ASoC: renesas: msiof: use reset controller

MSIOF has TXRST/RXRST to reset FIFO, but it shouldn't be used during SYNC
signal was asserted, because it will be cause of HW issue.

When MSIOF is used as Sound driver, this driver is assuming it is used as
clock consumer mode (= Codec is clock provider). This means, it can't
control SYNC signal by itself.

We need to use SW reset (= reset_control_xxx()) instead of TXRST/RXRST.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Yusuke Goda <yusuke.goda.sx@renesas.com>
Link: https://patch.msgid.link/87cy7fyuug.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: morimoto

sound/soc/renesas/rcar/msiof.c

@@ -24,12 +24,25 @@
  * Clock/Frame Consumer Mode.
  */
 
+/*
+ * [NOTE-RESET]
+ *
+ * MSIOF has TXRST/RXRST to reset FIFO, but it shouldn't be used during SYNC signal was asserted,
+ * because it will be cause of HW issue.
+ *
+ * When MSIOF is used as Sound driver, this driver is assuming it is used as clock consumer mode
+ * (= Codec is clock provider). This means, it can't control SYNC signal by itself.
+ *
+ * We need to use SW reset (= reset_control_xxx()) instead of TXRST/RXRST.
+ */
+
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_dma.h>
 #include <linux/of_graph.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/spi/sh_msiof.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/soc.h>
@@ -60,10 +73,13 @@
 struct msiof_priv {
 	struct device *dev;
 	struct snd_pcm_substream *substream[SNDRV_PCM_STREAM_LAST + 1];
+	struct reset_control *reset;
 	spinlock_t lock;
 	void __iomem *base;
 	resource_size_t phy_addr;
 
+	int count;
+
 	/* for error */
 	int err_syc[SNDRV_PCM_STREAM_LAST + 1];
 	int err_ovf[SNDRV_PCM_STREAM_LAST + 1];
@@ -131,6 +147,16 @@ static int msiof_hw_start(struct snd_soc_component *component,
 	 *	RX: Fig 109.15
 	 */
 
+	/*
+	 * Use reset_control_xx() instead of TXRST/RXRST.
+	 * see
+	 *	[NOTE-RESET]
+	 */
+	if (!priv->count)
+		reset_control_deassert(priv->reset);
+
+	priv->count++;
+
 	/* reset errors */
 	priv->err_syc[substream->stream] =
 	priv->err_ovf[substream->stream] =
@@ -152,7 +178,6 @@ static int msiof_hw_start(struct snd_soc_component *component,
 		val = FIELD_PREP(SIMDR2_BITLEN1, width - 1);
 		msiof_write(priv, SITMDR2, val | FIELD_PREP(SIMDR2_GRP, 1));
 		msiof_write(priv, SITMDR3, val);
-
 	}
 	/* SIRMDRx */
 	else {
@@ -227,6 +252,11 @@ static int msiof_hw_stop(struct snd_soc_component *component,
 			 priv->err_ovf[substream->stream],
 			 priv->err_udf[substream->stream]);
 
+	priv->count--;
+
+	if (!priv->count)
+		reset_control_assert(priv->reset);
+
 	return 0;
 }
 
@@ -490,12 +520,19 @@ static int msiof_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
 
+	priv->reset = devm_reset_control_get_exclusive(dev, NULL);
+	if (IS_ERR(priv->reset))
+		return PTR_ERR(priv->reset);
+
+	reset_control_assert(priv->reset);
+
 	ret = devm_request_irq(dev, irq, msiof_interrupt, 0, dev_name(dev), priv);
 	if (ret)
 		return ret;
 
 	priv->dev	= dev;
 	priv->phy_addr	= res->start;
+	priv->count	= 0;
 
 	spin_lock_init(&priv->lock);
 	platform_set_drvdata(pdev, priv);