Date: Sun, 04 Feb 2007 22:09:21 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: freebsd-hackers@dino.sk Cc: freebsd-hackers@freebsd.org Subject: Re: Geode SC1100 i2c bus Message-ID: <20070204.220921.-566238288.imp@bsdimp.com> In-Reply-To: <200702042135.25962.freebsd-hackers@dino.sk> References: <200702040918.37825.freebsd-hackers@dino.sk> <20070204.132150.1288664462.imp@bsdimp.com> <200702042135.25962.freebsd-hackers@dino.sk>
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In message: <200702042135.25962.freebsd-hackers@dino.sk>
Milan Obuch <freebsd-hackers@dino.sk> writes:
: On Sunday 04 February 2007 21:21, M. Warner Losh wrote:
: > In message: <200702040918.37825.freebsd-hackers@dino.sk>
: >
: > Milan Obuch <freebsd-hackers@dino.sk> writes:
: > : On Sunday 04 February 2007 01:21, perryh@pluto.rain.com wrote:
: > : > > > The ACB is at the same level than Uart, so I had a look at sio
: > : > > > source and got a big headache. I'm not really used to drivers
: > : > > > nor kernel programming stuff, that's why I need your help.
: > : > >
: > : > > Why do you compare ACB and UART? In FreeBSD, sio is serial i/o
: > : > > controller, not superIO, maybe you are confused... ACB and UART
: > : > > does not have much in common...
: > : >
: > : > As I read the OP, both the ACB and the serial are in the same chip
: > : > (the superIO), so it would seem reasonable to expect that the method
: > : > of accessing the device registers in the (currently unsupported) ACB
: > : > might be similar to the method of accessing the device registers in
: > : > the (supported) serial port.
: > :
: > : You are right from the point of view 'how to access registers'. But what
: > : OP wrote could be understand another way, too - he tried to modify sio to
: > : create acb driver, which would not achieve the correct results. There is
: > : i2c infrastructure in FreeBSD, acb driver should fit into its place there
: > : and it is not that easy - I tried to understand it, but nobody could/was
: > : willing to/did not care to help me understand it.
: >
: > I'm happy to help you understand it.
: >
: > Warner
: >
:
: Great, I will go through the code and will ask. What made me not achieve
: progress was lack of docs - this area is, ehm, under-documented, and lack of
: description in pcf, the only i2c hardware controller in source tree
: currently.
pcf isn't the only i2c hardware controller in the tree. I personally
comitted at91_twi.c quite some time ago.
: Correct me, if I am wrong and there are more - but not smbus, they
: are not the same thing, even if very near to each other. SMbus
: controller in FreeBSD does not expose i2c device to userland, as far
: as I read it, but this was some time ago.
smbus has a higher level interface than i2c, so doesn't expose i2c to
userland because it can't.
: I need some time to prepare myself, but I would like to get this working.
: There are some projects waiting for it...
Sure thing. Like I said, I've done a lot with i2c in FreeBSD
lately...
Warner
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