Hey Hans,
On 16-03-15 10:51, Hans de Goede wrote:
Hi,
On 16-03-15 10:04, Olliver Schinagl wrote:
Hey all,
On 16-03-15 09:12, Hans de Goede wrote:
Hi,
On 15-03-15 22:38, Paul Kocialkowski wrote:
As far as I know, there is currently no mechanism in place to give
each
device a unique serial number, that would be shown in
e.g. /proc/cpuinfo. This can seem not very useful, but it would be
nice to have that for USB gadget drivers that make use of it (e.g.
ADB on
Android, fastboot, etc). This would allow having multiple sunxi
devices
connected at the same time.
Normally, the serial number has to be figured out by the bootloader
and
passed to the kernel through ATAGs. In U-Boot, it is defined using
get_board_serial, that is not yet implemented on sunxi.
I'm interested in figuring out the best way to do this. As far as I
can
see, Allwinner SoCs have some e-fuses, known as SID (Security ID):
http://linux-sunxi.org/SID_Register_Guide for which Oliver has
written a
mainline Linux driver. Those should have device-specific values,
except
when they are set to 0.
Do you have any better idea to do this, or is there some reference
that
I am missing?
AFAIK the only way to do a serial number on sunxi devices is using
the SID,
note that Oliver's driver will only work on A10, A13 and A20, with the
A31, A23 and others the SID is burned into the pmic rather then the SoC
I vaguely recall that the A31 had a SID aswell according to its
datasheet
Yes it has a SID entry in its memory map, that is probably a copy and
paste error though,
the real SID is stored in the axp221, not in the A31 itself, reading
from the
addresses in the memory map always returns 0 on all A31-s.
Ah, okay, I never tested it on those as i don't have hardware. I do have
an A33 based device, so i'll probe /dev/mem to see if we have a SID
there. I guess some a23 device owners can probe their sid's aswell then.
> I'll go over the datasheets for a23 and a33 to confirm on those, and
will look at the a31/a31s/a80's also.
itself, but it should be easy to implement get_board_serial() in u-boot
as we already have a sunxi_get_sid() helper to do that in a SoC
independent way (this is currently used to set the ethernet MAC
address).
I'l slowly (in a few weeks time) working on a patch to get the mac
from the EEPROM for the olinuxino's, though i think we need to
upgrade the i2c driver a bit (multiple adapter support).
Hmm, not sure if that is really useful, 2 questions:
1) Is there anything wrong with the current SID based approach on the
olinuxino-s, AFAIK all olinuxino's have non pre-production SOCs and so
have proper SID-s and thus a proper MAC set.
That's still an "illegal", e.g. it is a mac address based on the
'internal development'. We have a mac prefix and want to base our mac
partially on our serial numbers (and it has to be _guaranteed_ unique
etc). So we will be storing our serial numbers in the eerpom anyway and
be basing the mac on that anyhow.
2) Are the eeproms prepolulated on ALL olinuxino-s ? If they are not
populated from the factory, I see little added value and I think I may
end up nacking any patches for this, but first lets hear your
arguments :)
We will be using Lime2's which all have them, all lime's have them.
Obviously there will be a check, to check if there is a valid eeprom
with valid data, but for our product it will be required.
Since we will be flashing a generic image (all devices equal) and thus
need to have the 'uniqueness' of a device in the eeprom
Note that sunxi_get_sid() can fail, so you need to error check it,
and currently it will happily return an all 0 SID, you should probably
make it return an error in that case, as that check really belongs
inside sunxi_get_sid().
The big problem with the sunxi-sid, is that it can be often blank :S
very annoying. Also, which part of the SID do we want in
/proc/cpuinfo? The one is bigger then the other, though looking at
http://linux-sunxi.org/SID_Register_Guide there's a lot of
non-uniqueness that can be ignored (chip ID (1623 for example).
Often? In my experience it is empty on cubieboard2 and some early
mele A1000 models, and that is it.
I should have said 'sometimes' :) My bad. It is not yet guaranteed to be
unique unfortunately.
Regards,
Hans
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