[PATCH] ASoC: atmel-i2s: add driver for the new Atmel I2S controller

[Cyrille Pitchen]

This patch adds support for the Atmel I2S controller embedded into
sama5d2x SoCs.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@xxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 sound/soc/atmel/Kconfig     |   9 +
 sound/soc/atmel/Makefile    |   2 +
 sound/soc/atmel/atmel-i2s.c | 765 ++++++++++++++++++++++++++++++++++++
 3 files changed, 776 insertions(+)
 create mode 100644 sound/soc/atmel/atmel-i2s.c

diff --git a/sound/soc/atmel/Kconfig b/sound/soc/atmel/Kconfig
index dcee145dd179..64b784e96f84 100644
--- a/sound/soc/atmel/Kconfig
+++ b/sound/soc/atmel/Kconfig
@@ -88,4 +88,13 @@ config SND_ATMEL_SOC_TSE850_PCM5142
 	help
 	  Say Y if you want to add support for the ASoC driver for the
 	  Axentia TSE-850 with a PCM5142 codec.
+
+config SND_ATMEL_SOC_I2S
+	tristate "Atmel ASoC driver for boards using I2S"
+	depends on OF && (ARCH_AT91 || COMPILE_TEST)
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select REGMAP_MMIO
+	help
+	  Say Y or M if you want to add support for Atmel ASoc driver for boards
+	  using I2S.
 endif
diff --git a/sound/soc/atmel/Makefile b/sound/soc/atmel/Makefile
index 4440646416e8..cd87cb4bcff5 100644
--- a/sound/soc/atmel/Makefile
+++ b/sound/soc/atmel/Makefile
@@ -3,10 +3,12 @@
 snd-soc-atmel-pcm-pdc-objs := atmel-pcm-pdc.o
 snd-soc-atmel-pcm-dma-objs := atmel-pcm-dma.o
 snd-soc-atmel_ssc_dai-objs := atmel_ssc_dai.o
+snd-soc-atmel-i2s-objs := atmel-i2s.o
 
 obj-$(CONFIG_SND_ATMEL_SOC_PDC) += snd-soc-atmel-pcm-pdc.o
 obj-$(CONFIG_SND_ATMEL_SOC_DMA) += snd-soc-atmel-pcm-dma.o
 obj-$(CONFIG_SND_ATMEL_SOC_SSC) += snd-soc-atmel_ssc_dai.o
+obj-$(CONFIG_SND_ATMEL_SOC_I2S) += snd-soc-atmel-i2s.o
 
 # AT91 Machine Support
 snd-soc-sam9g20-wm8731-objs := sam9g20_wm8731.o
diff --git a/sound/soc/atmel/atmel-i2s.c b/sound/soc/atmel/atmel-i2s.c
new file mode 100644
index 000000000000..5d3b5af9fd92
--- /dev/null
+++ b/sound/soc/atmel/atmel-i2s.c
@@ -0,0 +1,765 @@
+/*
+ * Driver for Atmel I2S controller
+ *
+ * Copyright (C) 2015 Atmel Corporation
+ *
+ * Author: Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/mfd/syscon.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/initval.h>
+#include <sound/soc.h>
+#include <sound/dmaengine_pcm.h>
+
+#define ATMEL_I2SC_MAX_TDM_CHANNELS	8
+
+/*
+ * ---- I2S Controller Register map ----
+ */
+#define ATMEL_I2SC_CR		0x0000	/* Control Register */
+#define ATMEL_I2SC_MR		0x0004	/* Mode Register */
+#define ATMEL_I2SC_SR		0x0008	/* Status Register */
+#define ATMEL_I2SC_SCR		0x000c	/* Status Clear Register */
+#define ATMEL_I2SC_SSR		0x0010	/* Status Set Register */
+#define ATMEL_I2SC_IER		0x0014	/* Interrupt Enable Register */
+#define ATMEL_I2SC_IDR		0x0018	/* Interrupt Disable Register */
+#define ATMEL_I2SC_IMR		0x001c	/* Interrupt Mask Register */
+#define ATMEL_I2SC_RHR		0x0020	/* Receiver Holding Register */
+#define ATMEL_I2SC_THR		0x0024	/* Transmitter Holding Register */
+#define ATMEL_I2SC_VERSION	0x0028	/* Version Register */
+
+/*
+ * ---- Control Register (Write-only) ----
+ */
+#define ATMEL_I2SC_CR_RXEN	BIT(0)	/* Receiver Enable */
+#define ATMEL_I2SC_CR_RXDIS	BIT(1)	/* Receiver Disable */
+#define ATMEL_I2SC_CR_CKEN	BIT(2)	/* Clock Enable */
+#define ATMEL_I2SC_CR_CKDIS	BIT(3)	/* Clock Disable */
+#define ATMEL_I2SC_CR_TXEN	BIT(4)	/* Transmitter Enable */
+#define ATMEL_I2SC_CR_TXDIS	BIT(5)	/* Transmitter Disable */
+#define ATMEL_I2SC_CR_SWRST	BIT(7)	/* Software Reset */
+
+/*
+ * ---- Mode Register (Read/Write) ----
+ */
+#define ATMEL_I2SC_MR_MODE_MASK		GENMASK(0, 0)
+#define ATMEL_I2SC_MR_MODE_SLAVE	(0 << 0)
+#define ATMEL_I2SC_MR_MODE_MASTER	(1 << 0)
+
+#define ATMEL_I2SC_MR_DATALENGTH_MASK		GENMASK(4, 2)
+#define ATMEL_I2SC_MR_DATALENGTH_32_BITS	(0 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_24_BITS	(1 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_20_BITS	(2 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_18_BITS	(3 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_16_BITS	(4 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_16_BITS_COMPACT	(5 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_8_BITS		(6 << 2)
+#define ATMEL_I2SC_MR_DATALENGTH_8_BITS_COMPACT	(7 << 2)
+
+#define ATMEL_I2SC_MR_FORMAT_MASK	GENMASK(7, 6)
+#define ATMEL_I2SC_MR_FORMAT_I2S	(0 << 6)
+#define ATMEL_I2SC_MR_FORMAT_LJ		(1 << 6)  /* Left Justified */
+#define ATMEL_I2SC_MR_FORMAT_TDM	(2 << 6)
+#define ATMEL_I2SC_MR_FORMAT_TDMLJ	(3 << 6)
+
+/* Left audio samples duplicated to right audio channel */
+#define ATMEL_I2SC_MR_RXMONO		BIT(8)
+
+/* Receiver uses one DMA channel ... */
+#define ATMEL_I2SC_MR_RXDMA_MASK	GENMASK(9, 9)
+#define ATMEL_I2SC_MR_RXDMA_SINGLE	(0 << 9)  /* for all audio channels */
+#define ATMEL_I2SC_MR_RXDMA_MULTIPLE	(1 << 9)  /* per audio channel */
+
+/* I2SDO output of I2SC is internally connected to I2SDI input */
+#define ATMEL_I2SC_MR_RXLOOP		BIT(10)
+
+/* Left audio samples duplicated to right audio channel */
+#define ATMEL_I2SC_MR_TXMONO		BIT(12)
+
+/* Transmitter uses one DMA channel ... */
+#define ATMEL_I2SC_MR_TXDMA_MASK	GENMASK(13, 13)
+#define ATMEL_I2SC_MR_TXDMA_SINGLE	(0 << 13)  /* for all audio channels */
+#define ATMEL_I2SC_MR_TXDME_MULTIPLE	(1 << 13)  /* per audio channel */
+
+/* x sample transmitted when underrun */
+#define ATMEL_I2SC_MR_TXSAME_MASK	GENMASK(14, 14)
+#define ATMEL_I2SC_MR_TXSAME_ZERO	(0 << 14)  /* Zero sample */
+#define ATMEL_I2SC_MR_TXSAME_PREVIOUS	(1 << 14)  /* Previous sample */
+
+/* Audio Clock to I2SC Master Clock ratio */
+#define ATMEL_I2SC_MR_IMCKDIV_MASK	GENMASK(21, 16)
+#define ATMEL_I2SC_MR_IMCKDIV(div) \
+	(((div) << 16) & ATMEL_I2SC_MR_IMCKDIV_MASK)
+
+/* Master Clock to fs ratio */
+#define ATMEL_I2SC_MR_IMCKFS_MASK	GENMASK(29, 24)
+#define ATMEL_I2SC_MR_IMCKFS(fs) \
+	(((fs) << 24) & ATMEL_I2SC_MR_IMCKFS_MASK)
+
+/* Master Clock mode */
+#define ATMEL_I2SC_MR_IMCKMODE_MASK	GENMASK(30, 30)
+/* 0: No master clock generated (selected clock drives I2SCK pin) */
+#define ATMEL_I2SC_MR_IMCKMODE_I2SCK	(0 << 30)
+/* 1: master clock generated (internally generated clock drives I2SMCK pin) */
+#define ATMEL_I2SC_MR_IMCKMODE_I2SMCK	(1 << 30)
+
+/* Slot Width */
+/* 0: slot is 32 bits wide for DATALENGTH = 18/20/24 bits. */
+/* 1: slot is 24 bits wide for DATALENGTH = 18/20/24 bits. */
+#define ATMEL_I2SC_MR_IWS		BIT(31)
+
+/*
+ * ---- Status Registers ----
+ */
+#define ATMEL_I2SC_SR_RXEN	BIT(0)	/* Receiver Enabled */
+#define ATMEL_I2SC_SR_RXRDY	BIT(1)	/* Receive Ready */
+#define ATMEL_I2SC_SR_RXOR	BIT(2)	/* Receive Overrun */
+
+#define ATMEL_I2SC_SR_TXEN	BIT(4)	/* Transmitter Enabled */
+#define ATMEL_I2SC_SR_TXRDY	BIT(5)	/* Transmit Ready */
+#define ATMEL_I2SC_SR_TXUR	BIT(6)	/* Transmit Underrun */
+
+/* Receive Overrun Channel */
+#define ATMEL_I2SC_SR_RXORCH_MASK	GENMASK(15, 8)
+#define ATMEL_I2SC_SR_RXORCH(ch)	(1 << (((ch) & 0x7) + 8))
+
+/* Transmit Underrun Channel */
+#define ATMEL_I2SC_SR_TXURCH_MASK	GENMASK(27, 20)
+#define ATMEL_I2SC_SR_TXURCH(ch)	(1 << (((ch) & 0x7) + 20))
+
+/*
+ * ---- Interrupt Enable/Disable/Mask Registers ----
+ */
+#define ATMEL_I2SC_INT_RXRDY	ATMEL_I2SC_SR_RXRDY
+#define ATMEL_I2SC_INT_RXOR	ATMEL_I2SC_SR_RXOR
+#define ATMEL_I2SC_INT_TXRDY	ATMEL_I2SC_SR_TXRDY
+#define ATMEL_I2SC_INT_TXUR	ATMEL_I2SC_SR_TXUR
+
+static const struct regmap_config atmel_i2s_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.max_register = ATMEL_I2SC_VERSION,
+};
+
+struct atmel_i2s_gck_param {
+	int		fs;
+	unsigned long	mck;
+	int		imckdiv;
+	int		imckfs;
+};
+
+#define I2S_MCK_12M288		12288000UL
+#define I2S_MCK_11M2896		11289600UL
+
+/* mck = (32 * (imckfs+1) / (imckdiv+1)) * fs */
+static const struct atmel_i2s_gck_param gck_params[] = {
+	/* mck = 12.288MHz */
+	{  8000, I2S_MCK_12M288, 0, 47},	/* mck = 1536 fs */
+	{ 16000, I2S_MCK_12M288, 1, 47},	/* mck =  768 fs */
+	{ 24000, I2S_MCK_12M288, 3, 63},	/* mck =  512 fs */
+	{ 32000, I2S_MCK_12M288, 3, 47},	/* mck =  384 fs */
+	{ 48000, I2S_MCK_12M288, 7, 63},	/* mck =  256 fs */
+	{ 64000, I2S_MCK_12M288, 7, 47},	/* mck =  192 fs */
+	{ 96000, I2S_MCK_12M288, 7, 31},	/* mck =  128 fs */
+	{192000, I2S_MCK_12M288, 7, 15},	/* mck =   64 fs */
+
+	/* mck = 11.2896MHz */
+	{ 11025, I2S_MCK_11M2896, 1, 63},	/* mck = 1024 fs */
+	{ 22050, I2S_MCK_11M2896, 3, 63},	/* mck =  512 fs */
+	{ 44100, I2S_MCK_11M2896, 7, 63},	/* mck =  256 fs */
+	{ 88200, I2S_MCK_11M2896, 7, 31},	/* mck =  128 fs */
+	{176400, I2S_MCK_11M2896, 7, 15},	/* mck =   64 fs */
+};
+
+struct atmel_i2s_dev;
+
+struct atmel_i2s_caps {
+	int	(*mck_init)(struct atmel_i2s_dev *, struct device_node *np);
+};
+
+struct atmel_i2s_dev {
+	struct device				*dev;
+	struct regmap				*regmap;
+	struct clk				*pclk;
+	struct clk				*gclk;
+	struct clk				*aclk;
+	struct snd_dmaengine_dai_dma_data	playback;
+	struct snd_dmaengine_dai_dma_data	capture;
+	unsigned int				fmt;
+	const struct atmel_i2s_gck_param	*gck_param;
+	const struct atmel_i2s_caps		*caps;
+};
+
+static irqreturn_t atmel_i2s_interrupt(int irq, void *dev_id)
+{
+	struct atmel_i2s_dev *dev = dev_id;
+	unsigned int sr, imr, pending, ch, mask;
+	irqreturn_t ret = IRQ_NONE;
+
+	regmap_read(dev->regmap, ATMEL_I2SC_SR, &sr);
+	regmap_read(dev->regmap, ATMEL_I2SC_IMR, &imr);
+	pending = sr & imr;
+
+	if (!pending)
+		return IRQ_NONE;
+
+	if (pending & ATMEL_I2SC_INT_RXOR) {
+		mask = ATMEL_I2SC_SR_RXOR;
+
+		for (ch = 0; ch < ATMEL_I2SC_MAX_TDM_CHANNELS; ++ch) {
+			if (sr & ATMEL_I2SC_SR_RXORCH(ch)) {
+				mask |= ATMEL_I2SC_SR_RXORCH(ch);
+				dev_err(dev->dev,
+					"RX overrun on channel %d\n", ch);
+			}
+		}
+		regmap_write(dev->regmap, ATMEL_I2SC_SCR, mask);
+		ret = IRQ_HANDLED;
+	}
+
+	if (pending & ATMEL_I2SC_INT_TXUR) {
+		mask = ATMEL_I2SC_SR_TXUR;
+
+		for (ch = 0; ch < ATMEL_I2SC_MAX_TDM_CHANNELS; ++ch) {
+			if (sr & ATMEL_I2SC_SR_TXURCH(ch)) {
+				mask |= ATMEL_I2SC_SR_TXURCH(ch);
+				dev_err(dev->dev,
+					"TX underrun on channel %d\n", ch);
+			}
+		}
+		regmap_write(dev->regmap, ATMEL_I2SC_SCR, mask);
+		ret = IRQ_HANDLED;
+	}
+
+	return ret;
+}
+
+#define ATMEL_I2S_RATES		SNDRV_PCM_RATE_8000_192000
+
+#define ATMEL_I2S_FORMATS	(SNDRV_PCM_FMTBIT_S8 |		\
+				 SNDRV_PCM_FMTBIT_S16_LE |	\
+				 SNDRV_PCM_FMTBIT_S18_3LE |	\
+				 SNDRV_PCM_FMTBIT_S20_3LE |	\
+				 SNDRV_PCM_FMTBIT_S24_3LE |	\
+				 SNDRV_PCM_FMTBIT_S24_LE |	\
+				 SNDRV_PCM_FMTBIT_S32_LE)
+
+static int atmel_i2s_set_dai_fmt(struct snd_soc_dai *dai, unsigned int fmt)
+{
+	struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	dev->fmt = fmt;
+	return 0;
+}
+
+static int atmel_i2s_prepare(struct snd_pcm_substream *substream,
+			     struct snd_soc_dai *dai)
+{
+	struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
+	unsigned int rhr, sr = 0;
+
+	if (is_playback) {
+		regmap_read(dev->regmap, ATMEL_I2SC_SR, &sr);
+		if (sr & ATMEL_I2SC_SR_RXRDY) {
+			/*
+			 * The RX Ready flag should not be set. However if here,
+			 * we flush (read) the Receive Holding Register to start
+			 * from a clean state.
+			 */
+			dev_dbg(dev->dev, "RXRDY is set\n");
+			regmap_read(dev->regmap, ATMEL_I2SC_RHR, &rhr);
+		}
+	}
+
+	return 0;
+}
+
+static int atmel_i2s_get_gck_param(struct atmel_i2s_dev *dev, int fs)
+{
+	int i, best;
+
+	if (!dev->gclk || !dev->aclk) {
+		dev_err(dev->dev, "cannot generate the I2S Master Clock\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Find the best possible settings to generate the I2S Master Clock
+	 * from the PLL Audio.
+	 */
+	dev->gck_param = NULL;
+	best = INT_MAX;
+	for (i = 0; i < ARRAY_SIZE(gck_params); ++i) {
+		const struct atmel_i2s_gck_param *gck_param = &gck_params[i];
+		int val = abs(fs - gck_param->fs);
+
+		if (val < best) {
+			best = val;
+			dev->gck_param = gck_param;
+		}
+	}
+
+	return 0;
+}
+
+static int atmel_i2s_hw_params(struct snd_pcm_substream *substream,
+			       struct snd_pcm_hw_params *params,
+			       struct snd_soc_dai *dai)
+{
+	struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
+	unsigned int mr = 0;
+	int ret;
+
+	switch (dev->fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
+	case SND_SOC_DAIFMT_I2S:
+		mr |= ATMEL_I2SC_MR_FORMAT_I2S;
+		break;
+
+	default:
+		dev_err(dev->dev, "unsupported bus format\n");
+		return -EINVAL;
+	}
+
+	switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+		/* codec is slave, so cpu is master */
+		mr |= ATMEL_I2SC_MR_MODE_MASTER;
+		ret = atmel_i2s_get_gck_param(dev, params_rate(params));
+		if (ret)
+			return ret;
+		break;
+
+	case SND_SOC_DAIFMT_CBM_CFM:
+		/* codec is master, so cpu is slave */
+		mr |= ATMEL_I2SC_MR_MODE_SLAVE;
+		dev->gck_param = NULL;
+		break;
+
+	default:
+		dev_err(dev->dev, "unsupported master/slave mode\n");
+		return -EINVAL;
+	}
+
+	switch (params_channels(params)) {
+	case 1:
+		if (is_playback)
+			mr |= ATMEL_I2SC_MR_TXMONO;
+		else
+			mr |= ATMEL_I2SC_MR_RXMONO;
+		break;
+	case 2:
+		break;
+	default:
+		dev_err(dev->dev, "unsupported number of audio channels\n");
+		return -EINVAL;
+	}
+
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_S8:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_8_BITS;
+		break;
+
+	case SNDRV_PCM_FORMAT_S16_LE:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_16_BITS;
+		break;
+
+	case SNDRV_PCM_FORMAT_S18_3LE:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_18_BITS | ATMEL_I2SC_MR_IWS;
+		break;
+
+	case SNDRV_PCM_FORMAT_S20_3LE:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_20_BITS | ATMEL_I2SC_MR_IWS;
+		break;
+
+	case SNDRV_PCM_FORMAT_S24_3LE:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_24_BITS | ATMEL_I2SC_MR_IWS;
+		break;
+
+	case SNDRV_PCM_FORMAT_S24_LE:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_24_BITS;
+		break;
+
+	case SNDRV_PCM_FORMAT_S32_LE:
+		mr |= ATMEL_I2SC_MR_DATALENGTH_32_BITS;
+		break;
+
+	default:
+		dev_err(dev->dev, "unsupported size/endianness for audio samples\n");
+		return -EINVAL;
+	}
+
+	return regmap_write(dev->regmap, ATMEL_I2SC_MR, mr);
+}
+
+static int atmel_i2s_switch_mck_generator(struct atmel_i2s_dev *dev,
+					  bool enabled)
+{
+	unsigned int mr, mr_mask;
+	unsigned long aclk_rate;
+	int ret;
+
+	mr = 0;
+	mr_mask = (ATMEL_I2SC_MR_IMCKDIV_MASK |
+		   ATMEL_I2SC_MR_IMCKFS_MASK |
+		   ATMEL_I2SC_MR_IMCKMODE_MASK);
+
+	if (!enabled) {
+		/* Disable the I2S Master Clock generator. */
+		ret = regmap_write(dev->regmap, ATMEL_I2SC_CR,
+				   ATMEL_I2SC_CR_CKDIS);
+		if (ret)
+			return ret;
+
+		/* Reset the I2S Master Clock generator settings. */
+		ret = regmap_update_bits(dev->regmap, ATMEL_I2SC_MR,
+					 mr_mask, mr);
+		if (ret)
+			return ret;
+
+		/* Disable/unprepare the PMC generated clock. */
+		clk_disable_unprepare(dev->gclk);
+
+		/* Disable/unprepare the PLL audio clock. */
+		clk_disable_unprepare(dev->aclk);
+		return 0;
+	}
+
+	if (!dev->gck_param)
+		return -EINVAL;
+
+	aclk_rate = dev->gck_param->mck * (dev->gck_param->imckdiv + 1);
+
+	/* Fist change the PLL audio clock frequency ... */
+	ret = clk_set_rate(dev->aclk, aclk_rate);
+	if (ret)
+		return ret;
+
+	/*
+	 * ... then set the PMC generated clock rate to the very same frequency
+	 * to set the gclk parent to aclk.
+	 */
+	ret = clk_set_rate(dev->gclk, aclk_rate);
+	if (ret)
+		return ret;
+
+	/* Prepare and enable the PLL audio clock first ... */
+	ret = clk_prepare_enable(dev->aclk);
+	if (ret)
+		return ret;
+
+	/* ... then prepare and enable the PMC generated clock. */
+	ret = clk_prepare_enable(dev->gclk);
+	if (ret)
+		return ret;
+
+	/* Update the Mode Register to generate the I2S Master Clock. */
+	mr |= ATMEL_I2SC_MR_IMCKDIV(dev->gck_param->imckdiv);
+	mr |= ATMEL_I2SC_MR_IMCKFS(dev->gck_param->imckfs);
+	mr |= ATMEL_I2SC_MR_IMCKMODE_I2SMCK;
+	ret = regmap_update_bits(dev->regmap, ATMEL_I2SC_MR, mr_mask, mr);
+	if (ret)
+		return ret;
+
+	/* Finally enable the I2S Master Clock generator. */
+	return regmap_write(dev->regmap, ATMEL_I2SC_CR,
+			    ATMEL_I2SC_CR_CKEN);
+}
+
+static int atmel_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
+			     struct snd_soc_dai *dai)
+{
+	struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
+	bool is_master, mck_enabled;
+	unsigned int cr, mr;
+	int err;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		cr = is_playback ? ATMEL_I2SC_CR_TXEN : ATMEL_I2SC_CR_RXEN;
+		mck_enabled = true;
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		cr = is_playback ? ATMEL_I2SC_CR_TXDIS : ATMEL_I2SC_CR_RXDIS;
+		mck_enabled = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Read the Mode Register to retrieve the master/slave state. */
+	err = regmap_read(dev->regmap, ATMEL_I2SC_MR, &mr);
+	if (err)
+		return err;
+	is_master = (mr & ATMEL_I2SC_MR_MODE_MASK) == ATMEL_I2SC_MR_MODE_MASTER;
+
+	/* If master starts, enable the audio clock. */
+	if (is_master && mck_enabled)
+		err = atmel_i2s_switch_mck_generator(dev, true);
+	if (err)
+		return err;
+
+	err = regmap_write(dev->regmap, ATMEL_I2SC_CR, cr);
+	if (err)
+		return err;
+
+	/* If master stops, disable the audio clock. */
+	if (is_master && !mck_enabled)
+		err = atmel_i2s_switch_mck_generator(dev, false);
+
+	return err;
+}
+
+static const struct snd_soc_dai_ops atmel_i2s_dai_ops = {
+	.prepare	= atmel_i2s_prepare,
+	.trigger	= atmel_i2s_trigger,
+	.hw_params	= atmel_i2s_hw_params,
+	.set_fmt	= atmel_i2s_set_dai_fmt,
+};
+
+static int atmel_i2s_dai_probe(struct snd_soc_dai *dai)
+{
+	struct atmel_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	snd_soc_dai_init_dma_data(dai, &dev->playback, &dev->capture);
+	return 0;
+}
+
+static struct snd_soc_dai_driver atmel_i2s_dai = {
+	.probe	= atmel_i2s_dai_probe,
+	.playback = {
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = ATMEL_I2S_RATES,
+		.formats = ATMEL_I2S_FORMATS,
+	},
+	.capture = {
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = ATMEL_I2S_RATES,
+		.formats = ATMEL_I2S_FORMATS,
+	},
+	.ops = &atmel_i2s_dai_ops,
+	.symmetric_rates = 1,
+};
+
+static const struct snd_soc_component_driver atmel_i2s_component = {
+	.name	= "atmel-i2s",
+};
+
+static int atmel_i2s_sama5d2_mck_init(struct atmel_i2s_dev *dev,
+				      struct device_node *np)
+{
+	struct clk *muxclk;
+	int err;
+
+	if (!dev->gclk)
+		return 0;
+
+	/* muxclk is optional, so we return error for probe defer only */
+	muxclk = devm_clk_get(dev->dev, "muxclk");
+	if (IS_ERR(muxclk)) {
+		err = PTR_ERR(muxclk);
+		if (err == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_warn(dev->dev,
+			 "failed to get the I2S clock control: %d\n", err);
+		return 0;
+	}
+
+	return clk_set_parent(muxclk, dev->gclk);
+}
+
+static const struct atmel_i2s_caps atmel_i2s_sama5d2_caps = {
+	.mck_init = atmel_i2s_sama5d2_mck_init,
+};
+
+static const struct of_device_id atmel_i2s_dt_ids[] = {
+	{
+		.compatible = "atmel,sama5d2-i2s",
+		.data = (void *)&atmel_i2s_sama5d2_caps,
+	},
+
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, atmel_i2s_dt_ids);
+
+static int atmel_i2s_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *match;
+	struct atmel_i2s_dev *dev;
+	struct resource *mem;
+	struct regmap *regmap;
+	void __iomem *base;
+	int irq;
+	int err = -ENXIO;
+	unsigned int pcm_flags = 0;
+	unsigned int version;
+
+	/* Get memory for driver data. */
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	/* Get hardware capabilities. */
+	match = of_match_node(atmel_i2s_dt_ids, np);
+	if (match)
+		dev->caps = match->data;
+
+	/* Map I/O registers. */
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(&pdev->dev, base,
+				       &atmel_i2s_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	/* Request IRQ. */
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	err = devm_request_irq(&pdev->dev, irq, atmel_i2s_interrupt, 0,
+			       dev_name(&pdev->dev), dev);
+	if (err)
+		return err;
+
+	/* Get the peripheral clock. */
+	dev->pclk = devm_clk_get(&pdev->dev, "pclk");
+	if (IS_ERR(dev->pclk)) {
+		err = PTR_ERR(dev->pclk);
+		dev_err(&pdev->dev,
+			"failed to get the peripheral clock: %d\n", err);
+		return err;
+	}
+
+	/* Get audio clocks to generate the I2S Master Clock (I2S_MCK) */
+	dev->aclk = devm_clk_get(&pdev->dev, "aclk");
+	dev->gclk = devm_clk_get(&pdev->dev, "gclk");
+	if (IS_ERR(dev->aclk) && IS_ERR(dev->gclk)) {
+		if (PTR_ERR(dev->aclk) == -EPROBE_DEFER ||
+		    PTR_ERR(dev->gclk) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		/* Master Mode not supported */
+		dev->aclk = NULL;
+		dev->gclk = NULL;
+	} else if (IS_ERR(dev->gclk)) {
+		err = PTR_ERR(dev->gclk);
+		dev_err(&pdev->dev,
+			"failed to get the PMC generated clock: %d\n", err);
+		return err;
+	} else if (IS_ERR(dev->aclk)) {
+		err = PTR_ERR(dev->aclk);
+		dev_err(&pdev->dev,
+			"failed to get the PLL audio clock: %d\n", err);
+		return err;
+	}
+
+	dev->dev = &pdev->dev;
+	dev->regmap = regmap;
+	platform_set_drvdata(pdev, dev);
+
+	/* Do hardware specific settings to initialize I2S_MCK generator */
+	if (dev->caps && dev->caps->mck_init) {
+		err = dev->caps->mck_init(dev, np);
+		if (err)
+			return err;
+	}
+
+	/* Enable the peripheral clock. */
+	err = clk_prepare_enable(dev->pclk);
+	if (err)
+		return err;
+
+	/* Get IP version. */
+	regmap_read(dev->regmap, ATMEL_I2SC_VERSION, &version);
+	dev_info(&pdev->dev, "hw version: %#x\n", version);
+
+	/* Enable error interrupts. */
+	regmap_write(dev->regmap, ATMEL_I2SC_IER,
+		     ATMEL_I2SC_INT_RXOR | ATMEL_I2SC_INT_TXUR);
+
+	err = devm_snd_soc_register_component(&pdev->dev,
+					      &atmel_i2s_component,
+					      &atmel_i2s_dai, 1);
+	if (err) {
+		dev_err(&pdev->dev, "failed to register DAI: %d\n", err);
+		clk_disable_unprepare(dev->pclk);
+		return err;
+	}
+
+	/* Prepare DMA config. */
+	dev->playback.addr	= (dma_addr_t)mem->start + ATMEL_I2SC_THR;
+	dev->playback.maxburst	= 1;
+	dev->capture.addr	= (dma_addr_t)mem->start + ATMEL_I2SC_RHR;
+	dev->capture.maxburst	= 1;
+
+	if (of_property_match_string(np, "dma-names", "rx-tx") == 0)
+		pcm_flags |= SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX;
+	err = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, pcm_flags);
+	if (err) {
+		dev_err(&pdev->dev, "failed to register PCM: %d\n", err);
+		clk_disable_unprepare(dev->pclk);
+		return err;
+	}
+
+	return 0;
+}
+
+static int atmel_i2s_remove(struct platform_device *pdev)
+{
+	struct atmel_i2s_dev *dev = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(dev->pclk);
+
+	return 0;
+}
+
+static struct platform_driver atmel_i2s_driver = {
+	.driver		= {
+		.name	= "atmel_i2s",
+		.of_match_table	= of_match_ptr(atmel_i2s_dt_ids),
+	},
+	.probe		= atmel_i2s_probe,
+	.remove		= atmel_i2s_remove,
+};
+module_platform_driver(atmel_i2s_driver);
+
+MODULE_DESCRIPTION("Atmel I2S Controller driver");
+MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@xxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
-- 
2.17.0