[alsa-devel] [PATCH 3/5] ASoC: fsl_spdif: Add sysclk df support to derive txclk from sysclk

[Nicolin Chen]

The sysclk is one the clock sources that could be selected to derive
tx clock. But the route for sysclk is a bit different that it does
not only contain txclk df divider but also have an extra sysclk df.

So this patch mainly adds syclk df configuration support so as to
let the driver be able to get clock from sysclk.

Signed-off-by: Nicolin Chen <Guangyu.Chen at freescale.com>
---
 sound/soc/fsl/fsl_spdif.c | 81 +++++++++++++++++++++++++++++------------------
 1 file changed, 51 insertions(+), 30 deletions(-)

diff --git a/sound/soc/fsl/fsl_spdif.c b/sound/soc/fsl/fsl_spdif.c
index af8bc37..1abfb00 100644
--- a/sound/soc/fsl/fsl_spdif.c
+++ b/sound/soc/fsl/fsl_spdif.c
@@ -76,6 +76,7 @@ struct fsl_spdif_priv {
 	struct regmap *regmap;
 	bool dpll_locked;
 	u8 txclk_df[SPDIF_TXRATE_MAX];
+	u8 sysclk_df[SPDIF_TXRATE_MAX];
 	u8 txclk_src[SPDIF_TXRATE_MAX];
 	u8 rxclk_src;
 	struct clk *txclk[SPDIF_TXRATE_MAX];
@@ -351,7 +352,7 @@ static int spdif_set_sample_rate(struct snd_pcm_substream *substream,
 	struct platform_device *pdev = spdif_priv->pdev;
 	unsigned long csfs = 0;
 	u32 stc, mask, rate;
-	u8 clk, txclk_df;
+	u8 clk, txclk_df, sysclk_df;
 	int ret;
 
 	switch (sample_rate) {
@@ -384,6 +385,8 @@ static int spdif_set_sample_rate(struct snd_pcm_substream *substream,
 		return -EINVAL;
 	}
 
+	sysclk_df = spdif_priv->sysclk_df[rate];
+
 	/* Don't mess up the clocks from other modules */
 	if (clk != STC_TXCLK_SPDIF_ROOT)
 		goto clk_set_bypass;
@@ -400,7 +403,7 @@ static int spdif_set_sample_rate(struct snd_pcm_substream *substream,
 
 clk_set_bypass:
 	dev_dbg(&pdev->dev, "expected clock rate = %d\n",
-			(64 * sample_rate * txclk_df));
+			(64 * sample_rate * txclk_df * sysclk_df));
 	dev_dbg(&pdev->dev, "actual clock rate = %ld\n",
 			clk_get_rate(spdif_priv->txclk[rate]));
 
@@ -412,6 +415,9 @@ clk_set_bypass:
 	mask = STC_TXCLK_ALL_EN_MASK | STC_TXCLK_SRC_MASK | STC_TXCLK_DF_MASK;
 	regmap_update_bits(regmap, REG_SPDIF_STC, mask, stc);
 
+	regmap_update_bits(regmap, REG_SPDIF_STC,
+			   STC_SYSCLK_DF_MASK, STC_SYSCLK_DF(sysclk_df));
+
 	dev_dbg(&pdev->dev, "set sample rate to %d\n", sample_rate);
 
 	return 0;
@@ -1018,43 +1024,55 @@ static u32 fsl_spdif_txclk_caldiv(struct fsl_spdif_priv *spdif_priv,
 				enum spdif_txrate index, bool round)
 {
 	const u32 rate[] = { 32000, 44100, 48000 };
+	bool is_sysclk = clk == spdif_priv->sysclk;
 	u64 rate_ideal, rate_actual, sub;
-	u32 txclk_df, arate;
-
-	for (txclk_df = 1; txclk_df <= 128; txclk_df++) {
-		rate_ideal = rate[index] * (txclk_df + 1) * 64;
-		if (round)
-			rate_actual = clk_round_rate(clk, rate_ideal);
-		else
-			rate_actual = clk_get_rate(clk);
-
-		arate = rate_actual / 64;
-		arate /= txclk_df;
-
-		if (arate == rate[index]) {
-			/* We are lucky */
-			savesub = 0;
-			spdif_priv->txclk_df[index] = txclk_df;
-			break;
-		} else if (arate / rate[index] == 1) {
-			/* A little bigger than expect */
-			sub = (arate - rate[index]) * 100000;
-			do_div(sub, rate[index]);
-			if (sub < savesub) {
+	u32 sysclk_dfmin, sysclk_dfmax;
+	u32 txclk_df, sysclk_df, arate;
+
+	/* The sysclk has an extra divisor [2, 512] */
+	sysclk_dfmin = is_sysclk ? 2 : 1;
+	sysclk_dfmax = is_sysclk ? 512 : 1;
+
+	for (sysclk_df = sysclk_dfmin; sysclk_df <= sysclk_dfmax; sysclk_df++) {
+		for (txclk_df = 1; txclk_df <= 128; txclk_df++) {
+			rate_ideal = rate[index] * (txclk_df + 1) * 64;
+			if (round)
+				rate_actual = clk_round_rate(clk, rate_ideal);
+			else
+				rate_actual = clk_get_rate(clk);
+
+			arate = rate_actual / 64;
+			arate /= txclk_df * sysclk_df;
+
+			if (arate == rate[index]) {
+				/* We are lucky */
+				savesub = 0;
+				spdif_priv->txclk_df[index] = txclk_df;
+				spdif_priv->sysclk_df[index] = sysclk_df;
+				goto out;
+			} else if (arate / rate[index] == 1) {
+				/* A little bigger than expect */
+				sub = (arate - rate[index]) * 100000;
+				do_div(sub, rate[index]);
+				if (sub >= savesub)
+					continue;
 				savesub = sub;
 				spdif_priv->txclk_df[index] = txclk_df;
-			}
-		} else if (rate[index] / arate == 1) {
-			/* A little smaller than expect */
-			sub = (rate[index] - arate) * 100000;
-			do_div(sub, rate[index]);
-			if (sub < savesub) {
+				spdif_priv->sysclk_df[index] = sysclk_df;
+			} else if (rate[index] / arate == 1) {
+				/* A little smaller than expect */
+				sub = (rate[index] - arate) * 100000;
+				do_div(sub, rate[index]);
+				if (sub >= savesub)
+					continue;
 				savesub = sub;
 				spdif_priv->txclk_df[index] = txclk_df;
+				spdif_priv->sysclk_df[index] = sysclk_df;
 			}
 		}
 	}
 
+out:
 	return savesub;
 }
 
@@ -1097,6 +1115,9 @@ static int fsl_spdif_probe_txclk(struct fsl_spdif_priv *spdif_priv,
 			spdif_priv->txclk_src[index], rate[index]);
 	dev_dbg(&pdev->dev, "use txclk df %d for %dHz sample rate\n",
 			spdif_priv->txclk_df[index], rate[index]);
+	if (spdif_priv->txclk[index] == spdif_priv->sysclk)
+		dev_dbg(&pdev->dev, "use sysclk df %d for %dHz sample rate\n",
+				spdif_priv->sysclk_df[index], rate[index]);
 
 	return 0;
 }
-- 
1.8.4