ASoC: sun8i-codec: Constrain to compatible sample rates

While another stream is active, only allow userspace to use sample rates
that are compatible with the current SYSCLK frequency. This ensures the
actual sample rate will always match what is given in hw_params.
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20201014061941.4306-12-samuel@sholland.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sunxi/sun8i-codec.c

@@ -126,6 +126,8 @@ struct sun8i_codec {
 	struct clk			*clk_module;
 	const struct sun8i_codec_quirks	*quirks;
 	struct sun8i_codec_aif		aifs[SUN8I_CODEC_NAIFS];
+	unsigned int			sysclk_rate;
+	int				sysclk_refcnt;
 };
 
 static int sun8i_codec_runtime_resume(struct device *dev)
@@ -324,6 +326,47 @@ static int sun8i_codec_set_tdm_slot(struct snd_soc_dai *dai,
 	return 0;
 }
 
+static const unsigned int sun8i_codec_rates[] = {
+	  7350,   8000,  11025,  12000,  14700,  16000,  22050,  24000,
+	 29400,  32000,  44100,  48000,  88200,  96000, 176400, 192000,
+};
+
+static const struct snd_pcm_hw_constraint_list sun8i_codec_all_rates = {
+	.list	= sun8i_codec_rates,
+	.count	= ARRAY_SIZE(sun8i_codec_rates),
+};
+
+static const struct snd_pcm_hw_constraint_list sun8i_codec_22M_rates = {
+	.list	= sun8i_codec_rates,
+	.count	= ARRAY_SIZE(sun8i_codec_rates),
+	.mask	= 0x5555,
+};
+
+static const struct snd_pcm_hw_constraint_list sun8i_codec_24M_rates = {
+	.list	= sun8i_codec_rates,
+	.count	= ARRAY_SIZE(sun8i_codec_rates),
+	.mask	= 0xaaaa,
+};
+
+static int sun8i_codec_startup(struct snd_pcm_substream *substream,
+			       struct snd_soc_dai *dai)
+{
+	struct sun8i_codec *scodec = snd_soc_dai_get_drvdata(dai);
+	const struct snd_pcm_hw_constraint_list *list;
+
+	if (!scodec->sysclk_refcnt)
+		list = &sun8i_codec_all_rates;
+	else if (scodec->sysclk_rate == 22579200)
+		list = &sun8i_codec_22M_rates;
+	else if (scodec->sysclk_rate == 24576000)
+		list = &sun8i_codec_24M_rates;
+	else
+		return -EINVAL;
+
+	return snd_pcm_hw_constraint_list(substream->runtime, 0,
+					  SNDRV_PCM_HW_PARAM_RATE, list);
+}
+
 struct sun8i_codec_clk_div {
 	u8	div;
 	u8	val;
@@ -346,12 +389,11 @@ static const struct sun8i_codec_clk_div sun8i_codec_bclk_div[] = {
 	{ .div = 192,	.val = 13 },
 };
 
-static u8 sun8i_codec_get_bclk_div(struct sun8i_codec *scodec,
+static u8 sun8i_codec_get_bclk_div(unsigned int sysclk_rate,
 				   unsigned int lrck_div_order,
 				   unsigned int sample_rate)
 {
-	unsigned long clk_rate = clk_get_rate(scodec->clk_module);
-	unsigned int div = clk_rate / sample_rate >> lrck_div_order;
+	unsigned int div = sysclk_rate / sample_rate >> lrck_div_order;
 	unsigned int best_val = 0, best_diff = ~0;
 	int i;
 
@@ -388,6 +430,7 @@ static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
 	unsigned int sample_rate = params_rate(params);
 	unsigned int slots = aif->slots ?: params_channels(params);
 	unsigned int slot_width = aif->slot_width ?: params_width(params);
+	unsigned int sysclk_rate = clk_get_rate(scodec->clk_module);
 	int lrck_div_order, word_size;
 	u8 bclk_div;
 
@@ -423,11 +466,15 @@ static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
 			   (lrck_div_order - 4) << SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV);
 
 	/* BCLK divider (SYSCLK/BCLK ratio) */
-	bclk_div = sun8i_codec_get_bclk_div(scodec, lrck_div_order, sample_rate);
+	bclk_div = sun8i_codec_get_bclk_div(sysclk_rate, lrck_div_order, sample_rate);
 	regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
 			   SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV_MASK,
 			   bclk_div << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV);
 
+	if (!aif->open_streams)
+		scodec->sysclk_refcnt++;
+	scodec->sysclk_rate = sysclk_rate;
+
 	aif->sample_rate = sample_rate;
 	aif->open_streams |= BIT(substream->stream);
 
@@ -443,6 +490,7 @@ static int sun8i_codec_hw_free(struct snd_pcm_substream *substream,
 	if (aif->open_streams != BIT(substream->stream))
 		goto done;
 
+	scodec->sysclk_refcnt--;
 	aif->sample_rate = 0;
 
 done:
@@ -453,6 +501,7 @@ static int sun8i_codec_hw_free(struct snd_pcm_substream *substream,
 static const struct snd_soc_dai_ops sun8i_codec_dai_ops = {
 	.set_fmt	= sun8i_codec_set_fmt,
 	.set_tdm_slot	= sun8i_codec_set_tdm_slot,
+	.startup	= sun8i_codec_startup,
 	.hw_params	= sun8i_codec_hw_params,
 	.hw_free	= sun8i_codec_hw_free,
 };