Merge branch 'dpll-add-reference-sync-feature'

Merge branch 'dpll-add-reference-sync-feature'

Arkadiusz Kubalewski says:

====================
dpll: add Reference SYNC feature

The device may support the Reference SYNC feature, which allows the
combination of two inputs into a input pair. In this configuration,
clock signals from both inputs are used to synchronize the DPLL device.
The higher frequency signal is utilized for the loop bandwidth of the DPLL,
while the lower frequency signal is used to syntonize the output signal of
the DPLL device. This feature enables the provision of a high-quality loop
bandwidth signal from an external source.

A capable input provides a list of inputs that can be bound with to create
Reference SYNC. To control this feature, the user must request a
desired state for a target pin: use ``DPLL_PIN_STATE_CONNECTED`` to
enable or ``DPLL_PIN_STATE_DISCONNECTED`` to disable the feature. An input
pin can be bound to only one other pin at any given time.

Verify pins bind state/capabilities:
$ ./tools/net/ynl/pyynl/cli.py \
 --spec Documentation/netlink/specs/dpll.yaml \
 --do pin-get \
 --json '{"id":0}'
{'board-label': 'CVL-SDP22',
 'id': 0,
 [...]
 'reference-sync': [{'id': 1, 'state': 'disconnected'}],
 [...]}

Bind the pins by setting connected state between them:
$ ./tools/net/ynl/pyynl/cli.py \
 --spec Documentation/netlink/specs/dpll.yaml \
 --do pin-set \
 --json '{"id":0, "reference-sync":{"id":1, "state":"connected"}}'

Verify pins bind state:
$ ./tools/net/ynl/pyynl/cli.py \
 --spec Documentation/netlink/specs/dpll.yaml \
 --do pin-get \
 --json '{"id":0}'
{'board-label': 'CVL-SDP22',
 'id': 0,
 [...]
 'reference-sync': [{'id': 1, 'state': 'connected'}],
 [...]}

Unbind the pins by setting disconnected state between them:
$ ./tools/net/ynl/pyynl/cli.py \
 --spec Documentation/netlink/specs/dpll.yaml \
 --do pin-set \
 --json '{"id":0, "reference-sync":{"id":1, "state":"disconnected"}}'
====================

Link: https://patch.msgid.link/20250626135219.1769350-1-arkadiusz.kubalewski@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>