jtag"
176 * subsystem if the link may not be in JTAG mode...
177 */
178
179 retval = jtag_add_tms_seq(8 * sizeof(jtag2swd_bitseq),
180 jtag2swd_bitseq, TAP_INVALID);
181 if (retval == ERROR_OK)
182 retval = jtag_execute_queue();
183
184 /* set up the DAP's ops vector for SWD mode. */
185 arm->dap->ops = &swd_dap_ops;
186
187 return retval;
188 }
189
190
191
192 COMMAND_HANDLER(handle_swd_wcr)
193 {
194 int retval;
195 struct target *target = get_current_target(CMD_CTX);
196 struct arm *arm = target_to_arm(target);
197 struct adiv5_dap *dap = arm->dap;
198 uint32_t wcr;
199 unsigned trn, scale = 0;
200
201
202 switch (CMD_ARGC) {
203 /* no-args: just dump state */
204 case 0:
205 //retval = swd_queue_dp_read(dap, DP_WCR, &wcr);
206 retval = dap_queue_dp_read(dap, DP_WCR, &wcr);
207 if (retval == ERROR_OK)
208 dap->ops->run(dap);
209 if (retval != ERROR_OK) {
210 LOG_ERROR("can't read WCR?");
211 return retval;
212 }
213
214 command_print(CMD_CTX,
215 "turnaround=%d, prescale=%d",
216 WCR_TO_TRN(wcr),
217 WCR_TO_PRESCALE(wcr));
218 return ERROR_OK;
219
220 case 2: /* TRN and prescale */
221 COMMAND_PARSE_NUMBER(uint, CMD_ARGV[1], scale);
222 if (scale > 7) {
223 LOG_ERROR("prescale %d is too big", scale);
224 return ERROR_FAIL;
225 }
226 /* FALL THROUGH */
227
228 case 1: /* TRN only */
229 COMMAND_PARSE_NUMBER(uint, CMD_ARGV[0], trn);
230 if (trn < 1 || trn > 4) {
231 LOG_ERROR("turnaround %d is invalid", trn);
232 return ERROR_FAIL;
233 }
234
235 wcr = ((trn - 1) << 8) | scale;
236 /* FIXME
237 * write WCR ...
238 * then, re-init adapter with new TRN
239 */
240 LOG_ERROR("can't yet modify WCR");
241 return ERROR_FAIL;
242
243 default: /* too many arguments */
244 return ERROR_COMMAND_SYNTAX_ERROR;
245 }
246 }
247
248 static const struct command_registration swd_commands[] = {
249 {
250 /*
251 * Set up SWD and JTAG targets identically, unless/until
252 * infrastructure improves ... meanwhile, ignore all
253 * JTAG-specific stuff like IR length for SWD.
254 *
255 * REVISIT can we verify "just one SWD DAP" here/early?
256 */
257 .name = "newdap",
258 .jim_handler = jim_jtag_newtap,
259 .mode = COMMAND_CONFIG,
260 .help = "declare a new SWD DAP"
261 },
262 {
263 .name = "wcr",
264 .handler = handle_swd_wcr,
265 .mode = COMMAND_ANY,
266 .help = "display or update DAP's WCR register",
267 .usage = "turnaround (1..4), prescale (0..7)",
268 },
269
270 /* REVISIT -- add a command for SWV trace on/off */
271 COMMAND_REGISTRATION_DONE
272 };
273
274 static const struct command_registration swd_handlers[] = {
275 {
276 .name = "swd",
277 .mode = COMMAND_ANY,
278 .help = "SWD command group",
279 .chain = swd_commands,
280 },
281 COMMAND_REGISTRATION_DONE
282 };
283
284 static int swd_select(struct command_context *ctx)
285 {
286 struct target *target = get_current_target(ctx);
287 int retval;
288
289 retval = register_commands(ctx, NULL, swd_handlers);
290
291 if (retval != ERROR_OK)
292 return retval;
293
294 /* be sure driver is in SWD mode; start
295 * with hardware default TRN (1), it can be changed later
296 */
297 if (!swd || !swd->read_reg || !swd->write_reg || !swd->init) {
298 LOG_DEBUG("no SWD driver?");
299 return ERROR_FAIL;
300 }
301
302 retval = swd->init(1);
303 if (retval != ERROR_OK) {
304 LOG_DEBUG("can't init SWD driver");
305 return retval;
306 }
307
308 /* force DAP into SWD mode (not JTAG) */
309 retval = dap_to_swd(target);
310
311 return retval;
312 }
313
314 static int swd_init(struct command_context *ctx)
315 {
316 struct target *target = get_current_target(ctx);
317 struct arm *arm = target_to_arm(target);
318 struct adiv5_dap *dap = arm->dap;
319 uint32_t idcode;
320 int status;
321
322
323 /* FIXME validate transport config ... is the
324 * configured DAP present (check IDCODE)?
325 * Is *only* one DAP configured?
326 *
327 * MUST READ IDCODE
328 */
329
330 /* Note, debugport_init() does setup too */
331
332 uint8_t ack;
333
334 status = swd_queue_idcode_read(dap, &ack, &idcode);
335
336 if (status == ERROR_OK)
337 LOG_INFO("SWD IDCODE %#8.8x", idcode);
338
339 return status;
340
341 }
342
343 static struct transport swd_transport = {
344 .name = "swd",
345 .select = swd_select,
346 .init = swd_init,
347 };
348
349 static void swd_constructor(void) __attribute__((constructor));
350 static void swd_constructor(void)
351 {
352 transport_register(&swd_transport);
353 }
354
355 /** Returns true if the current debug session
356 * is using SWD as its transport.
357 */
358 bool transport_is_swd(void)
359 {
360 return get_current_transport() == &swd_transport;
361 }