[PATCH 3/3] ASoC: atmel: mchp-pdmc: Retain Non-Runtime Controls

[Andrei Simion <andrei.simion@microchip.com>]

From: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>

Avoid removing these controls, as doing so can cause issues if the stream
is initiated from another control. Ensure these controls remain intact when
the stream is started or finished. Instead of removing them, return an
-EBUSY error code to indicate that the controller is busy, especially when
the audio filter and the SINC filter are in use.

[andrei.simion@microchip.com: Reword the commit title and the commit
message. Adapt the code from kernel v6.1 -> v6.6 -> latest kernel version.]

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Signed-off-by: Andrei Simion <andrei.simion@microchip.com>
---
 sound/soc/atmel/mchp-pdmc.c | 78 ++++++++++++++++---------------------
 1 file changed, 34 insertions(+), 44 deletions(-)

diff --git a/sound/soc/atmel/mchp-pdmc.c b/sound/soc/atmel/mchp-pdmc.c
index d97d153ee375..758b3c550b97 100644
--- a/sound/soc/atmel/mchp-pdmc.c
+++ b/sound/soc/atmel/mchp-pdmc.c
@@ -14,6 +14,7 @@
 #include <linux/of.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
+#include <linux/spinlock.h>
 
 #include <sound/core.h>
 #include <sound/dmaengine_pcm.h>
@@ -113,6 +114,7 @@ struct mchp_pdmc_chmap {
 
 struct mchp_pdmc {
 	struct mic_map channel_mic_map[MCHP_PDMC_MAX_CHANNELS];
+	spinlock_t busy_lock;		/* lock protecting busy */
 	struct device *dev;
 	struct snd_dmaengine_dai_dma_data addr;
 	struct regmap *regmap;
@@ -124,6 +126,7 @@ struct mchp_pdmc {
 	int mic_no;
 	int sinc_order;
 	bool audio_filter_en;
+	u8 busy:1;
 };
 
 static const char *const mchp_pdmc_sinc_filter_order_text[] = {
@@ -167,10 +170,19 @@ static int mchp_pdmc_sinc_order_put(struct snd_kcontrol *kcontrol,
 		return -EINVAL;
 
 	val = snd_soc_enum_item_to_val(e, item[0]) << e->shift_l;
-	if (val == dd->sinc_order)
+
+	spin_lock(&dd->busy_lock);
+	if (dd->busy) {
+		spin_unlock((&dd->busy_lock));
+		return -EBUSY;
+	}
+	if (val == dd->sinc_order) {
+		spin_unlock((&dd->busy_lock));
 		return 0;
+	}
 
 	dd->sinc_order = val;
+	spin_unlock((&dd->busy_lock));
 
 	return 1;
 }
@@ -193,10 +205,18 @@ static int mchp_pdmc_af_put(struct snd_kcontrol *kcontrol,
 	struct mchp_pdmc *dd = snd_soc_component_get_drvdata(component);
 	bool af = uvalue->value.integer.value[0] ? true : false;
 
-	if (dd->audio_filter_en == af)
+	spin_lock(&dd->busy_lock);
+	if (dd->busy) {
+		spin_unlock((&dd->busy_lock));
+		return -EBUSY;
+	}
+	if (dd->audio_filter_en == af) {
+		spin_unlock((&dd->busy_lock));
 		return 0;
+	}
 
 	dd->audio_filter_en = af;
+	spin_unlock((&dd->busy_lock));
 
 	return 1;
 }
@@ -379,52 +399,10 @@ static const struct snd_kcontrol_new mchp_pdmc_snd_controls[] = {
 	},
 };
 
-static int mchp_pdmc_close(struct snd_soc_component *component,
-			   struct snd_pcm_substream *substream)
-{
-	return snd_soc_add_component_controls(component, mchp_pdmc_snd_controls,
-					      ARRAY_SIZE(mchp_pdmc_snd_controls));
-}
-
-static int mchp_pdmc_open(struct snd_soc_component *component,
-			  struct snd_pcm_substream *substream)
-{
-	int i;
-
-	/* remove controls that can't be changed at runtime */
-	for (i = 0; i < ARRAY_SIZE(mchp_pdmc_snd_controls); i++) {
-		const struct snd_kcontrol_new *control = &mchp_pdmc_snd_controls[i];
-		struct snd_ctl_elem_id id;
-		int err;
-
-		if (component->name_prefix)
-			snprintf(id.name, sizeof(id.name), "%s %s", component->name_prefix,
-				 control->name);
-		else
-			strscpy(id.name, control->name, sizeof(id.name));
-
-		id.numid = 0;
-		id.iface = control->iface;
-		id.device = control->device;
-		id.subdevice = control->subdevice;
-		id.index = control->index;
-		err = snd_ctl_remove_id(component->card->snd_card, &id);
-		if (err < 0)
-			dev_err(component->dev, "%d: Failed to remove %s\n", err,
-				control->name);
-	}
-
-	return 0;
-}
-
 static const struct snd_soc_component_driver mchp_pdmc_dai_component = {
 	.name = "mchp-pdmc",
 	.controls = mchp_pdmc_snd_controls,
 	.num_controls = ARRAY_SIZE(mchp_pdmc_snd_controls),
-	.open = &mchp_pdmc_open,
-	.close = &mchp_pdmc_close,
-	.legacy_dai_naming = 1,
-	.trigger_start = SND_SOC_TRIGGER_ORDER_LDC,
 };
 
 static const unsigned int mchp_pdmc_1mic[] = {1};
@@ -587,6 +565,13 @@ static int mchp_pdmc_hw_params(struct snd_pcm_substream *substream,
 			cfgr_val |= MCHP_PDMC_CFGR_BSSEL(i);
 	}
 
+	/*
+	 * from these point forward, we consider the controller busy, so the
+	 * audio filter and SINC order can't be changed
+	 */
+	spin_lock(&dd->busy_lock);
+	dd->busy = 1;
+	spin_unlock((&dd->busy_lock));
 	for (osr_start = dd->audio_filter_en ? 64 : 8;
 	     osr_start <= 256 && best_diff_rate; osr_start *= 2) {
 		long round_rate;
@@ -1099,6 +1084,7 @@ static int mchp_pdmc_probe(struct platform_device *pdev)
 	 */
 	dd->audio_filter_en = true;
 	dd->sinc_order = 3;
+	spin_lock_init(&dd->busy_lock);
 
 	dd->addr.addr = (dma_addr_t)res->start + MCHP_PDMC_RHR;
 	platform_set_drvdata(pdev, dd);
@@ -1143,6 +1129,10 @@ static void mchp_pdmc_remove(struct platform_device *pdev)
 {
 	struct mchp_pdmc *dd = platform_get_drvdata(pdev);
 
+	spin_lock(&dd->busy_lock);
+	dd->busy = 0;
+	spin_unlock((&dd->busy_lock));
+
 	if (!pm_runtime_status_suspended(dd->dev))
 		mchp_pdmc_runtime_suspend(dd->dev);
 
-- 
2.34.1