[PATCH v9 1/4] ASoC: SDCA: Add PDE verification reusable helper

[Niranjan H Y]

  Implement sdca_asoc_pde_ensure_ps() helper function to poll for PDE
power state transitions. Per SDCA specification, after writing
REQUESTED_PS, drivers must poll ACTUAL_PS until the target power state
is reached.

Changes include:
- Add sdca_asoc_pde_ensure_ps() to handle ACTUAL_PS polling with
  support for device-specific delay tables or default intervals
- Export function via sdca_asoc.h for use by SDCA-compliant drivers
- Refactor entity_pde_event() in sdca_asoc.c to use the helper

Signed-off-by: Niranjan H Y <niranjan.hy@xxxxxx>
---
v9:
- newly added interface
---
 include/sound/sdca_asoc.h  |   9 ++++
 sound/soc/sdca/sdca_asoc.c | 105 ++++++++++++++++++++++++++-----------
 2 files changed, 82 insertions(+), 32 deletions(-)

diff --git a/include/sound/sdca_asoc.h b/include/sound/sdca_asoc.h
index 46a61a52decc5..6c1c8af514122 100644
--- a/include/sound/sdca_asoc.h
+++ b/include/sound/sdca_asoc.h
@@ -99,4 +99,13 @@ int sdca_asoc_q78_put_volsw(struct snd_kcontrol *kcontrol,
 			    struct snd_ctl_elem_value *ucontrol);
 int sdca_asoc_q78_get_volsw(struct snd_kcontrol *kcontrol,
 			    struct snd_ctl_elem_value *ucontrol);
+
+struct device;
+struct sdca_pde_delay;
+
+int sdca_asoc_pde_ensure_ps(struct device *dev, struct regmap *regmap,
+			    int function_id, int entity_id,
+			    int from_ps, int to_ps,
+			    const struct sdca_pde_delay *pde_delays,
+			    int num_delays);
 #endif // __SDCA_ASOC_H__
diff --git a/sound/soc/sdca/sdca_asoc.c b/sound/soc/sdca/sdca_asoc.c
index 2bfc8e5aee31d..d5bccb2e04375 100644
--- a/sound/soc/sdca/sdca_asoc.c
+++ b/sound/soc/sdca/sdca_asoc.c
@@ -359,16 +359,78 @@ static int entity_parse_ot(struct device *dev,
 	return 0;
 }
 
+/**
+ * sdca_asoc_pde_ensure_ps - Verify PDE power state reached target state
+ * @dev: Pointer to the device for error logging.
+ * @regmap: Register map for reading ACTUAL_PS register.
+ * @function_id: SDCA function identifier.
+ * @entity_id: SDCA entity identifier for the power domain.
+ * @from_ps: Source power state (SDCA_PDE_PSn value).
+ * @to_ps: Target power state (SDCA_PDE_PSn value).
+ * @pde_delays: Pointer to array of PDE delay specifications for this device,
+ *              or NULL to use default polling interval.
+ * @num_delays: Number of entries in pde_delays array.
+ *
+ * This function polls the ACTUAL_PS register to verify that a PDE power state
+ * transition has completed. Per SDCA specification, after writing REQUESTED_PS,
+ * the caller must poll ACTUAL_PS until it reflects the requested state.
+ *
+ * This function implements the polling logic but does NOT modify the power state.
+ * The caller is responsible for writing REQUESTED_PS before invoking this function.
+ *
+ * If a delay table is provided, appropriate polling intervals are extracted based
+ * on the from_ps and to_ps transition. If no table is provided or no matching entry
+ * is found, a default polling interval is used.
+ *
+ * Return: Returns zero when ACTUAL_PS reaches the target state, -ETIMEDOUT if the
+ * polling times out before reaching the target state, or a negative error code if
+ * a register read fails.
+ */
+int sdca_asoc_pde_ensure_ps(struct device *dev, struct regmap *regmap,
+			    int function_id, int entity_id,
+			    int from_ps, int to_ps,
+			    const struct sdca_pde_delay *pde_delays,
+			    int num_delays)
+{
+	static const int polls = 100;
+	static const int default_poll_us = 1000;
+	unsigned int reg, val;
+	int i, poll_us = default_poll_us;
+	int ret;
+
+	if (pde_delays && num_delays > 0) {
+		for (i = 0; i < num_delays; i++) {
+			if (pde_delays[i].from_ps == from_ps && pde_delays[i].to_ps == to_ps) {
+				poll_us = pde_delays[i].us / polls;
+				break;
+			}
+		}
+	}
+
+	reg = SDW_SDCA_CTL(function_id, entity_id, SDCA_CTL_PDE_ACTUAL_PS, 0);
+
+	for (i = 0; i < polls; i++) {
+		if (i)
+			fsleep(poll_us);
+
+		ret = regmap_read(regmap, reg, &val);
+		if (ret)
+			return ret;
+		else if (val == to_ps)
+			return 0;
+	}
+
+	dev_err(dev, "PDE power transition failed: expected 0x%x, got 0x%x\n", to_ps, val);
+	return -ETIMEDOUT;
+}
+EXPORT_SYMBOL(sdca_asoc_pde_ensure_ps);
+
 static int entity_pde_event(struct snd_soc_dapm_widget *widget,
 			    struct snd_kcontrol *kctl, int event)
 {
 	struct snd_soc_component *component = snd_soc_dapm_to_component(widget->dapm);
 	struct sdca_entity *entity = widget->priv;
-	static const int polls = 100;
-	unsigned int reg, val;
-	int from, to, i;
-	int poll_us;
-	int ret;
+	int from, to;
 
 	if (!component)
 		return -EIO;
@@ -386,33 +448,12 @@ static int entity_pde_event(struct snd_soc_dapm_widget *widget,
 		return 0;
 	}
 
-	for (i = 0; i < entity->pde.num_max_delay; i++) {
-		struct sdca_pde_delay *delay = &entity->pde.max_delay[i];
-
-		if (delay->from_ps == from && delay->to_ps == to) {
-			poll_us = delay->us / polls;
-			break;
-		}
-	}
-
-	reg = SDW_SDCA_CTL(SDW_SDCA_CTL_FUNC(widget->reg),
-			   SDW_SDCA_CTL_ENT(widget->reg),
-			   SDCA_CTL_PDE_ACTUAL_PS, 0);
-
-	for (i = 0; i < polls; i++) {
-		if (i)
-			fsleep(poll_us);
-
-		ret = regmap_read(component->regmap, reg, &val);
-		if (ret)
-			return ret;
-		else if (val == to)
-			return 0;
-	}
-
-	dev_err(component->dev, "%s: power transition failed: %x\n",
-		entity->label, val);
-	return -ETIMEDOUT;
+	return sdca_asoc_pde_ensure_ps(component->dev, component->regmap,
+				       SDW_SDCA_CTL_FUNC(widget->reg),
+				       SDW_SDCA_CTL_ENT(widget->reg),
+				       from, to,
+				       entity->pde.max_delay,
+				       entity->pde.num_max_delay);
 }
 
 static int entity_parse_pde(struct device *dev,
-- 
2.34.1