[PATCH net-next 2/3] dpll: zl3073x: add input reference frequency measurement

[Ivan Vecera <ivecera@redhat.com>]

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.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
---
 drivers/dpll/zl3073x/core.c | 80 +++++++++++++++++++++++++++++++------
 drivers/dpll/zl3073x/ref.h  | 14 +++++++
 2 files changed, 81 insertions(+), 13 deletions(-)

diff --git a/drivers/dpll/zl3073x/core.c b/drivers/dpll/zl3073x/core.c
index dcea98c31d694..67e65f8e7e7d4 100644
--- a/drivers/dpll/zl3073x/core.c
+++ b/drivers/dpll/zl3073x/core.c
@@ -633,22 +633,21 @@ 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)
@@ -664,15 +663,63 @@ 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 update fractional frequency offsets latch
+ * registers the latest measured values, reads and stores them into
+ *
+ * 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;
 
@@ -715,6 +762,13 @@ 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 */
+	rc = zl3073x_ref_freq_meas_update(zldev);
+	if (rc)
+		dev_warn(zldev->dev,
+			 "Failed to update measured frequencies: %pe\n",
+			 ERR_PTR(rc));
+
 	/* Update references' fractional frequency offsets */
 	rc = zl3073x_ref_ffo_update(zldev);
 	if (rc)
diff --git a/drivers/dpll/zl3073x/ref.h b/drivers/dpll/zl3073x/ref.h
index 09fab97a71d7e..55e80e4f08734 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