dpll: add frequency monitoring to netlink spec

Add DPLL_A_FREQUENCY_MONITOR device attribute to allow control over
the frequency monitor feature. The attribute uses the existing
dpll_feature_state enum (enable/disable) and is present in both
device-get reply and device-set request.

Add DPLL_A_PIN_MEASURED_FREQUENCY pin attribute to expose the measured
input frequency in millihertz (mHz). The attribute is present in the
pin-get reply. Add DPLL_PIN_MEASURED_FREQUENCY_DIVIDER constant to
allow userspace to extract integer and fractional parts.

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20260402184057.1890514-2-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 55 insertions, 0 deletions

diff --git a/Documentation/driver-api/dpll.rst b/Documentation/driver-api/dpll.rst
index 83118c728ed9..93c191b2d089 100644
--- a/Documentation/driver-api/dpll.rst
+++ b/Documentation/driver-api/dpll.rst
@@ -250,6 +250,24 @@ in the ``DPLL_A_PIN_PHASE_OFFSET`` attribute.
   ``DPLL_A_PHASE_OFFSET_MONITOR`` attr state of a feature
   =============================== ========================
 
+Frequency monitor
+=================
+
+Some DPLL devices may offer the capability to measure the actual
+frequency of all available input pins. The attribute and current feature state
+shall be included in the response message of the ``DPLL_CMD_DEVICE_GET``
+command for supported DPLL devices. In such cases, users can also control
+the feature using the ``DPLL_CMD_DEVICE_SET`` command by setting the
+``enum dpll_feature_state`` values for the attribute.
+Once enabled the measured input frequency for each input pin shall be
+returned in the ``DPLL_A_PIN_MEASURED_FREQUENCY`` attribute. The value
+is in millihertz (mHz), using ``DPLL_PIN_MEASURED_FREQUENCY_DIVIDER``
+as the divider.
+
+  =============================== ========================
+  ``DPLL_A_FREQUENCY_MONITOR``    attr state of a feature
+  =============================== ========================
+
 Embedded SYNC
 =============
 
@@ -411,6 +429,8 @@ according to attribute purpose.
       ``DPLL_A_PIN_STATE``             attr state of pin on the parent
                                        pin
     ``DPLL_A_PIN_CAPABILITIES``        attr bitmask of pin capabilities
+    ``DPLL_A_PIN_MEASURED_FREQUENCY``  attr measured frequency of
+                                       an input pin in mHz
   ==================================== ==================================
 
   ==================================== =================================
diff --git a/Documentation/netlink/specs/dpll.yaml b/Documentation/netlink/specs/dpll.yaml
index 3dd48a32f783..40465a3d7fc2 100644
--- a/Documentation/netlink/specs/dpll.yaml
+++ b/Documentation/netlink/specs/dpll.yaml
@@ -241,6 +241,20 @@ definitions:
       Value of (DPLL_A_PHASE_OFFSET % DPLL_PHASE_OFFSET_DIVIDER) is a
       fractional part of a measured phase offset value.
   -
+    type: const
+    name: pin-measured-frequency-divider
+    value: 1000
+    doc: |
+      pin measured frequency divider allows userspace to calculate
+      a value of measured input frequency as a fractional value with
+      three digit decimal precision (millihertz).
+      Value of (DPLL_A_PIN_MEASURED_FREQUENCY /
+      DPLL_PIN_MEASURED_FREQUENCY_DIVIDER) is an integer part of
+      a measured frequency value.
+      Value of (DPLL_A_PIN_MEASURED_FREQUENCY %
+      DPLL_PIN_MEASURED_FREQUENCY_DIVIDER) is a fractional part of
+      a measured frequency value.
+  -
     type: enum
     name: feature-state
     doc: |
@@ -319,6 +333,13 @@ attribute-sets:
         name: phase-offset-avg-factor
         type: u32
         doc: Averaging factor applied to calculation of reported phase offset.
+      -
+        name: frequency-monitor
+        type: u32
+        enum: feature-state
+        doc: Current or desired state of the frequency monitor feature.
+          If enabled, dpll device shall measure all currently available
+          inputs for their actual input frequency.
   -
     name: pin
     enum-name: dpll_a_pin
@@ -456,6 +477,17 @@ attribute-sets:
           Value is in PPT (parts per trillion, 10^-12).
           Note: This attribute provides higher resolution than the standard
           fractional-frequency-offset (which is in PPM).
+      -
+        name: measured-frequency
+        type: u64
+        doc: |
+          The measured frequency of the input pin in millihertz (mHz).
+          Value of (DPLL_A_PIN_MEASURED_FREQUENCY /
+          DPLL_PIN_MEASURED_FREQUENCY_DIVIDER) is an integer part (Hz)
+          of a measured frequency value.
+          Value of (DPLL_A_PIN_MEASURED_FREQUENCY %
+          DPLL_PIN_MEASURED_FREQUENCY_DIVIDER) is a fractional part
+          of a measured frequency value.
 
   -
     name: pin-parent-device
@@ -544,6 +576,7 @@ operations:
             - type
             - phase-offset-monitor
             - phase-offset-avg-factor
+            - frequency-monitor
 
       dump:
         reply: *dev-attrs
@@ -563,6 +596,7 @@ operations:
             - mode
             - phase-offset-monitor
             - phase-offset-avg-factor
+            - frequency-monitor
     -
       name: device-create-ntf
       doc: Notification about device appearing
@@ -643,6 +677,7 @@ operations:
             - esync-frequency-supported
             - esync-pulse
             - reference-sync
+            - measured-frequency
 
       dump:
         request: