Initial import

1 files changed, 878 insertions, 0 deletions

diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c
new file mode 100644
index 000000000..03fa1cbf8
--- /dev/null
+++ b/sound/soc/bcm/bcm2835-i2s.c
@@ -0,0 +1,878 @@
+/*
+ * ALSA SoC I2S Audio Layer for Broadcom BCM2835 SoC
+ *
+ * Author:	Florian Meier <florian.meier@koalo.de>
+ *		Copyright 2013
+ *
+ * Based on
+ *	Raspberry Pi PCM I2S ALSA Driver
+ *	Copyright (c) by Phil Poole 2013
+ *
+ *	ALSA SoC I2S (McBSP) Audio Layer for TI DAVINCI processor
+ *      Vladimir Barinov, <vbarinov@embeddedalley.com>
+ *	Copyright (C) 2007 MontaVista Software, Inc., <source@mvista.com>
+ *
+ *	OMAP ALSA SoC DAI driver using McBSP port
+ *	Copyright (C) 2008 Nokia Corporation
+ *	Contact: Jarkko Nikula <jarkko.nikula@bitmer.com>
+ *		 Peter Ujfalusi <peter.ujfalusi@ti.com>
+ *
+ *	Freescale SSI ALSA SoC Digital Audio Interface (DAI) driver
+ *	Author: Timur Tabi <timur@freescale.com>
+ *	Copyright 2007-2010 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
+ * 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.
+ */
+
+#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 <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>
+
+/* Clock registers */
+#define BCM2835_CLK_PCMCTL_REG  0x00
+#define BCM2835_CLK_PCMDIV_REG  0x04
+
+/* Clock register settings */
+#define BCM2835_CLK_PASSWD		(0x5a000000)
+#define BCM2835_CLK_PASSWD_MASK	(0xff000000)
+#define BCM2835_CLK_MASH(v)		((v) << 9)
+#define BCM2835_CLK_FLIP		BIT(8)
+#define BCM2835_CLK_BUSY		BIT(7)
+#define BCM2835_CLK_KILL		BIT(5)
+#define BCM2835_CLK_ENAB		BIT(4)
+#define BCM2835_CLK_SRC(v)		(v)
+
+#define BCM2835_CLK_SHIFT		(12)
+#define BCM2835_CLK_DIVI(v)		((v) << BCM2835_CLK_SHIFT)
+#define BCM2835_CLK_DIVF(v)		(v)
+#define BCM2835_CLK_DIVF_MASK		(0xFFF)
+
+enum {
+	BCM2835_CLK_MASH_0 = 0,
+	BCM2835_CLK_MASH_1,
+	BCM2835_CLK_MASH_2,
+	BCM2835_CLK_MASH_3,
+};
+
+enum {
+	BCM2835_CLK_SRC_GND = 0,
+	BCM2835_CLK_SRC_OSC,
+	BCM2835_CLK_SRC_DBG0,
+	BCM2835_CLK_SRC_DBG1,
+	BCM2835_CLK_SRC_PLLA,
+	BCM2835_CLK_SRC_PLLC,
+	BCM2835_CLK_SRC_PLLD,
+	BCM2835_CLK_SRC_HDMI,
+};
+
+/* Most clocks are not useable (freq = 0) */
+static const unsigned int bcm2835_clk_freq[BCM2835_CLK_SRC_HDMI+1] = {
+	[BCM2835_CLK_SRC_GND]		= 0,
+	[BCM2835_CLK_SRC_OSC]		= 19200000,
+	[BCM2835_CLK_SRC_DBG0]		= 0,
+	[BCM2835_CLK_SRC_DBG1]		= 0,
+	[BCM2835_CLK_SRC_PLLA]		= 0,
+	[BCM2835_CLK_SRC_PLLC]		= 0,
+	[BCM2835_CLK_SRC_PLLD]		= 500000000,
+	[BCM2835_CLK_SRC_HDMI]		= 0,
+};
+
+/* I2S registers */
+#define BCM2835_I2S_CS_A_REG		0x00
+#define BCM2835_I2S_FIFO_A_REG		0x04
+#define BCM2835_I2S_MODE_A_REG		0x08
+#define BCM2835_I2S_RXC_A_REG		0x0c
+#define BCM2835_I2S_TXC_A_REG		0x10
+#define BCM2835_I2S_DREQ_A_REG		0x14
+#define BCM2835_I2S_INTEN_A_REG	0x18
+#define BCM2835_I2S_INTSTC_A_REG	0x1c
+#define BCM2835_I2S_GRAY_REG		0x20
+
+/* I2S register settings */
+#define BCM2835_I2S_STBY		BIT(25)
+#define BCM2835_I2S_SYNC		BIT(24)
+#define BCM2835_I2S_RXSEX		BIT(23)
+#define BCM2835_I2S_RXF		BIT(22)
+#define BCM2835_I2S_TXE		BIT(21)
+#define BCM2835_I2S_RXD		BIT(20)
+#define BCM2835_I2S_TXD		BIT(19)
+#define BCM2835_I2S_RXR		BIT(18)
+#define BCM2835_I2S_TXW		BIT(17)
+#define BCM2835_I2S_CS_RXERR		BIT(16)
+#define BCM2835_I2S_CS_TXERR		BIT(15)
+#define BCM2835_I2S_RXSYNC		BIT(14)
+#define BCM2835_I2S_TXSYNC		BIT(13)
+#define BCM2835_I2S_DMAEN		BIT(9)
+#define BCM2835_I2S_RXTHR(v)		((v) << 7)
+#define BCM2835_I2S_TXTHR(v)		((v) << 5)
+#define BCM2835_I2S_RXCLR		BIT(4)
+#define BCM2835_I2S_TXCLR		BIT(3)
+#define BCM2835_I2S_TXON		BIT(2)
+#define BCM2835_I2S_RXON		BIT(1)
+#define BCM2835_I2S_EN			(1)
+
+#define BCM2835_I2S_CLKDIS		BIT(28)
+#define BCM2835_I2S_PDMN		BIT(27)
+#define BCM2835_I2S_PDME		BIT(26)
+#define BCM2835_I2S_FRXP		BIT(25)
+#define BCM2835_I2S_FTXP		BIT(24)
+#define BCM2835_I2S_CLKM		BIT(23)
+#define BCM2835_I2S_CLKI		BIT(22)
+#define BCM2835_I2S_FSM		BIT(21)
+#define BCM2835_I2S_FSI		BIT(20)
+#define BCM2835_I2S_FLEN(v)		((v) << 10)
+#define BCM2835_I2S_FSLEN(v)		(v)
+
+#define BCM2835_I2S_CHWEX		BIT(15)
+#define BCM2835_I2S_CHEN		BIT(14)
+#define BCM2835_I2S_CHPOS(v)		((v) << 4)
+#define BCM2835_I2S_CHWID(v)		(v)
+#define BCM2835_I2S_CH1(v)		((v) << 16)
+#define BCM2835_I2S_CH2(v)		(v)
+
+#define BCM2835_I2S_TX_PANIC(v)	((v) << 24)
+#define BCM2835_I2S_RX_PANIC(v)	((v) << 16)
+#define BCM2835_I2S_TX(v)		((v) << 8)
+#define BCM2835_I2S_RX(v)		(v)
+
+#define BCM2835_I2S_INT_RXERR		BIT(3)
+#define BCM2835_I2S_INT_TXERR		BIT(2)
+#define BCM2835_I2S_INT_RXR		BIT(1)
+#define BCM2835_I2S_INT_TXW		BIT(0)
+
+/* I2S DMA interface */
+/* FIXME: Needs IOMMU support */
+#define BCM2835_VCMMU_SHIFT		(0x7E000000 - 0x20000000)
+
+/* General device struct */
+struct bcm2835_i2s_dev {
+	struct device				*dev;
+	struct snd_dmaengine_dai_dma_data	dma_data[2];
+	unsigned int				fmt;
+	unsigned int				bclk_ratio;
+
+	struct regmap *i2s_regmap;
+	struct regmap *clk_regmap;
+};
+
+static void bcm2835_i2s_start_clock(struct bcm2835_i2s_dev *dev)
+{
+	/* Start the clock if in master mode */
+	unsigned int master = dev->fmt & SND_SOC_DAIFMT_MASTER_MASK;
+
+	switch (master) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBS_CFM:
+		regmap_update_bits(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+			BCM2835_CLK_PASSWD_MASK | BCM2835_CLK_ENAB,
+			BCM2835_CLK_PASSWD | BCM2835_CLK_ENAB);
+		break;
+	default:
+		break;
+	}
+}
+
+static void bcm2835_i2s_stop_clock(struct bcm2835_i2s_dev *dev)
+{
+	uint32_t clkreg;
+	int timeout = 1000;
+
+	/* Stop clock */
+	regmap_update_bits(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+			BCM2835_CLK_PASSWD_MASK | BCM2835_CLK_ENAB,
+			BCM2835_CLK_PASSWD);
+
+	/* Wait for the BUSY flag going down */
+	while (--timeout) {
+		regmap_read(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG, &clkreg);
+		if (!(clkreg & BCM2835_CLK_BUSY))
+			break;
+	}
+
+	if (!timeout) {
+		/* KILL the clock */
+		dev_err(dev->dev, "I2S clock didn't stop. Kill the clock!\n");
+		regmap_update_bits(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+			BCM2835_CLK_KILL | BCM2835_CLK_PASSWD_MASK,
+			BCM2835_CLK_KILL | BCM2835_CLK_PASSWD);
+	}
+}
+
+static void bcm2835_i2s_clear_fifos(struct bcm2835_i2s_dev *dev,
+				    bool tx, bool rx)
+{
+	int timeout = 1000;
+	uint32_t syncval;
+	uint32_t csreg;
+	uint32_t i2s_active_state;
+	uint32_t clkreg;
+	uint32_t clk_active_state;
+	uint32_t off;
+	uint32_t clr;
+
+	off =  tx ? BCM2835_I2S_TXON : 0;
+	off |= rx ? BCM2835_I2S_RXON : 0;
+
+	clr =  tx ? BCM2835_I2S_TXCLR : 0;
+	clr |= rx ? BCM2835_I2S_RXCLR : 0;
+
+	/* Backup the current state */
+	regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &csreg);
+	i2s_active_state = csreg & (BCM2835_I2S_RXON | BCM2835_I2S_TXON);
+
+	regmap_read(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG, &clkreg);
+	clk_active_state = clkreg & BCM2835_CLK_ENAB;
+
+	/* Start clock if not running */
+	if (!clk_active_state) {
+		regmap_update_bits(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+			BCM2835_CLK_PASSWD_MASK | BCM2835_CLK_ENAB,
+			BCM2835_CLK_PASSWD | BCM2835_CLK_ENAB);
+	}
+
+	/* Stop I2S module */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, off, 0);
+
+	/*
+	 * Clear the FIFOs
+	 * Requires at least 2 PCM clock cycles to take effect
+	 */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, clr, clr);
+
+	/* Wait for 2 PCM clock cycles */
+
+	/*
+	 * Toggle the SYNC flag. After 2 PCM clock cycles it can be read back
+	 * FIXME: This does not seem to work for slave mode!
+	 */
+	regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &syncval);
+	syncval &= BCM2835_I2S_SYNC;
+
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_SYNC, ~syncval);
+
+	/* Wait for the SYNC flag changing it's state */
+	while (--timeout) {
+		regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &csreg);
+		if ((csreg & BCM2835_I2S_SYNC) != syncval)
+			break;
+	}
+
+	if (!timeout)
+		dev_err(dev->dev, "I2S SYNC error!\n");
+
+	/* Stop clock if it was not running before */
+	if (!clk_active_state)
+		bcm2835_i2s_stop_clock(dev);
+
+	/* Restore I2S state */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_RXON | BCM2835_I2S_TXON, i2s_active_state);
+}
+
+static int bcm2835_i2s_set_dai_fmt(struct snd_soc_dai *dai,
+				      unsigned int fmt)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	dev->fmt = fmt;
+	return 0;
+}
+
+static int bcm2835_i2s_set_dai_bclk_ratio(struct snd_soc_dai *dai,
+				      unsigned int ratio)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	dev->bclk_ratio = ratio;
+	return 0;
+}
+
+static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
+				 struct snd_pcm_hw_params *params,
+				 struct snd_soc_dai *dai)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	unsigned int sampling_rate = params_rate(params);
+	unsigned int data_length, data_delay, bclk_ratio;
+	unsigned int ch1pos, ch2pos, mode, format;
+	unsigned int mash = BCM2835_CLK_MASH_1;
+	unsigned int divi, divf, target_frequency;
+	int clk_src = -1;
+	unsigned int master = dev->fmt & SND_SOC_DAIFMT_MASTER_MASK;
+	bool bit_master =	(master == SND_SOC_DAIFMT_CBS_CFS
+					|| master == SND_SOC_DAIFMT_CBS_CFM);
+
+	bool frame_master =	(master == SND_SOC_DAIFMT_CBS_CFS
+					|| master == SND_SOC_DAIFMT_CBM_CFS);
+	uint32_t csreg;
+
+	/*
+	 * If a stream is already enabled,
+	 * the registers are already set properly.
+	 */
+	regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &csreg);
+
+	if (csreg & (BCM2835_I2S_TXON | BCM2835_I2S_RXON))
+		return 0;
+
+	/*
+	 * Adjust the data length according to the format.
+	 * We prefill the half frame length with an integer
+	 * divider of 2400 as explained at the clock settings.
+	 * Maybe it is overwritten there, if the Integer mode
+	 * does not apply.
+	 */
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_S16_LE:
+		data_length = 16;
+		bclk_ratio = 40;
+		break;
+	case SNDRV_PCM_FORMAT_S32_LE:
+		data_length = 32;
+		bclk_ratio = 80;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* If bclk_ratio already set, use that one. */
+	if (dev->bclk_ratio)
+		bclk_ratio = dev->bclk_ratio;
+
+	/*
+	 * Clock Settings
+	 *
+	 * The target frequency of the bit clock is
+	 *	sampling rate * frame length
+	 *
+	 * Integer mode:
+	 * Sampling rates that are multiples of 8000 kHz
+	 * can be driven by the oscillator of 19.2 MHz
+	 * with an integer divider as long as the frame length
+	 * is an integer divider of 19200000/8000=2400 as set up above.
+	 * This is no longer possible if the sampling rate
+	 * is too high (e.g. 192 kHz), because the oscillator is too slow.
+	 *
+	 * MASH mode:
+	 * For all other sampling rates, it is not possible to
+	 * have an integer divider. Approximate the clock
+	 * with the MASH module that induces a slight frequency
+	 * variance. To minimize that it is best to have the fastest
+	 * clock here. That is PLLD with 500 MHz.
+	 */
+	target_frequency = sampling_rate * bclk_ratio;
+	clk_src = BCM2835_CLK_SRC_OSC;
+	mash = BCM2835_CLK_MASH_0;
+
+	if (bcm2835_clk_freq[clk_src] % target_frequency == 0
+			&& bit_master && frame_master) {
+		divi = bcm2835_clk_freq[clk_src] / target_frequency;
+		divf = 0;
+	} else {
+		uint64_t dividend;
+
+		if (!dev->bclk_ratio) {
+			/*
+			 * Overwrite bclk_ratio, because the
+			 * above trick is not needed or can
+			 * not be used.
+			 */
+			bclk_ratio = 2 * data_length;
+		}
+
+		target_frequency = sampling_rate * bclk_ratio;
+
+		clk_src = BCM2835_CLK_SRC_PLLD;
+		mash = BCM2835_CLK_MASH_1;
+
+		dividend = bcm2835_clk_freq[clk_src];
+		dividend <<= BCM2835_CLK_SHIFT;
+		do_div(dividend, target_frequency);
+		divi = dividend >> BCM2835_CLK_SHIFT;
+		divf = dividend & BCM2835_CLK_DIVF_MASK;
+	}
+
+	/* Set clock divider */
+	regmap_write(dev->clk_regmap, BCM2835_CLK_PCMDIV_REG, BCM2835_CLK_PASSWD
+			| BCM2835_CLK_DIVI(divi)
+			| BCM2835_CLK_DIVF(divf));
+
+	/* Setup clock, but don't start it yet */
+	regmap_write(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG, BCM2835_CLK_PASSWD
+			| BCM2835_CLK_MASH(mash)
+			| BCM2835_CLK_SRC(clk_src));
+
+	/* Setup the frame format */
+	format = BCM2835_I2S_CHEN;
+
+	if (data_length > 24)
+		format |= BCM2835_I2S_CHWEX;
+
+	format |= BCM2835_I2S_CHWID((data_length-8)&0xf);
+
+	switch (dev->fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
+	case SND_SOC_DAIFMT_I2S:
+		data_delay = 1;
+		break;
+	default:
+		/*
+		 * TODO
+		 * Others are possible but are not implemented at the moment.
+		 */
+		dev_err(dev->dev, "%s:bad format\n", __func__);
+		return -EINVAL;
+	}
+
+	ch1pos = data_delay;
+	ch2pos = bclk_ratio / 2 + data_delay;
+
+	switch (params_channels(params)) {
+	case 2:
+		format = BCM2835_I2S_CH1(format) | BCM2835_I2S_CH2(format);
+		format |= BCM2835_I2S_CH1(BCM2835_I2S_CHPOS(ch1pos));
+		format |= BCM2835_I2S_CH2(BCM2835_I2S_CHPOS(ch2pos));
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/*
+	 * Set format for both streams.
+	 * We cannot set another frame length
+	 * (and therefore word length) anyway,
+	 * so the format will be the same.
+	 */
+	regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG, format);
+	regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG, format);
+
+	/* Setup the I2S mode */
+	mode = 0;
+
+	if (data_length <= 16) {
+		/*
+		 * Use frame packed mode (2 channels per 32 bit word)
+		 * We cannot set another frame length in the second stream
+		 * (and therefore word length) anyway,
+		 * so the format will be the same.
+		 */
+		mode |= BCM2835_I2S_FTXP | BCM2835_I2S_FRXP;
+	}
+
+	mode |= BCM2835_I2S_FLEN(bclk_ratio - 1);
+	mode |= BCM2835_I2S_FSLEN(bclk_ratio / 2);
+
+	/* Master or slave? */
+	switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+		/* CPU is master */
+		break;
+	case SND_SOC_DAIFMT_CBM_CFS:
+		/*
+		 * CODEC is bit clock master
+		 * CPU is frame master
+		 */
+		mode |= BCM2835_I2S_CLKM;
+		break;
+	case SND_SOC_DAIFMT_CBS_CFM:
+		/*
+		 * CODEC is frame master
+		 * CPU is bit clock master
+		 */
+		mode |= BCM2835_I2S_FSM;
+		break;
+	case SND_SOC_DAIFMT_CBM_CFM:
+		/* CODEC is master */
+		mode |= BCM2835_I2S_CLKM;
+		mode |= BCM2835_I2S_FSM;
+		break;
+	default:
+		dev_err(dev->dev, "%s:bad master\n", __func__);
+		return -EINVAL;
+	}
+
+	/*
+	 * Invert clocks?
+	 *
+	 * The BCM approach seems to be inverted to the classical I2S approach.
+	 */
+	switch (dev->fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_NF:
+		/* None. Therefore, both for BCM */
+		mode |= BCM2835_I2S_CLKI;
+		mode |= BCM2835_I2S_FSI;
+		break;
+	case SND_SOC_DAIFMT_IB_IF:
+		/* Both. Therefore, none for BCM */
+		break;
+	case SND_SOC_DAIFMT_NB_IF:
+		/*
+		 * Invert only frame sync. Therefore,
+		 * invert only bit clock for BCM
+		 */
+		mode |= BCM2835_I2S_CLKI;
+		break;
+	case SND_SOC_DAIFMT_IB_NF:
+		/*
+		 * Invert only bit clock. Therefore,
+		 * invert only frame sync for BCM
+		 */
+		mode |= BCM2835_I2S_FSI;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap_write(dev->i2s_regmap, BCM2835_I2S_MODE_A_REG, mode);
+
+	/* Setup the DMA parameters */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_RXTHR(1)
+			| BCM2835_I2S_TXTHR(1)
+			| BCM2835_I2S_DMAEN, 0xffffffff);
+
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_DREQ_A_REG,
+			  BCM2835_I2S_TX_PANIC(0x10)
+			| BCM2835_I2S_RX_PANIC(0x30)
+			| BCM2835_I2S_TX(0x30)
+			| BCM2835_I2S_RX(0x20), 0xffffffff);
+
+	/* Clear FIFOs */
+	bcm2835_i2s_clear_fifos(dev, true, true);
+
+	return 0;
+}
+
+static int bcm2835_i2s_prepare(struct snd_pcm_substream *substream,
+		struct snd_soc_dai *dai)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	uint32_t cs_reg;
+
+	bcm2835_i2s_start_clock(dev);
+
+	/*
+	 * Clear both FIFOs if the one that should be started
+	 * is not empty at the moment. This should only happen
+	 * after overrun. Otherwise, hw_params would have cleared
+	 * the FIFO.
+	 */
+	regmap_read(dev->i2s_regmap, BCM2835_I2S_CS_A_REG, &cs_reg);
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK
+			&& !(cs_reg & BCM2835_I2S_TXE))
+		bcm2835_i2s_clear_fifos(dev, true, false);
+	else if (substream->stream == SNDRV_PCM_STREAM_CAPTURE
+			&& (cs_reg & BCM2835_I2S_RXD))
+		bcm2835_i2s_clear_fifos(dev, false, true);
+
+	return 0;
+}
+
+static void bcm2835_i2s_stop(struct bcm2835_i2s_dev *dev,
+		struct snd_pcm_substream *substream,
+		struct snd_soc_dai *dai)
+{
+	uint32_t mask;
+
+	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+		mask = BCM2835_I2S_RXON;
+	else
+		mask = BCM2835_I2S_TXON;
+
+	regmap_update_bits(dev->i2s_regmap,
+			BCM2835_I2S_CS_A_REG, mask, 0);
+
+	/* Stop also the clock when not SND_SOC_DAIFMT_CONT */
+	if (!dai->active && !(dev->fmt & SND_SOC_DAIFMT_CONT))
+		bcm2835_i2s_stop_clock(dev);
+}
+
+static int bcm2835_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
+			       struct snd_soc_dai *dai)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+	uint32_t mask;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		bcm2835_i2s_start_clock(dev);
+
+		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+			mask = BCM2835_I2S_RXON;
+		else
+			mask = BCM2835_I2S_TXON;
+
+		regmap_update_bits(dev->i2s_regmap,
+				BCM2835_I2S_CS_A_REG, mask, mask);
+		break;
+
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		bcm2835_i2s_stop(dev, substream, dai);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int bcm2835_i2s_startup(struct snd_pcm_substream *substream,
+			       struct snd_soc_dai *dai)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	if (dai->active)
+		return 0;
+
+	/* Should this still be running stop it */
+	bcm2835_i2s_stop_clock(dev);
+
+	/* Enable PCM block */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_EN, BCM2835_I2S_EN);
+
+	/*
+	 * Disable STBY.
+	 * Requires at least 4 PCM clock cycles to take effect.
+	 */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_STBY, BCM2835_I2S_STBY);
+
+	return 0;
+}
+
+static void bcm2835_i2s_shutdown(struct snd_pcm_substream *substream,
+		struct snd_soc_dai *dai)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	bcm2835_i2s_stop(dev, substream, dai);
+
+	/* If both streams are stopped, disable module and clock */
+	if (dai->active)
+		return;
+
+	/* Disable the module */
+	regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
+			BCM2835_I2S_EN, 0);
+
+	/*
+	 * Stopping clock is necessary, because stop does
+	 * not stop the clock when SND_SOC_DAIFMT_CONT
+	 */
+	bcm2835_i2s_stop_clock(dev);
+}
+
+static const struct snd_soc_dai_ops bcm2835_i2s_dai_ops = {
+	.startup	= bcm2835_i2s_startup,
+	.shutdown	= bcm2835_i2s_shutdown,
+	.prepare	= bcm2835_i2s_prepare,
+	.trigger	= bcm2835_i2s_trigger,
+	.hw_params	= bcm2835_i2s_hw_params,
+	.set_fmt	= bcm2835_i2s_set_dai_fmt,
+	.set_bclk_ratio	= bcm2835_i2s_set_dai_bclk_ratio
+};
+
+static int bcm2835_i2s_dai_probe(struct snd_soc_dai *dai)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	snd_soc_dai_init_dma_data(dai,
+			&dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK],
+			&dev->dma_data[SNDRV_PCM_STREAM_CAPTURE]);
+
+	return 0;
+}
+
+static struct snd_soc_dai_driver bcm2835_i2s_dai = {
+	.name	= "bcm2835-i2s",
+	.probe	= bcm2835_i2s_dai_probe,
+	.playback = {
+		.channels_min = 2,
+		.channels_max = 2,
+		.rates =	SNDRV_PCM_RATE_8000_192000,
+		.formats =	SNDRV_PCM_FMTBIT_S16_LE
+				| SNDRV_PCM_FMTBIT_S32_LE
+		},
+	.capture = {
+		.channels_min = 2,
+		.channels_max = 2,
+		.rates =	SNDRV_PCM_RATE_8000_192000,
+		.formats =	SNDRV_PCM_FMTBIT_S16_LE
+				| SNDRV_PCM_FMTBIT_S32_LE
+		},
+	.ops = &bcm2835_i2s_dai_ops,
+	.symmetric_rates = 1
+};
+
+static bool bcm2835_i2s_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BCM2835_I2S_CS_A_REG:
+	case BCM2835_I2S_FIFO_A_REG:
+	case BCM2835_I2S_INTSTC_A_REG:
+	case BCM2835_I2S_GRAY_REG:
+		return true;
+	default:
+		return false;
+	};
+}
+
+static bool bcm2835_i2s_precious_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BCM2835_I2S_FIFO_A_REG:
+		return true;
+	default:
+		return false;
+	};
+}
+
+static bool bcm2835_clk_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BCM2835_CLK_PCMCTL_REG:
+		return true;
+	default:
+		return false;
+	};
+}
+
+static const struct regmap_config bcm2835_regmap_config[] = {
+	{
+		.reg_bits = 32,
+		.reg_stride = 4,
+		.val_bits = 32,
+		.max_register = BCM2835_I2S_GRAY_REG,
+		.precious_reg = bcm2835_i2s_precious_reg,
+		.volatile_reg = bcm2835_i2s_volatile_reg,
+		.cache_type = REGCACHE_RBTREE,
+	},
+	{
+		.reg_bits = 32,
+		.reg_stride = 4,
+		.val_bits = 32,
+		.max_register = BCM2835_CLK_PCMDIV_REG,
+		.volatile_reg = bcm2835_clk_volatile_reg,
+		.cache_type = REGCACHE_RBTREE,
+	},
+};
+
+static const struct snd_soc_component_driver bcm2835_i2s_component = {
+	.name		= "bcm2835-i2s-comp",
+};
+
+static int bcm2835_i2s_probe(struct platform_device *pdev)
+{
+	struct bcm2835_i2s_dev *dev;
+	int i;
+	int ret;
+	struct regmap *regmap[2];
+	struct resource *mem[2];
+
+	/* Request both ioareas */
+	for (i = 0; i <= 1; i++) {
+		void __iomem *base;
+
+		mem[i] = platform_get_resource(pdev, IORESOURCE_MEM, i);
+		base = devm_ioremap_resource(&pdev->dev, mem[i]);
+		if (IS_ERR(base))
+			return PTR_ERR(base);
+
+		regmap[i] = devm_regmap_init_mmio(&pdev->dev, base,
+					    &bcm2835_regmap_config[i]);
+		if (IS_ERR(regmap[i]))
+			return PTR_ERR(regmap[i]);
+	}
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev),
+			   GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	dev->i2s_regmap = regmap[0];
+	dev->clk_regmap = regmap[1];
+
+	/* Set the DMA address */
+	dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].addr =
+		(dma_addr_t)mem[0]->start + BCM2835_I2S_FIFO_A_REG
+					  + BCM2835_VCMMU_SHIFT;
+
+	dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].addr =
+		(dma_addr_t)mem[0]->start + BCM2835_I2S_FIFO_A_REG
+					  + BCM2835_VCMMU_SHIFT;
+
+	/* Set the bus width */
+	dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].addr_width =
+		DMA_SLAVE_BUSWIDTH_4_BYTES;
+	dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].addr_width =
+		DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+	/* Set burst */
+	dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].maxburst = 2;
+	dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].maxburst = 2;
+
+	/* BCLK ratio - use default */
+	dev->bclk_ratio = 0;
+
+	/* Store the pdev */
+	dev->dev = &pdev->dev;
+	dev_set_drvdata(&pdev->dev, dev);
+
+	ret = devm_snd_soc_register_component(&pdev->dev,
+			&bcm2835_i2s_component, &bcm2835_i2s_dai, 1);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not register DAI: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, 0);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not register PCM: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835_i2s_of_match[] = {
+	{ .compatible = "brcm,bcm2835-i2s", },
+	{},
+};
+
+static struct platform_driver bcm2835_i2s_driver = {
+	.probe		= bcm2835_i2s_probe,
+	.driver		= {
+		.name	= "bcm2835-i2s",
+		.of_match_table = bcm2835_i2s_of_match,
+	},
+};
+
+module_platform_driver(bcm2835_i2s_driver);
+
+MODULE_ALIAS("platform:bcm2835-i2s");
+MODULE_DESCRIPTION("BCM2835 I2S interface");
+MODULE_AUTHOR("Florian Meier <florian.meier@koalo.de>");
+MODULE_LICENSE("GPL v2");