> >> Fair enough. But there's no such thing a 'hotplug enumeration
> >> construct' in Linux yet, and a bus is the closest thing to it. It does
> >> take advantage of the nice way device code matches drivers and devices
> >> though.
A bus is the wrong construct. You need something to add devices onto the
busses. You can do that. The Intel SFI layer on phones for example
enumerates devices through a firmware table set and creates them on the
right actual physical bus not on their own fake one.
It's not hotplug in the sense that the phone happens be a fixed
configuration but it does support hotplug behaviour because the order of
the drivers and enumeration is undefined (and both orders work).
> >>
> >> I'm afraid that having the I2C/SPI drivers doing the detection won't
> >> work. The capes can have arbitrary I2C/SPI devices (and even more
> >> weird components). There is no way to assure for example that the I2C
> >> device responding to address 'foo' in cape A is the same I2C device
> >> responding to the same address in cape B.
> >
> > your ->detect() method should take care of that.
>
> There isn't some magical serial number in I²C devices that a
> ->detect() method can read and the implementation of I²C is somewhat
It doesn't matter.
What you are basically talking about is
cape layer
- wtf is this
- how do I plumb it
- create device nodes with correct name for
binding, address etc on the right bus
i2c layer
- ooh a new i2c device
- probe as indicated by device name
- attach correct driver
Architecturally its possible you want to make some caps MFDs if they have
their own bus heirarchies etc but generally I doubt it.
Take a look at arch/x86/platform/mrst/mrst.c. It's a specific example of
a platform which parses tables and attaches devices to the right physical
bus in a manner they can be reliably probed even when the device has no
sane autodetect.
Alan
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