linux-kernel - [PATCH 2/6] ASoC: samsung: i2s: configure PSR from sound card

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Date:   Fri, 14 Oct 2022 15:51:47 +0530
From:   Padmanabhan Rajanbabu <p.rajanbabu@...sung.com>
To:     lgirdwood@...il.com, broonie@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, s.nawrocki@...sung.com,
        perex@...ex.cz, tiwai@...e.com, pankaj.dubey@...sung.com,
        alim.akhtar@...sung.com, rcsekar@...sung.com,
        aswani.reddy@...sung.com
Cc:     alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        Padmanabhan Rajanbabu <p.rajanbabu@...sung.com>
Subject: [PATCH 2/6] ASoC: samsung: i2s: configure PSR from sound card

Currently the prescaler value in samsung I2S dai is calculated by
dividing the peripheral input clock frequency with frame clock
frequency and root clock frequency divider. This prescaler value is
used to divide the input clock to generate root clock (RCLK) from which
frame clock is generated for I2S communication.

However for the platforms which does not have a dedicated audio PLL as
an input clock source, the prescaler divider will not generate accurate
root clock frequency, which inturn affects sampling frequency also.

To overcome this scenario, support has been added to let the sound card
identify right prescaler divider value and configure the prescaler (PSR)
divider directly the from the sound card to achieve near accurate sample
frequencies

Signed-off-by: Padmanabhan Rajanbabu <p.rajanbabu@...sung.com>
---
 sound/soc/samsung/i2s-regs.h |  2 ++
 sound/soc/samsung/i2s.c      | 36 ++++++++++++++++++++++++++++++++----
 sound/soc/samsung/i2s.h      |  1 +
 3 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/sound/soc/samsung/i2s-regs.h b/sound/soc/samsung/i2s-regs.h
index cb2be4a3b70b..e2581dc73df2 100644
--- a/sound/soc/samsung/i2s-regs.h
+++ b/sound/soc/samsung/i2s-regs.h
@@ -132,6 +132,8 @@
 #define EXYNOS7_MOD_RCLK_192FS	7
 
 #define PSR_PSREN		(1 << 15)
+#define PSR_PSVAL_SHIFT		8
+#define PSR_PSVAL_MASK		0x3f
 
 #define FIC_TX2COUNT(x)		(((x) >>  24) & 0xf)
 #define FIC_TX1COUNT(x)		(((x) >>  16) & 0xf)
diff --git a/sound/soc/samsung/i2s.c b/sound/soc/samsung/i2s.c
index fb806b0af6ab..a96286b27f1d 100644
--- a/sound/soc/samsung/i2s.c
+++ b/sound/soc/samsung/i2s.c
@@ -59,10 +59,10 @@ struct i2s_dai {
 	/* Frame clock */
 	unsigned frmclk;
 	/*
-	 * Specifically requested RCLK, BCLK by machine driver.
+	 * Specifically requested RCLK, BCLK and PSR by machine driver.
 	 * 0 indicates CPU driver is free to choose any value.
 	 */
-	unsigned rfs, bfs;
+	unsigned int rfs, bfs, psr;
 	/* Pointer to the Primary_Fifo if this is Sec_Fifo, NULL otherwise */
 	struct i2s_dai *pri_dai;
 	/* Pointer to the Secondary_Fifo if it has one, NULL otherwise */
@@ -389,6 +389,17 @@ static inline int get_blc(struct i2s_dai *i2s)
 	}
 }
 
+static inline unsigned int get_psval(struct i2s_dai *i2s)
+{
+	struct samsung_i2s_priv *priv = i2s->priv;
+	u32 psr;
+
+	psr = readl(priv->addr + I2SPSR) >> PSR_PSVAL_SHIFT;
+	psr &= PSR_PSVAL_MASK;
+
+	return (psr + 1);
+}
+
 /* TX channel control */
 static void i2s_txctrl(struct i2s_dai *i2s, int on)
 {
@@ -994,7 +1005,11 @@ static int config_setup(struct i2s_dai *i2s)
 		return 0;
 
 	if (!(priv->quirks & QUIRK_NO_MUXPSR)) {
-		psr = priv->rclk_srcrate / i2s->frmclk / rfs;
+		if (i2s->psr)
+			psr = i2s->psr;
+		else
+			psr = priv->rclk_srcrate / i2s->frmclk / rfs;
+
 		writel(((psr - 1) << 8) | PSR_PSREN, priv->addr + I2SPSR);
 		dev_dbg(&i2s->pdev->dev,
 			"RCLK_SRC=%luHz PSR=%u, RCLK=%dfs, BCLK=%dfs\n",
@@ -1072,6 +1087,18 @@ static int i2s_set_clkdiv(struct snd_soc_dai *dai,
 		i2s->bfs = div;
 		pm_runtime_put(dai->dev);
 		break;
+	case SAMSUNG_I2S_DIV_RCLK:
+		pm_runtime_get_sync(dai->dev);
+		if ((any_active(i2s) && div && (get_psval(i2s) != div))
+			|| (other && other->psr && (other->psr != div))) {
+			pm_runtime_put(dai->dev);
+			dev_err(&i2s->pdev->dev,
+				"%s:%d Other DAI busy\n", __func__, __LINE__);
+			return -EAGAIN;
+		}
+		i2s->psr = div;
+		pm_runtime_put(dai->dev);
+		break;
 	default:
 		dev_err(&i2s->pdev->dev,
 			"Invalid clock divider(%d)\n", div_id);
@@ -1140,9 +1167,10 @@ static int samsung_i2s_dai_probe(struct snd_soc_dai *dai)
 					   other->idma_playback.addr);
 	}
 
-	/* Reset any constraint on RFS and BFS */
+	/* Reset any constraint on RFS, BFS and PSR*/
 	i2s->rfs = 0;
 	i2s->bfs = 0;
+	i2s->psr = 0;
 
 	spin_lock_irqsave(&priv->lock, flags);
 	i2s_txctrl(i2s, 0);
diff --git a/sound/soc/samsung/i2s.h b/sound/soc/samsung/i2s.h
index 78b475ef98d9..e783d33fdfac 100644
--- a/sound/soc/samsung/i2s.h
+++ b/sound/soc/samsung/i2s.h
@@ -13,6 +13,7 @@
 #define SAMSUNG_I2S_DAI_SEC    "samsung-i2s-sec"
 
 #define SAMSUNG_I2S_DIV_BCLK		1
+#define SAMSUNG_I2S_DIV_RCLK		2
 
 #define SAMSUNG_I2S_RCLKSRC_0		0
 #define SAMSUNG_I2S_RCLKSRC_1		1
-- 
2.17.1