Merge branch 'dpll-ice-add-generic-dpll-type-and-full-tx-reference-clock-control...

Grzegorz Nitka says:

====================
dpll/ice: Add generic DPLL type and full TX reference clock control for E825

NOTE: This series is intentionally submitted on net-next (not
intel-wired-lan) as early feedback of DPLL subsystem changes is
welcomed. In the past possible approaches were discussed in [1].

This series adds TX reference clock support for E825 devices and exposes
TX clock selection and synchronization status via the Linux DPLL
subsystem.

Here is the high-level connection diagram for E825 device:
  +------------------------------------------------------------------+
  |                                                                  |
  |                           +-----------------------------+        |
  |                           |                             |        |
  |                           |         MAC                 |        |
  |                           |+------------+-----+         |        |
  |                           ||RX/1588 |PHC|tspll<----\    |        |
+---+----+                    ||MUX     +---+-^---|    |    |        |
| E | RX >--------------------->              |   >--\ |    |        |
| T |    |    /---------------->              |   >-\| |    |        |
| H |----+    |               |+---------+----^---+ || |    |        |
| 1 | TX <----|----------------+TX MUX   < OCXO   | || |    |        |
|   |PLL |    |               ||         |--------| || |    |        |
+---+----+    |           /----+         <-ext_ref<-||-|----|------ext_ref
| E | RX >----/           |   ||         |--------+ || |    |        |
| T |    |                |   ||         <  SyncE | || |    |        |
| H |----+                |   |+-----------^------+ || |    |        |
| 2 | TX <----------------/   |            | /------||-/    |        |
|   |PLL |                    +------------|-|------||------+        |
+---+----+                              /--/ |      ||               |
| . | RX >---                           |    |      ||               |
| . |    |                   +----------|----|------||--+            |
| . |----+                   |        +-^-+--^+     ||  |            |
|   | TX <---                |        |EEC|PPS|     ||  |            |
|   |PLL |                   |        +-------+     ||  |            |
+---+----+                   |        |       <-CLK0/|  |            |
| E | RX >---                |        |  DPLL |      |  |            |
| T |    |                   |        |       <-CLK1-/  |            |
| H |----+                   |        |       |         |            |
| X | TX <---                |        |       <---SMA---<            |
|   |PLL |                   |        |       |         |            |
+---+----+                   |        |       <---GPS---<            |
  |                          |        |       |         |            |
  |                          |        |       <---...---<            |
  |                          |        |       |         |            |
  |                          |        +-------+         |            |
  |                          | External timing module   |            |
  |                          +--------------------------+            |
  +------------------------------------------------------------------+

E825 hardware contains a dedicated TX clock domain with per-port source
selection behavior that is distinct from PPS handling and from board-level
EEC distribution. TX reference clock selection is device-wide, shared
across ports, and mediated by firmware as part of link bring-up. As a
result, TX clock selection intent may differ from effective hardware
configuration, and software must verify outcome after link-up.

To support this, the series extends the DPLL core and the ice driver
incrementally. The series also introduces DPLL_TYPE_GENERIC as a broad
UAPI class for DPLL instances outside PPS/EEC categories. The intent is
to keep type naming reusable and scalable across different ASIC
topologies while preserving functional discoverability via
driver/device context and pin topology.

This follows netdev discussion guidance that UAPI type naming should avoid
location-specific or vendor-specific taxonomy, because such labels do not
scale across different ASIC designs. The function of a given DPLL instance
is already discoverable from driver/device context and pin topology, and
does not require an additional narrow type identifier in UAPI.

At the same time, a separate DPLL object is still needed for E825 TX clock
control/reporting semantics. Using DPLL_TYPE_GENERIC provides a reusable
class for devices outside PPS/EEC without overfitting UAPI naming to one
topology.

The relevant discussion is in [2].

Series content
- add a new generic DPLL type for devices outside PPS/EEC classes;
- relax DPLL pin registration rules for firmware-described shared pins
  and extend pin notifications with a source identifier;
- allow dynamic state control of SyncE reference pins where hardware
  supports it;
- add CPI infrastructure for PHY-side TX clock control on E825C;
- introduce a TX-clock DPLL device and TX reference clock pins
  (EXT_EREF0 and SYNCE) in the ice driver;
- extend the Restart Auto-Negotiation command to carry a TX reference
  clock index;
- implement hardware-backed TX reference clock switching, post-link
  verification, and TX synchronization reporting.

TXCLK pins report TX reference topology only. Actual synchronization
success is reported via DPLL lock status, updated after hardware
verification: external TX references report LOCKED, while the internal
ENET/TXCO source reports UNLOCKED.

This provides reliable TX reference selection and observability on E825
devices using standard DPLL interfaces, without conflating user intent
with effective hardware behavior.

[1] https://lore.kernel.org/netdev/20250905160333.715c34ac@kernel.org/
[2] https://lore.kernel.org/netdev/20260402230626.3826719-1-grzegorz.nitka@intel.com/
====================

Link: https://patch.msgid.link/20260607183045.1213735-1-grzegorz.nitka@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>