README.dfutftp 3.5 KB

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  1. # SPDX-License-Identifier: GPL-2.0+
  2. #
  3. # Copyright (C) 2015
  4. #
  5. # Lukasz Majewski <l.majewski@majess.pl>
  6. Device Firmware Upgrade (DFU) - extension to use TFTP
  7. =====================================================
  8. Why?
  9. ----
  10. * Update TFTP (CONFIG_UPDATE_TFTP) only supports writing
  11. code to NAND memory via TFTP.
  12. * DFU supports writing data to the variety of mediums (NAND,
  13. eMMC, SD, partitions, RAM, etc) via USB.
  14. Combination of both solves their shortcomings!
  15. Overview
  16. --------
  17. This document briefly describes how to use DFU for
  18. upgrading firmware (e.g. kernel, u-boot, rootfs, etc.)
  19. via TFTP protocol.
  20. By using Ethernet (TFTP protocol to be precise) it is
  21. possible to overcome the major problem of USB based DFU -
  22. the relatively low transfer speed for large files.
  23. This was caused by DFU standard, which imposed utilization
  24. of only EP0 for transfer. By using Ethernet we can circumvent
  25. this shortcoming.
  26. Beagle Bone Black rev. C (BBB) powered by TI's am335x CPU has
  27. been used as a demo board.
  28. To utilize this feature, one needs to first enable support
  29. for USB based DFU (CONFIG_DFU_*) and DFU TFTP update
  30. (CONFIG_DFU_TFTP) described in ./doc/README.update.
  31. The "dfu" command has been extended to support transfer via TFTP - one
  32. needs to type for example "dfu tftp 0 mmc 0"
  33. This feature does not depend on "fitupd" command enabled.
  34. As of this writing (SHA1:8d77576371381ade83de475bb639949b44941e8c v2015.10-rc2)
  35. the update.c code is not enabled (CONFIG_UPDATE_TFTP) by any board in the
  36. contemporary u-boot tree.
  37. Environment variables
  38. ---------------------
  39. The "dfu tftp" command can be used in the "preboot" environment variable
  40. (when it is enabled by defining CONFIG_PREBOOT).
  41. This is the preferable way of using this command in the early boot stage
  42. as opposed to legacy update_tftp() function invocation.
  43. Beagle Bone Black (BBB) setup
  44. -----------------------------
  45. 1. Setup tftp env variables:
  46. * select desired eth device - 'ethact' variable ["ethact=cpsw"]
  47. (use "bdinfo" to check current setting)
  48. * setup "serverip" and "ipaddr" variables
  49. * set "loadaddr" as a fixed buffer where incoming data is placed
  50. ["loadaddr=0x81000000"]
  51. #########
  52. # BONUS #
  53. #########
  54. It is possible to use USB interface to emulate ETH connection by setting
  55. "ethact=usb_ether". In this way one can have very fast DFU transfer via USB.
  56. For 33MiB test image the transfer rate was 1MiB/s for ETH over USB and 200KiB/s
  57. for pure DFU USB transfer.
  58. 2. Setup update_tftp variables:
  59. * set "updatefile" - the file name to be downloaded via TFTP (stored on
  60. the HOST at e.g. /srv/tftp)
  61. 3. If required, to update firmware on boot, put the "dfu tftp 0 mmc 0" in the
  62. "preboot" env variable. Otherwise use this command from u-boot prompt.
  63. 4. Inspect "dfu" specific variables:
  64. * "dfu_alt_info" - information about available DFU entities
  65. * "dfu_bufsiz" - variable to set buffer size [in bytes] - when it is not
  66. possible to set large enough default buffer (8 MiB @ BBB)
  67. FIT image format for download
  68. -----------------------------
  69. To create FIT image for download one should follow the update tftp README file
  70. (./doc/README.update) with one notable difference:
  71. The original snippet of ./doc/uImage.FIT/update_uboot.its
  72. images {
  73. update@1 {
  74. description = "U-Boot binary";
  75. should look like
  76. images {
  77. u-boot.bin@1 {
  78. description = "U-Boot binary";
  79. where "u-boot.bin" is the DFU entity name to be stored.
  80. To do
  81. -----
  82. * Extend dfu-util command to support TFTP based transfers
  83. * Upload support (via TFTP)