ASoC: fsl_sai: add sai master mode support

When sai works on master mode, set its bit clock and frame clock.

SAI has 4 MCLK source, bus clock, MCLK1, MCLK2 and MCLK3. fsl_sai_set_bclk
will select proper MCLK source, then calculate and set the bit clock divider.

After fsl_sai_set_bclk, enable the selected mclk in hw_params(), and add
hw_free() to disable the mclk.
Signed-off-by: Zidan Wang <zidan.wang@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_sai.c

 /*
  * Freescale ALSA SoC Digital Audio Interface (SAI) driver.
  *
- * Copyright 2012-2013 Freescale Semiconductor, Inc.
+ * Copyright 2012-2015 Freescale Semiconductor, Inc.
  *
  * This program is free software, you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -251,12 +251,14 @@ static int fsl_sai_set_dai_fmt_tr(struct snd_soc_dai *cpu_dai,
 		val_cr4 |= FSL_SAI_CR4_FSD_MSTR;
 		break;
 	case SND_SOC_DAIFMT_CBM_CFM:
+		sai->is_slave_mode = true;
 		break;
 	case SND_SOC_DAIFMT_CBS_CFM:
 		val_cr2 |= FSL_SAI_CR2_BCD_MSTR;
 		break;
 	case SND_SOC_DAIFMT_CBM_CFS:
 		val_cr4 |= FSL_SAI_CR4_FSD_MSTR;
+		sai->is_slave_mode = true;
 		break;
 	default:
 		return -EINVAL;
@@ -288,6 +290,79 @@ static int fsl_sai_set_dai_fmt(struct snd_soc_dai *cpu_dai, unsigned int fmt)
 	return ret;
 }
 
+static int fsl_sai_set_bclk(struct snd_soc_dai *dai, bool tx, u32 freq)
+{
+	struct fsl_sai *sai = snd_soc_dai_get_drvdata(dai);
+	unsigned long clk_rate;
+	u32 savediv = 0, ratio, savesub = freq;
+	u32 id;
+	int ret = 0;
+
+	/* Don't apply to slave mode */
+	if (sai->is_slave_mode)
+		return 0;
+
+	for (id = 0; id < FSL_SAI_MCLK_MAX; id++) {
+		clk_rate = clk_get_rate(sai->mclk_clk[id]);
+		if (!clk_rate)
+			continue;
+
+		ratio = clk_rate / freq;
+
+		ret = clk_rate - ratio * freq;
+
+		/*
+		 * Drop the source that can not be
+		 * divided into the required rate.
+		 */
+		if (ret != 0 && clk_rate / ret < 1000)
+			continue;
+
+		dev_dbg(dai->dev,
+			"ratio %d for freq %dHz based on clock %ldHz\n",
+			ratio, freq, clk_rate);
+
+		if (ratio % 2 == 0 && ratio >= 2 && ratio <= 512)
+			ratio /= 2;
+		else
+			continue;
+
+		if (ret < savesub) {
+			savediv = ratio;
+			sai->mclk_id[tx] = id;
+			savesub = ret;
+		}
+
+		if (ret == 0)
+			break;
+	}
+
+	if (savediv == 0) {
+		dev_err(dai->dev, "failed to derive required %cx rate: %d\n",
+				tx ? 'T' : 'R', freq);
+		return -EINVAL;
+	}
+
+	if ((tx && sai->synchronous[TX]) || (!tx && !sai->synchronous[RX])) {
+		regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
+				   FSL_SAI_CR2_MSEL_MASK,
+				   FSL_SAI_CR2_MSEL(sai->mclk_id[tx]));
+		regmap_update_bits(sai->regmap, FSL_SAI_RCR2,
+				   FSL_SAI_CR2_DIV_MASK, savediv - 1);
+	} else {
+		regmap_update_bits(sai->regmap, FSL_SAI_TCR2,
+				   FSL_SAI_CR2_MSEL_MASK,
+				   FSL_SAI_CR2_MSEL(sai->mclk_id[tx]));
+		regmap_update_bits(sai->regmap, FSL_SAI_TCR2,
+				   FSL_SAI_CR2_DIV_MASK, savediv - 1);
+	}
+
+	dev_dbg(dai->dev, "best fit: clock id=%d, div=%d, deviation =%d\n",
+			sai->mclk_id[tx], savediv, savesub);
+
+	return 0;
+}
+
 static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 		struct snd_pcm_hw_params *params,
 		struct snd_soc_dai *cpu_dai)
@@ -297,6 +372,24 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 	unsigned int channels = params_channels(params);
 	u32 word_width = snd_pcm_format_width(params_format(params));
 	u32 val_cr4 = 0, val_cr5 = 0;
+	int ret;
+
+	if (!sai->is_slave_mode) {
+		ret = fsl_sai_set_bclk(cpu_dai, tx,
+			2 * word_width * params_rate(params));
+		if (ret)
+			return ret;
+
+		/* Do not enable the clock if it is already enabled */
+		if (!(sai->mclk_streams & BIT(substream->stream))) {
+			ret = clk_prepare_enable(sai->mclk_clk[sai->mclk_id[tx]]);
+			if (ret)
+				return ret;
+
+			sai->mclk_streams |= BIT(substream->stream);
+		}
+
+	}
 
 	if (!sai->is_dsp_mode)
 		val_cr4 |= FSL_SAI_CR4_SYWD(word_width);
@@ -322,6 +415,22 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+static int fsl_sai_hw_free(struct snd_pcm_substream *substream,
+		struct snd_soc_dai *cpu_dai)
+{
+	struct fsl_sai *sai = snd_soc_dai_get_drvdata(cpu_dai);
+	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
+
+	if (!sai->is_slave_mode &&
+			sai->mclk_streams & BIT(substream->stream)) {
+		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[tx]]);
+		sai->mclk_streams &= ~BIT(substream->stream);
+	}
+
+	return 0;
+}
+
+
 static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
 		struct snd_soc_dai *cpu_dai)
 {
@@ -428,6 +537,7 @@ static const struct snd_soc_dai_ops fsl_sai_pcm_dai_ops = {
 	.set_sysclk	= fsl_sai_set_dai_sysclk,
 	.set_fmt	= fsl_sai_set_dai_fmt,
 	.hw_params	= fsl_sai_hw_params,
+	.hw_free	= fsl_sai_hw_free,
 	.trigger	= fsl_sai_trigger,
 	.startup	= fsl_sai_startup,
 	.shutdown	= fsl_sai_shutdown,
@@ -600,8 +710,9 @@ static int fsl_sai_probe(struct platform_device *pdev)
 		sai->bus_clk = NULL;
 	}
 
-	for (i = 0; i < FSL_SAI_MCLK_MAX; i++) {
-		sprintf(tmp, "mclk%d", i + 1);
+	sai->mclk_clk[0] = sai->bus_clk;
+	for (i = 1; i < FSL_SAI_MCLK_MAX; i++) {
+		sprintf(tmp, "mclk%d", i);
 		sai->mclk_clk[i] = devm_clk_get(&pdev->dev, tmp);
 		if (IS_ERR(sai->mclk_clk[i])) {
 			dev_err(&pdev->dev, "failed to get mclk%d clock: %ld\n",

sound/soc/fsl/fsl_sai.h

@@ -72,13 +72,15 @@
 
 /* SAI Transmit and Recieve Configuration 2 Register */
 #define FSL_SAI_CR2_SYNC	BIT(30)
-#define FSL_SAI_CR2_MSEL_MASK	(0xff << 26)
+#define FSL_SAI_CR2_MSEL_MASK	(0x3 << 26)
 #define FSL_SAI_CR2_MSEL_BUS	0
 #define FSL_SAI_CR2_MSEL_MCLK1	BIT(26)
 #define FSL_SAI_CR2_MSEL_MCLK2	BIT(27)
 #define FSL_SAI_CR2_MSEL_MCLK3	(BIT(26) | BIT(27))
+#define FSL_SAI_CR2_MSEL(ID)	((ID) << 26)
 #define FSL_SAI_CR2_BCP		BIT(25)
 #define FSL_SAI_CR2_BCD_MSTR	BIT(24)
+#define FSL_SAI_CR2_DIV_MASK	0xff
 
 /* SAI Transmit and Recieve Configuration 3 Register */
 #define FSL_SAI_CR3_TRCE	BIT(16)
@@ -120,7 +122,7 @@
 #define FSL_SAI_CLK_MAST2	2
 #define FSL_SAI_CLK_MAST3	3
 
-#define FSL_SAI_MCLK_MAX	3
+#define FSL_SAI_MCLK_MAX	4
 
 /* SAI data transfer numbers per DMA request */
 #define FSL_SAI_MAXBURST_TX 6
@@ -132,11 +134,14 @@ struct fsl_sai {
 	struct clk *bus_clk;
 	struct clk *mclk_clk[FSL_SAI_MCLK_MAX];
 
+	bool is_slave_mode;
 	bool is_lsb_first;
 	bool is_dsp_mode;
 	bool sai_on_imx;
 	bool synchronous[2];
 
+	unsigned int mclk_id[2];
+	unsigned int mclk_streams;
 	struct snd_dmaengine_dai_dma_data dma_params_rx;
 	struct snd_dmaengine_dai_dma_data dma_params_tx;
 };