smb(4): address format
M. Warner Losh
imp at bsdimp.com
Thu Jan 15 10:09:00 PST 2009
In message: <FC7CC7A3-18D5-4408-8F52-62B9DF189A74 at lassitu.de>
Stefan Bethke <stb at lassitu.de> writes:
: Am 13.01.2009 um 13:43 schrieb Andriy Gapon:
: > So, in practice, there two conventions of specifying a slave address:
: > either as 0XXXXXXXb or XXXXXXX0b.
: Device datasheets generally specify the hard-wired or configurable
: address as a bit string, with a slight preference to format that as
: bbbb bbb.
: > In wider world 0XXXXXXXb format seems to be preferred, Linux also
: > sticks
: > to it.
: I personally find having the address right-aligned a sensible choice.
: I think of the address as logical unit, and normally would rather have
: the SMBus bit banging abstracted away by the driver/hardware.
The format that is preferred on FreeBSD is xxxxxxxx0b. That's the
format that the existing IIC bridge drivers use and deal with. I've
not looked at the SMB drivers, but I went through all the iic bridge
drivers in the 6.x time frame and made sure they were all consistent.
If I missed the smb drivers, that's my bad.
I could find no evidence that there was a format that was more
preferred apart from the dozen data sheets that I'd read at the time
which used the xxxxxxx0b.
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