dpll: add generic DPLL type

Add DPLL_TYPE_GENERIC to represent DPLL devices which do not fit the
existing PPS or EEC classes.

The UAPI type is intentionally generic. During netdev discussion,
maintainers pointed out that introducing identifiers tied to a specific
placement or single design does not scale across ASICs and vendors.
The role of a DPLL is already inferable from the spawning driver,
bus device, and pin topology, without encoding additional
purpose-specific taxonomy in the type name.

Using a generic type keeps the UAPI extensible and avoids premature
naming that may become incorrect as new hardware topologies are
exposed through the DPLL subsystem.

Expose the new type through UAPI and netlink specification as "generic".

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Grzegorz Nitka <grzegorz.nitka@intel.com>
Link: https://patch.msgid.link/20260607183045.1213735-2-grzegorz.nitka@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/specs/dpll.yaml

@@ -138,6 +138,9 @@ definitions:
       -
         name: eec
         doc: dpll drives the Ethernet Equipment Clock
+      -
+        name: generic
+        doc: generic dpll type for devices outside PPS/EEC classes
     render-max: true
   -
     type: enum

drivers/dpll/dpll_nl.c

@@ -37,7 +37,7 @@ const struct nla_policy dpll_reference_sync_nl_policy[DPLL_A_PIN_STATE + 1] = {
 static const struct nla_policy dpll_device_id_get_nl_policy[DPLL_A_TYPE + 1] = {
 	[DPLL_A_MODULE_NAME] = { .type = NLA_NUL_STRING, },
 	[DPLL_A_CLOCK_ID] = { .type = NLA_U64, },
-	[DPLL_A_TYPE] = NLA_POLICY_RANGE(NLA_U32, 1, 2),
+	[DPLL_A_TYPE] = NLA_POLICY_RANGE(NLA_U32, 1, 3),
 };
 
 /* DPLL_CMD_DEVICE_GET - do */

include/uapi/linux/dpll.h

@@ -109,10 +109,12 @@ enum dpll_clock_quality_level {
  * enum dpll_type - type of dpll, valid values for DPLL_A_TYPE attribute
  * @DPLL_TYPE_PPS: dpll produces Pulse-Per-Second signal
  * @DPLL_TYPE_EEC: dpll drives the Ethernet Equipment Clock
+ * @DPLL_TYPE_GENERIC: generic dpll type for devices outside PPS/EEC classes
  */
 enum dpll_type {
 	DPLL_TYPE_PPS = 1,
 	DPLL_TYPE_EEC,
+	DPLL_TYPE_GENERIC,
 
 	/* private: */
 	__DPLL_TYPE_MAX,