dpll: zl3073x: Add output pin frequency helper

Introduce zl3073x_dev_output_pin_freq_get() helper function to compute
the output pin frequency based on synthesizer frequency, output divisor,
and signal format. For N-div signal formats, the N-pin frequency is
additionally divided by esync_n_period.

Add zl3073x_out_is_ndiv() helper to check if an output is configured
in N-div mode (2_NDIV or 2_NDIV_INV signal formats).

Refactor zl3073x_dpll_output_pin_frequency_get() callback to use the
new helper, reducing code duplication and enabling reuse of the
frequency calculation logic in other contexts.

This is a preparatory change for adding current frequency to the
supported frequencies list in pin properties.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20260205154350.3180465-2-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: ivecera

drivers/dpll/zl3073x/core.h

@@ -301,6 +301,36 @@ u8 zl3073x_dev_out_dpll_get(struct zl3073x_dev *zldev, u8 index)
 	return zl3073x_synth_dpll_get(synth);
 }
 
+/**
+ * zl3073x_dev_output_pin_freq_get - get output pin frequency
+ * @zldev: pointer to zl3073x device
+ * @id: output pin id
+ *
+ * Computes the output pin frequency based on the synth frequency, output
+ * divisor, and signal format. For N-div formats, N-pin frequency is
+ * additionally divided by esync_n_period.
+ *
+ * Return: frequency of the given output pin in Hz
+ */
+static inline u32
+zl3073x_dev_output_pin_freq_get(struct zl3073x_dev *zldev, u8 id)
+{
+	const struct zl3073x_synth *synth;
+	const struct zl3073x_out *out;
+	u8 out_id;
+	u32 freq;
+
+	out_id = zl3073x_output_pin_out_get(id);
+	out = zl3073x_out_state_get(zldev, out_id);
+	synth = zl3073x_synth_state_get(zldev, zl3073x_out_synth_get(out));
+	freq = zl3073x_synth_freq_get(synth) / out->div;
+
+	if (zl3073x_out_is_ndiv(out) && zl3073x_is_n_pin(id))
+		freq /= out->esync_n_period;
+
+	return freq;
+}
+
 /**
  * zl3073x_dev_out_is_diff - check if the given output is differential
  * @zldev: pointer to zl3073x device

drivers/dpll/zl3073x/dpll.c

@@ -916,46 +916,9 @@ zl3073x_dpll_output_pin_frequency_get(const struct dpll_pin *dpll_pin,
 				      struct netlink_ext_ack *extack)
 {
 	struct zl3073x_dpll *zldpll = dpll_priv;
-	struct zl3073x_dev *zldev = zldpll->dev;
 	struct zl3073x_dpll_pin *pin = pin_priv;
-	const struct zl3073x_synth *synth;
-	const struct zl3073x_out *out;
-	u32 synth_freq;
-	u8 out_id;
 
-	out_id = zl3073x_output_pin_out_get(pin->id);
-	out = zl3073x_out_state_get(zldev, out_id);
-
-	/* Get attached synth frequency */
-	synth = zl3073x_synth_state_get(zldev, zl3073x_out_synth_get(out));
-	synth_freq = zl3073x_synth_freq_get(synth);
-
-	switch (zl3073x_out_signal_format_get(out)) {
-	case ZL_OUTPUT_MODE_SIGNAL_FORMAT_2_NDIV:
-	case ZL_OUTPUT_MODE_SIGNAL_FORMAT_2_NDIV_INV:
-		/* In case of divided format we have to distiguish between
-		 * given output pin type.
-		 *
-		 * For P-pin the resulting frequency is computed as simple
-		 * division of synth frequency and output divisor.
-		 *
-		 * For N-pin we have to divide additionally by divisor stored
-		 * in esync_n_period output mailbox register that is used as
-		 * N-pin divisor for these modes.
-		 */
-		*frequency = synth_freq / out->div;
-
-		if (!zl3073x_dpll_is_p_pin(pin))
-			*frequency = (u32)*frequency / out->esync_n_period;
-
-		break;
-	default:
-		/* In other modes the resulting frequency is computed as
-		 * division of synth frequency and output divisor.
-		 */
-		*frequency = synth_freq / out->div;
-		break;
-	}
+	*frequency = zl3073x_dev_output_pin_freq_get(zldpll->dev, pin->id);
 
 	return 0;
 }

drivers/dpll/zl3073x/out.h

@@ -79,6 +79,23 @@ static inline bool zl3073x_out_is_enabled(const struct zl3073x_out *out)
 	return !!FIELD_GET(ZL_OUTPUT_CTRL_EN, out->ctrl);
 }
 
+/**
+ * zl3073x_out_is_ndiv - check if the given output is in N-div mode
+ * @out: pointer to out state
+ *
+ * Return: true if output is in N-div mode, false otherwise
+ */
+static inline bool zl3073x_out_is_ndiv(const struct zl3073x_out *out)
+{
+	switch (zl3073x_out_signal_format_get(out)) {
+	case ZL_OUTPUT_MODE_SIGNAL_FORMAT_2_NDIV:
+	case ZL_OUTPUT_MODE_SIGNAL_FORMAT_2_NDIV_INV:
+		return true;
+	default:
+		return false;
+	}
+}
+
 /**
  * zl3073x_out_synth_get - get synth connected to given output
  * @out: pointer to out state