dpll: add fractional frequency offset to pin-parent-device

Add both fractional-frequency-offset (PPM) and
fractional-frequency-offset-ppt (PPT) attributes to the
pin-parent-device nested attribute set, alongside the existing
top-level pin attributes. Both carry the same measurement at
different precisions.

Introduce enum dpll_ffo_type and struct dpll_ffo_param to
distinguish FFO contexts: DPLL_FFO_PORT_RXTX_RATE for the RX vs
TX symbol rate offset reported at the top level, and
DPLL_FFO_PIN_DEVICE for the pin vs parent DPLL offset reported
in the pin-parent-device nest.

Add a supported_ffo bitmask to struct dpll_pin_ops so drivers
declare which FFO types they support. The core only calls ffo_get
for types the driver has opted into, eliminating the need for
per-driver NULL pointer guards. Validate at pin registration time
that supported_ffo is not set without an ffo_get callback.

Update mlx5 (DPLL_FFO_PORT_RXTX_RATE) and zl3073x
(DPLL_FFO_PORT_RXTX_RATE) drivers to use the new API.

Add documentation for both FFO types to dpll.rst.

Changes v3 -> v4:
- Replace dpll=NULL overloading with enum dpll_ffo_type and
  struct dpll_ffo_param (Jakub Kicinski)
- Add supported_ffo opt-in bitmask in dpll_pin_ops for fail-close
  driver validation (Jakub Kicinski)
- Add WARN_ON in dpll_pin_register for supported_ffo without
  ffo_get callback

Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20260511155816.99936-2-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/include/linux/dpll.h b/include/linux/dpll.h
index 193abfb6ce66..82dfadd9f593 100644
--- a/include/linux/dpll.h
+++ b/include/linux/dpll.h
@@ -60,7 +60,20 @@ struct dpll_device_ops {
 				struct netlink_ext_ack *extack);
 };
 
+enum dpll_ffo_type {
+	DPLL_FFO_PORT_RXTX_RATE,
+	DPLL_FFO_PIN_DEVICE,
+
+	__DPLL_FFO_TYPE_MAX,
+};
+
+struct dpll_ffo_param {
+	enum dpll_ffo_type type;
+	s64 ffo;
+};
+
 struct dpll_pin_ops {
+	unsigned long supported_ffo;
 	int (*frequency_set)(const struct dpll_pin *pin, void *pin_priv,
 			     const struct dpll_device *dpll, void *dpll_priv,
 			     const u64 frequency,
@@ -121,7 +134,8 @@ struct dpll_pin_ops {
 				struct netlink_ext_ack *extack);
 	int (*ffo_get)(const struct dpll_pin *pin, void *pin_priv,
 		       const struct dpll_device *dpll, void *dpll_priv,
-		       s64 *ffo, struct netlink_ext_ack *extack);
+		       struct dpll_ffo_param *ffo,
+		       struct netlink_ext_ack *extack);
 	int (*measured_freq_get)(const struct dpll_pin *pin, void *pin_priv,
 				 const struct dpll_device *dpll,
 				 void *dpll_priv, u64 *measured_freq,