bootloader/main-pp.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 by Barry Wardell
  11  *
  12  * Based on Rockbox iriver bootloader by Linus Nielsen Feltzing
  13  * and the ipodlinux bootloader by Daniel Palffy and Bernard Leach
  14  *
  15  * All files in this archive are subject to the GNU General Public License.
  16  * See the file COPYING in the source tree root for full license agreement.
  17  *
  18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  19  * KIND, either express or implied.
  20  *
  21  ****************************************************************************/
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include "common.h"
  25 #include "cpu.h"
  26 #include "file.h"
  27 #include "system.h"
  28 #include "kernel.h"
  29 #include "lcd.h"
  30 #include "font.h"
  31 #include "ata.h"
  32 #include "button.h"
  33 #include "disk.h"
  34 #include "crc32-mi4.h"
  35 #include <string.h>
  36 #include "power.h"
  37 #if defined(SANSA_E200) || defined(PHILIPS_SA9200)
  38 #include "i2c.h"
  39 #include "backlight-target.h"
  40 #endif
  41 #if defined(SANSA_E200) || defined(SANSA_C200) || defined(PHILIPS_SA9200)
  42 #include "usb.h"
  43 #include "usb_drv.h"
  44 #endif
  45
  46 /* Show the Rockbox logo - in show_logo.c */
  47 extern int show_logo(void);
  48
  49 /* Button definitions */
  50 #if CONFIG_KEYPAD == IRIVER_H10_PAD
  51 #define BOOTLOADER_BOOT_OF      BUTTON_LEFT
  52
  53 #elif CONFIG_KEYPAD == SANSA_E200_PAD
  54 #define BOOTLOADER_BOOT_OF      BUTTON_LEFT
  55
  56 #elif CONFIG_KEYPAD == SANSA_C200_PAD
  57 #define BOOTLOADER_BOOT_OF      BUTTON_LEFT
  58
  59 #elif CONFIG_KEYPAD == MROBE100_PAD
  60 #define BOOTLOADER_BOOT_OF      BUTTON_POWER
  61
  62 #elif CONFIG_KEYPAD == PHILIPS_SA9200_PAD
  63 #define BOOTLOADER_BOOT_OF      BUTTON_VOL_UP
  64
  65 #elif CONFIG_KEYPAD == PHILIPS_HDD1630_PAD
  66 #define BOOTLOADER_BOOT_OF      BUTTON_MENU
  67
  68 #endif
  69
  70 /* Maximum allowed firmware image size. 10MB is more than enough */
  71 #define MAX_LOADSIZE (10*1024*1024)
  72
  73 /* A buffer to load the original firmware or Rockbox into */
  74 unsigned char *loadbuffer = (unsigned char *)DRAM_START;
  75
  76 /* Bootloader version */
  77 char version[] = APPSVERSION;
  78
  79 /* Locations and sizes in hidden partition on Sansa */
  80 #if defined(HAVE_ATA_SD)
  81 #define PPMI_SECTOR_OFFSET  1024
  82 #define PPMI_SECTORS        1
  83 #define MI4_HEADER_SECTORS  1
  84 #define NUM_PARTITIONS      2
  85
  86 #else
  87 #define NUM_PARTITIONS      1
  88
  89 #endif
  90
  91 #define MI4_HEADER_SIZE     0x200
  92
  93 /* mi4 header structure */
  94 struct mi4header_t {
  95     unsigned char magic[4];
  96     uint32_t version;
  97     uint32_t length;
  98     uint32_t crc32;
  99     uint32_t enctype;
 100     uint32_t mi4size;
 101     uint32_t plaintext;
 102     uint32_t dsa_key[10];
 103     uint32_t pad[109];
 104     unsigned char type[4];
 105     unsigned char model[4];
 106 };
 107
 108 /* PPMI header structure */
 109 struct ppmi_header_t {
 110     unsigned char magic[4];
 111     uint32_t length;
 112     uint32_t pad[126];
 113 };
 114
 115 inline unsigned int le2int(unsigned char* buf)
 116 {
 117    int32_t res = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
 118
 119    return res;
 120 }
 121
 122 inline void int2le(unsigned int val, unsigned char* addr)
 123 {
 124     addr[0] = val & 0xFF;
 125     addr[1] = (val >> 8) & 0xff;
 126     addr[2] = (val >> 16) & 0xff;
 127     addr[3] = (val >> 24) & 0xff;
 128 }
 129
 130 struct tea_key {
 131   const char * name;
 132   uint32_t     key[4];
 133 };
 134
 135 #define NUM_KEYS (sizeof(tea_keytable)/sizeof(tea_keytable[0]))
 136 struct tea_key tea_keytable[] = {
 137   { "default" ,          { 0x20d36cc0, 0x10e8c07d, 0xc0e7dcaa, 0x107eb080 } },
 138   { "sansa",             { 0xe494e96e, 0x3ee32966, 0x6f48512b, 0xa93fbb42 } },
 139   { "sansa_gh",          { 0xd7b10538, 0xc662945b, 0x1b3fce68, 0xf389c0e6 } },
 140   { "sansa_103",         { 0x1d29ddc0, 0x2579c2cd, 0xce339e1a, 0x75465dfe } },
 141   { "rhapsody",          { 0x7aa9c8dc, 0xbed0a82a, 0x16204cc7, 0x5904ef38 } },
 142   { "p610",              { 0x950e83dc, 0xec4907f9, 0x023734b9, 0x10cfb7c7 } },
 143   { "p640",              { 0x220c5f23, 0xd04df68e, 0x431b5e25, 0x4dcc1fa1 } },
 144   { "virgin",            { 0xe83c29a1, 0x04862973, 0xa9b3f0d4, 0x38be2a9c } },
 145   { "20gc_eng",          { 0x0240772c, 0x6f3329b5, 0x3ec9a6c5, 0xb0c9e493 } },
 146   { "20gc_fre",          { 0xbede8817, 0xb23bfe4f, 0x80aa682d, 0xd13f598c } },
 147   { "elio_p722",         { 0x6af3b9f8, 0x777483f5, 0xae8181cc, 0xfa6d8a84 } },
 148   { "c200",              { 0xbf2d06fa, 0xf0e23d59, 0x29738132, 0xe2d04ca7 } },
 149   { "c200_103",          { 0x2a7968de, 0x15127979, 0x142e60a7, 0xe49c1893 } },
 150   { "c200_106",          { 0xa913d139, 0xf842f398, 0x3e03f1a6, 0x060ee012 } },
 151   { "view",              { 0x70e19bda, 0x0c69ea7d, 0x2b8b1ad1, 0xe9767ced } },
 152   { "sa9200",            { 0x33ea0236, 0x9247bdc5, 0xdfaedf9f, 0xd67c9d30 } },
 153   { "hdd1630",           { 0x04543ced, 0xcebfdbad, 0xf7477872, 0x0d12342e } },
 154 };
 155
 156 /*
 157
 158 tea_decrypt() from http://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm
 159
 160 "Following is an adaptation of the reference encryption and decryption
 161 routines in C, released into the public domain by David Wheeler and
 162 Roger Needham:"
 163
 164 */
 165
 166 /* NOTE: The mi4 version of TEA uses a different initial value to sum compared
 167          to the reference implementation and the main loop is 8 iterations, not
 168          32.
 169 */
 170
 171 static void tea_decrypt(uint32_t* v0, uint32_t* v1, uint32_t* k) {
 172     uint32_t sum=0xF1BBCDC8, i;                    /* set up */
 173     uint32_t delta=0x9E3779B9;                     /* a key schedule constant */
 174     uint32_t k0=k[0], k1=k[1], k2=k[2], k3=k[3];   /* cache key */
 175     for(i=0; i<8; i++) {                               /* basic cycle start */
 176         *v1 -= ((*v0<<4) + k2) ^ (*v0 + sum) ^ ((*v0>>5) + k3);
 177         *v0 -= ((*v1<<4) + k0) ^ (*v1 + sum) ^ ((*v1>>5) + k1);
 178         sum -= delta;                                   /* end cycle */
 179     }
 180 }
 181
 182 /* mi4 files are encrypted in 64-bit blocks (two little-endian 32-bit
 183    integers) and the key is incremented after each block
 184  */
 185
 186 static void tea_decrypt_buf(unsigned char* src, unsigned char* dest, size_t n, uint32_t * key)
 187 {
 188     uint32_t v0, v1;
 189     unsigned int i;
 190
 191     for (i = 0; i < (n / 8); i++) {
 192         v0 = le2int(src);
 193         v1 = le2int(src+4);
 194
 195         tea_decrypt(&v0, &v1, key);
 196
 197         int2le(v0, dest);
 198         int2le(v1, dest+4);
 199
 200         src += 8;
 201         dest += 8;
 202
 203         /* Now increment the key */
 204         key[0]++;
 205         if (key[0]==0) {
 206             key[1]++;
 207             if (key[1]==0) {
 208                 key[2]++;
 209                 if (key[2]==0) {
 210                     key[3]++;
 211                 }
 212             }
 213         }
 214     }
 215 }
 216
 217 static inline bool tea_test_key(unsigned char magic_enc[8], uint32_t * key, int unaligned)
 218 {
 219     unsigned char magic_dec[8];
 220     tea_decrypt_buf(magic_enc, magic_dec, 8, key);
 221
 222     return (le2int(&magic_dec[4*unaligned]) == 0xaa55aa55);
 223 }
 224
 225 static int tea_find_key(struct mi4header_t *mi4header, int fd)
 226 {
 227     unsigned int i;
 228     int rc;
 229     unsigned int j;
 230     uint32_t key[4];
 231     unsigned char magic_enc[8];
 232     int key_found = -1;
 233     unsigned int magic_location = mi4header->length-4;
 234     int unaligned = 0;
 235
 236     if ( (magic_location % 8) != 0 )
 237     {
 238         unaligned = 1;
 239         magic_location -= 4;
 240     }
 241
 242     /* Load encrypted magic 0xaa55aa55 to check key */
 243     lseek(fd, MI4_HEADER_SIZE + magic_location, SEEK_SET);
 244     rc = read(fd, magic_enc, 8);
 245     if(rc < 8 )
 246         return EREAD_IMAGE_FAILED;
 247
 248     printf("Searching for key:");
 249
 250     for (i=0; i < NUM_KEYS && (key_found<0) ; i++) {
 251         key[0] = tea_keytable[i].key[0];
 252         key[1] = tea_keytable[i].key[1];
 253         key[2] = tea_keytable[i].key[2];
 254         key[3] = tea_keytable[i].key[3];
 255
 256         /* Now increment the key */
 257         for(j=0; j<((magic_location-mi4header->plaintext)/8); j++){
 258             key[0]++;
 259             if (key[0]==0) {
 260                 key[1]++;
 261                 if (key[1]==0) {
 262                     key[2]++;
 263                     if (key[2]==0) {
 264                         key[3]++;
 265                     }
 266                 }
 267             }
 268         }
 269
 270         if (tea_test_key(magic_enc,key,unaligned))
 271         {
 272             key_found = i;
 273             printf("%s...found", tea_keytable[i].name);
 274         } else {
 275            /* printf("%s...failed", tea_keytable[i].name); */
 276         }
 277     }
 278
 279     return key_found;
 280 }
 281
 282
 283 /* Load mi4 format firmware image */
 284 int load_mi4(unsigned char* buf, char* firmware, unsigned int buffer_size)
 285 {
 286     int fd;
 287     struct mi4header_t mi4header;
 288     int rc;
 289     unsigned long sum;
 290     char filename[MAX_PATH];
 291
 292     snprintf(filename,sizeof(filename),"/.rockbox/%s",firmware);
 293     fd = open(filename, O_RDONLY);
 294     if(fd < 0)
 295     {
 296         snprintf(filename,sizeof(filename),"/%s",firmware);
 297         fd = open(filename, O_RDONLY);
 298         if(fd < 0)
 299             return EFILE_NOT_FOUND;
 300     }
 301
 302     read(fd, &mi4header, MI4_HEADER_SIZE);
 303
 304     /* MI4 file size */
 305     printf("mi4 size: %x", mi4header.mi4size);
 306
 307     if ((mi4header.mi4size-MI4_HEADER_SIZE) > buffer_size)
 308         return EFILE_TOO_BIG;
 309
 310     /* CRC32 */
 311     printf("CRC32: %x", mi4header.crc32);
 312
 313     /* Rockbox model id */
 314     printf("Model id: %.4s", mi4header.model);
 315
 316     /* Read binary type (RBOS, RBBL) */
 317     printf("Binary type: %.4s", mi4header.type);
 318
 319     /* Load firmware file */
 320     lseek(fd, MI4_HEADER_SIZE, SEEK_SET);
 321     rc = read(fd, buf, mi4header.mi4size-MI4_HEADER_SIZE);
 322     if(rc < (int)mi4header.mi4size-MI4_HEADER_SIZE)
 323         return EREAD_IMAGE_FAILED;
 324
 325     /* Check CRC32 to see if we have a valid file */
 326     sum = chksum_crc32 (buf, mi4header.mi4size - MI4_HEADER_SIZE);
 327
 328     printf("Calculated CRC32: %x", sum);
 329
 330     if(sum != mi4header.crc32)
 331         return EBAD_CHKSUM;
 332
 333     if( (mi4header.plaintext + MI4_HEADER_SIZE) != mi4header.mi4size)
 334     {
 335         /* Load encrypted firmware */
 336         int key_index = tea_find_key(&mi4header, fd);
 337
 338         if (key_index < 0)
 339             return EINVALID_FORMAT;
 340
 341         /* Plaintext part is already loaded */
 342         buf += mi4header.plaintext;
 343
 344         /* Decrypt in-place */
 345         tea_decrypt_buf(buf, buf,
 346                         mi4header.mi4size-(mi4header.plaintext+MI4_HEADER_SIZE),
 347                         tea_keytable[key_index].key);
 348
 349         printf("%s key used", tea_keytable[key_index].name);
 350
 351         /* Check decryption was successfull */
 352         if(le2int(&buf[mi4header.length-mi4header.plaintext-4]) != 0xaa55aa55)
 353         {
 354             return EREAD_IMAGE_FAILED;
 355         }
 356     }
 357
 358     return EOK;
 359 }
 360
 361 #if defined(HAVE_ATA_SD)
 362 /* Load mi4 firmware from a hidden disk partition */
 363 int load_mi4_part(unsigned char* buf, struct partinfo* pinfo,
 364                   unsigned int buffer_size, bool disable_rebuild)
 365 {
 366     struct mi4header_t mi4header;
 367     struct ppmi_header_t ppmi_header;
 368     unsigned long sum;
 369
 370     /* Read header to find out how long the mi4 file is. */
 371     ata_read_sectors(IF_MV2(0,) pinfo->start + PPMI_SECTOR_OFFSET,
 372                             PPMI_SECTORS, &ppmi_header);
 373
 374     /* The first four characters at 0x80000 (sector 1024) should be PPMI*/
 375     if( memcmp(ppmi_header.magic, "PPMI", 4) )
 376         return EFILE_NOT_FOUND;
 377
 378     printf("BL mi4 size: %x", ppmi_header.length);
 379
 380     /* Read mi4 header of the OF */
 381     ata_read_sectors(IF_MV2(0,) pinfo->start + PPMI_SECTOR_OFFSET + PPMI_SECTORS
 382                        + (ppmi_header.length/512), MI4_HEADER_SECTORS, &mi4header);
 383
 384     /* We don't support encrypted mi4 files yet */
 385     if( (mi4header.plaintext) != (mi4header.mi4size-MI4_HEADER_SIZE))
 386         return EINVALID_FORMAT;
 387
 388     /* MI4 file size */
 389     printf("OF mi4 size: %x", mi4header.mi4size);
 390
 391     if ((mi4header.mi4size-MI4_HEADER_SIZE) > buffer_size)
 392         return EFILE_TOO_BIG;
 393
 394     /* CRC32 */
 395     printf("CRC32: %x", mi4header.crc32);
 396
 397     /* Rockbox model id */
 398     printf("Model id: %.4s", mi4header.model);
 399
 400     /* Read binary type (RBOS, RBBL) */
 401     printf("Binary type: %.4s", mi4header.type);
 402
 403     /* Load firmware */
 404     ata_read_sectors(IF_MV2(0,) pinfo->start + PPMI_SECTOR_OFFSET + PPMI_SECTORS
 405                         + (ppmi_header.length/512) + MI4_HEADER_SECTORS,
 406                         (mi4header.mi4size-MI4_HEADER_SIZE)/512, buf);
 407
 408     /* Check CRC32 to see if we have a valid file */
 409     sum = chksum_crc32 (buf,mi4header.mi4size-MI4_HEADER_SIZE);
 410
 411     printf("Calculated CRC32: %x", sum);
 412
 413     if(sum != mi4header.crc32)
 414         return EBAD_CHKSUM;
 415
 416 #ifdef SANSA_E200
 417     if (disable_rebuild)
 418     {
 419         char block[512];
 420
 421         printf("Disabling database rebuild");
 422
 423         ata_read_sectors(IF_MV2(0,) pinfo->start + 0x3c08, 1, block);
 424         block[0xe1] = 0;
 425         ata_write_sectors(IF_MV2(0,) pinfo->start + 0x3c08, 1, block);
 426     }
 427 #else
 428     (void) disable_rebuild;
 429 #endif
 430
 431     return EOK;
 432 }
 433 #endif
 434
 435 void* main(void)
 436 {
 437     int i;
 438     int btn;
 439     int rc;
 440     int num_partitions;
 441     struct partinfo* pinfo;
 442 #if defined(SANSA_E200) || defined(SANSA_C200) || defined(PHILIPS_SA9200)
 443     int usb_retry = 0;
 444     bool usb = false;
 445 #else
 446     char buf[256];
 447     unsigned short* identify_info;
 448 #endif
 449
 450     chksum_crc32gentab ();
 451
 452     system_init();
 453     kernel_init();
 454
 455     lcd_init();
 456
 457     font_init();
 458     show_logo();
 459
 460     button_init();
 461 #if defined(SANSA_E200) || defined(PHILIPS_SA9200)
 462     i2c_init();
 463     _backlight_on();
 464 #endif
 465
 466     if (button_hold())
 467     {
 468         verbose = true;
 469         lcd_clear_display();
 470         printf("Hold switch on");
 471         printf("Shutting down...");
 472         sleep(HZ);
 473         power_off();
 474     }
 475
 476     btn = button_read_device();
 477
 478     /* Enable bootloader messages if any button is pressed */
 479     if (btn) {
 480         lcd_clear_display();
 481         verbose = true;
 482     }
 483
 484 #if defined(SANSA_E200) || defined(SANSA_C200) || defined(PHILIPS_SA9200)
 485 #if !defined(USE_ROCKBOX_USB)
 486     usb_init();
 487     while (usb_drv_powered() && usb_retry < 5 && !usb)
 488     {
 489         usb_retry++;
 490         sleep(HZ/4);
 491         usb = (usb_detect() == USB_INSERTED);
 492     }
 493     if (usb)
 494         btn |= BOOTLOADER_BOOT_OF;
 495 #endif /* USE_ROCKBOX_USB */
 496 #endif
 497
 498     lcd_setfont(FONT_SYSFIXED);
 499
 500     printf("Rockbox boot loader");
 501     printf("Version: %s", version);
 502     printf(MODEL_NAME);
 503
 504     i=ata_init();
 505 #if !defined(HAVE_ATA_SD)
 506     if (i==0) {
 507         identify_info=ata_get_identify();
 508         /* Show model */
 509         for (i=0; i < 20; i++) {
 510             ((unsigned short*)buf)[i]=htobe16(identify_info[i+27]);
 511         }
 512         buf[40]=0;
 513         for (i=39; i && buf[i]==' '; i--) {
 514             buf[i]=0;
 515         }
 516         printf(buf);
 517     } else {
 518         error(EATA, i);
 519     }
 520 #endif
 521
 522     disk_init(IF_MV(0));
 523     num_partitions = disk_mount_all();
 524     if (num_partitions<=0)
 525     {
 526         error(EDISK,num_partitions);
 527     }
 528
 529     /* Just list the first 2 partitions since we don't have any devices yet
 530        that have more than that */
 531     for(i=0; i<NUM_PARTITIONS; i++)
 532     {
 533         pinfo = disk_partinfo(i);
 534         printf("Partition %d: 0x%02x %ld MB",
 535                 i, pinfo->type, pinfo->size / 2048);
 536     }
 537
 538     if(btn & BOOTLOADER_BOOT_OF)
 539     {
 540         /* Load original mi4 firmware in to a memory buffer called loadbuffer.
 541            The rest of the loading is done in crt0.S.
 542            1) First try reading from the hidden partition (on Sansa only).
 543            2) Next try a decrypted mi4 file in /System/OF.mi4
 544            3) Finally, try a raw firmware binary in /System/OF.mi4. It should be
 545               a mi4 firmware decrypted and header stripped using mi4code.
 546         */
 547         printf("Loading original firmware...");
 548
 549 #if defined(HAVE_ATA_SD)
 550         /* First try a (hidden) firmware partition */
 551         printf("Trying firmware partition");
 552         pinfo = disk_partinfo(1);
 553         if(pinfo->type == PARTITION_TYPE_OS2_HIDDEN_C_DRIVE)
 554         {
 555             rc = load_mi4_part(loadbuffer, pinfo, MAX_LOADSIZE, usb);
 556             if (rc < EOK) {
 557                 printf("Can't load from partition");
 558                 printf(strerror(rc));
 559             } else {
 560                 return (void*)loadbuffer;
 561             }
 562         } else {
 563             printf("No hidden partition found.");
 564         }
 565 #endif
 566
 567         printf("Trying /System/OF.mi4");
 568         rc=load_mi4(loadbuffer, "/System/OF.mi4", MAX_LOADSIZE);
 569         if (rc < EOK) {
 570             printf("Can't load /System/OF.mi4");
 571             printf(strerror(rc));
 572         } else {
 573             return (void*)loadbuffer;
 574         }
 575
 576         printf("Trying /System/OF.bin");
 577         rc=load_raw_firmware(loadbuffer, "/System/OF.bin", MAX_LOADSIZE);
 578         if (rc < EOK) {
 579             printf("Can't load /System/OF.bin");
 580             printf(strerror(rc));
 581         } else {
 582             return (void*)loadbuffer;
 583         }
 584
 585         error(0, 0);
 586
 587     } else {
 588 #if 0 /* e200: enable to be able to dump the hidden partition */
 589         if(btn & BUTTON_UP)
 590         {
 591             int fd;
 592             pinfo = disk_partinfo(1);
 593             fd = open("/part.bin", O_CREAT|O_RDWR);
 594             char sector[512];
 595             for(i=0; i<40960; i++){
 596                 if (!(i%100))
 597                 {
 598                     printf("dumping sector %d", i);
 599                 }
 600                 ata_read_sectors(IF_MV2(0,) pinfo->start + i, 1, sector);
 601                 write(fd,sector,512);
 602             }
 603             close(fd);
 604         }
 605 #endif
 606         printf("Loading Rockbox...");
 607         rc=load_mi4(loadbuffer, BOOTFILE, MAX_LOADSIZE);
 608         if (rc < EOK) {
 609             printf("Can't load %s:", BOOTFILE);
 610             printf(strerror(rc));
 611
 612 #ifdef OLD_BOOTFILE
 613             /* Try loading rockbox from old rockbox.e200/rockbox.h10 format */
 614             rc=load_firmware(loadbuffer, OLD_BOOTFILE, MAX_LOADSIZE);
 615             if (rc < EOK) {
 616                 printf("Can't load %s:", OLD_BOOTFILE);
 617                 error(EBOOTFILE, rc);
 618             }
 619 #endif
 620         }
 621     }
 622
 623     return (void*)loadbuffer;
 624 }
 625
 626 #if !defined(SANSA_E200) && !defined(SANSA_C200) && !defined(PHILIPS_SA9200)
 627 /* These functions are present in the firmware library, but we reimplement
 628    them here because the originals do a lot more than we want */
 629 void usb_acknowledge(void)
 630 {
 631 }
 632
 633 void usb_wait_for_disconnect(void)
 634 {
 635 }
 636 #endif
 637