1 # SPDX-License-Identifier: GPL-2.0+ 2 # 3 # Copyright (C) 2015 4 # 5 # Lukasz Majewski <l.majewski (a] majess.pl> 6 7 Device Firmware Upgrade (DFU) - extension to use TFTP 8 ===================================================== 9 10 Why? 11 ---- 12 13 * Update TFTP (CONFIG_UPDATE_TFTP) only supports writing 14 code to NAND memory via TFTP. 15 * DFU supports writing data to the variety of mediums (NAND, 16 eMMC, SD, partitions, RAM, etc) via USB. 17 18 Combination of both solves their shortcomings! 19 20 21 Overview 22 -------- 23 24 This document briefly describes how to use DFU for 25 upgrading firmware (e.g. kernel, u-boot, rootfs, etc.) 26 via TFTP protocol. 27 28 By using Ethernet (TFTP protocol to be precise) it is 29 possible to overcome the major problem of USB based DFU - 30 the relatively low transfer speed for large files. 31 This was caused by DFU standard, which imposed utilization 32 of only EP0 for transfer. By using Ethernet we can circumvent 33 this shortcoming. 34 35 Beagle Bone Black rev. C (BBB) powered by TI's am335x CPU has 36 been used as a demo board. 37 38 To utilize this feature, one needs to first enable support 39 for USB based DFU (CONFIG_DFU_*) and DFU TFTP update 40 (CONFIG_DFU_TFTP) described in ./doc/README.update. 41 42 The "dfu" command has been extended to support transfer via TFTP - one 43 needs to type for example "dfu tftp 0 mmc 0" 44 45 This feature does not depend on "fitupd" command enabled. 46 47 As of this writing (SHA1:8d77576371381ade83de475bb639949b44941e8c v2015.10-rc2) 48 the update.c code is not enabled (CONFIG_UPDATE_TFTP) by any board in the 49 contemporary u-boot tree. 50 51 52 Environment variables 53 --------------------- 54 55 The "dfu tftp" command can be used in the "preboot" environment variable 56 (when it is enabled by defining CONFIG_PREBOOT). 57 This is the preferable way of using this command in the early boot stage 58 as opposed to legacy update_tftp() function invocation. 59 60 61 Beagle Bone Black (BBB) setup 62 ----------------------------- 63 64 1. Setup tftp env variables: 65 * select desired eth device - 'ethact' variable ["ethact=cpsw"] 66 (use "bdinfo" to check current setting) 67 * setup "serverip" and "ipaddr" variables 68 * set "loadaddr" as a fixed buffer where incoming data is placed 69 ["loadaddr=0x81000000"] 70 71 ######### 72 # BONUS # 73 ######### 74 It is possible to use USB interface to emulate ETH connection by setting 75 "ethact=usb_ether". In this way one can have very fast DFU transfer via USB. 76 77 For 33MiB test image the transfer rate was 1MiB/s for ETH over USB and 200KiB/s 78 for pure DFU USB transfer. 79 80 2. Setup update_tftp variables: 81 * set "updatefile" - the file name to be downloaded via TFTP (stored on 82 the HOST at e.g. /srv/tftp) 83 84 3. If required, to update firmware on boot, put the "dfu tftp 0 mmc 0" in the 85 "preboot" env variable. Otherwise use this command from u-boot prompt. 86 87 4. Inspect "dfu" specific variables: 88 * "dfu_alt_info" - information about available DFU entities 89 * "dfu_bufsiz" - variable to set buffer size [in bytes] - when it is not 90 possible to set large enough default buffer (8 MiB @ BBB) 91 92 93 94 FIT image format for download 95 ----------------------------- 96 97 To create FIT image for download one should follow the update tftp README file 98 (./doc/README.update) with one notable difference: 99 100 The original snippet of ./doc/uImage.FIT/update_uboot.its 101 102 images { 103 update@1 { 104 description = "U-Boot binary"; 105 106 should look like 107 108 images { 109 u-boot.bin@1 { 110 description = "U-Boot binary"; 111 112 where "u-boot.bin" is the DFU entity name to be stored. 113 114 115 116 To do 117 ----- 118 119 * Extend dfu-util command to support TFTP based transfers 120 * Upload support (via TFTP) 121
