I2C and devicetrees

[Thomas De Schampheleire]

Hi,

On Tue, Feb 12, 2013 at 5:34 PM, Gerlando Falauto
<gerlando.falauto at keymile.com> wrote:
> Hi everyone,
>
> I have a similar question.
> I'd like to "name" i2c devices so that a userspace application can somehow
> identify those devices with the same function across different boards (which
> may have different addresses or be connected to a different i2c bus, or be a
> physically different chip).
>
> For instance "hwmon" devices get instantiated within sysfs under
> /sys/class/hwmon/hwmonX
>
> # cat /sys/class/hwmon/hwmon0/device/name
> lm75
>
> which I would like to be identified by the name "switch" (as in "switch
> temperature"). I was thinking about instantiating it as something like
> "lm75:switch" within i2c_board_info.type. For device-tree-less
> architectures, a trivial change within i2c_match_id() so to ignore the part
> following ":" seems to do the trick. Don't know about devicetree but I guess
> a similar approach could be imagined.
>
> Another example would be given by EEPROMs: all boards are equipped with an
> EEPROM containing inventory management, which I would like to identify as
> "ivm". So something like "24c08:ivm".
> After all, I'd like to be able to achive something like "named MTD
> partitions" which you can identify by looking at "/proc/mtd".
>
> Maybe some other symbol could be used instead of ":", but anyhow, does the
> above make any sense at all to you?
>

I have exactly the same request: I would like to put logical names in
the device tree for various devices (i2c, spi, ...) which are in some
way easily retrievable from a userspace application.
The purpose seems to be the same as Gerlando's: different boards have
different physical configuration but logically each has the same set
of devices.

How can one achieve that?

Thanks,
Thomas