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Commit | Line | Data |
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5a608727 LM |
1 | Device Firmware Upgrade (DFU) - extension to use TFTP |
2 | ===================================================== | |
3 | ||
4 | Why? | |
5 | ---- | |
6 | ||
7 | * Update TFTP (CONFIG_UPDATE_TFTP) only supports writing | |
8 | code to NAND memory via TFTP. | |
9 | * DFU supports writing data to the variety of mediums (NAND, | |
10 | eMMC, SD, partitions, RAM, etc) via USB. | |
11 | ||
12 | Combination of both solves their shortcomings! | |
13 | ||
14 | ||
15 | Overview | |
16 | -------- | |
17 | ||
18 | This document briefly describes how to use DFU for | |
19 | upgrading firmware (e.g. kernel, u-boot, rootfs, etc.) | |
20 | via TFTP protocol. | |
21 | ||
22 | By using Ethernet (TFTP protocol to be precise) it is | |
23 | possible to overcome the major problem of USB based DFU - | |
24 | the relatively low transfer speed for large files. | |
25 | This was caused by DFU standard, which imposed utilization | |
26 | of only EP0 for transfer. By using Ethernet we can circumvent | |
27 | this shortcoming. | |
28 | ||
29 | Beagle Bone Black rev. C (BBB) powered by TI's am335x CPU has | |
30 | been used as a demo board. | |
31 | ||
32 | To utilize this feature, one needs to first enable support | |
33 | for USB based DFU (CONFIG_DFU_*) and DFU TFTP update | |
34 | (CONFIG_DFU_TFTP) described in ./doc/README.update. | |
35 | ||
36 | The "dfu" command has been extended to support transfer via TFTP - one | |
37 | needs to type for example "dfu tftp 0 mmc 0" | |
38 | ||
39 | This feature does not depend on "fitupd" command enabled. | |
40 | ||
41 | As of this writing (SHA1:8d77576371381ade83de475bb639949b44941e8c v2015.10-rc2) | |
42 | the update.c code is not enabled (CONFIG_UPDATE_TFTP) by any board in the | |
43 | contemporary u-boot tree. | |
44 | ||
45 | ||
46 | Environment variables | |
47 | --------------------- | |
48 | ||
49 | The "dfu tftp" command can be used in the "preboot" environment variable | |
50 | (when it is enabled by defining CONFIG_PREBOOT). | |
51 | This is the preferable way of using this command in the early boot stage | |
52 | as opposed to legacy update_tftp() function invocation. | |
53 | ||
54 | ||
55 | Beagle Bone Black (BBB) setup | |
56 | ----------------------------- | |
57 | ||
58 | 1. Setup tftp env variables: | |
59 | * select desired eth device - 'ethact' variable ["ethact=cpsw"] | |
60 | (use "bdinfo" to check current setting) | |
61 | * setup "serverip" and "ipaddr" variables | |
62 | * set "loadaddr" as a fixed buffer where incoming data is placed | |
63 | ["loadaddr=0x81000000"] | |
64 | ||
65 | ######### | |
66 | # BONUS # | |
67 | ######### | |
68 | It is possible to use USB interface to emulate ETH connection by setting | |
69 | "ethact=usb_ether". In this way one can have very fast DFU transfer via USB. | |
70 | ||
71 | For 33MiB test image the transfer rate was 1MiB/s for ETH over USB and 200KiB/s | |
72 | for pure DFU USB transfer. | |
73 | ||
74 | 2. Setup update_tftp variables: | |
75 | * set "updatefile" - the file name to be downloaded via TFTP (stored on | |
76 | the HOST at e.g. /srv/tftp) | |
77 | ||
78 | 3. If required, to update firmware on boot, put the "dfu tftp 0 mmc 0" in the | |
79 | "preboot" env variable. Otherwise use this command from u-boot prompt. | |
80 | ||
81 | 4. Inspect "dfu" specific variables: | |
82 | * "dfu_alt_info" - information about available DFU entities | |
83 | * "dfu_bufsiz" - variable to set buffer size [in bytes] - when it is not | |
84 | possible to set large enough default buffer (8 MiB @ BBB) | |
85 | ||
86 | ||
87 | ||
88 | FIT image format for download | |
89 | ----------------------------- | |
90 | ||
91 | To create FIT image for download one should follow the update tftp README file | |
92 | (./doc/README.update) with one notable difference: | |
93 | ||
94 | The original snippet of ./doc/uImage.FIT/update_uboot.its | |
95 | ||
96 | images { | |
97 | update@1 { | |
98 | description = "U-Boot binary"; | |
99 | ||
100 | should look like | |
101 | ||
102 | images { | |
103 | u-boot.bin@1 { | |
104 | description = "U-Boot binary"; | |
105 | ||
106 | where "u-boot.bin" is the DFU entity name to be stored. | |
107 | ||
108 | ||
109 | ||
110 | To do | |
111 | ----- | |
112 | ||
113 | * Extend dfu-util command to support TFTP based transfers | |
114 | * Upload support (via TFTP) |