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 /*-----------------------------------------------------------------------*/
  50
  51 /*
  52  * Infrastructure internals
  53  */
  54
  55 /** List of transports known to OpenOCD. */
  56 static struct transport *transport_list;
  57
  58 /**
  59  * NULL-terminated Vector of names of transports which the
  60  * currently selected debug adapter supports.  This is declared
  61  * by the time that adapter is fully set up.
  62  */
  63 static const char **allowed_transports;
  64
  65 /** * The transport being used for the current OpenOCD session.  */
  66 static struct transport *session;
  67
  68 static  int transport_select(struct command_context *ctx, const char *name)
  69 {
  70         /* name may only identify a known transport;
  71          * caller guarantees session's transport isn't yet set.*/
  72         for (struct transport *t = transport_list; t; t = t->next) {
  73                         if (strcmp(t->name, name) == 0) {
  74                                 int retval = t->select(ctx);
  75                         /* select() registers commands specific to this
  76                          * transport, and may also reset the link, e.g.
  77                          * forcing it to JTAG or SWD mode.
  78                          */
  79                         if (retval == ERROR_OK)
  80                                 session = t;
  81                         else
  82                                 LOG_ERROR("Error %d selecting '%s' as "
  83                                         "transport", retval, t->name);
  84                         return retval;
  85                 }
  86         }
  87
  88         LOG_ERROR("No transport named '%s' is available.", name);
  89         return ERROR_FAIL;
  90 }
  91
  92 /**
  93  * Called by debug adapter drivers, or affiliated Tcl config scripts,
  94  * to declare the set of transports supported by an adapter.  When
  95  * there is only one member of that set, it is automatically selected.
  96  */
  97 int allow_transports(struct command_context *ctx, const char **vector)
  98 {
  99         /* NOTE:  caller is required to provide only a list
 100          * of *valid* transport names
 101          *
 102          * REVISIT should we validate that?  and insist there's
 103          * at least one non-NULL element in that list?
 104          *
 105          * ... allow removals, e.g. external strapping prevents use
 106          * of one transport; C code should be definitive about what
 107          * can be used when all goes well.
 108          */
 109         if (allowed_transports != NULL || session) {
 110                 LOG_ERROR("Can't modify the set of allowed transports.");
 111                 return ERROR_FAIL;
 112         }
 113
 114
 115         allowed_transports = vector;
 116
 117         /* autoselect if there's no choice ... */
 118         if (!vector[1]) {
 119                 LOG_INFO("only one transport option; autoselect '%s'",
 120                                 vector[0]);
 121                 return transport_select(ctx, vector [0]);
 122         } else {
 123                 /* guard against user config errors */
 124                 LOG_WARNING("must select a transport.");
 125                 while (*vector)
 126                         LOG_DEBUG("allow transport '%s'", *vector++);
 127                 return ERROR_OK;
 128         }
 129 }
 130
 131
 132 /**
 133  * Used to verify corrrect adapter driver initialization.
 134  *
 135  * @returns true iff the adapter declared one or more transports.
 136  */
 137 bool transports_are_declared(void)
 138 {
 139         return allowed_transports != NULL;
 140 }
 141
 142 /**
 143  * Registers a transport.  There are general purpose transports
 144  * (such as JTAG), as well as relatively proprietary ones which are
 145  * specific to a given chip (or chip family).
 146  *
 147  * Code implementing a transport needs to register it before it can
 148  * be selected and then activated.  This is a dynamic process, so
 149  * that chips (and families) can define transports as needed (without
 150  * nneeding error-prone static tables).
 151  *
 152  * @param new_transport the transport being registered.  On a
 153  * successful return, this memory is owned by the transport framework.
 154  *
 155  * @returns ERROR_OK on success, else a fault code.
 156  */
 157 int transport_register(struct transport *new_transport)
 158 {
 159         struct transport *t;
 160
 161         for (t = transport_list; t; t = t->next) {
 162                 if (strcmp(t->name, new_transport->name) == 0) {
 163                         LOG_ERROR("transport name already used");
 164                         return ERROR_FAIL;
 165                 }
 166         }
 167
 168         if (!new_transport->select || !new_transport->init) {
 169                 LOG_ERROR("invalid transport %s", new_transport->name);
 170         }
 171
 172         /* splice this into the list */
 173         new_transport->next = transport_list;
 174         transport_list = new_transport;
 175         LOG_DEBUG("register '%s'", new_transport->name);
 176
 177         return ERROR_OK;
 178 }
 179
 180 /**
 181  * Returns the transport currently being used by this debug or
 182  * programming session.
 183  *
 184  * @returns handle to the read-only transport entity.
 185  */
 186 struct transport *get_current_transport(void)
 187 {
 188
 189         /* REVISIT -- constify */
 190         return session;
 191 }
 192
 193
 194 /*-----------------------------------------------------------------------*/
 195
 196 /*
 197  * Infrastructure for Tcl interface to transports.
 198  */
 199
 200 /**
 201  * Makes and stores a copy of a set of transports passed as
 202  * parameters to a command.
 203  *
 204  * @param vector where the resulting copy is stored, as an argv-style
 205  *      NULL-terminated vector.
 206  */
 207 COMMAND_HELPER(transport_list_parse, char ***vector)
 208 {
 209         char **argv;
 210         unsigned n = CMD_ARGC;
 211         unsigned j = 0;
 212
 213         *vector = NULL;
 214
 215         if (n < 1)
 216                 return ERROR_COMMAND_SYNTAX_ERROR;
 217
 218         /* our return vector must be NULL terminated */
 219         argv = (char **) calloc(n + 1, sizeof(char *));
 220         if (argv == NULL)
 221                 return ERROR_FAIL;
 222
 223         for (unsigned i = 0; i < n; i++) {
 224                 struct transport *t;
 225
 226                 for (t = transport_list; t; t = t->next) {
 227                         if (strcmp(t->name, CMD_ARGV[i]) != 0)
 228                                 continue;
 229                         argv[j++] = strdup(CMD_ARGV[i]);
 230                         break;
 231                 }
 232                 if (!t) {
 233                         LOG_ERROR("no such transport '%s'", CMD_ARGV[i]);
 234                         goto fail;
 235                 }
 236         }
 237
 238         *vector = argv;
 239         return ERROR_OK;
 240
 241 fail:
 242         for (unsigned i = 0; i < n; i++)
 243                 free(argv[i]);
 244         free(argv);
 245         return ERROR_FAIL;
 246 }
 247
 248 COMMAND_HANDLER(handle_transport_init)
 249 {
 250         LOG_DEBUG("%s", __func__);
 251         if (!session) {
 252                 LOG_ERROR("session's transport is not selected.");
 253                 return ERROR_FAIL;
 254         }
 255
 256         return session->init(CMD_CTX);
 257 }
 258
 259 COMMAND_HANDLER(handle_transport_list)
 260 {
 261         if (CMD_ARGC != 0)
 262                 return ERROR_COMMAND_SYNTAX_ERROR;
 263
 264         command_print(CMD_CTX, "The following transports are available:");
 265
 266         for (struct transport *t = transport_list; t; t = t->next)
 267                 command_print(CMD_CTX, "\t%s", t->name);
 268
 269         return ERROR_OK;
 270 }
 271
 272 /**
 273  * Implements the Tcl "transport select" command, choosing the
 274  * transport to be used in this debug session from among the
 275  * set supported by the debug adapter being used.
 276  */
 277 COMMAND_HANDLER(handle_transport_select)
 278 {
 279         int retval = ERROR_OK;;
 280
 281         switch (CMD_ARGC) {
 282         case 0:                 /* "select" */
 283                 if (session) {
 284                         goto show;
 285                 }
 286                 LOG_ERROR("session's transport is not selected.");
 287                 return ERROR_FAIL;
 288
 289         case 1:                 /* "select FOO" */
 290                 if ((session!= NULL) && strcmp(session->name, CMD_ARGV[0]) == 0) {
 291                         /* NOP */
 292                         LOG_DEBUG("transport '%s' is already selected",
 293                                         CMD_ARGV[0]);
 294                         return ERROR_OK;
 295                 } else {
 296                         /* we can't change this session's transport after-the-fact */
 297                         if (session) {
 298                                 LOG_ERROR("session's transport is already selected.");
 299                                 return ERROR_FAIL;
 300                         }
 301                 }
 302                 break;
 303
 304         default:                /* select FOO BAR */
 305                 /* we only select *one* transport per session */
 306                 LOG_ERROR("may only select one transport!");
 307                 return ERROR_COMMAND_SYNTAX_ERROR;
 308         }
 309
 310         /* Is this transport supported by our debug adapter?
 311          * Example, "JTAG-only" means SWD is not supported.
 312          *
 313          * NOTE:  requires adapter to have been set up, with
 314          * transports declared via C.
 315          */
 316         if (!allowed_transports) {
 317                 LOG_ERROR("Debug adapter doesn't support any transports?");
 318                 return ERROR_FAIL;
 319         }
 320
 321         for (unsigned i = 0; allowed_transports[i]; i++) {
 322
 323                 if (strcmp(allowed_transports[i], CMD_ARGV[0]) == 0)
 324                         return transport_select(CMD_CTX, CMD_ARGV[0]);
 325         }
 326
 327         LOG_ERROR("Debug adapter doesn't support '%s' "
 328                         "transport?", CMD_ARGV[0]);
 329         return ERROR_FAIL;
 330
 331
 332 show:
 333         /* report the current transport selection */
 334         command_print(CMD_CTX, "%s", session->name);
 335         return retval;
 336 }
 337
 338 static const struct command_registration transport_commands[] = {
 339         {
 340                 .name = "init",
 341                 .handler = handle_transport_init,
 342                 /* this would be COMMAND_CONFIG ... except that
 343                  * it needs to trigger event handlers that may
 344                  * require COMMAND_EXEC ...
 345                  */
 346                 .mode = COMMAND_ANY,
 347                 .help = "Initialize this session's transport",
 348         },
 349         {
 350                 .name = "list",
 351                 .handler = handle_transport_list,
 352                 .mode = COMMAND_ANY,
 353                 .help = "list all built-in transports",
 354         },
 355         {
 356                 .name = "select",
 357                 .handler = handle_transport_select,
 358                 .mode = COMMAND_ANY,
 359                 .help = "Select this session's transport",
 360                 .usage = "[transport_name]",
 361         },
 362         COMMAND_REGISTRATION_DONE
 363 };
 364
 365 static const struct command_registration transport_group[] = {
 366         {
 367                 .name = "transport",
 368                 .mode = COMMAND_ANY,
 369                 .help = "Transport command group",
 370                 .chain = transport_commands,
 371         },
 372         COMMAND_REGISTRATION_DONE
 373 };
 374
 375
 376 int transport_register_commands(struct command_context *ctx)
 377 {
 378         return register_commands(ctx, NULL, transport_group);
 379 }