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raspberrypi / usbboot

Raspberry Pi USB booting code, moved from tools repository
Apache License 2.0
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[RFC?] Read board revision and serial number #127

Open bryceschober opened 2 years ago

bryceschober commented 2 years ago

Is it possible to use rpiboot (or enhance it) to get a dump of the connected CM's board revision and serial number? This would be really handy to use in production...

timg236 commented 2 years ago

This information is reported in the USB string descriptor from bootcode4.bin but it also reported by the new mass-storage-gadget. Since the descriptor is generated by a Linux script you can put anything there

https://github.com/timg236/cm4-scripts/blob/master/usr/local/bin/configure-gadgets#L33 cd mass-storage-gadget ../rpiboot -d .

From USB Device Tree Viewer https://www.uwe-sieber.de/

             ------ String Descriptor 3 ------
bLength                  : 0x22 (34 bytes)
bDescriptorType          : 0x03 (String Descriptor)
Language 0x0409          : "10000000b29d2da0"
Data (HexDump)           : 22 03 31 00 30 00 30 00 30 00 30 00 30 00 30 00   ".1.0.0.0.0.0.0.
                           30 00 62 00 32 00 39 00 64 00 32 00 64 00 61 00   0.b.2.9.d.2.d.a.
                           30 00                                             0.

bootcode4.bin could probably be updated to dump string descriptors e.g. boot the CM4 without a firmware .elf so that it just sits there and waits

mkdir serial
cp msd/bootcode4.bin serial
cd serial
../rpiboot -d .

bit busy to look at this right now but hopefully that's enough to hack something in main.c

bryceschober commented 2 years ago

@timg236

  1. Ok, I now see that I can get the serial number by finding the right node and reading /sys/bus/usb/devices/*/serial So what about the board revision?
  2. The rpiboot -vv output does print a serial number, but not the right one that is available in the USB string descriptor.
bryceschober commented 2 years ago

@timg236 This forum post seems to indicate that rpiboot used to provide some functionality that it no longer does... at least not the correct serial number for CM4.

timg236 commented 2 years ago

The board revision (and serial number) can be read from /proc/cpuinfo.

I don't think rpiboot has ever automatically extracted these values on 2711 and it might require a patch to bootcode4.bin to make this work nicely. I think it's useful but can't promise when we'll be able to do this.