[PATCH net-next v3 3/3] dpll: zl3073x: implement frequency monitoring

Ivan Vecera
2026-04-01T09:13:07Z

Extract common measurement latch logic from zl3073x_ref_ffo_update()
into a new zl3073x_ref_freq_meas_latch() helper and add
zl3073x_ref_freq_meas_update() that uses it to latch and read absolute
input reference frequencies in Hz.

Add meas_freq field to struct zl3073x_ref and the corresponding
zl3073x_ref_meas_freq_get() accessor. The measured frequencies are
updated periodically alongside the existing FFO measurements.

Add freq_monitor boolean to struct zl3073x_dpll and implement the
freq_monitor_set/get device callbacks to enable/disable frequency
monitoring via the DPLL netlink interface.

Implement measured_freq_get pin callback for input pins that returns the
measured input frequency in mHz.

Reviewed-by: Petr Oros <poros@redhat.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
Changes v2 -> v3:
- Changed measured_freq_get to return value in mHz

Changes v1 -> v2:
- Renamed actual-frequency to measured-frequency (Vadim)
---
drivers/dpll/zl3073x/core.c | 88 ++++++++++++++++++++++++++-----
drivers/dpll/zl3073x/dpll.c | 100 ++++++++++++++++++++++++++++++++++--
drivers/dpll/zl3073x/dpll.h | 2 +
drivers/dpll/zl3073x/ref.h | 14 +++++
4 files changed, 187 insertions(+), 17 deletions(-)

diff --git a/drivers/dpll/zl3073x/core.c b/drivers/dpll/zl3073x/core.c
index 6363002d48d46..cb47a5db061aa 100644
--- a/drivers/dpll/zl3073x/core.c
+++ b/drivers/dpll/zl3073x/core.c
@@ -632,22 +632,21 @@ int zl3073x_ref_phase_offsets_update(struct zl3073x_dev *zldev, int channel)
}

/**
- * zl3073x_ref_ffo_update - update reference fractional frequency offsets
+ * zl3073x_ref_freq_meas_latch - latch reference frequency measurements
* @zldev: pointer to zl3073x_dev structure
+ * @type: measurement type (ZL_REF_FREQ_MEAS_CTRL_*)
*
- * The function asks device to update fractional frequency offsets latch
- * registers the latest measured values, reads and stores them into
+ * The function waits for the previous measurement to finish, selects all
+ * references and requests a new measurement of the given type.
*
* Return: 0 on success, <0 on error
*/
static int
-zl3073x_ref_ffo_update(struct zl3073x_dev *zldev)
+zl3073x_ref_freq_meas_latch(struct zl3073x_dev *zldev, u8 type)
{
- int i, rc;
+ int rc;

- /* Per datasheet we have to wait for 'ref_freq_meas_ctrl' to be zero
- * to ensure that the measured data are coherent.
- */
+ /* Wait for previous measurement to finish */
rc = zl3073x_poll_zero_u8(zldev, ZL_REG_REF_FREQ_MEAS_CTRL,
ZL_REF_FREQ_MEAS_CTRL);
if (rc)
@@ -663,15 +662,64 @@ zl3073x_ref_ffo_update(struct zl3073x_dev *zldev)
if (rc)
return rc;

- /* Request frequency offset measurement */
- rc = zl3073x_write_u8(zldev, ZL_REG_REF_FREQ_MEAS_CTRL,
- ZL_REF_FREQ_MEAS_CTRL_REF_FREQ_OFF);
+ /* Request measurement */
+ rc = zl3073x_write_u8(zldev, ZL_REG_REF_FREQ_MEAS_CTRL, type);
if (rc)
return rc;

/* Wait for finish */
- rc = zl3073x_poll_zero_u8(zldev, ZL_REG_REF_FREQ_MEAS_CTRL,
- ZL_REF_FREQ_MEAS_CTRL);
+ return zl3073x_poll_zero_u8(zldev, ZL_REG_REF_FREQ_MEAS_CTRL,
+ ZL_REF_FREQ_MEAS_CTRL);
+}
+
+/**
+ * zl3073x_ref_freq_meas_update - update measured input reference frequencies
+ * @zldev: pointer to zl3073x_dev structure
+ *
+ * The function asks device to latch measured input reference frequencies
+ * and stores the results in the ref state.
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int
+zl3073x_ref_freq_meas_update(struct zl3073x_dev *zldev)
+{
+ int i, rc;
+
+ rc = zl3073x_ref_freq_meas_latch(zldev, ZL_REF_FREQ_MEAS_CTRL_REF_FREQ);
+ if (rc)
+ return rc;
+
+ /* Read measured frequencies in Hz (unsigned 32-bit, LSB = 1 Hz) */
+ for (i = 0; i < ZL3073X_NUM_REFS; i++) {
+ u32 value;
+
+ rc = zl3073x_read_u32(zldev, ZL_REG_REF_FREQ(i), &value);
+ if (rc)
+ return rc;
+
+ zldev->ref[i].meas_freq = value;
+ }
+
+ return 0;
+}
+
+/**
+ * zl3073x_ref_ffo_update - update reference fractional frequency offsets
+ * @zldev: pointer to zl3073x_dev structure
+ *
+ * The function asks device to latch the latest measured fractional
+ * frequency offset values, reads and stores them into the ref state.
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int
+zl3073x_ref_ffo_update(struct zl3073x_dev *zldev)
+{
+ int i, rc;
+
+ rc = zl3073x_ref_freq_meas_latch(zldev,
+ ZL_REF_FREQ_MEAS_CTRL_REF_FREQ_OFF);
if (rc)
return rc;

@@ -714,6 +762,20 @@ zl3073x_dev_periodic_work(struct kthread_work *work)
dev_warn(zldev->dev, "Failed to update phase offsets: %pe\n",
ERR_PTR(rc));

+ /* Update measured input reference frequencies if any DPLL has
+ * frequency monitoring enabled.
+ */
+ list_for_each_entry(zldpll, &zldev->dplls, list) {
+ if (zldpll->freq_monitor) {
+ rc = zl3073x_ref_freq_meas_update(zldev);
+ if (rc)
+ dev_warn(zldev->dev,
+ "Failed to update measured frequencies: %pe\n",
+ ERR_PTR(rc));
+ break;
+ }
+ }
+
/* Update references' fractional frequency offsets */
rc = zl3073x_ref_ffo_update(zldev);
if (rc)
diff --git a/drivers/dpll/zl3073x/dpll.c b/drivers/dpll/zl3073x/dpll.c
index a29f606318f6d..d788ca45a17e5 100644
--- a/drivers/dpll/zl3073x/dpll.c
+++ b/drivers/dpll/zl3073x/dpll.c
@@ -39,6 +39,7 @@
* @pin_state: last saved pin state
* @phase_offset: last saved pin phase offset
* @freq_offset: last saved fractional frequency offset
+ * @measured_freq: last saved measured frequency
*/
struct zl3073x_dpll_pin {
struct list_head list;
@@ -54,6 +55,7 @@ struct zl3073x_dpll_pin {
enum dpll_pin_state pin_state;
s64 phase_offset;
s64 freq_offset;
+ u32 measured_freq;
};

/*
@@ -202,6 +204,21 @@ zl3073x_dpll_input_pin_ffo_get(const struct dpll_pin *dpll_pin, void *pin_priv,
return 0;
}

+static int
+zl3073x_dpll_input_pin_measured_freq_get(const struct dpll_pin *dpll_pin,
+ void *pin_priv,
+ const struct dpll_device *dpll,
+ void *dpll_priv, u64 *measured_freq,
+ struct netlink_ext_ack *extack)
+{
+ struct zl3073x_dpll_pin *pin = pin_priv;
+
+ *measured_freq = pin->measured_freq;
+ *measured_freq *= DPLL_PIN_MEASURED_FREQUENCY_DIVIDER;
+
+ return 0;
+}
+
static int
zl3073x_dpll_input_pin_frequency_get(const struct dpll_pin *dpll_pin,
void *pin_priv,
@@ -1116,6 +1133,35 @@ zl3073x_dpll_phase_offset_monitor_set(const struct dpll_device *dpll,
return 0;
}

+static int
+zl3073x_dpll_freq_monitor_get(const struct dpll_device *dpll,
+ void *dpll_priv,
+ enum dpll_feature_state *state,
+ struct netlink_ext_ack *extack)
+{
+ struct zl3073x_dpll *zldpll = dpll_priv;
+
+ if (zldpll->freq_monitor)
+ *state = DPLL_FEATURE_STATE_ENABLE;
+ else
+ *state = DPLL_FEATURE_STATE_DISABLE;
+
+ return 0;
+}
+
+static int
+zl3073x_dpll_freq_monitor_set(const struct dpll_device *dpll,
+ void *dpll_priv,
+ enum dpll_feature_state state,
+ struct netlink_ext_ack *extack)
+{
+ struct zl3073x_dpll *zldpll = dpll_priv;
+
+ zldpll->freq_monitor = (state == DPLL_FEATURE_STATE_ENABLE);
+
+ return 0;
+}
+
static const struct dpll_pin_ops zl3073x_dpll_input_pin_ops = {
.direction_get = zl3073x_dpll_pin_direction_get,
.esync_get = zl3073x_dpll_input_pin_esync_get,
@@ -1123,6 +1169,7 @@ static const struct dpll_pin_ops zl3073x_dpll_input_pin_ops = {
.ffo_get = zl3073x_dpll_input_pin_ffo_get,
.frequency_get = zl3073x_dpll_input_pin_frequency_get,
.frequency_set = zl3073x_dpll_input_pin_frequency_set,
+ .measured_freq_get = zl3073x_dpll_input_pin_measured_freq_get,
.phase_offset_get = zl3073x_dpll_input_pin_phase_offset_get,
.phase_adjust_get = zl3073x_dpll_input_pin_phase_adjust_get,
.phase_adjust_set = zl3073x_dpll_input_pin_phase_adjust_set,
@@ -1151,6 +1198,8 @@ static const struct dpll_device_ops zl3073x_dpll_device_ops = {
.phase_offset_avg_factor_set = zl3073x_dpll_phase_offset_avg_factor_set,
.phase_offset_monitor_get = zl3073x_dpll_phase_offset_monitor_get,
.phase_offset_monitor_set = zl3073x_dpll_phase_offset_monitor_set,
+ .freq_monitor_get = zl3073x_dpll_freq_monitor_get,
+ .freq_monitor_set = zl3073x_dpll_freq_monitor_set,
.supported_modes_get = zl3073x_dpll_supported_modes_get,
};

@@ -1572,6 +1621,7 @@ zl3073x_dpll_pin_ffo_check(struct zl3073x_dpll_pin *pin)
struct zl3073x_dev *zldev = zldpll->dev;
const struct zl3073x_ref *ref;
u8 ref_id;
+ s64 ffo;

/* Get reference monitor status */
ref_id = zl3073x_input_pin_ref_get(pin->id);
@@ -1582,10 +1632,47 @@ zl3073x_dpll_pin_ffo_check(struct zl3073x_dpll_pin *pin)
return false;

/* Compare with previous value */
- if (pin->freq_offset != ref->ffo) {
+ ffo = zl3073x_ref_ffo_get(ref);
+ if (pin->freq_offset != ffo) {
dev_dbg(zldev->dev, "%s freq offset changed: %lld -> %lld\n",
- pin->label, pin->freq_offset, ref->ffo);
- pin->freq_offset = ref->ffo;
+ pin->label, pin->freq_offset, ffo);
+ pin->freq_offset = ffo;
+
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * zl3073x_dpll_pin_measured_freq_check - check for pin measured frequency
+ * change
+ * @pin: pin to check
+ *
+ * Check for the given pin's measured frequency change.
+ *
+ * Return: true on measured frequency change, false otherwise
+ */
+static bool
+zl3073x_dpll_pin_measured_freq_check(struct zl3073x_dpll_pin *pin)
+{
+ struct zl3073x_dpll *zldpll = pin->dpll;
+ struct zl3073x_dev *zldev = zldpll->dev;
+ const struct zl3073x_ref *ref;
+ u8 ref_id;
+ u32 freq;
+
+ if (!zldpll->freq_monitor)
+ return false;
+
+ ref_id = zl3073x_input_pin_ref_get(pin->id);
+ ref = zl3073x_ref_state_get(zldev, ref_id);
+
+ freq = zl3073x_ref_meas_freq_get(ref);
+ if (pin->measured_freq != freq) {
+ dev_dbg(zldev->dev, "%s measured freq changed: %u -> %u\n",
+ pin->label, pin->measured_freq, freq);
+ pin->measured_freq = freq;

return true;
}
@@ -1677,13 +1764,18 @@ zl3073x_dpll_changes_check(struct zl3073x_dpll *zldpll)
pin_changed = true;
}

- /* Check for phase offset and ffo change once per second */
+ /* Check for phase offset, ffo, and measured freq change
+ * once per second.
+ */
if (zldpll->check_count % 2 == 0) {
if (zl3073x_dpll_pin_phase_offset_check(pin))
pin_changed = true;

if (zl3073x_dpll_pin_ffo_check(pin))
pin_changed = true;
+
+ if (zl3073x_dpll_pin_measured_freq_check(pin))
+ pin_changed = true;
}

if (pin_changed)
diff --git a/drivers/dpll/zl3073x/dpll.h b/drivers/dpll/zl3073x/dpll.h
index 115ee4f67e7ab..434c32a7db123 100644
--- a/drivers/dpll/zl3073x/dpll.h
+++ b/drivers/dpll/zl3073x/dpll.h
@@ -15,6 +15,7 @@
* @id: DPLL index
* @check_count: periodic check counter
* @phase_monitor: is phase offset monitor enabled
+ * @freq_monitor: is frequency monitor enabled
* @ops: DPLL device operations for this instance
* @dpll_dev: pointer to registered DPLL device
* @tracker: tracking object for the acquired reference
@@ -28,6 +29,7 @@ struct zl3073x_dpll {
u8 id;
u8 check_count;
bool phase_monitor;
+ bool freq_monitor;
struct dpll_device_ops ops;
struct dpll_device *dpll_dev;
dpll_tracker tracker;
diff --git a/drivers/dpll/zl3073x/ref.h b/drivers/dpll/zl3073x/ref.h
index 06d8d4d97ea26..be16be20dbc7e 100644
--- a/drivers/dpll/zl3073x/ref.h
+++ b/drivers/dpll/zl3073x/ref.h
@@ -23,6 +23,7 @@ struct zl3073x_dev;
* @sync_ctrl: reference sync control
* @config: reference config
* @ffo: current fractional frequency offset
+ * @meas_freq: measured input frequency in Hz
* @mon_status: reference monitor status
*/
struct zl3073x_ref {
@@ -40,6 +41,7 @@ struct zl3073x_ref {
);
struct_group(stat, /* Status */
s64 ffo;
+ u32 meas_freq;
u8 mon_status;
);
};
@@ -68,6 +70,18 @@ zl3073x_ref_ffo_get(const struct zl3073x_ref *ref)
return ref->ffo;
}

+/**
+ * zl3073x_ref_meas_freq_get - get measured input frequency
+ * @ref: pointer to ref state
+ *
+ * Return: measured input frequency in Hz
+ */
+static inline u32
+zl3073x_ref_meas_freq_get(const struct zl3073x_ref *ref)
+{
+ return ref->meas_freq;
+}
+
/**
* zl3073x_ref_freq_get - get given input reference frequency
* @ref: pointer to ref state
--
2.52.0