Allow device tree devices to make use of 60-evdev.rules

[agx]

Device tree devices currently have some issues using hwdb since they can't use dmi/id. The corresponding thing in DT is the compatible of the root node. Add a udev rule to make use of this and as example add the Librem 5's wakup keys to ignore (so this depends on #32261 .

I've split this out as the to get feedback on adding match by device tree compatible. This could be useful for lots of things that so far needed DT changes to export properties relevant for userspace only.

[poettering]

lgtm, but the test suite needs some updating:

Failed to parse: 'WAKEUP_KEY_114=0'
Failed to parse: 'WAKEUP_KEY_115=0'

[agx]

Thanks for having a look. Tests will pass once #32261 landed. I'll rebase then.

[agx]

I've removed the bits that depend on #32261 and undrafted.

[poettering]

hmm, i'd prefer if this is merged with at least one matching entry in in hwdb.

I think it might make sense to just add this as an additional commit to #32261 and merge it together.

[agx]

I couldn't make an entry up that is really needed atm but without this 60-evdev.rules is about impossible to use on DT based devices. Having that in would allow us to explore #32261 further out of tree and then come up with more use cases.

[whot]

I couldn't make an entry up that is really needed atm but without this 60-evdev.rules is about impossible to use on DT based devices. Having that in would allow us to explore #32261 further out of tree and then come up with more use cases.

In #32261 (comment) I mentioned that rules and hwdb have a "contract" and for your case that is basically down to the hwdb lookup method. So you can have this:

$ cat /etc/udev/rules.d/99-wakeup.rules
ACTION=="remove", GOTO="wakeup_end"
KERNEL!="event*", GOTO="wakeup_end"

# Device matching the input device name and device tree compatible
KERNELS=="input*", \
  IMPORT{builtin}="hwdb 'wakeup:name:$attr{name}:dt:$attr{[devicetree/base]compatible}'", \
  ENV{.HAVE_HWDB_PROPERTIES}="1"

# Device matching the modalias string (bustype, vendor, product, version, other properties)
IMPORT{builtin}="hwdb --subsystem=input --lookup-prefix=wakeup:", \
    ENV{.HAVE_HWDB_PROPERTIES}="1"

LABEL="wakeup_end"

(Apologies for any typos 😄)

So basically: have a udev rule (which can be a near-duplicate of 60-evdev.rules) that does things the way you want to. In this case I just renamed evdev to wakeup for demonstration, your matching hwdb entries the need to have that same prefix:

wakeup:atkbd:dmi:bvn*:bvr*:svnPurism:pnLibrem11:*
  BLAH=1

Really, neither udev nor the hwdb care about the content of the match string or how it's composed, it's a simple "build this string" and "lookup this string as key" with the only special behaviour being the * and other wildcards.

If you want a udev rule that calls date and then uses the day of the week as hwdb lookup prefix then that is possible (don't ask me for the exact syntax though... but oh, the use-cases!).

So while the addition to 60-evdev.rules looks correct I agree with @poettering that without a hwdb entry this is just dead weight. And for your current use-case you don't need it added to 60-evdev.rules (and indeed if the hwdb is outside 60-evdev.hwdb arguably it should have its own rules file anyway).

[agx]

So basically: have a udev rule (which can be a near-duplicate of 60-evdev.rules) that does things the way you want to. In this case I just renamed evdev to wakeup for demonstration, your matching hwdb entries the need to have that same prefix:

Switching the lookup prefix is a good idea. I'll do that downstream too. Thanks!