src/transport/transport.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 /*
   4  * Copyright (c) 2010 by David Brownell
   5  */
   6
   7 #ifdef HAVE_CONFIG_H
   8 #include "config.h"
   9 #endif
  10
  11 /** @file
  12  * Infrastructure for specifying and managing the transport protocol
  13  * used in a given debug or programming session.
  14  *
  15  * Examples of "debug-capable" transports are JTAG or SWD.
  16  * Additionally, JTAG supports boundary scan testing.
  17  *
  18  * Examples of "programming-capable" transports include SPI or UART;
  19  * those are used (often mediated by a ROM bootloader) for ISP style
  20  * programming, to perform an initial load of code into flash, or
  21  * sometimes into SRAM.  Target code could use "variant" options to
  22  * decide how to use such protocols.  For example, Cortex-M3 cores
  23  * from TI/Luminary and from NXP use different protocols for for
  24  * UART or SPI based firmware loading.
  25  *
  26  * As a rule, there are protocols layered on top of the transport.
  27  * For example, different chip families use JTAG in different ways
  28  * for debugging.  Also, each family that supports programming over
  29  * a UART link for initial firmware loading tends to define its own
  30  * messaging and error handling.
  31  */
  32
  33 #include <helper/log.h>
  34 #include <helper/replacements.h>
  35 #include <transport/transport.h>
  36
  37 extern struct command_context *global_cmd_ctx;
  38
  39 /*-----------------------------------------------------------------------*/
  40
  41 /*
  42  * Infrastructure internals
  43  */
  44
  45 /** List of transports known to OpenOCD. */
  46 static struct transport *transport_list;
  47
  48 /**
  49  * NULL-terminated Vector of names of transports which the
  50  * currently selected debug adapter supports.  This is declared
  51  * by the time that adapter is fully set up.
  52  */
  53 static const char * const *allowed_transports;
  54
  55 /** * The transport being used for the current OpenOCD session.  */
  56 static struct transport *session;
  57
  58 static int transport_select(struct command_context *ctx, const char *name)
  59 {
  60         /* name may only identify a known transport;
  61          * caller guarantees session's transport isn't yet set.*/
  62         for (struct transport *t = transport_list; t; t = t->next) {
  63                 if (strcmp(t->name, name) == 0) {
  64                         int retval = t->select(ctx);
  65                         /* select() registers commands specific to this
  66                          * transport, and may also reset the link, e.g.
  67                          * forcing it to JTAG or SWD mode.
  68                          */
  69                         if (retval == ERROR_OK)
  70                                 session = t;
  71                         else
  72                                 LOG_ERROR("Error selecting '%s' as transport", t->name);
  73                         return retval;
  74                 }
  75         }
  76
  77         LOG_ERROR("No transport named '%s' is available.", name);
  78         return ERROR_FAIL;
  79 }
  80
  81 /**
  82  * Called by debug adapter drivers, or affiliated Tcl config scripts,
  83  * to declare the set of transports supported by an adapter.  When
  84  * there is only one member of that set, it is automatically selected.
  85  */
  86 int allow_transports(struct command_context *ctx, const char * const *vector)
  87 {
  88         /* NOTE:  caller is required to provide only a list
  89          * of *valid* transport names
  90          *
  91          * REVISIT should we validate that?  and insist there's
  92          * at least one non-NULL element in that list?
  93          *
  94          * ... allow removals, e.g. external strapping prevents use
  95          * of one transport; C code should be definitive about what
  96          * can be used when all goes well.
  97          */
  98         if (allowed_transports || session) {
  99                 LOG_ERROR("Can't modify the set of allowed transports.");
 100                 return ERROR_FAIL;
 101         }
 102
 103         allowed_transports = vector;
 104
 105         /* autoselect if there's no choice ... */
 106         if (!vector[1]) {
 107                 LOG_INFO("only one transport option; autoselecting '%s'", vector[0]);
 108                 return transport_select(ctx, vector[0]);
 109         }
 110
 111         return ERROR_OK;
 112 }
 113
 114 /**
 115  * Registers a transport.  There are general purpose transports
 116  * (such as JTAG), as well as relatively proprietary ones which are
 117  * specific to a given chip (or chip family).
 118  *
 119  * Code implementing a transport needs to register it before it can
 120  * be selected and then activated.  This is a dynamic process, so
 121  * that chips (and families) can define transports as needed (without
 122  * needing error-prone static tables).
 123  *
 124  * @param new_transport the transport being registered.  On a
 125  * successful return, this memory is owned by the transport framework.
 126  *
 127  * @returns ERROR_OK on success, else a fault code.
 128  */
 129 int transport_register(struct transport *new_transport)
 130 {
 131         struct transport *t;
 132
 133         for (t = transport_list; t; t = t->next) {
 134                 if (strcmp(t->name, new_transport->name) == 0) {
 135                         LOG_ERROR("transport name already used");
 136                         return ERROR_FAIL;
 137                 }
 138         }
 139
 140         if (!new_transport->select || !new_transport->init)
 141                 LOG_ERROR("invalid transport %s", new_transport->name);
 142
 143         /* splice this into the list */
 144         new_transport->next = transport_list;
 145         transport_list = new_transport;
 146         LOG_DEBUG("register '%s'", new_transport->name);
 147
 148         return ERROR_OK;
 149 }
 150
 151 /**
 152  * Returns the transport currently being used by this debug or
 153  * programming session.
 154  *
 155  * @returns handle to the read-only transport entity.
 156  */
 157 struct transport *get_current_transport(void)
 158 {
 159         /* REVISIT -- constify */
 160         return session;
 161 }
 162
 163 /*-----------------------------------------------------------------------*/
 164
 165 /*
 166  * Infrastructure for Tcl interface to transports.
 167  */
 168
 169 /**
 170  * Makes and stores a copy of a set of transports passed as
 171  * parameters to a command.
 172  *
 173  * @param vector where the resulting copy is stored, as an argv-style
 174  *      NULL-terminated vector.
 175  */
 176 COMMAND_HELPER(transport_list_parse, char ***vector)
 177 {
 178         char **argv;
 179         unsigned n = CMD_ARGC;
 180         unsigned j = 0;
 181
 182         *vector = NULL;
 183
 184         if (n < 1)
 185                 return ERROR_COMMAND_SYNTAX_ERROR;
 186
 187         /* our return vector must be NULL terminated */
 188         argv = calloc(n + 1, sizeof(char *));
 189         if (!argv)
 190                 return ERROR_FAIL;
 191
 192         for (unsigned i = 0; i < n; i++) {
 193                 struct transport *t;
 194
 195                 for (t = transport_list; t; t = t->next) {
 196                         if (strcmp(t->name, CMD_ARGV[i]) != 0)
 197                                 continue;
 198                         argv[j++] = strdup(CMD_ARGV[i]);
 199                         break;
 200                 }
 201                 if (!t) {
 202                         LOG_ERROR("no such transport '%s'", CMD_ARGV[i]);
 203                         goto fail;
 204                 }
 205         }
 206
 207         *vector = argv;
 208         return ERROR_OK;
 209
 210 fail:
 211         for (unsigned i = 0; i < n; i++)
 212                 free(argv[i]);
 213         free(argv);
 214         return ERROR_FAIL;
 215 }
 216
 217 COMMAND_HANDLER(handle_transport_init)
 218 {
 219         LOG_DEBUG("%s", __func__);
 220         if (!session) {
 221                 LOG_ERROR("session transport was not selected. Use 'transport select <transport>'");
 222
 223                 /* no session transport configured, print transports then fail */
 224                 LOG_ERROR("Transports available:");
 225                 const char * const *vector = allowed_transports;
 226                 while (*vector) {
 227                         LOG_ERROR("%s", *vector);
 228                         vector++;
 229                 }
 230                 return ERROR_FAIL;
 231         }
 232
 233         return session->init(CMD_CTX);
 234 }
 235
 236 COMMAND_HANDLER(handle_transport_list)
 237 {
 238         if (CMD_ARGC != 0)
 239                 return ERROR_COMMAND_SYNTAX_ERROR;
 240
 241         command_print(CMD, "The following transports are available:");
 242
 243         for (struct transport *t = transport_list; t; t = t->next)
 244                 command_print(CMD, "\t%s", t->name);
 245
 246         return ERROR_OK;
 247 }
 248
 249 /**
 250  * Implements the Tcl "transport select" command, choosing the
 251  * transport to be used in this debug session from among the
 252  * set supported by the debug adapter being used.  Return value
 253  * is scriptable (allowing "if swd then..." etc).
 254  */
 255 COMMAND_HANDLER(handle_transport_select)
 256 {
 257         if (CMD_ARGC > 1)
 258                 return ERROR_COMMAND_SYNTAX_ERROR;
 259
 260         if (CMD_ARGC == 0) {
 261                 /* autoselect if necessary, then return/display current config */
 262                 if (!session) {
 263                         if (!allowed_transports) {
 264                                 command_print(CMD, "Debug adapter does not support any transports? Check config file order.");
 265                                 return ERROR_FAIL;
 266                         }
 267                         LOG_INFO("auto-selecting first available session transport \"%s\". "
 268                                 "To override use 'transport select <transport>'.", allowed_transports[0]);
 269                         int retval = transport_select(CMD_CTX, allowed_transports[0]);
 270                         if (retval != ERROR_OK)
 271                                 return retval;
 272                 }
 273                 command_print(CMD, "%s", session->name);
 274                 return ERROR_OK;
 275         }
 276
 277         /* assign transport */
 278         if (session) {
 279                 if (!strcmp(session->name, CMD_ARGV[0])) {
 280                         LOG_WARNING("Transport \"%s\" was already selected", session->name);
 281                         command_print(CMD, "%s", session->name);
 282                         return ERROR_OK;
 283                 }
 284                 command_print(CMD, "Can't change session's transport after the initial selection was made");
 285                 return ERROR_FAIL;
 286         }
 287
 288         /* Is this transport supported by our debug adapter?
 289          * Example, "JTAG-only" means SWD is not supported.
 290          *
 291          * NOTE:  requires adapter to have been set up, with
 292          * transports declared via C.
 293          */
 294         if (!allowed_transports) {
 295                 command_print(CMD, "Debug adapter doesn't support any transports?");
 296                 return ERROR_FAIL;
 297         }
 298
 299         for (unsigned int i = 0; allowed_transports[i]; i++) {
 300                 if (!strcmp(allowed_transports[i], CMD_ARGV[0])) {
 301                         int retval = transport_select(CMD_CTX, CMD_ARGV[0]);
 302                         if (retval != ERROR_OK)
 303                                 return retval;
 304                         command_print(CMD, "%s", session->name);
 305                         return ERROR_OK;
 306                 }
 307         }
 308
 309         command_print(CMD, "Debug adapter doesn't support '%s' transport", CMD_ARGV[0]);
 310         return ERROR_FAIL;
 311 }
 312
 313 static const struct command_registration transport_commands[] = {
 314         {
 315                 .name = "init",
 316                 .handler = handle_transport_init,
 317                 /* this would be COMMAND_CONFIG ... except that
 318                  * it needs to trigger event handlers that may
 319                  * require COMMAND_EXEC ...
 320                  */
 321                 .mode = COMMAND_ANY,
 322                 .help = "Initialize this session's transport",
 323                 .usage = ""
 324         },
 325         {
 326                 .name = "list",
 327                 .handler = handle_transport_list,
 328                 .mode = COMMAND_ANY,
 329                 .help = "list all built-in transports",
 330                 .usage = ""
 331         },
 332         {
 333                 .name = "select",
 334                 .handler = handle_transport_select,
 335                 .mode = COMMAND_ANY,
 336                 .help = "Select this session's transport",
 337                 .usage = "[transport_name]",
 338         },
 339         COMMAND_REGISTRATION_DONE
 340 };
 341
 342 static const struct command_registration transport_group[] = {
 343         {
 344                 .name = "transport",
 345                 .mode = COMMAND_ANY,
 346                 .help = "Transport command group",
 347                 .chain = transport_commands,
 348                 .usage = ""
 349         },
 350         COMMAND_REGISTRATION_DONE
 351 };
 352
 353 int transport_register_commands(struct command_context *ctx)
 354 {
 355         return register_commands(ctx, NULL, transport_group);
 356 }