lib/efi_loader/efi_device_path.c

   1 /*
   2  * EFI device path from u-boot device-model mapping
   3  *
   4  * (C) Copyright 2017 Rob Clark
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #define LOG_CATEGORY LOGL_ERR
  10
  11 #include <common.h>
  12 #include <blk.h>
  13 #include <dm.h>
  14 #include <usb.h>
  15 #include <mmc.h>
  16 #include <efi_loader.h>
  17 #include <inttypes.h>
  18 #include <part.h>
  19
  20 /* template END node: */
  21 static const struct efi_device_path END = {
  22         .type     = DEVICE_PATH_TYPE_END,
  23         .sub_type = DEVICE_PATH_SUB_TYPE_END,
  24         .length   = sizeof(END),
  25 };
  26
  27 #define U_BOOT_GUID \
  28         EFI_GUID(0xe61d73b9, 0xa384, 0x4acc, \
  29                  0xae, 0xab, 0x82, 0xe8, 0x28, 0xf3, 0x62, 0x8b)
  30
  31 /* template ROOT node: */
  32 static const struct efi_device_path_vendor ROOT = {
  33         .dp = {
  34                 .type     = DEVICE_PATH_TYPE_HARDWARE_DEVICE,
  35                 .sub_type = DEVICE_PATH_SUB_TYPE_VENDOR,
  36                 .length   = sizeof(ROOT),
  37         },
  38         .guid = U_BOOT_GUID,
  39 };
  40
  41 #if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
  42 /*
  43  * Determine if an MMC device is an SD card.
  44  *
  45  * @desc        block device descriptor
  46  * @return      true if the device is an SD card
  47  */
  48 static bool is_sd(struct blk_desc *desc)
  49 {
  50         struct mmc *mmc = find_mmc_device(desc->devnum);
  51
  52         if (!mmc)
  53                 return false;
  54
  55         return IS_SD(mmc) != 0U;
  56 }
  57 #endif
  58
  59 static void *dp_alloc(size_t sz)
  60 {
  61         void *buf;
  62
  63         if (efi_allocate_pool(EFI_ALLOCATE_ANY_PAGES, sz, &buf) !=
  64             EFI_SUCCESS) {
  65                 debug("EFI: ERROR: out of memory in %s\n", __func__);
  66                 return NULL;
  67         }
  68
  69         memset(buf, 0, sz);
  70         return buf;
  71 }
  72
  73 /*
  74  * Iterate to next block in device-path, terminating (returning NULL)
  75  * at /End* node.
  76  */
  77 struct efi_device_path *efi_dp_next(const struct efi_device_path *dp)
  78 {
  79         if (dp == NULL)
  80                 return NULL;
  81         if (dp->type == DEVICE_PATH_TYPE_END)
  82                 return NULL;
  83         dp = ((void *)dp) + dp->length;
  84         if (dp->type == DEVICE_PATH_TYPE_END)
  85                 return NULL;
  86         return (struct efi_device_path *)dp;
  87 }
  88
  89 /*
  90  * Compare two device-paths, stopping when the shorter of the two hits
  91  * an End* node.  This is useful to, for example, compare a device-path
  92  * representing a device with one representing a file on the device, or
  93  * a device with a parent device.
  94  */
  95 int efi_dp_match(const struct efi_device_path *a,
  96                  const struct efi_device_path *b)
  97 {
  98         while (1) {
  99                 int ret;
 100
 101                 ret = memcmp(&a->length, &b->length, sizeof(a->length));
 102                 if (ret)
 103                         return ret;
 104
 105                 ret = memcmp(a, b, a->length);
 106                 if (ret)
 107                         return ret;
 108
 109                 a = efi_dp_next(a);
 110                 b = efi_dp_next(b);
 111
 112                 if (!a || !b)
 113                         return 0;
 114         }
 115 }
 116
 117 /*
 118  * See UEFI spec (section 3.1.2, about short-form device-paths..
 119  * tl;dr: we can have a device-path that starts with a USB WWID
 120  * or USB Class node, and a few other cases which don't encode
 121  * the full device path with bus hierarchy:
 122  *
 123  *   - MESSAGING:USB_WWID
 124  *   - MESSAGING:USB_CLASS
 125  *   - MEDIA:FILE_PATH
 126  *   - MEDIA:HARD_DRIVE
 127  *   - MESSAGING:URI
 128  */
 129 static struct efi_device_path *shorten_path(struct efi_device_path *dp)
 130 {
 131         while (dp) {
 132                 /*
 133                  * TODO: Add MESSAGING:USB_WWID and MESSAGING:URI..
 134                  * in practice fallback.efi just uses MEDIA:HARD_DRIVE
 135                  * so not sure when we would see these other cases.
 136                  */
 137                 if (EFI_DP_TYPE(dp, MESSAGING_DEVICE, MSG_USB_CLASS) ||
 138                     EFI_DP_TYPE(dp, MEDIA_DEVICE, HARD_DRIVE_PATH) ||
 139                     EFI_DP_TYPE(dp, MEDIA_DEVICE, FILE_PATH))
 140                         return dp;
 141
 142                 dp = efi_dp_next(dp);
 143         }
 144
 145         return dp;
 146 }
 147
 148 static struct efi_object *find_obj(struct efi_device_path *dp, bool short_path,
 149                                    struct efi_device_path **rem)
 150 {
 151         struct efi_object *efiobj;
 152         unsigned int dp_size = efi_dp_size(dp);
 153
 154         list_for_each_entry(efiobj, &efi_obj_list, link) {
 155                 struct efi_handler *handler;
 156                 struct efi_device_path *obj_dp;
 157                 efi_status_t ret;
 158
 159                 ret = efi_search_protocol(efiobj->handle,
 160                                           &efi_guid_device_path, &handler);
 161                 if (ret != EFI_SUCCESS)
 162                         continue;
 163                 obj_dp = handler->protocol_interface;
 164
 165                 do {
 166                         if (efi_dp_match(dp, obj_dp) == 0) {
 167                                 if (rem) {
 168                                         /*
 169                                          * Allow partial matches, but inform
 170                                          * the caller.
 171                                          */
 172                                         *rem = ((void *)dp) +
 173                                                 efi_dp_size(obj_dp);
 174                                         return efiobj;
 175                                 } else {
 176                                         /* Only return on exact matches */
 177                                         if (efi_dp_size(obj_dp) == dp_size)
 178                                                 return efiobj;
 179                                 }
 180                         }
 181
 182                         obj_dp = shorten_path(efi_dp_next(obj_dp));
 183                 } while (short_path && obj_dp);
 184         }
 185
 186         return NULL;
 187 }
 188
 189 /*
 190  * Find an efiobj from device-path, if 'rem' is not NULL, returns the
 191  * remaining part of the device path after the matched object.
 192  */
 193 struct efi_object *efi_dp_find_obj(struct efi_device_path *dp,
 194                                    struct efi_device_path **rem)
 195 {
 196         struct efi_object *efiobj;
 197
 198         /* Search for an exact match first */
 199         efiobj = find_obj(dp, false, NULL);
 200
 201         /* Then for a fuzzy match */
 202         if (!efiobj)
 203                 efiobj = find_obj(dp, false, rem);
 204
 205         /* And now for a fuzzy short match */
 206         if (!efiobj)
 207                 efiobj = find_obj(dp, true, rem);
 208
 209         return efiobj;
 210 }
 211
 212 /*
 213  * Determine the last device path node that is not the end node.
 214  *
 215  * @dp          device path
 216  * @return      last node before the end node if it exists
 217  *              otherwise NULL
 218  */
 219 const struct efi_device_path *efi_dp_last_node(const struct efi_device_path *dp)
 220 {
 221         struct efi_device_path *ret;
 222
 223         if (!dp || dp->type == DEVICE_PATH_TYPE_END)
 224                 return NULL;
 225         while (dp) {
 226                 ret = (struct efi_device_path *)dp;
 227                 dp = efi_dp_next(dp);
 228         }
 229         return ret;
 230 }
 231
 232 /* return size not including End node: */
 233 unsigned efi_dp_size(const struct efi_device_path *dp)
 234 {
 235         unsigned sz = 0;
 236
 237         if (!dp || dp->type == DEVICE_PATH_TYPE_END)
 238                 return 0;
 239         while (dp) {
 240                 sz += dp->length;
 241                 dp = efi_dp_next(dp);
 242         }
 243
 244         return sz;
 245 }
 246
 247 struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
 248 {
 249         struct efi_device_path *ndp;
 250         unsigned sz = efi_dp_size(dp) + sizeof(END);
 251
 252         if (!dp)
 253                 return NULL;
 254
 255         ndp = dp_alloc(sz);
 256         if (!ndp)
 257                 return NULL;
 258         memcpy(ndp, dp, sz);
 259
 260         return ndp;
 261 }
 262
 263 struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
 264                                       const struct efi_device_path *dp2)
 265 {
 266         struct efi_device_path *ret;
 267
 268         if (!dp1 && !dp2) {
 269                 /* return an end node */
 270                 ret = efi_dp_dup(&END);
 271         } else if (!dp1) {
 272                 ret = efi_dp_dup(dp2);
 273         } else if (!dp2) {
 274                 ret = efi_dp_dup(dp1);
 275         } else {
 276                 /* both dp1 and dp2 are non-null */
 277                 unsigned sz1 = efi_dp_size(dp1);
 278                 unsigned sz2 = efi_dp_size(dp2);
 279                 void *p = dp_alloc(sz1 + sz2 + sizeof(END));
 280                 if (!p)
 281                         return NULL;
 282                 memcpy(p, dp1, sz1);
 283                 /* the end node of the second device path has to be retained */
 284                 memcpy(p + sz1, dp2, sz2 + sizeof(END));
 285                 ret = p;
 286         }
 287
 288         return ret;
 289 }
 290
 291 struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
 292                                            const struct efi_device_path *node)
 293 {
 294         struct efi_device_path *ret;
 295
 296         if (!node && !dp) {
 297                 ret = efi_dp_dup(&END);
 298         } else if (!node) {
 299                 ret = efi_dp_dup(dp);
 300         } else if (!dp) {
 301                 unsigned sz = node->length;
 302                 void *p = dp_alloc(sz + sizeof(END));
 303                 if (!p)
 304                         return NULL;
 305                 memcpy(p, node, sz);
 306                 memcpy(p + sz, &END, sizeof(END));
 307                 ret = p;
 308         } else {
 309                 /* both dp and node are non-null */
 310                 unsigned sz = efi_dp_size(dp);
 311                 void *p = dp_alloc(sz + node->length + sizeof(END));
 312                 if (!p)
 313                         return NULL;
 314                 memcpy(p, dp, sz);
 315                 memcpy(p + sz, node, node->length);
 316                 memcpy(p + sz + node->length, &END, sizeof(END));
 317                 ret = p;
 318         }
 319
 320         return ret;
 321 }
 322
 323 struct efi_device_path *efi_dp_create_device_node(const u8 type,
 324                                                   const u8 sub_type,
 325                                                   const u16 length)
 326 {
 327         struct efi_device_path *ret;
 328
 329         ret = dp_alloc(length);
 330         if (!ret)
 331                 return ret;
 332         ret->type = type;
 333         ret->sub_type = sub_type;
 334         ret->length = length;
 335         return ret;
 336 }
 337
 338 #ifdef CONFIG_DM
 339 /* size of device-path not including END node for device and all parents
 340  * up to the root device.
 341  */
 342 static unsigned dp_size(struct udevice *dev)
 343 {
 344         if (!dev || !dev->driver)
 345                 return sizeof(ROOT);
 346
 347         switch (dev->driver->id) {
 348         case UCLASS_ROOT:
 349         case UCLASS_SIMPLE_BUS:
 350                 /* stop traversing parents at this point: */
 351                 return sizeof(ROOT);
 352         case UCLASS_ETH:
 353                 return dp_size(dev->parent) +
 354                         sizeof(struct efi_device_path_mac_addr);
 355 #ifdef CONFIG_BLK
 356         case UCLASS_BLK:
 357                 switch (dev->parent->uclass->uc_drv->id) {
 358 #ifdef CONFIG_IDE
 359                 case UCLASS_IDE:
 360                         return dp_size(dev->parent) +
 361                                 sizeof(struct efi_device_path_atapi);
 362 #endif
 363 #if defined(CONFIG_SCSI) && defined(CONFIG_DM_SCSI)
 364                 case UCLASS_SCSI:
 365                         return dp_size(dev->parent) +
 366                                 sizeof(struct efi_device_path_scsi);
 367 #endif
 368 #if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
 369                 case UCLASS_MMC:
 370                         return dp_size(dev->parent) +
 371                                 sizeof(struct efi_device_path_sd_mmc_path);
 372 #endif
 373                 default:
 374                         return dp_size(dev->parent);
 375                 }
 376 #endif
 377 #if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
 378         case UCLASS_MMC:
 379                 return dp_size(dev->parent) +
 380                         sizeof(struct efi_device_path_sd_mmc_path);
 381 #endif
 382         case UCLASS_MASS_STORAGE:
 383         case UCLASS_USB_HUB:
 384                 return dp_size(dev->parent) +
 385                         sizeof(struct efi_device_path_usb_class);
 386         default:
 387                 /* just skip over unknown classes: */
 388                 return dp_size(dev->parent);
 389         }
 390 }
 391
 392 /*
 393  * Recursively build a device path.
 394  *
 395  * @buf         pointer to the end of the device path
 396  * @dev         device
 397  * @return      pointer to the end of the device path
 398  */
 399 static void *dp_fill(void *buf, struct udevice *dev)
 400 {
 401         if (!dev || !dev->driver)
 402                 return buf;
 403
 404         switch (dev->driver->id) {
 405         case UCLASS_ROOT:
 406         case UCLASS_SIMPLE_BUS: {
 407                 /* stop traversing parents at this point: */
 408                 struct efi_device_path_vendor *vdp = buf;
 409                 *vdp = ROOT;
 410                 return &vdp[1];
 411         }
 412 #ifdef CONFIG_DM_ETH
 413         case UCLASS_ETH: {
 414                 struct efi_device_path_mac_addr *dp =
 415                         dp_fill(buf, dev->parent);
 416                 struct eth_pdata *pdata = dev->platdata;
 417
 418                 dp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 419                 dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR;
 420                 dp->dp.length = sizeof(*dp);
 421                 memset(&dp->mac, 0, sizeof(dp->mac));
 422                 /* We only support IPv4 */
 423                 memcpy(&dp->mac, &pdata->enetaddr, ARP_HLEN);
 424                 /* Ethernet */
 425                 dp->if_type = 1;
 426                 return &dp[1];
 427         }
 428 #endif
 429 #ifdef CONFIG_BLK
 430         case UCLASS_BLK:
 431                 switch (dev->parent->uclass->uc_drv->id) {
 432 #ifdef CONFIG_IDE
 433                 case UCLASS_IDE: {
 434                         struct efi_device_path_atapi *dp =
 435                         dp_fill(buf, dev->parent);
 436                         struct blk_desc *desc = dev_get_uclass_platdata(dev);
 437
 438                         dp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 439                         dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_ATAPI;
 440                         dp->dp.length = sizeof(*dp);
 441                         dp->logical_unit_number = desc->devnum;
 442                         dp->primary_secondary = IDE_BUS(desc->devnum);
 443                         dp->slave_master = desc->devnum %
 444                                 (CONFIG_SYS_IDE_MAXDEVICE /
 445                                  CONFIG_SYS_IDE_MAXBUS);
 446                         return &dp[1];
 447                         }
 448 #endif
 449 #if defined(CONFIG_SCSI) && defined(CONFIG_DM_SCSI)
 450                 case UCLASS_SCSI: {
 451                         struct efi_device_path_scsi *dp =
 452                                 dp_fill(buf, dev->parent);
 453                         struct blk_desc *desc = dev_get_uclass_platdata(dev);
 454
 455                         dp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 456                         dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_SCSI;
 457                         dp->dp.length = sizeof(*dp);
 458                         dp->logical_unit_number = desc->lun;
 459                         dp->target_id = desc->target;
 460                         return &dp[1];
 461                         }
 462 #endif
 463 #if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
 464                 case UCLASS_MMC: {
 465                         struct efi_device_path_sd_mmc_path *sddp =
 466                                 dp_fill(buf, dev->parent);
 467                         struct blk_desc *desc = dev_get_uclass_platdata(dev);
 468
 469                         sddp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 470                         sddp->dp.sub_type = is_sd(desc) ?
 471                                 DEVICE_PATH_SUB_TYPE_MSG_SD :
 472                                 DEVICE_PATH_SUB_TYPE_MSG_MMC;
 473                         sddp->dp.length   = sizeof(*sddp);
 474                         sddp->slot_number = dev->seq;
 475                         return &sddp[1];
 476                         }
 477 #endif
 478                 default:
 479                         debug("%s(%u) %s: unhandled parent class: %s (%u)\n",
 480                               __FILE__, __LINE__, __func__,
 481                               dev->name, dev->parent->uclass->uc_drv->id);
 482                         return dp_fill(buf, dev->parent);
 483                 }
 484 #endif
 485 #if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
 486         case UCLASS_MMC: {
 487                 struct efi_device_path_sd_mmc_path *sddp =
 488                         dp_fill(buf, dev->parent);
 489                 struct mmc *mmc = mmc_get_mmc_dev(dev);
 490                 struct blk_desc *desc = mmc_get_blk_desc(mmc);
 491
 492                 sddp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 493                 sddp->dp.sub_type = is_sd(desc) ?
 494                         DEVICE_PATH_SUB_TYPE_MSG_SD :
 495                         DEVICE_PATH_SUB_TYPE_MSG_MMC;
 496                 sddp->dp.length   = sizeof(*sddp);
 497                 sddp->slot_number = dev->seq;
 498
 499                 return &sddp[1];
 500         }
 501 #endif
 502         case UCLASS_MASS_STORAGE:
 503         case UCLASS_USB_HUB: {
 504                 struct efi_device_path_usb_class *udp =
 505                         dp_fill(buf, dev->parent);
 506                 struct usb_device *udev = dev_get_parent_priv(dev);
 507                 struct usb_device_descriptor *desc = &udev->descriptor;
 508
 509                 udp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 510                 udp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_USB_CLASS;
 511                 udp->dp.length   = sizeof(*udp);
 512                 udp->vendor_id   = desc->idVendor;
 513                 udp->product_id  = desc->idProduct;
 514                 udp->device_class    = desc->bDeviceClass;
 515                 udp->device_subclass = desc->bDeviceSubClass;
 516                 udp->device_protocol = desc->bDeviceProtocol;
 517
 518                 return &udp[1];
 519         }
 520         default:
 521                 debug("%s(%u) %s: unhandled device class: %s (%u)\n",
 522                       __FILE__, __LINE__, __func__,
 523                       dev->name, dev->driver->id);
 524                 return dp_fill(buf, dev->parent);
 525         }
 526 }
 527
 528 /* Construct a device-path from a device: */
 529 struct efi_device_path *efi_dp_from_dev(struct udevice *dev)
 530 {
 531         void *buf, *start;
 532
 533         start = buf = dp_alloc(dp_size(dev) + sizeof(END));
 534         if (!buf)
 535                 return NULL;
 536         buf = dp_fill(buf, dev);
 537         *((struct efi_device_path *)buf) = END;
 538
 539         return start;
 540 }
 541 #endif
 542
 543 static unsigned dp_part_size(struct blk_desc *desc, int part)
 544 {
 545         unsigned dpsize;
 546
 547 #ifdef CONFIG_BLK
 548         {
 549                 struct udevice *dev;
 550                 int ret = blk_find_device(desc->if_type, desc->devnum, &dev);
 551
 552                 if (ret)
 553                         dev = desc->bdev->parent;
 554                 dpsize = dp_size(dev);
 555         }
 556 #else
 557         dpsize = sizeof(ROOT) + sizeof(struct efi_device_path_usb);
 558 #endif
 559
 560         if (part == 0) /* the actual disk, not a partition */
 561                 return dpsize;
 562
 563         if (desc->part_type == PART_TYPE_ISO)
 564                 dpsize += sizeof(struct efi_device_path_cdrom_path);
 565         else
 566                 dpsize += sizeof(struct efi_device_path_hard_drive_path);
 567
 568         return dpsize;
 569 }
 570
 571 /*
 572  * Create a device node for a block device partition.
 573  *
 574  * @buf         buffer to which the device path is wirtten
 575  * @desc        block device descriptor
 576  * @part        partition number, 0 identifies a block device
 577  */
 578 static void *dp_part_node(void *buf, struct blk_desc *desc, int part)
 579 {
 580         disk_partition_t info;
 581
 582         part_get_info(desc, part, &info);
 583
 584         if (desc->part_type == PART_TYPE_ISO) {
 585                 struct efi_device_path_cdrom_path *cddp = buf;
 586
 587                 cddp->boot_entry = part;
 588                 cddp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
 589                 cddp->dp.sub_type = DEVICE_PATH_SUB_TYPE_CDROM_PATH;
 590                 cddp->dp.length = sizeof(*cddp);
 591                 cddp->partition_start = info.start;
 592                 cddp->partition_end = info.size;
 593
 594                 buf = &cddp[1];
 595         } else {
 596                 struct efi_device_path_hard_drive_path *hddp = buf;
 597
 598                 hddp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
 599                 hddp->dp.sub_type = DEVICE_PATH_SUB_TYPE_HARD_DRIVE_PATH;
 600                 hddp->dp.length = sizeof(*hddp);
 601                 hddp->partition_number = part;
 602                 hddp->partition_start = info.start;
 603                 hddp->partition_end = info.size;
 604                 if (desc->part_type == PART_TYPE_EFI)
 605                         hddp->partmap_type = 2;
 606                 else
 607                         hddp->partmap_type = 1;
 608
 609                 switch (desc->sig_type) {
 610                 case SIG_TYPE_NONE:
 611                 default:
 612                         hddp->signature_type = 0;
 613                         memset(hddp->partition_signature, 0,
 614                                sizeof(hddp->partition_signature));
 615                         break;
 616                 case SIG_TYPE_MBR:
 617                         hddp->signature_type = 1;
 618                         memset(hddp->partition_signature, 0,
 619                                sizeof(hddp->partition_signature));
 620                         memcpy(hddp->partition_signature, &desc->mbr_sig,
 621                                sizeof(desc->mbr_sig));
 622                         break;
 623                 case SIG_TYPE_GUID:
 624                         hddp->signature_type = 2;
 625                         memcpy(hddp->partition_signature, &desc->guid_sig,
 626                                sizeof(hddp->partition_signature));
 627                         break;
 628                 }
 629
 630                 buf = &hddp[1];
 631         }
 632
 633         return buf;
 634 }
 635
 636 /*
 637  * Create a device path for a block device or one of its partitions.
 638  *
 639  * @buf         buffer to which the device path is wirtten
 640  * @desc        block device descriptor
 641  * @part        partition number, 0 identifies a block device
 642  */
 643 static void *dp_part_fill(void *buf, struct blk_desc *desc, int part)
 644 {
 645 #ifdef CONFIG_BLK
 646         {
 647                 struct udevice *dev;
 648                 int ret = blk_find_device(desc->if_type, desc->devnum, &dev);
 649
 650                 if (ret)
 651                         dev = desc->bdev->parent;
 652                 buf = dp_fill(buf, dev);
 653         }
 654 #else
 655         /*
 656          * We *could* make a more accurate path, by looking at if_type
 657          * and handling all the different cases like we do for non-
 658          * legacy (ie CONFIG_BLK=y) case.  But most important thing
 659          * is just to have a unique device-path for if_type+devnum.
 660          * So map things to a fictitious USB device.
 661          */
 662         struct efi_device_path_usb *udp;
 663
 664         memcpy(buf, &ROOT, sizeof(ROOT));
 665         buf += sizeof(ROOT);
 666
 667         udp = buf;
 668         udp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 669         udp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_USB;
 670         udp->dp.length = sizeof(*udp);
 671         udp->parent_port_number = desc->if_type;
 672         udp->usb_interface = desc->devnum;
 673         buf = &udp[1];
 674 #endif
 675
 676         if (part == 0) /* the actual disk, not a partition */
 677                 return buf;
 678
 679         return dp_part_node(buf, desc, part);
 680 }
 681
 682 /* Construct a device-path from a partition on a blk device: */
 683 struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part)
 684 {
 685         void *buf, *start;
 686
 687         start = buf = dp_alloc(dp_part_size(desc, part) + sizeof(END));
 688         if (!buf)
 689                 return NULL;
 690
 691         buf = dp_part_fill(buf, desc, part);
 692
 693         *((struct efi_device_path *)buf) = END;
 694
 695         return start;
 696 }
 697
 698 /*
 699  * Create a device node for a block device partition.
 700  *
 701  * @buf         buffer to which the device path is wirtten
 702  * @desc        block device descriptor
 703  * @part        partition number, 0 identifies a block device
 704  */
 705 struct efi_device_path *efi_dp_part_node(struct blk_desc *desc, int part)
 706 {
 707         efi_uintn_t dpsize;
 708         void *buf;
 709
 710         if (desc->part_type == PART_TYPE_ISO)
 711                 dpsize = sizeof(struct efi_device_path_cdrom_path);
 712         else
 713                 dpsize = sizeof(struct efi_device_path_hard_drive_path);
 714         buf = dp_alloc(dpsize);
 715
 716         dp_part_node(buf, desc, part);
 717
 718         return buf;
 719 }
 720
 721 /* convert path to an UEFI style path (ie. DOS style backslashes and utf16) */
 722 static void path_to_uefi(u16 *uefi, const char *path)
 723 {
 724         while (*path) {
 725                 char c = *(path++);
 726                 if (c == '/')
 727                         c = '\\';
 728                 *(uefi++) = c;
 729         }
 730         *uefi = '\0';
 731 }
 732
 733 /*
 734  * If desc is NULL, this creates a path with only the file component,
 735  * otherwise it creates a full path with both device and file components
 736  */
 737 struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
 738                 const char *path)
 739 {
 740         struct efi_device_path_file_path *fp;
 741         void *buf, *start;
 742         unsigned dpsize = 0, fpsize;
 743
 744         if (desc)
 745                 dpsize = dp_part_size(desc, part);
 746
 747         fpsize = sizeof(struct efi_device_path) + 2 * (strlen(path) + 1);
 748         dpsize += fpsize;
 749
 750         start = buf = dp_alloc(dpsize + sizeof(END));
 751         if (!buf)
 752                 return NULL;
 753
 754         if (desc)
 755                 buf = dp_part_fill(buf, desc, part);
 756
 757         /* add file-path: */
 758         fp = buf;
 759         fp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
 760         fp->dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH;
 761         fp->dp.length = fpsize;
 762         path_to_uefi(fp->str, path);
 763         buf += fpsize;
 764
 765         *((struct efi_device_path *)buf) = END;
 766
 767         return start;
 768 }
 769
 770 #ifdef CONFIG_NET
 771 struct efi_device_path *efi_dp_from_eth(void)
 772 {
 773 #ifndef CONFIG_DM_ETH
 774         struct efi_device_path_mac_addr *ndp;
 775 #endif
 776         void *buf, *start;
 777         unsigned dpsize = 0;
 778
 779         assert(eth_get_dev());
 780
 781 #ifdef CONFIG_DM_ETH
 782         dpsize += dp_size(eth_get_dev());
 783 #else
 784         dpsize += sizeof(ROOT);
 785         dpsize += sizeof(*ndp);
 786 #endif
 787
 788         start = buf = dp_alloc(dpsize + sizeof(END));
 789         if (!buf)
 790                 return NULL;
 791
 792 #ifdef CONFIG_DM_ETH
 793         buf = dp_fill(buf, eth_get_dev());
 794 #else
 795         memcpy(buf, &ROOT, sizeof(ROOT));
 796         buf += sizeof(ROOT);
 797
 798         ndp = buf;
 799         ndp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
 800         ndp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR;
 801         ndp->dp.length = sizeof(*ndp);
 802         ndp->if_type = 1; /* Ethernet */
 803         memcpy(ndp->mac.addr, eth_get_ethaddr(), ARP_HLEN);
 804         buf = &ndp[1];
 805 #endif
 806
 807         *((struct efi_device_path *)buf) = END;
 808
 809         return start;
 810 }
 811 #endif
 812
 813 /* Construct a device-path for memory-mapped image */
 814 struct efi_device_path *efi_dp_from_mem(uint32_t memory_type,
 815                                         uint64_t start_address,
 816                                         uint64_t end_address)
 817 {
 818         struct efi_device_path_memory *mdp;
 819         void *buf, *start;
 820
 821         start = buf = dp_alloc(sizeof(*mdp) + sizeof(END));
 822         if (!buf)
 823                 return NULL;
 824
 825         mdp = buf;
 826         mdp->dp.type = DEVICE_PATH_TYPE_HARDWARE_DEVICE;
 827         mdp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MEMORY;
 828         mdp->dp.length = sizeof(*mdp);
 829         mdp->memory_type = memory_type;
 830         mdp->start_address = start_address;
 831         mdp->end_address = end_address;
 832         buf = &mdp[1];
 833
 834         *((struct efi_device_path *)buf) = END;
 835
 836         return start;
 837 }
 838
 839 /*
 840  * Helper to split a full device path (containing both device and file
 841  * parts) into it's constituent parts.
 842  */
 843 efi_status_t efi_dp_split_file_path(struct efi_device_path *full_path,
 844                                     struct efi_device_path **device_path,
 845                                     struct efi_device_path **file_path)
 846 {
 847         struct efi_device_path *p, *dp, *fp;
 848
 849         *device_path = NULL;
 850         *file_path = NULL;
 851         dp = efi_dp_dup(full_path);
 852         if (!dp)
 853                 return EFI_OUT_OF_RESOURCES;
 854         p = dp;
 855         while (!EFI_DP_TYPE(p, MEDIA_DEVICE, FILE_PATH)) {
 856                 p = efi_dp_next(p);
 857                 if (!p)
 858                         return EFI_OUT_OF_RESOURCES;
 859         }
 860         fp = efi_dp_dup(p);
 861         if (!fp)
 862                 return EFI_OUT_OF_RESOURCES;
 863         p->type = DEVICE_PATH_TYPE_END;
 864         p->sub_type = DEVICE_PATH_SUB_TYPE_END;
 865         p->length = sizeof(*p);
 866
 867         *device_path = dp;
 868         *file_path = fp;
 869         return EFI_SUCCESS;
 870 }