src/jtag/transport.c

   1 /*
   2  * Copyright (c) 2010 by David Brownell
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software Foundation,
  16  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 #include "config.h"
  21 #endif
  22
  23 /** @file
  24  * Infrastructure for specifying and managing the transport protocol
  25  * used in a given debug or programming session.
  26  *
  27  * Examples of "debug-capable" transports are JTAG or SWD.
  28  * Additionally, JTAG supports boundary scan testing.
  29  *
  30  * Examples of "programming-capable" transports include SPI or UART;
  31  * those are used (often mediated by a ROM bootloader) for ISP style
  32  * programming, to perform an initial load of code into flash, or
  33  * sometimes into SRAM.  Target code could use "variant" options to
  34  * decide how to use such protocols.  For example, Cortex-M3 cores
  35  * from TI/Luminary and from NXP use different protocols for for
  36  * UART or SPI based firmware loading.
  37  *
  38  * As a rule, there are protocols layered on top of the transport.
  39  * For example, different chip families use JTAG in different ways
  40  * for debugging.  Also, each family that supports programming over
  41  * a UART link for initial firmware loading tends to define its own
  42  * messaging and error handling.
  43  */
  44
  45 #include <helper/log.h>
  46
  47 #include "transport.h"
  48
  49 extern struct command_context *global_cmd_ctx;
  50
  51
  52 /*-----------------------------------------------------------------------*/
  53
  54 /*
  55  * Infrastructure internals
  56  */
  57
  58 /** List of transports known to OpenOCD. */
  59 static struct transport *transport_list;
  60
  61 /**
  62  * NULL-terminated Vector of names of transports which the
  63  * currently selected debug adapter supports.  This is declared
  64  * by the time that adapter is fully set up.
  65  */
  66 static const char **allowed_transports;
  67
  68 /** * The transport being used for the current OpenOCD session.  */
  69 static struct transport *session;
  70
  71 static  int transport_select(struct command_context *ctx, const char *name)
  72 {
  73         /* name may only identify a known transport;
  74          * caller guarantees session's transport isn't yet set.*/
  75         for (struct transport *t = transport_list; t; t = t->next) {
  76                         if (strcmp(t->name, name) == 0) {
  77                                 int retval = t->select(ctx);
  78                         /* select() registers commands specific to this
  79                          * transport, and may also reset the link, e.g.
  80                          * forcing it to JTAG or SWD mode.
  81                          */
  82                         if (retval == ERROR_OK)
  83                                 session = t;
  84                         else
  85                                 LOG_ERROR("Error %d selecting '%s' as "
  86                                         "transport", retval, t->name);
  87                         return retval;
  88                 }
  89         }
  90
  91         LOG_ERROR("No transport named '%s' is available.", name);
  92         return ERROR_FAIL;
  93 }
  94
  95 /**
  96  * Called by debug adapter drivers, or affiliated Tcl config scripts,
  97  * to declare the set of transports supported by an adapter.  When
  98  * there is only one member of that set, it is automatically selected.
  99  */
 100 int allow_transports(struct command_context *ctx, const char **vector)
 101 {
 102         /* NOTE:  caller is required to provide only a list
 103          * of *valid* transport names
 104          *
 105          * REVISIT should we validate that?  and insist there's
 106          * at least one non-NULL element in that list?
 107          *
 108          * ... allow removals, e.g. external strapping prevents use
 109          * of one transport; C code should be definitive about what
 110          * can be used when all goes well.
 111          */
 112         if (allowed_transports != NULL || session) {
 113                 LOG_ERROR("Can't modify the set of allowed transports.");
 114                 return ERROR_FAIL;
 115         }
 116
 117
 118         allowed_transports = vector;
 119
 120         /* autoselect if there's no choice ... */
 121         if (!vector[1]) {
 122                 LOG_INFO("only one transport option; autoselect '%s'",
 123                                 vector[0]);
 124                 return transport_select(ctx, vector [0]);
 125         } else {
 126                 /* guard against user config errors */
 127                 LOG_WARNING("must select a transport.");
 128                 while (*vector)
 129                         LOG_DEBUG("allow transport '%s'", *vector++);
 130                 return ERROR_OK;
 131         }
 132 }
 133
 134
 135 /**
 136  * Used to verify corrrect adapter driver initialization.
 137  *
 138  * @returns true iff the adapter declared one or more transports.
 139  */
 140 bool transports_are_declared(void)
 141 {
 142         return allowed_transports != NULL;
 143 }
 144
 145 /**
 146  * Registers a transport.  There are general purpose transports
 147  * (such as JTAG), as well as relatively proprietary ones which are
 148  * specific to a given chip (or chip family).
 149  *
 150  * Code implementing a transport needs to register it before it can
 151  * be selected and then activated.  This is a dynamic process, so
 152  * that chips (and families) can define transports as needed (without
 153  * nneeding error-prone static tables).
 154  *
 155  * @param new_transport the transport being registered.  On a
 156  * successful return, this memory is owned by the transport framework.
 157  *
 158  * @returns ERROR_OK on success, else a fault code.
 159  */
 160 int transport_register(struct transport *new_transport)
 161 {
 162         struct transport *t;
 163
 164         for (t = transport_list; t; t = t->next) {
 165                 if (strcmp(t->name, new_transport->name) == 0) {
 166                         LOG_ERROR("transport name already used");
 167                         return ERROR_FAIL;
 168                 }
 169         }
 170
 171         if (!new_transport->select || !new_transport->init) {
 172                 LOG_ERROR("invalid transport %s", new_transport->name);
 173         }
 174
 175         /* splice this into the list */
 176         new_transport->next = transport_list;
 177         transport_list = new_transport;
 178         LOG_DEBUG("register '%s'", new_transport->name);
 179
 180         return ERROR_OK;
 181 }
 182
 183 /**
 184  * Returns the transport currently being used by this debug or
 185  * programming session.
 186  *
 187  * @returns handle to the read-only transport entity.
 188  */
 189 struct transport *get_current_transport(void)
 190 {
 191
 192         /* REVISIT -- constify */
 193         return session;
 194 }
 195
 196
 197 /*-----------------------------------------------------------------------*/
 198
 199 /*
 200  * Infrastructure for Tcl interface to transports.
 201  */
 202
 203 /**
 204  * Makes and stores a copy of a set of transports passed as
 205  * parameters to a command.
 206  *
 207  * @param vector where the resulting copy is stored, as an argv-style
 208  *      NULL-terminated vector.
 209  */
 210 COMMAND_HELPER(transport_list_parse, char ***vector)
 211 {
 212         char **argv;
 213         unsigned n = CMD_ARGC;
 214         unsigned j = 0;
 215
 216         *vector = NULL;
 217
 218         if (n < 1)
 219                 return ERROR_COMMAND_SYNTAX_ERROR;
 220
 221         /* our return vector must be NULL terminated */
 222         argv = (char **) calloc(n + 1, sizeof(char *));
 223         if (argv == NULL)
 224                 return ERROR_FAIL;
 225
 226         for (unsigned i = 0; i < n; i++) {
 227                 struct transport *t;
 228
 229                 for (t = transport_list; t; t = t->next) {
 230                         if (strcmp(t->name, CMD_ARGV[i]) != 0)
 231                                 continue;
 232                         argv[j++] = strdup(CMD_ARGV[i]);
 233                         break;
 234                 }
 235                 if (!t) {
 236                         LOG_ERROR("no such transport '%s'", CMD_ARGV[i]);
 237                         goto fail;
 238                 }
 239         }
 240
 241         *vector = argv;
 242         return ERROR_OK;
 243
 244 fail:
 245         for (unsigned i = 0; i < n; i++)
 246                 free(argv[i]);
 247         free(argv);
 248         return ERROR_FAIL;
 249 }
 250
 251 COMMAND_HANDLER(handle_transport_init)
 252 {
 253         LOG_DEBUG("%s", __func__);
 254         if (!session) {
 255                 LOG_ERROR("session's transport is not selected.");
 256                 return ERROR_FAIL;
 257         }
 258
 259         return session->init(CMD_CTX);
 260 }
 261
 262 COMMAND_HANDLER(handle_transport_list)
 263 {
 264         if (CMD_ARGC != 0)
 265                 return ERROR_COMMAND_SYNTAX_ERROR;
 266
 267         command_print(CMD_CTX, "The following transports are available:");
 268
 269         for (struct transport *t = transport_list; t; t = t->next)
 270                 command_print(CMD_CTX, "\t%s", t->name);
 271
 272         return ERROR_OK;
 273 }
 274
 275 /**
 276  * Implements the Tcl "transport select" command, choosing the
 277  * transport to be used in this debug session from among the
 278  * set supported by the debug adapter being used.  Return value
 279  * is scriptable (allowing "if swd then..." etc).
 280  */
 281 static int jim_transport_select(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
 282 {
 283         switch (argc) {
 284         case 1:                 /* return/display */
 285                 if (!session) {
 286                         LOG_ERROR("session's transport is not selected.");
 287                         return JIM_ERR;
 288                 } else {
 289                         Jim_SetResultString(interp, session->name, -1);
 290                         return JIM_OK;
 291                 }
 292                 break;
 293         case 2:                 /* assign */
 294         if (session) {
 295                 /* can't change session's transport after-the-fact */
 296                 LOG_ERROR("session's transport is already selected.");
 297                 return JIM_ERR;
 298         }
 299
 300         /* Is this transport supported by our debug adapter?
 301          * Example, "JTAG-only" means SWD is not supported.
 302          *
 303          * NOTE:  requires adapter to have been set up, with
 304          * transports declared via C.
 305          */
 306         if (!allowed_transports) {
 307                 LOG_ERROR("Debug adapter doesn't support any transports?");
 308                 return JIM_ERR;
 309         }
 310
 311         for (unsigned i = 0; allowed_transports[i]; i++) {
 312
 313                 if (strcmp(allowed_transports[i], argv[0]->bytes) == 0)
 314                 return transport_select(global_cmd_ctx, argv[0]->bytes);
 315         }
 316
 317                 LOG_ERROR("Debug adapter doesn't support '%s' "
 318                         "transport", argv[0]->bytes);
 319                 return JIM_ERR;
 320                 break;
 321         default:
 322                 Jim_WrongNumArgs(interp, 1, argv, "[too many parameters]");
 323                 return JIM_ERR;
 324         }
 325 }
 326
 327 static const struct command_registration transport_commands[] = {
 328         {
 329                 .name = "init",
 330                 .handler = handle_transport_init,
 331                 /* this would be COMMAND_CONFIG ... except that
 332                  * it needs to trigger event handlers that may
 333                  * require COMMAND_EXEC ...
 334                  */
 335                 .mode = COMMAND_ANY,
 336                 .help = "Initialize this session's transport",
 337         },
 338         {
 339                 .name = "list",
 340                 .handler = handle_transport_list,
 341                 .mode = COMMAND_ANY,
 342                 .help = "list all built-in transports",
 343         },
 344         {
 345                 .name = "select",
 346                 .jim_handler = jim_transport_select,
 347                 .mode = COMMAND_ANY,
 348                 .help = "Select this session's transport",
 349                 .usage = "[transport_name]",
 350         },
 351         COMMAND_REGISTRATION_DONE
 352 };
 353
 354 static const struct command_registration transport_group[] = {
 355         {
 356                 .name = "transport",
 357                 .mode = COMMAND_ANY,
 358                 .help = "Transport command group",
 359                 .chain = transport_commands,
 360         },
 361         COMMAND_REGISTRATION_DONE
 362 };
 363
 364
 365 int transport_register_commands(struct command_context *ctx)
 366 {
 367         return register_commands(ctx, NULL, transport_group);
 368 }