* [ECOS] AT91 I2C driver @ 2009-10-28 11:27 Steven Clugston 2009-10-28 12:38 ` Andrew Lunn 0 siblings, 1 reply; 3+ messages in thread From: Steven Clugston @ 2009-10-28 11:27 UTC (permalink / raw) To: ecos-discuss Is anybody out there interested in having/testing an AT91 I2C driver? I'm currently having a stab at writing one using the lpc2xxx one as a reference, although I'm not sure if I'll actually have time to see it through to completion yet. Just though I would post my intentions. Regards, Steven -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [ECOS] AT91 I2C driver 2009-10-28 11:27 [ECOS] AT91 I2C driver Steven Clugston @ 2009-10-28 12:38 ` Andrew Lunn 2009-10-28 13:04 ` Steven Clugston 0 siblings, 1 reply; 3+ messages in thread From: Andrew Lunn @ 2009-10-28 12:38 UTC (permalink / raw) To: Steven Clugston; +Cc: ecos-discuss On Wed, Oct 28, 2009 at 11:27:36AM +0000, Steven Clugston wrote: > Is anybody out there interested in having/testing an AT91 I2C driver? > > I'm currently having a stab at writing one using the lpc2xxx one as > a reference, although I'm not sure if I'll actually have time to see > it through to completion yet. A word of caution. The Linux kernel guys consider the AT91 I2C device to be FUBAR. http://cateee.net/lkddb/web-lkddb/I2C_AT91.html http://www.mail-archive.com/git-commits-head@vger.kernel.org/msg24797.html http://www.mail-archive.com/i2c@lm-sensors.org/msg02209.html I think it is O.K. for single byte transfers, but anything more than that could lead to problems. Maybe you should consider bit banging the pins? Andrew -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss ^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: [ECOS] AT91 I2C driver 2009-10-28 12:38 ` Andrew Lunn @ 2009-10-28 13:04 ` Steven Clugston 0 siblings, 0 replies; 3+ messages in thread From: Steven Clugston @ 2009-10-28 13:04 UTC (permalink / raw) To: ecos-discuss >> Is anybody out there interested in having/testing an AT91 I2C driver? >> >> I'm currently having a stab at writing one using the lpc2xxx one as >> a reference, although I'm not sure if I'll actually have time to see >> it through to completion yet. > A word of caution. The Linux kernel guys consider the AT91 I2C device > to be FOOBAR. > http://cateee.net/lkddb/web-lkddb/I2C_AT91.html > http://www.mail-archive.com/git-commits-head@vger.kernel.org/msg24797.html > http://www.mail-archive.com/i2c@lm-sensors.org/msg02209.html > I think it is O.K. for single byte transfers, but anything more than > that could lead to problems. > Maybe you should consider bit banging the pins? > Andrew Andrew, Thanks very much for pointing this out. It must explain why nobody has written the driver before. I was in two minds whether to just try the generic bit bang driver instead, but I thought it was worth an attempt at using the chip's hardware first particularly if anybody else was interested. I've shot myself in the foot now because it turns out I do need multi-byte transfers and I've used a part that has a timeout of 35ms on the clock which might make bit-bang problematic if its too slow for some reason. Steven -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2009-10-28 13:04 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2009-10-28 11:27 [ECOS] AT91 I2C driver Steven Clugston 2009-10-28 12:38 ` Andrew Lunn 2009-10-28 13:04 ` Steven Clugston
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