common/cmd_fdt.c

   1 /*
   2  * (C) Copyright 2007
   3  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com
   4  * Based on code written by:
   5  *   Pantelis Antoniou <pantelis.antoniou@gmail.com> and
   6  *   Matthew McClintock <msm@freescale.com>
   7  *
   8  * See file CREDITS for list of people who contributed to this
   9  * project.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation; either version 2 of
  14  * the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  24  * MA 02111-1307 USA
  25  */
  26
  27 #include <common.h>
  28 #include <command.h>
  29 #include <linux/ctype.h>
  30 #include <linux/types.h>
  31
  32 #ifdef CONFIG_OF_LIBFDT
  33
  34 #include <asm/global_data.h>
  35 #include <fdt.h>
  36 #include <libfdt.h>
  37 #include <fdt_support.h>
  38
  39 #define MAX_LEVEL       32              /* how deeply nested we will go */
  40 #define SCRATCHPAD      1024            /* bytes of scratchpad memory */
  41
  42 /*
  43  * Global data (for the gd->bd)
  44  */
  45 DECLARE_GLOBAL_DATA_PTR;
  46
  47 /*
  48  * Function prototypes/declarations.
  49  */
  50 #ifdef CONFIG_OF_BOARD_SETUP
  51 void ft_board_setup(void *blob, bd_t *bd);
  52 #endif
  53
  54 static int fdt_valid(void);
  55 static int fdt_parse_prop(char *pathp, char *prop, char *newval,
  56         char *data, int *len);
  57 static int fdt_print(char *pathp, char *prop, int depth);
  58
  59 /*
  60  * Flattened Device Tree command, see the help for parameter definitions.
  61  */
  62 int do_fdt (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
  63 {
  64         if (argc < 2) {
  65                 printf ("Usage:\n%s\n", cmdtp->usage);
  66                 return 1;
  67         }
  68
  69         /********************************************************************
  70          * Set the address of the fdt
  71          ********************************************************************/
  72         if (argv[1][0] == 'a') {
  73                 /*
  74                  * Set the address [and length] of the fdt.
  75                  */
  76                 fdt = (struct fdt_header *)simple_strtoul(argv[2], NULL, 16);
  77
  78                 if (!fdt_valid()) {
  79                         return 1;
  80                 }
  81
  82                 if (argc >= 4) {
  83                         int  len;
  84                         int  err;
  85                         /*
  86                          * Optional new length
  87                          */
  88                         len =  simple_strtoul(argv[3], NULL, 16);
  89                         if (len < fdt_totalsize(fdt)) {
  90                                 printf ("New length %d < existing length %d, "
  91                                         "ignoring.\n",
  92                                         len, fdt_totalsize(fdt));
  93                         } else {
  94                                 /*
  95                                  * Open in place with a new length.
  96                                  */
  97                                 err = fdt_open_into(fdt, fdt, len);
  98                                 if (err != 0) {
  99                                         printf ("libfdt fdt_open_into(): %s\n",
 100                                                 fdt_strerror(err));
 101                                 }
 102                         }
 103                 }
 104
 105         /********************************************************************
 106          * Move the fdt
 107          ********************************************************************/
 108         } else if ((argv[1][0] == 'm') && (argv[1][1] == 'o')) {
 109                 struct fdt_header *newaddr;
 110                 int  len;
 111                 int  err;
 112
 113                 if (argc < 4) {
 114                         printf ("Usage:\n%s\n", cmdtp->usage);
 115                         return 1;
 116                 }
 117
 118                 /*
 119                  * Set the address and length of the fdt.
 120                  */
 121                 fdt = (struct fdt_header *)simple_strtoul(argv[2], NULL, 16);
 122                 if (!fdt_valid()) {
 123                         return 1;
 124                 }
 125
 126                 newaddr = (struct fdt_header *)simple_strtoul(argv[3],NULL,16);
 127
 128                 /*
 129                  * If the user specifies a length, use that.  Otherwise use the
 130                  * current length.
 131                  */
 132                 if (argc <= 4) {
 133                         len = fdt_totalsize(fdt);
 134                 } else {
 135                         len = simple_strtoul(argv[4], NULL, 16);
 136                         if (len < fdt_totalsize(fdt)) {
 137                                 printf ("New length 0x%X < existing length "
 138                                         "0x%X, aborting.\n",
 139                                         len, fdt_totalsize(fdt));
 140                                 return 1;
 141                         }
 142                 }
 143
 144                 /*
 145                  * Copy to the new location.
 146                  */
 147                 err = fdt_open_into(fdt, newaddr, len);
 148                 if (err != 0) {
 149                         printf ("libfdt fdt_open_into(): %s\n",
 150                                 fdt_strerror(err));
 151                         return 1;
 152                 }
 153                 fdt = newaddr;
 154
 155         /********************************************************************
 156          * Make a new node
 157          ********************************************************************/
 158         } else if ((argv[1][0] == 'm') && (argv[1][1] == 'k')) {
 159                 char *pathp;            /* path */
 160                 char *nodep;            /* new node to add */
 161                 int  nodeoffset;        /* node offset from libfdt */
 162                 int  err;
 163
 164                 /*
 165                  * Parameters: Node path, new node to be appended to the path.
 166                  */
 167                 if (argc < 4) {
 168                         printf ("Usage:\n%s\n", cmdtp->usage);
 169                         return 1;
 170                 }
 171
 172                 pathp = argv[2];
 173                 nodep = argv[3];
 174
 175                 nodeoffset = fdt_find_node_by_path (fdt, pathp);
 176                 if (nodeoffset < 0) {
 177                         /*
 178                          * Not found or something else bad happened.
 179                          */
 180                         printf ("libfdt fdt_find_node_by_path() returned %s\n",
 181                                 fdt_strerror(nodeoffset));
 182                         return 1;
 183                 }
 184                 err = fdt_add_subnode(fdt, nodeoffset, nodep);
 185                 if (err < 0) {
 186                         printf ("libfdt fdt_add_subnode(): %s\n",
 187                                 fdt_strerror(err));
 188                         return 1;
 189                 }
 190
 191         /********************************************************************
 192          * Set the value of a property in the fdt.
 193          ********************************************************************/
 194         } else if (argv[1][0] == 's') {
 195                 char *pathp;            /* path */
 196                 char *prop;             /* property */
 197                 char *newval;           /* value from the user (as a string) */
 198                 int  nodeoffset;        /* node offset from libfdt */
 199                 static char data[SCRATCHPAD];   /* storage for the property */
 200                 int  len;               /* new length of the property */
 201                 int  ret;               /* return value */
 202
 203                 /*
 204                  * Parameters: Node path, property, value.
 205                  */
 206                 if (argc < 5) {
 207                         printf ("Usage:\n%s\n", cmdtp->usage);
 208                         return 1;
 209                 }
 210
 211                 pathp  = argv[2];
 212                 prop   = argv[3];
 213                 newval = argv[4];
 214
 215                 nodeoffset = fdt_find_node_by_path (fdt, pathp);
 216                 if (nodeoffset < 0) {
 217                         /*
 218                          * Not found or something else bad happened.
 219                          */
 220                         printf ("libfdt fdt_find_node_by_path() returned %s\n",
 221                                 fdt_strerror(nodeoffset));
 222                         return 1;
 223                 }
 224                 ret = fdt_parse_prop(pathp, prop, newval, data, &len);
 225                 if (ret != 0)
 226                         return ret;
 227
 228                 ret = fdt_setprop(fdt, nodeoffset, prop, data, len);
 229                 if (ret < 0) {
 230                         printf ("libfdt fdt_setprop(): %s\n", fdt_strerror(ret));
 231                         return 1;
 232                 }
 233
 234         /********************************************************************
 235          * Print (recursive) / List (single level)
 236          ********************************************************************/
 237         } else if ((argv[1][0] == 'p') || (argv[1][0] == 'l')) {
 238                 int depth = MAX_LEVEL;  /* how deep to print */
 239                 char *pathp;            /* path */
 240                 char *prop;             /* property */
 241                 int  ret;               /* return value */
 242
 243                 /*
 244                  * list is an alias for print, but limited to 1 level
 245                  */
 246                 if (argv[1][0] == 'l') {
 247                         depth = 1;
 248                 }
 249
 250                 /*
 251                  * Get the starting path.  The root node is an oddball,
 252                  * the offset is zero and has no name.
 253                  */
 254                 pathp = argv[2];
 255                 if (argc > 3)
 256                         prop = argv[3];
 257                 else
 258                         prop = NULL;
 259
 260                 ret = fdt_print(pathp, prop, depth);
 261                 if (ret != 0)
 262                         return ret;
 263
 264         /********************************************************************
 265          * Remove a property/node
 266          ********************************************************************/
 267         } else if (argv[1][0] == 'r') {
 268                 int  nodeoffset;        /* node offset from libfdt */
 269                 int  err;
 270
 271                 /*
 272                  * Get the path.  The root node is an oddball, the offset
 273                  * is zero and has no name.
 274                  */
 275                 nodeoffset = fdt_find_node_by_path (fdt, argv[2]);
 276                 if (nodeoffset < 0) {
 277                         /*
 278                          * Not found or something else bad happened.
 279                          */
 280                         printf ("libfdt fdt_find_node_by_path() returned %s\n",
 281                                 fdt_strerror(nodeoffset));
 282                         return 1;
 283                 }
 284                 /*
 285                  * Do the delete.  A fourth parameter means delete a property,
 286                  * otherwise delete the node.
 287                  */
 288                 if (argc > 3) {
 289                         err = fdt_delprop(fdt, nodeoffset, argv[3]);
 290                         if (err < 0) {
 291                                 printf("libfdt fdt_delprop():  %s\n",
 292                                         fdt_strerror(err));
 293                                 return err;
 294                         }
 295                 } else {
 296                         err = fdt_del_node(fdt, nodeoffset);
 297                         if (err < 0) {
 298                                 printf("libfdt fdt_del_node():  %s\n",
 299                                         fdt_strerror(err));
 300                                 return err;
 301                         }
 302                 }
 303
 304 #ifdef CONFIG_OF_BOARD_SETUP
 305         /********************************************************************
 306          * Call the board-specific fixup routine
 307          ********************************************************************/
 308         } else if (argv[1][0] == 'b') {
 309                 ft_board_setup(fdt, gd->bd);
 310 #endif
 311         /********************************************************************
 312          * Create a chosen node
 313          ********************************************************************/
 314         } else if (argv[1][0] == 'c') {
 315                 fdt_chosen(fdt, 0, 0, 1);
 316
 317         /********************************************************************
 318          * Create a u-boot-env node
 319          ********************************************************************/
 320         } else if (argv[1][0] == 'e') {
 321                 fdt_env(fdt);
 322
 323         /********************************************************************
 324          * Create a bd_t node
 325          ********************************************************************/
 326         } else if (argv[1][0] == 'b') {
 327                 fdt_bd_t(fdt);
 328
 329         /********************************************************************
 330          * Unrecognized command
 331          ********************************************************************/
 332         } else {
 333                 printf ("Usage:\n%s\n", cmdtp->usage);
 334                 return 1;
 335         }
 336
 337         return 0;
 338 }
 339
 340 /****************************************************************************/
 341
 342 static int fdt_valid(void)
 343 {
 344         int  err;
 345
 346         if (fdt == NULL) {
 347                 printf ("The address of the fdt is invalid (NULL).\n");
 348                 return 0;
 349         }
 350
 351         err = fdt_check_header(fdt);
 352         if (err == 0)
 353                 return 1;       /* valid */
 354
 355         if (err < 0) {
 356                 printf("libfdt fdt_check_header(): %s", fdt_strerror(err));
 357                 /*
 358                  * Be more informative on bad version.
 359                  */
 360                 if (err == -FDT_ERR_BADVERSION) {
 361                         if (fdt_version(fdt) < FDT_FIRST_SUPPORTED_VERSION) {
 362                                 printf (" - too old, fdt $d < %d",
 363                                         fdt_version(fdt),
 364                                         FDT_FIRST_SUPPORTED_VERSION);
 365                                 fdt = NULL;
 366                         }
 367                         if (fdt_last_comp_version(fdt) > FDT_LAST_SUPPORTED_VERSION) {
 368                                 printf (" - too new, fdt $d > %d",
 369                                         fdt_version(fdt),
 370                                         FDT_LAST_SUPPORTED_VERSION);
 371                                 fdt = NULL;
 372                         }
 373                         return 0;
 374                 }
 375                 printf("\n");
 376                 return 0;
 377         }
 378         return 1;
 379 }
 380
 381 /****************************************************************************/
 382
 383 /*
 384  * Parse the user's input, partially heuristic.  Valid formats:
 385  * <00>         - hex byte
 386  * <0011>       - hex half word (16 bits)
 387  * <00112233>   - hex word (32 bits)
 388  *              - hex double words (64 bits) are not supported, must use
 389  *                      a byte stream instead.
 390  * [00 11 22 .. nn] - byte stream
 391  * "string"     - If the the value doesn't start with "<" or "[", it is
 392  *                      treated as a string.  Note that the quotes are
 393  *                      stripped by the parser before we get the string.
 394  */
 395 static int fdt_parse_prop(char *pathp, char *prop, char *newval,
 396         char *data, int *len)
 397 {
 398         char *cp;               /* temporary char pointer */
 399         unsigned long tmp;      /* holds converted values */
 400
 401         if (*newval == '<') {
 402                 /*
 403                  * Bigger values than bytes.
 404                  */
 405                 *len = 0;
 406                 newval++;
 407                 while ((*newval != '>') && (*newval != '\0')) {
 408                         cp = newval;
 409                         tmp = simple_strtoul(cp, &newval, 16);
 410                         if ((newval - cp) <= 2) {
 411                                 *data = tmp & 0xFF;
 412                                 data  += 1;
 413                                 *len += 1;
 414                         } else if ((newval - cp) <= 4) {
 415                                 *(uint16_t *)data = __cpu_to_be16(tmp);
 416                                 data  += 2;
 417                                 *len += 2;
 418                         } else if ((newval - cp) <= 8) {
 419                                 *(uint32_t *)data = __cpu_to_be32(tmp);
 420                                 data  += 4;
 421                                 *len += 4;
 422                         } else {
 423                                 printf("Sorry, I could not convert \"%s\"\n",
 424                                         cp);
 425                                 return 1;
 426                         }
 427                         while (*newval == ' ')
 428                                 newval++;
 429                 }
 430                 if (*newval != '>') {
 431                         printf("Unexpected character '%c'\n", *newval);
 432                         return 1;
 433                 }
 434         } else if (*newval == '[') {
 435                 /*
 436                  * Byte stream.  Convert the values.
 437                  */
 438                 *len = 0;
 439                 newval++;
 440                 while ((*newval != ']') && (*newval != '\0')) {
 441                         tmp = simple_strtoul(newval, &newval, 16);
 442                         *data++ = tmp & 0xFF;
 443                         *len    = *len + 1;
 444                         while (*newval == ' ')
 445                                 newval++;
 446                 }
 447                 if (*newval != ']') {
 448                         printf("Unexpected character '%c'\n", *newval);
 449                         return 1;
 450                 }
 451         } else {
 452                 /*
 453                  * Assume it is a string.  Copy it into our data area for
 454                  * convenience (including the terminating '\0').
 455                  */
 456                 *len = strlen(newval) + 1;
 457                 strcpy(data, newval);
 458         }
 459         return 0;
 460 }
 461
 462 /****************************************************************************/
 463
 464 /*
 465  * Heuristic to guess if this is a string or concatenated strings.
 466  */
 467
 468 static int is_printable_string(const void *data, int len)
 469 {
 470         const char *s = data;
 471
 472         /* zero length is not */
 473         if (len == 0)
 474                 return 0;
 475
 476         /* must terminate with zero */
 477         if (s[len - 1] != '\0')
 478                 return 0;
 479
 480         /* printable or a null byte (concatenated strings) */
 481         while (((*s == '\0') || isprint(*s)) && (len > 0)) {
 482                 /*
 483                  * If we see a null, there are three possibilities:
 484                  * 1) If len == 1, it is the end of the string, printable
 485                  * 2) Next character also a null, not printable.
 486                  * 3) Next character not a null, continue to check.
 487                  */
 488                 if (s[0] == '\0') {
 489                         if (len == 1)
 490                                 return 1;
 491                         if (s[1] == '\0')
 492                                 return 0;
 493                 }
 494                 s++;
 495                 len--;
 496         }
 497
 498         /* Not the null termination, or not done yet: not printable */
 499         if (*s != '\0' || (len != 0))
 500                 return 0;
 501
 502         return 1;
 503 }
 504
 505
 506 /*
 507  * Print the property in the best format, a heuristic guess.  Print as
 508  * a string, concatenated strings, a byte, word, double word, or (if all
 509  * else fails) it is printed as a stream of bytes.
 510  */
 511 static void print_data(const void *data, int len)
 512 {
 513         int j;
 514         const u8 *s;
 515
 516         /* no data, don't print */
 517         if (len == 0)
 518                 return;
 519
 520         /*
 521          * It is a string, but it may have multiple strings (embedded '\0's).
 522          */
 523         if (is_printable_string(data, len)) {
 524                 puts("\"");
 525                 j = 0;
 526                 while (j < len) {
 527                         if (j > 0)
 528                                 puts("\", \"");
 529                         puts(data);
 530                         j    += strlen(data) + 1;
 531                         data += strlen(data) + 1;
 532                 }
 533                 puts("\"");
 534                 return;
 535         }
 536
 537         switch (len) {
 538         case 1:  /* byte */
 539                 printf("<%02x>", (*(u8 *) data) & 0xff);
 540                 break;
 541         case 2:  /* half-word */
 542                 printf("<%04x>", be16_to_cpu(*(u16 *) data) & 0xffff);
 543                 break;
 544         case 4:  /* word */
 545                 printf("<%08x>", be32_to_cpu(*(u32 *) data) & 0xffffffffU);
 546                 break;
 547         case 8:  /* double-word */
 548 #if __WORDSIZE == 64
 549                 printf("<%016llx>", be64_to_cpu(*(uint64_t *) data));
 550 #else
 551                 printf("<%08x ", be32_to_cpu(*(u32 *) data) & 0xffffffffU);
 552                 data += 4;
 553                 printf("%08x>", be32_to_cpu(*(u32 *) data) & 0xffffffffU);
 554 #endif
 555                 break;
 556         default:                /* anything else... hexdump */
 557                 printf("[");
 558                 for (j = 0, s = data; j < len; j++)
 559                         printf("%02x%s", s[j], j < len - 1 ? " " : "");
 560                 printf("]");
 561
 562                 break;
 563         }
 564 }
 565
 566 /****************************************************************************/
 567
 568 /*
 569  * Recursively print (a portion of) the fdt.  The depth parameter
 570  * determines how deeply nested the fdt is printed.
 571  */
 572 static int fdt_print(char *pathp, char *prop, int depth)
 573 {
 574         static int offstack[MAX_LEVEL];
 575         static char tabs[MAX_LEVEL+1] =
 576                 "\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"
 577                 "\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t";
 578         void *nodep;            /* property node pointer */
 579         int  nodeoffset;        /* node offset from libfdt */
 580         int  nextoffset;        /* next node offset from libfdt */
 581         uint32_t tag;           /* tag */
 582         int  len;               /* length of the property */
 583         int  level = 0;         /* keep track of nesting level */
 584
 585         nodeoffset = fdt_find_node_by_path (fdt, pathp);
 586         if (nodeoffset < 0) {
 587                 /*
 588                  * Not found or something else bad happened.
 589                  */
 590                 printf ("libfdt fdt_find_node_by_path() returned %s\n",
 591                         fdt_strerror(nodeoffset));
 592                 return 1;
 593         }
 594         /*
 595          * The user passed in a property as well as node path.
 596          * Print only the given property and then return.
 597          */
 598         if (prop) {
 599                 nodep = fdt_getprop (fdt, nodeoffset, prop, &len);
 600                 if (len == 0) {
 601                         /* no property value */
 602                         printf("%s %s\n", pathp, prop);
 603                         return 0;
 604                 } else if (len > 0) {
 605                         printf("%s=", prop);
 606                         print_data (nodep, len);
 607                         printf("\n");
 608                         return 0;
 609                 } else {
 610                         printf ("libfdt fdt_getprop(): %s\n",
 611                                 fdt_strerror(len));
 612                         return 1;
 613                 }
 614         }
 615
 616         /*
 617          * The user passed in a node path and no property,
 618          * print the node and all subnodes.
 619          */
 620         offstack[0] = nodeoffset;
 621
 622         while(level >= 0) {
 623                 tag = fdt_next_tag(fdt, nodeoffset, &nextoffset, &pathp);
 624                 switch(tag) {
 625                 case FDT_BEGIN_NODE:
 626                         if(level <= depth)
 627                                 printf("%s%s {\n",
 628                                         &tabs[MAX_LEVEL - level], pathp);
 629                         level++;
 630                         offstack[level] = nodeoffset;
 631                         if (level >= MAX_LEVEL) {
 632                                 printf("Aaaiii <splat> nested too deep. "
 633                                         "Aborting.\n");
 634                                 return 1;
 635                         }
 636                         break;
 637                 case FDT_END_NODE:
 638                         level--;
 639                         if(level <= depth)
 640                                 printf("%s};\n", &tabs[MAX_LEVEL - level]);
 641                         if (level == 0) {
 642                                 level = -1;             /* exit the loop */
 643                         }
 644                         break;
 645                 case FDT_PROP:
 646                         nodep = fdt_getprop (fdt, offstack[level], pathp, &len);
 647                         if (len < 0) {
 648                                 printf ("libfdt fdt_getprop(): %s\n",
 649                                         fdt_strerror(len));
 650                                 return 1;
 651                         } else if (len == 0) {
 652                                 /* the property has no value */
 653                                 if(level <= depth)
 654                                         printf("%s%s;\n",
 655                                                 &tabs[MAX_LEVEL - level],
 656                                                 pathp);
 657                         } else {
 658                                 if(level <= depth) {
 659                                         printf("%s%s=",
 660                                                 &tabs[MAX_LEVEL - level],
 661                                                 pathp);
 662                                         print_data (nodep, len);
 663                                         printf(";\n");
 664                                 }
 665                         }
 666                         break;
 667                 case FDT_NOP:
 668                         break;
 669                 case FDT_END:
 670                         return 1;
 671                 default:
 672                         if(level <= depth)
 673                                 printf("Unknown tag 0x%08X\n", tag);
 674                         return 1;
 675                 }
 676                 nodeoffset = nextoffset;
 677         }
 678         return 0;
 679 }
 680
 681 /********************************************************************/
 682
 683 U_BOOT_CMD(
 684         fdt,    5,      0,      do_fdt,
 685         "fdt     - flattened device tree utility commands\n",
 686             "addr   <addr> [<length>]        - Set the fdt location to <addr>\n"
 687 #ifdef CONFIG_OF_BOARD_SETUP
 688         "fdt boardsetup                      - Do board-specific set up\n"
 689 #endif
 690         "fdt move   <fdt> <newaddr> <length> - Copy the fdt to <addr>\n"
 691         "fdt print  <path> [<prop>]          - Recursive print starting at <path>\n"
 692         "fdt list   <path> [<prop>]          - Print one level starting at <path>\n"
 693         "fdt set    <path> <prop> [<val>]    - Set <property> [to <val>]\n"
 694         "fdt mknode <path> <node>            - Create a new node after <path>\n"
 695         "fdt rm     <path> [<prop>]          - Delete the node or <property>\n"
 696         "fdt chosen - Add/update the /chosen branch in the tree\n"
 697 #ifdef CONFIG_OF_HAS_UBOOT_ENV
 698         "fdt env    - Add/replace the /u-boot-env branch in the tree\n"
 699 #endif
 700 #ifdef CONFIG_OF_HAS_BD_T
 701         "fdt bd_t   - Add/replace the /bd_t branch in the tree\n"
 702 #endif
 703         "Hints:\n"
 704         " If the property you are setting/printing has a '#' character or spaces,\n"
 705         "     you MUST escape it with a \\ character or quote it with \".\n"
 706         "Examples: fdt print /               # print the whole tree\n"
 707         "          fdt print /cpus \"#address-cells\"\n"
 708         "          fdt set   /cpus \"#address-cells\" \"[00 00 00 01]\"\n"
 709 );
 710
 711 #endif /* CONFIG_OF_LIBFDT */