[PATCH 2/3] ASoC: wm8940: Rewrite code to set proper clocks

[Lukasz Majewski]

Without this change, the wm8940 driver is not working when
set_sysclk callback (wm8940_set_dai_sysclk) is called with
freqency not listed in the switch clause.

This change adjusts this driver to allow non-standard frequency
set (just after the boot) being adjusted afterwards by the sound
system core code.

Moreover, support for internal wm8940's PLL is provided, so it
can generate clocks when HOST system is not able to do it.

Code in this commit is based on previous change done for wm8974
(SHA1: 51b2bb3f2568e6d9d81a001d38b8d70c2ba4af99).

Signed-off-by: Lukasz Majewski <lukma at denx.de>
---
 sound/soc/codecs/wm8940.c | 103 ++++++++++++++++++++++++++++++--------
 1 file changed, 83 insertions(+), 20 deletions(-)

diff --git a/sound/soc/codecs/wm8940.c b/sound/soc/codecs/wm8940.c
index 7cea54720436..6fb1c3780439 100644
--- a/sound/soc/codecs/wm8940.c
+++ b/sound/soc/codecs/wm8940.c
@@ -37,7 +37,9 @@
 #include "wm8940.h"
 
 struct wm8940_priv {
-	unsigned int sysclk;
+	unsigned int mclk;
+	unsigned int fs;
+
 	struct regmap *regmap;
 };
 
@@ -387,17 +389,24 @@ static int wm8940_set_dai_fmt(struct snd_soc_dai *codec_dai,
 	return 0;
 }
 
+static int wm8940_update_clocks(struct snd_soc_dai *dai);
 static int wm8940_i2s_hw_params(struct snd_pcm_substream *substream,
 				struct snd_pcm_hw_params *params,
 				struct snd_soc_dai *dai)
 {
 	struct snd_soc_component *component = dai->component;
+	struct wm8940_priv *wm8940 = snd_soc_component_get_drvdata(component);
 	u16 iface = snd_soc_component_read(component, WM8940_IFACE) & 0xFD9F;
 	u16 addcntrl = snd_soc_component_read(component, WM8940_ADDCNTRL) & 0xFFF1;
 	u16 companding =  snd_soc_component_read(component,
 						WM8940_COMPANDINGCTL) & 0xFFDF;
 	int ret;
 
+	wm8940->fs = params_rate(params);
+	ret = wm8940_update_clocks(dai);
+	if (ret)
+		return ret;
+
 	/* LoutR control */
 	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE
 	    && params_channels(params) == 2)
@@ -496,7 +505,6 @@ static int wm8940_set_bias_level(struct snd_soc_component *component,
 				return ret;
 			}
 		}
-
 		/* ensure bufioen and biasen */
 		pwr_reg |= (1 << 2) | (1 << 3);
 		/* set vmid to 300k for standby */
@@ -611,24 +619,6 @@ static int wm8940_set_dai_pll(struct snd_soc_dai *codec_dai, int pll_id,
 	return 0;
 }
 
-static int wm8940_set_dai_sysclk(struct snd_soc_dai *codec_dai,
-				 int clk_id, unsigned int freq, int dir)
-{
-	struct snd_soc_component *component = codec_dai->component;
-	struct wm8940_priv *wm8940 = snd_soc_component_get_drvdata(component);
-
-	switch (freq) {
-	case 11289600:
-	case 12000000:
-	case 12288000:
-	case 16934400:
-	case 18432000:
-		wm8940->sysclk = freq;
-		return 0;
-	}
-	return -EINVAL;
-}
-
 static int wm8940_set_dai_clkdiv(struct snd_soc_dai *codec_dai,
 				 int div_id, int div)
 {
@@ -653,6 +643,79 @@ static int wm8940_set_dai_clkdiv(struct snd_soc_dai *codec_dai,
 	return ret;
 }
 
+static unsigned int wm8940_get_mclkdiv(unsigned int f_in, unsigned int f_out,
+				       int *mclkdiv)
+{
+	unsigned int ratio = 2 * f_in / f_out;
+
+	if (ratio <= 2) {
+		*mclkdiv = WM8940_MCLKDIV_1;
+		ratio = 2;
+	} else if (ratio == 3) {
+		*mclkdiv = WM8940_MCLKDIV_1_5;
+	} else if (ratio == 4) {
+		*mclkdiv = WM8940_MCLKDIV_2;
+	} else if (ratio <= 6) {
+		*mclkdiv = WM8940_MCLKDIV_3;
+		ratio = 6;
+	} else if (ratio <= 8) {
+		*mclkdiv = WM8940_MCLKDIV_4;
+		ratio = 8;
+	} else if (ratio <= 12) {
+		*mclkdiv = WM8940_MCLKDIV_6;
+		ratio = 12;
+	} else if (ratio <= 16) {
+		*mclkdiv = WM8940_MCLKDIV_8;
+		ratio = 16;
+	} else {
+		*mclkdiv = WM8940_MCLKDIV_12;
+		ratio = 24;
+	}
+
+	return f_out * ratio / 2;
+}
+
+static int wm8940_update_clocks(struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	struct wm8940_priv *priv = snd_soc_component_get_drvdata(component);
+	unsigned int fs256;
+	unsigned int fpll = 0;
+	unsigned int f;
+	int mclkdiv;
+
+	if (!priv->mclk || !priv->fs)
+		return 0;
+
+	fs256 = 256 * priv->fs;
+
+	f = wm8940_get_mclkdiv(priv->mclk, fs256, &mclkdiv);
+	if (f != priv->mclk) {
+		/* The PLL performs best around 90MHz */
+		fpll = wm8940_get_mclkdiv(22500000, fs256, &mclkdiv);
+	}
+
+	wm8940_set_dai_pll(dai, 0, 0, priv->mclk, fpll);
+	wm8940_set_dai_clkdiv(dai, WM8940_MCLKDIV, mclkdiv);
+
+	return 0;
+}
+
+static int wm8940_set_dai_sysclk(struct snd_soc_dai *dai, int clk_id,
+				 unsigned int freq, int dir)
+{
+	struct snd_soc_component *component = dai->component;
+	struct wm8940_priv *priv = snd_soc_component_get_drvdata(component);
+
+	if (dir != SND_SOC_CLOCK_IN)
+		return -EINVAL;
+
+	priv->mclk = freq;
+
+	return wm8940_update_clocks(dai);
+}
+
+
 #define WM8940_RATES SNDRV_PCM_RATE_8000_48000
 
 #define WM8940_FORMATS (SNDRV_PCM_FMTBIT_S8 |				\
-- 
2.20.1