When DT overlays are being added, some drivers/subsystems
need to see device tree overlays before the changes go into
the live tree.
This is distinct from reconfig notifiers that are
post-apply or post-remove and which issue very granular
notifications without providing access to the context
of a whole overlay.
The following 4 notificatons are issued:
OF_OVERLAY_PRE_APPLY
OF_OVERLAY_POST_APPLY
OF_OVERLAY_PRE_REMOVE
OF_OVERLAY_POST_REMOVE
In the case of pre-apply notification, if the notifier
returns error, the overlay will be rejected.
This patch exports two functions for registering/unregistering
notifications:
of_overlay_notifier_register(struct notifier_block *nb)
of_overlay_notifier_unregister(struct notifier_block *nb)
The of_mutex is held during these notifications. The
notification data includes pointers to the overlay target
and the overlay: