drm/nouveau/disp: add head class

v2: remove extra whitespace

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/disp: add output class

Will be used to more cleanly implement existing method interfaces that
take some confusing (IEDTkey, inherited from VBIOS, which RM no longer
uses on Ampere) match values to determine which display path to operate
on.

Methods will be protected from racing with supervisor, and from being
called where they shouldn't be (ie. without an OR assigned).

v2:
- use ?: (lyude)
v3:
- fix return code if noacquire() method fails

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drm/nouveau/disp: add connector class

Will be used to provide more solid driver interfaces in general, but
the immediate motivation is work towards fixing issues with handling
hotplug/DP IRQ events.

Its use is currently limited to where we support non-polled hotplug
already (ie. any GPU since NV40ish era, where our DCB handling works
well enough), until that gets cleaned up someday.

v2:
- use ?: (lyude)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drm/nouveau/disp: add common class handling between <nv50 and >=nv50

About to expose head/output path/connector objects everywhere, so we will
need support for child classes prior to nv50 now.

Somewhat cleaner than the code >=nv50 used previously.

v2:
- use ?: (lyude)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>