ASoC: pcm512x: Support mastering BCLK/LRCLK using the PLL

Using the PLL in master mode requires using an external connection
between one of the GPIO pins (configured as PLL/4 output) and the
SCK pin. It also requires the external clock to be fed to some other
GPIO pin instead of the SCK pin.

This is described for the PCM5122 chip in the answers to the forum post
"PCM5122 DAC as I2S master troubles with PLL mode" at the TI E2E
community pages (1). The clocking functionality is also much better
described in the datasheet for the chip PCM5242, which seems to be
register compatible with PCM512x and PCM514x (which both have severely
lacking datasheets).

(1) http://e2e.ti.com/support/data_converters/audio_converters/f/64/t/267830

Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 435 insertions, 23 deletions

diff --git a/sound/soc/codecs/pcm512x.c b/sound/soc/codecs/pcm512x.c
index 526e6b30cdde..66dd036f0141 100644
--- a/sound/soc/codecs/pcm512x.c
+++ b/sound/soc/codecs/pcm512x.c
@@ -21,6 +21,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/gcd.h>
 #include <sound/soc.h>
 #include <sound/soc-dapm.h>
 #include <sound/pcm_params.h>
@@ -28,6 +29,11 @@
 
 #include "pcm512x.h"
 
+#define DIV_ROUND_DOWN_ULL(ll, d) \
+	({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
+#define DIV_ROUND_CLOSEST_ULL(ll, d) \
+	({ unsigned long long _tmp = (ll)+(d)/2; do_div(_tmp, d); _tmp; })
+
 #define PCM512x_NUM_SUPPLIES 3
 static const char * const pcm512x_supply_names[PCM512x_NUM_SUPPLIES] = {
 	"AVDD",
@@ -41,6 +47,13 @@ struct pcm512x_priv {
 	struct regulator_bulk_data supplies[PCM512x_NUM_SUPPLIES];
 	struct notifier_block supply_nb[PCM512x_NUM_SUPPLIES];
 	int fmt;
+	int pll_in;
+	int pll_out;
+	int pll_r;
+	int pll_j;
+	int pll_d;
+	int pll_p;
+	unsigned long real_pll;
 };
 
 /*
@@ -92,7 +105,13 @@ static const struct reg_default pcm512x_reg_defaults[] = {
 	{ PCM512x_VCOM_CTRL_2,       0x01 },
 	{ PCM512x_BCLK_LRCLK_CFG,    0x00 },
 	{ PCM512x_MASTER_MODE,       0x7c },
+	{ PCM512x_GPIO_PLLIN,        0x00 },
 	{ PCM512x_SYNCHRONIZE,       0x10 },
+	{ PCM512x_PLL_COEFF_0,       0x00 },
+	{ PCM512x_PLL_COEFF_1,       0x00 },
+	{ PCM512x_PLL_COEFF_2,       0x00 },
+	{ PCM512x_PLL_COEFF_3,       0x00 },
+	{ PCM512x_PLL_COEFF_4,       0x00 },
 	{ PCM512x_DSP_CLKDIV,        0x00 },
 	{ PCM512x_DAC_CLKDIV,        0x00 },
 	{ PCM512x_NCP_CLKDIV,        0x00 },
@@ -119,6 +138,7 @@ static bool pcm512x_readable(struct device *dev, unsigned int reg)
 	case PCM512x_MASTER_MODE:
 	case PCM512x_PLL_REF:
 	case PCM512x_DAC_REF:
+	case PCM512x_GPIO_PLLIN:
 	case PCM512x_SYNCHRONIZE:
 	case PCM512x_PLL_COEFF_0:
 	case PCM512x_PLL_COEFF_1:
@@ -160,6 +180,7 @@ static bool pcm512x_readable(struct device *dev, unsigned int reg)
 	case PCM512x_RATE_DET_2:
 	case PCM512x_RATE_DET_3:
 	case PCM512x_RATE_DET_4:
+	case PCM512x_CLOCK_STATUS:
 	case PCM512x_ANALOG_MUTE_DET:
 	case PCM512x_GPIN:
 	case PCM512x_DIGITAL_MUTE_DET:
@@ -171,6 +192,8 @@ static bool pcm512x_readable(struct device *dev, unsigned int reg)
 	case PCM512x_VCOM_CTRL_1:
 	case PCM512x_VCOM_CTRL_2:
 	case PCM512x_CRAM_CTRL:
+	case PCM512x_FLEX_A:
+	case PCM512x_FLEX_B:
 		return true;
 	default:
 		/* There are 256 raw register addresses */
@@ -187,6 +210,7 @@ static bool pcm512x_volatile(struct device *dev, unsigned int reg)
 	case PCM512x_RATE_DET_2:
 	case PCM512x_RATE_DET_3:
 	case PCM512x_RATE_DET_4:
+	case PCM512x_CLOCK_STATUS:
 	case PCM512x_ANALOG_MUTE_DET:
 	case PCM512x_GPIN:
 	case PCM512x_DIGITAL_MUTE_DET:
@@ -330,6 +354,38 @@ static const struct snd_pcm_hw_constraint_list constraints_slave = {
 	.list  = pcm512x_dai_rates,
 };
 
+static const struct snd_interval pcm512x_dai_ranges_64bpf[] = {
+	{
+		.min = 8000,
+		.max = 195312,
+	}, {
+		.min = 250000,
+		.max = 390625,
+	},
+};
+
+static struct snd_pcm_hw_constraint_ranges constraints_64bpf = {
+	.count  = ARRAY_SIZE(pcm512x_dai_ranges_64bpf),
+	.ranges = pcm512x_dai_ranges_64bpf,
+};
+
+static int pcm512x_hw_rule_rate(struct snd_pcm_hw_params *params,
+				struct snd_pcm_hw_rule *rule)
+{
+	struct snd_pcm_hw_constraint_ranges *r = rule->private;
+	int frame_size;
+
+	frame_size = snd_soc_params_to_frame_size(params);
+	if (frame_size < 0)
+		return frame_size;
+
+	if (frame_size != 64)
+		return 0;
+
+	return snd_interval_ranges(hw_param_interval(params, rule->var),
+				   r->count, r->ranges, r->mask);
+}
+
 static int pcm512x_dai_startup_master(struct snd_pcm_substream *substream,
 				      struct snd_soc_dai *dai)
 {
@@ -345,6 +401,14 @@ static int pcm512x_dai_startup_master(struct snd_pcm_substream *substream,
 		return PTR_ERR(pcm512x->sclk);
 	}
 
+	if (pcm512x->pll_out)
+		return snd_pcm_hw_rule_add(substream->runtime, 0,
+					   SNDRV_PCM_HW_PARAM_RATE,
+					   pcm512x_hw_rule_rate,
+					   (void *)&constraints_64bpf,
+					   SNDRV_PCM_HW_PARAM_FRAME_BITS,
+					   SNDRV_PCM_HW_PARAM_CHANNELS, -1);
+
 	constraints_no_pll = devm_kzalloc(dev, sizeof(*constraints_no_pll),
 					  GFP_KERNEL);
 	if (!constraints_no_pll)
@@ -445,12 +509,164 @@ static int pcm512x_set_bias_level(struct snd_soc_codec *codec,
 	return 0;
 }
 
+static unsigned long pcm512x_find_sck(struct snd_soc_dai *dai,
+				      unsigned long bclk_rate)
+{
+	struct device *dev = dai->dev;
+	unsigned long sck_rate;
+	int pow2;
+
+	/* 64 MHz <= pll_rate <= 100 MHz, VREF mode */
+	/* 16 MHz <= sck_rate <=  25 MHz, VREF mode */
+
+	/* select sck_rate as a multiple of bclk_rate but still with
+	 * as many factors of 2 as possible, as that makes it easier
+	 * to find a fast DAC rate
+	 */
+	pow2 = 1 << fls((25000000 - 16000000) / bclk_rate);
+	for (; pow2; pow2 >>= 1) {
+		sck_rate = rounddown(25000000, bclk_rate * pow2);
+		if (sck_rate >= 16000000)
+			break;
+	}
+	if (!pow2) {
+		dev_err(dev, "Impossible to generate a suitable SCK\n");
+		return 0;
+	}
+
+	dev_dbg(dev, "sck_rate %lu\n", sck_rate);
+	return sck_rate;
+}
+
+/* pll_rate = pllin_rate * R * J.D / P
+ * 1 <= R <= 16
+ * 1 <= J <= 63
+ * 0 <= D <= 9999
+ * 1 <= P <= 15
+ * 64 MHz <= pll_rate <= 100 MHz
+ * if D == 0
+ *     1 MHz <= pllin_rate / P <= 20 MHz
+ * else if D > 0
+ *     6.667 MHz <= pllin_rate / P <= 20 MHz
+ *     4 <= J <= 11
+ *     R = 1
+ */
+static int pcm512x_find_pll_coeff(struct snd_soc_dai *dai,
+				  unsigned long pllin_rate,
+				  unsigned long pll_rate)
+{
+	struct device *dev = dai->dev;
+	struct snd_soc_codec *codec = dai->codec;
+	struct pcm512x_priv *pcm512x = snd_soc_codec_get_drvdata(codec);
+	unsigned long common;
+	int R, J, D, P;
+	unsigned long K; /* 10000 * J.D */
+	unsigned long num;
+	unsigned long den;
+
+	common = gcd(pll_rate, pllin_rate);
+	dev_dbg(dev, "pll %lu pllin %lu common %lu\n",
+		pll_rate, pllin_rate, common);
+	num = pll_rate / common;
+	den = pllin_rate / common;
+
+	/* pllin_rate / P (or here, den) cannot be greater than 20 MHz */
+	if (pllin_rate / den > 20000000 && num < 8) {
+		num *= 20000000 / (pllin_rate / den);
+		den *= 20000000 / (pllin_rate / den);
+	}
+	dev_dbg(dev, "num / den = %lu / %lu\n", num, den);
+
+	P = den;
+	if (den <= 15 && num <= 16 * 63
+	    && 1000000 <= pllin_rate / P && pllin_rate / P <= 20000000) {
+		/* Try the case with D = 0 */
+		D = 0;
+		/* factor 'num' into J and R, such that R <= 16 and J <= 63 */
+		for (R = 16; R; R--) {
+			if (num % R)
+				continue;
+			J = num / R;
+			if (J == 0 || J > 63)
+				continue;
+
+			dev_dbg(dev, "R * J / P = %d * %d / %d\n", R, J, P);
+			pcm512x->real_pll = pll_rate;
+			goto done;
+		}
+		/* no luck */
+	}
+
+	R = 1;
+
+	if (num > 0xffffffffUL / 10000)
+		goto fallback;
+
+	/* Try to find an exact pll_rate using the D > 0 case */
+	common = gcd(10000 * num, den);
+	num = 10000 * num / common;
+	den /= common;
+	dev_dbg(dev, "num %lu den %lu common %lu\n", num, den, common);
+
+	for (P = den; P <= 15; P++) {
+		if (pllin_rate / P < 6667000 || 200000000 < pllin_rate / P)
+			continue;
+		if (num * P % den)
+			continue;
+		K = num * P / den;
+		/* J == 12 is ok if D == 0 */
+		if (K < 40000 || K > 120000)
+			continue;
+
+		J = K / 10000;
+		D = K % 10000;
+		dev_dbg(dev, "J.D / P = %d.%04d / %d\n", J, D, P);
+		pcm512x->real_pll = pll_rate;
+		goto done;
+	}
+
+	/* Fall back to an approximate pll_rate */
+
+fallback:
+	/* find smallest possible P */
+	P = DIV_ROUND_UP(pllin_rate, 20000000);
+	if (!P)
+		P = 1;
+	else if (P > 15) {
+		dev_err(dev, "Need a slower clock as pll-input\n");
+		return -EINVAL;
+	}
+	if (pllin_rate / P < 6667000) {
+		dev_err(dev, "Need a faster clock as pll-input\n");
+		return -EINVAL;
+	}
+	K = DIV_ROUND_CLOSEST_ULL(10000ULL * pll_rate * P, pllin_rate);
+	if (K < 40000)
+		K = 40000;
+	/* J == 12 is ok if D == 0 */
+	if (K > 120000)
+		K = 120000;
+	J = K / 10000;
+	D = K % 10000;
+	dev_dbg(dev, "J.D / P ~ %d.%04d / %d\n", J, D, P);
+	pcm512x->real_pll = DIV_ROUND_DOWN_ULL((u64)K * pllin_rate, 10000 * P);
+
+done:
+	pcm512x->pll_r = R;
+	pcm512x->pll_j = J;
+	pcm512x->pll_d = D;
+	pcm512x->pll_p = P;
+	return 0;
+}
+
 static int pcm512x_set_dividers(struct snd_soc_dai *dai,
 				struct snd_pcm_hw_params *params)
 {
 	struct device *dev = dai->dev;
 	struct snd_soc_codec *codec = dai->codec;
 	struct pcm512x_priv *pcm512x = snd_soc_codec_get_drvdata(codec);
+	unsigned long pllin_rate = 0;
+	unsigned long pll_rate;
 	unsigned long sck_rate;
 	unsigned long mck_rate;
 	unsigned long bclk_rate;
@@ -475,11 +691,74 @@ static int pcm512x_set_dividers(struct snd_soc_dai *dai,
 		return -EINVAL;
 	}
 
-	sck_rate = clk_get_rate(pcm512x->sclk);
-	bclk_div = params->rate_den * 64 / lrclk_div;
-	bclk_rate = DIV_ROUND_CLOSEST(sck_rate, bclk_div);
+	if (!pcm512x->pll_out) {
+		sck_rate = clk_get_rate(pcm512x->sclk);
+		bclk_div = params->rate_den * 64 / lrclk_div;
+		bclk_rate = DIV_ROUND_CLOSEST(sck_rate, bclk_div);
 
-	mck_rate = sck_rate;
+		mck_rate = sck_rate;
+	} else {
+		ret = snd_soc_params_to_bclk(params);
+		if (ret < 0) {
+			dev_err(dev, "Failed to find suitable BCLK: %d\n", ret);
+			return ret;
+		}
+		if (ret == 0) {
+			dev_err(dev, "No BCLK?\n");
+			return -EINVAL;
+		}
+		bclk_rate = ret;
+
+		pllin_rate = clk_get_rate(pcm512x->sclk);
+
+		sck_rate = pcm512x_find_sck(dai, bclk_rate);
+		if (!sck_rate)
+			return -EINVAL;
+		pll_rate = 4 * sck_rate;
+
+		ret = pcm512x_find_pll_coeff(dai, pllin_rate, pll_rate);
+		if (ret != 0)
+			return ret;
+
+		ret = regmap_write(pcm512x->regmap,
+				   PCM512x_PLL_COEFF_0, pcm512x->pll_p - 1);
+		if (ret != 0) {
+			dev_err(dev, "Failed to write PLL P: %d\n", ret);
+			return ret;
+		}
+
+		ret = regmap_write(pcm512x->regmap,
+				   PCM512x_PLL_COEFF_1, pcm512x->pll_j);
+		if (ret != 0) {
+			dev_err(dev, "Failed to write PLL J: %d\n", ret);
+			return ret;
+		}
+
+		ret = regmap_write(pcm512x->regmap,
+				   PCM512x_PLL_COEFF_2, pcm512x->pll_d >> 8);
+		if (ret != 0) {
+			dev_err(dev, "Failed to write PLL D msb: %d\n", ret);
+			return ret;
+		}
+
+		ret = regmap_write(pcm512x->regmap,
+				   PCM512x_PLL_COEFF_3, pcm512x->pll_d & 0xff);
+		if (ret != 0) {
+			dev_err(dev, "Failed to write PLL D lsb: %d\n", ret);
+			return ret;
+		}
+
+		ret = regmap_write(pcm512x->regmap,
+				   PCM512x_PLL_COEFF_4, pcm512x->pll_r - 1);
+		if (ret != 0) {
+			dev_err(dev, "Failed to write PLL R: %d\n", ret);
+			return ret;
+		}
+
+		mck_rate = pcm512x->real_pll;
+
+		bclk_div = DIV_ROUND_CLOSEST(sck_rate, bclk_rate);
+	}
 
 	if (bclk_div > 128) {
 		dev_err(dev, "Failed to find BCLK divider\n");
@@ -616,6 +895,7 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 	struct snd_soc_codec *codec = dai->codec;
 	struct pcm512x_priv *pcm512x = snd_soc_codec_get_drvdata(codec);
 	int alen;
+	int gpio;
 	int ret;
 
 	dev_dbg(codec->dev, "hw_params %u Hz, %u channels\n",
@@ -676,26 +956,55 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 		return ret;
 	}
 
-	ret = regmap_update_bits(pcm512x->regmap, PCM512x_ERROR_DETECT,
-				 PCM512x_IDFS | PCM512x_IDBK
-				 | PCM512x_IDSK | PCM512x_IDCH
-				 | PCM512x_IDCM | PCM512x_DCAS
-				 | PCM512x_IPLK,
-				 PCM512x_IDFS | PCM512x_IDBK
-				 | PCM512x_IDSK | PCM512x_IDCH
-				 | PCM512x_DCAS | PCM512x_IPLK);
-	if (ret != 0) {
-		dev_err(codec->dev,
-			"Failed to ignore auto-clock failures: %d\n",
-			ret);
-		return ret;
-	}
+	if (pcm512x->pll_out) {
+		ret = regmap_write(pcm512x->regmap, PCM512x_FLEX_A, 0x11);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to set FLEX_A: %d\n", ret);
+			return ret;
+		}
 
-	ret = regmap_update_bits(pcm512x->regmap, PCM512x_PLL_EN,
-				 PCM512x_PLLE, 0);
-	if (ret != 0) {
-		dev_err(codec->dev, "Failed to disable pll: %d\n", ret);
-		return ret;
+		ret = regmap_write(pcm512x->regmap, PCM512x_FLEX_B, 0xff);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to set FLEX_B: %d\n", ret);
+			return ret;
+		}
+
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_ERROR_DETECT,
+					 PCM512x_IDFS | PCM512x_IDBK
+					 | PCM512x_IDSK | PCM512x_IDCH
+					 | PCM512x_IDCM | PCM512x_DCAS
+					 | PCM512x_IPLK,
+					 PCM512x_IDFS | PCM512x_IDBK
+					 | PCM512x_IDSK | PCM512x_IDCH
+					 | PCM512x_DCAS);
+		if (ret != 0) {
+			dev_err(codec->dev,
+				"Failed to ignore auto-clock failures: %d\n",
+				ret);
+			return ret;
+		}
+	} else {
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_ERROR_DETECT,
+					 PCM512x_IDFS | PCM512x_IDBK
+					 | PCM512x_IDSK | PCM512x_IDCH
+					 | PCM512x_IDCM | PCM512x_DCAS
+					 | PCM512x_IPLK,
+					 PCM512x_IDFS | PCM512x_IDBK
+					 | PCM512x_IDSK | PCM512x_IDCH
+					 | PCM512x_DCAS | PCM512x_IPLK);
+		if (ret != 0) {
+			dev_err(codec->dev,
+				"Failed to ignore auto-clock failures: %d\n",
+				ret);
+			return ret;
+		}
+
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_PLL_EN,
+					 PCM512x_PLLE, 0);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to disable pll: %d\n", ret);
+			return ret;
+		}
 	}
 
 	ret = pcm512x_set_dividers(dai, params);
@@ -709,6 +1018,33 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 		return ret;
 	}
 
+	if (pcm512x->pll_out) {
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_PLL_REF,
+					 PCM512x_SREF, PCM512x_SREF_GPIO);
+		if (ret != 0) {
+			dev_err(codec->dev,
+				"Failed to set gpio as pllref: %d\n", ret);
+			return ret;
+		}
+
+		gpio = PCM512x_GREF_GPIO1 + pcm512x->pll_in - 1;
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_GPIO_PLLIN,
+					 PCM512x_GREF, gpio);
+		if (ret != 0) {
+			dev_err(codec->dev,
+				"Failed to set gpio %d as pllin: %d\n",
+				pcm512x->pll_in, ret);
+			return ret;
+		}
+
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_PLL_EN,
+					 PCM512x_PLLE, PCM512x_PLLE);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to enable pll: %d\n", ret);
+			return ret;
+		}
+	}
+
 	ret = regmap_update_bits(pcm512x->regmap, PCM512x_BCLK_LRCLK_CFG,
 				 PCM512x_BCKP | PCM512x_BCKO | PCM512x_LRKO,
 				 PCM512x_BCKO | PCM512x_LRKO);
@@ -725,6 +1061,45 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
 		return ret;
 	}
 
+	if (pcm512x->pll_out) {
+		gpio = PCM512x_G1OE << (pcm512x->pll_out - 1);
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_GPIO_EN,
+					 gpio, gpio);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to enable gpio %d: %d\n",
+				pcm512x->pll_out, ret);
+			return ret;
+		}
+
+		gpio = PCM512x_GPIO_OUTPUT_1 + pcm512x->pll_out - 1;
+		ret = regmap_update_bits(pcm512x->regmap, gpio,
+					 PCM512x_GxSL, PCM512x_GxSL_PLLCK);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to output pll on %d: %d\n",
+				ret, pcm512x->pll_out);
+			return ret;
+		}
+
+		gpio = PCM512x_G1OE << (4 - 1);
+		ret = regmap_update_bits(pcm512x->regmap, PCM512x_GPIO_EN,
+					 gpio, gpio);
+		if (ret != 0) {
+			dev_err(codec->dev, "Failed to enable gpio %d: %d\n",
+				4, ret);
+			return ret;
+		}
+
+		gpio = PCM512x_GPIO_OUTPUT_1 + 4 - 1;
+		ret = regmap_update_bits(pcm512x->regmap, gpio,
+					 PCM512x_GxSL, PCM512x_GxSL_PLLLK);
+		if (ret != 0) {
+			dev_err(codec->dev,
+				"Failed to output pll lock on %d: %d\n",
+				ret, 4);
+			return ret;
+		}
+	}
+
 	ret = regmap_update_bits(pcm512x->regmap, PCM512x_SYNCHRONIZE,
 				 PCM512x_RQSY, PCM512x_RQSY_HALT);
 	if (ret != 0) {
@@ -815,6 +1190,7 @@ int pcm512x_probe(struct device *dev, struct regmap *regmap)
 {
 	struct pcm512x_priv *pcm512x;
 	int i, ret;
+	u32 val;
 
 	pcm512x = devm_kzalloc(dev, sizeof(struct pcm512x_priv), GFP_KERNEL);
 	if (!pcm512x)
@@ -892,6 +1268,42 @@ int pcm512x_probe(struct device *dev, struct regmap *regmap)
 	pm_runtime_enable(dev);
 	pm_runtime_idle(dev);
 
+#ifdef CONFIG_OF
+	if (dev->of_node) {
+		const struct device_node *np = dev->of_node;
+
+		if (of_property_read_u32(np, "pll-in", &val) >= 0) {
+			if (val > 6) {
+				dev_err(dev, "Invalid pll-in\n");
+				ret = -EINVAL;
+				goto err_clk;
+			}
+			pcm512x->pll_in = val;
+		}
+
+		if (of_property_read_u32(np, "pll-out", &val) >= 0) {
+			if (val > 6) {
+				dev_err(dev, "Invalid pll-out\n");
+				ret = -EINVAL;
+				goto err_clk;
+			}
+			pcm512x->pll_out = val;
+		}
+
+		if (!pcm512x->pll_in != !pcm512x->pll_out) {
+			dev_err(dev,
+				"Error: both pll-in and pll-out, or none\n");
+			ret = -EINVAL;
+			goto err_clk;
+		}
+		if (pcm512x->pll_in && pcm512x->pll_in == pcm512x->pll_out) {
+			dev_err(dev, "Error: pll-in == pll-out\n");
+			ret = -EINVAL;
+			goto err_clk;
+		}
+	}
+#endif
+
 	ret = snd_soc_register_codec(dev, &pcm512x_codec_driver,
 				    &pcm512x_dai, 1);
 	if (ret != 0) {