Hi Jean, On 6/29/07, Jean Delvare <khali at linux-fr.org> wrote: > Hi Juerg, > > On Thu, 28 Jun 2007 11:28:18 -0700, Juerg Haefliger wrote: > > Hi all, > > > > I was playing around with adding support for the sch311x to the > > dme1737 driver but I'm not so sure anymore how to go about it. For > > those unfamiliar with the 2 chips, both chips implement the same > > (almost but very close) HW monitoring capabilities but the dme1737 > > only allows access via SMBus while the sch311x only supports the LPC > > interface. There are multiple ways to go about this: > > > > 1) 2 separate drivers. An i2c driver for the dme1737 and a platform > > driver for the sch311x. They would only differ in the way they access > > the HW, all the rest would be identical and could be shared. > > > > 2) 1 single driver that either registers itself as an i2c client or a > > platform driver, depending on which chip is detected. > > > > 3) 1 single driver that registers itself as an i2c client independent > > of the chip found. > > > > While option 1) would be preferred, I kind of shy away from the amount > > of work/changes necessary to implement it. I started of with option 2) > > but it turned out to be bigger than expected. Lots of code for > > registering/adding the platform stuff to support a chip that doesn't > > seem to be very popular. It blows up the code and makes it pretty > > ugly. I'm almost tempted to go with option 1)... > > Option 1) can't possibly be less code than option 2). It may be a > little less ugly, but not that much. > > > Not sure if option 3) is feasible. Sounds a little bit hacky and I > > don't know if it's even possible to register a 'bogus' i2c client or > > if it would break something somewhere that I'm not aware of. > > Option 3) has a name: i2c-isa. It took me years to get rid of it, and > I'm just there now. If you implement something similar again, I'll hate > you forever ;) So just forget about it, it's not going to happen. :-) I knew about i2c-isa and its status. I was not planing on using it. I don't know, I thought it might be possible to just register the i2c client somehow without having an actual device behind it. > > Oh and option 2) and 3) of course require an i2c bus driver to be > > present and loaded. So in case someone has a system with a sch311x > > that doesn't have a supported i2c controller, he/she couldn't load the > > dme1737 driver... Not very nice... > > Not true. Options 2) requires i2c-core to be loaded (due to symbol > dependencies) but that's about it. OK, good. > > Does anybody have any suggestions or comments or other ideas? > > I'd go for option 2) because we already have such drivers (lm78 and > w83781d). OK I see it now. I used to look at the old versions that still had the i2c-isa stuff. Good, I'll do the same thing then. Thanks ...juerg > -- > Jean Delvare >
