Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 942 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..d5f73a8ab
--- /dev/null
+++ b/sound/soc/bcm/bcm2835-i2s.c
@@ -0,0 +1,942 @@
+/*
+ * 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/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+
+#include <sound/core.h>
+#include <sound/dmaengine_pcm.h>
+#include <sound/initval.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+
+/* 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_CH1_POS(v)		BCM2835_I2S_CH1(BCM2835_I2S_CHPOS(v))
+#define BCM2835_I2S_CH2_POS(v)		BCM2835_I2S_CH2(BCM2835_I2S_CHPOS(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)
+
+/* Frame length register is 10 bit, maximum length 1024 */
+#define BCM2835_I2S_MAX_FRAME_LENGTH	1024
+
+/* General device struct */
+struct bcm2835_i2s_dev {
+	struct device				*dev;
+	struct snd_dmaengine_dai_dma_data	dma_data[2];
+	unsigned int				fmt;
+	unsigned int				tdm_slots;
+	unsigned int				rx_mask;
+	unsigned int				tx_mask;
+	unsigned int				slot_width;
+	unsigned int				frame_length;
+
+	struct regmap				*i2s_regmap;
+	struct clk				*clk;
+	bool					clk_prepared;
+	int					clk_rate;
+};
+
+static void bcm2835_i2s_start_clock(struct bcm2835_i2s_dev *dev)
+{
+	unsigned int master = dev->fmt & SND_SOC_DAIFMT_MASTER_MASK;
+
+	if (dev->clk_prepared)
+		return;
+
+	switch (master) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBS_CFM:
+		clk_prepare_enable(dev->clk);
+		dev->clk_prepared = true;
+		break;
+	default:
+		break;
+	}
+}
+
+static void bcm2835_i2s_stop_clock(struct bcm2835_i2s_dev *dev)
+{
+	if (dev->clk_prepared)
+		clk_disable_unprepare(dev->clk);
+	dev->clk_prepared = false;
+}
+
+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;
+	bool clk_was_prepared;
+	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);
+
+	/* Start clock if not running */
+	clk_was_prepared = dev->clk_prepared;
+	if (!clk_was_prepared)
+		bcm2835_i2s_start_clock(dev);
+
+	/* 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_was_prepared)
+		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);
+
+	if (!ratio) {
+		dev->tdm_slots = 0;
+		return 0;
+	}
+
+	if (ratio > BCM2835_I2S_MAX_FRAME_LENGTH)
+		return -EINVAL;
+
+	dev->tdm_slots = 2;
+	dev->rx_mask = 0x03;
+	dev->tx_mask = 0x03;
+	dev->slot_width = ratio / 2;
+	dev->frame_length = ratio;
+
+	return 0;
+}
+
+static int bcm2835_i2s_set_dai_tdm_slot(struct snd_soc_dai *dai,
+	unsigned int tx_mask, unsigned int rx_mask,
+	int slots, int width)
+{
+	struct bcm2835_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+	if (slots) {
+		if (slots < 0 || width < 0)
+			return -EINVAL;
+
+		/* Limit masks to available slots */
+		rx_mask &= GENMASK(slots - 1, 0);
+		tx_mask &= GENMASK(slots - 1, 0);
+
+		/*
+		 * The driver is limited to 2-channel setups.
+		 * Check that exactly 2 bits are set in the masks.
+		 */
+		if (hweight_long((unsigned long) rx_mask) != 2
+		    || hweight_long((unsigned long) tx_mask) != 2)
+			return -EINVAL;
+
+		if (slots * width > BCM2835_I2S_MAX_FRAME_LENGTH)
+			return -EINVAL;
+	}
+
+	dev->tdm_slots = slots;
+
+	dev->rx_mask = rx_mask;
+	dev->tx_mask = tx_mask;
+	dev->slot_width = width;
+	dev->frame_length = slots * width;
+
+	return 0;
+}
+
+/*
+ * Convert logical slot number into physical slot number.
+ *
+ * If odd_offset is 0 sequential number is identical to logical number.
+ * This is used for DSP modes with slot numbering 0 1 2 3 ...
+ *
+ * Otherwise odd_offset defines the physical offset for odd numbered
+ * slots. This is used for I2S and left/right justified modes to
+ * translate from logical slot numbers 0 1 2 3 ... into physical slot
+ * numbers 0 2 ... 3 4 ...
+ */
+static int bcm2835_i2s_convert_slot(unsigned int slot, unsigned int odd_offset)
+{
+	if (!odd_offset)
+		return slot;
+
+	if (slot & 1)
+		return (slot >> 1) + odd_offset;
+
+	return slot >> 1;
+}
+
+/*
+ * Calculate channel position from mask and slot width.
+ *
+ * Mask must contain exactly 2 set bits.
+ * Lowest set bit is channel 1 position, highest set bit channel 2.
+ * The constant offset is added to both channel positions.
+ *
+ * If odd_offset is > 0 slot positions are translated to
+ * I2S-style TDM slot numbering ( 0 2 ... 3 4 ...) with odd
+ * logical slot numbers starting at physical slot odd_offset.
+ */
+static void bcm2835_i2s_calc_channel_pos(
+	unsigned int *ch1_pos, unsigned int *ch2_pos,
+	unsigned int mask, unsigned int width,
+	unsigned int bit_offset, unsigned int odd_offset)
+{
+	*ch1_pos = bcm2835_i2s_convert_slot((ffs(mask) - 1), odd_offset)
+			* width + bit_offset;
+	*ch2_pos = bcm2835_i2s_convert_slot((fls(mask) - 1), odd_offset)
+			* width + bit_offset;
+}
+
+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 data_length, data_delay, framesync_length;
+	unsigned int slots, slot_width, odd_slot_offset;
+	int frame_length, bclk_rate;
+	unsigned int rx_mask, tx_mask;
+	unsigned int rx_ch1_pos, rx_ch2_pos, tx_ch1_pos, tx_ch2_pos;
+	unsigned int mode, format;
+	bool bit_clock_master = false;
+	bool frame_sync_master = false;
+	bool frame_start_falling_edge = false;
+	uint32_t csreg;
+	int ret = 0;
+
+	/*
+	 * 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;
+
+	data_length = params_width(params);
+	data_delay = 0;
+	odd_slot_offset = 0;
+	mode = 0;
+
+	if (dev->tdm_slots) {
+		slots = dev->tdm_slots;
+		slot_width = dev->slot_width;
+		frame_length = dev->frame_length;
+		rx_mask = dev->rx_mask;
+		tx_mask = dev->tx_mask;
+		bclk_rate = dev->frame_length * params_rate(params);
+	} else {
+		slots = 2;
+		slot_width = params_width(params);
+		rx_mask = 0x03;
+		tx_mask = 0x03;
+
+		frame_length = snd_soc_params_to_frame_size(params);
+		if (frame_length < 0)
+			return frame_length;
+
+		bclk_rate = snd_soc_params_to_bclk(params);
+		if (bclk_rate < 0)
+			return bclk_rate;
+	}
+
+	/* Check if data fits into slots */
+	if (data_length > slot_width)
+		return -EINVAL;
+
+	/* Check if CPU is bit clock master */
+	switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBS_CFM:
+		bit_clock_master = true;
+		break;
+	case SND_SOC_DAIFMT_CBM_CFS:
+	case SND_SOC_DAIFMT_CBM_CFM:
+		bit_clock_master = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Check if CPU is frame sync master */
+	switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBM_CFS:
+		frame_sync_master = true;
+		break;
+	case SND_SOC_DAIFMT_CBS_CFM:
+	case SND_SOC_DAIFMT_CBM_CFM:
+		frame_sync_master = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Clock should only be set up here if CPU is clock master */
+	if (bit_clock_master &&
+	    (!dev->clk_prepared || dev->clk_rate != bclk_rate)) {
+		if (dev->clk_prepared)
+			bcm2835_i2s_stop_clock(dev);
+
+		if (dev->clk_rate != bclk_rate) {
+			ret = clk_set_rate(dev->clk, bclk_rate);
+			if (ret)
+				return ret;
+			dev->clk_rate = bclk_rate;
+		}
+
+		bcm2835_i2s_start_clock(dev);
+	}
+
+	/* Setup the frame format */
+	format = BCM2835_I2S_CHEN;
+
+	if (data_length >= 24)
+		format |= BCM2835_I2S_CHWEX;
+
+	format |= BCM2835_I2S_CHWID((data_length-8)&0xf);
+
+	/* CH2 format is the same as for CH1 */
+	format = BCM2835_I2S_CH1(format) | BCM2835_I2S_CH2(format);
+
+	switch (dev->fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
+	case SND_SOC_DAIFMT_I2S:
+		/* I2S mode needs an even number of slots */
+		if (slots & 1)
+			return -EINVAL;
+
+		/*
+		 * Use I2S-style logical slot numbering: even slots
+		 * are in first half of frame, odd slots in second half.
+		 */
+		odd_slot_offset = slots >> 1;
+
+		/* MSB starts one cycle after frame start */
+		data_delay = 1;
+
+		/* Setup frame sync signal for 50% duty cycle */
+		framesync_length = frame_length / 2;
+		frame_start_falling_edge = true;
+		break;
+	case SND_SOC_DAIFMT_LEFT_J:
+		if (slots & 1)
+			return -EINVAL;
+
+		odd_slot_offset = slots >> 1;
+		data_delay = 0;
+		framesync_length = frame_length / 2;
+		frame_start_falling_edge = false;
+		break;
+	case SND_SOC_DAIFMT_RIGHT_J:
+		if (slots & 1)
+			return -EINVAL;
+
+		/* Odd frame lengths aren't supported */
+		if (frame_length & 1)
+			return -EINVAL;
+
+		odd_slot_offset = slots >> 1;
+		data_delay = slot_width - data_length;
+		framesync_length = frame_length / 2;
+		frame_start_falling_edge = false;
+		break;
+	case SND_SOC_DAIFMT_DSP_A:
+		data_delay = 1;
+		framesync_length = 1;
+		frame_start_falling_edge = false;
+		break;
+	case SND_SOC_DAIFMT_DSP_B:
+		data_delay = 0;
+		framesync_length = 1;
+		frame_start_falling_edge = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	bcm2835_i2s_calc_channel_pos(&rx_ch1_pos, &rx_ch2_pos,
+		rx_mask, slot_width, data_delay, odd_slot_offset);
+	bcm2835_i2s_calc_channel_pos(&tx_ch1_pos, &tx_ch2_pos,
+		tx_mask, slot_width, data_delay, odd_slot_offset);
+
+	/*
+	 * Transmitting data immediately after frame start, eg
+	 * in left-justified or DSP mode A, only works stable
+	 * if bcm2835 is the frame clock master.
+	 */
+	if ((!rx_ch1_pos || !tx_ch1_pos) && !frame_sync_master)
+		dev_warn(dev->dev,
+			"Unstable slave config detected, L/R may be swapped");
+
+	/*
+	 * 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
+		| BCM2835_I2S_CH1_POS(rx_ch1_pos)
+		| BCM2835_I2S_CH2_POS(rx_ch2_pos));
+	regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG, 
+		  format
+		| BCM2835_I2S_CH1_POS(tx_ch1_pos)
+		| BCM2835_I2S_CH2_POS(tx_ch2_pos));
+
+	/* Setup the I2S mode */
+
+	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(frame_length - 1);
+	mode |= BCM2835_I2S_FSLEN(framesync_length);
+
+	/* CLKM selects bcm2835 clock slave mode */
+	if (!bit_clock_master)
+		mode |= BCM2835_I2S_CLKM;
+
+	/* FSM selects bcm2835 frame sync slave mode */
+	if (!frame_sync_master)
+		mode |= BCM2835_I2S_FSM;
+
+	/* CLKI selects normal clocking mode, sampling on rising edge */
+        switch (dev->fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_NF:
+	case SND_SOC_DAIFMT_NB_IF:
+		mode |= BCM2835_I2S_CLKI;
+		break;
+	case SND_SOC_DAIFMT_IB_NF:
+	case SND_SOC_DAIFMT_IB_IF:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* FSI selects frame start on falling edge */
+	switch (dev->fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_NF:
+	case SND_SOC_DAIFMT_IB_NF:
+		if (frame_start_falling_edge)
+			mode |= BCM2835_I2S_FSI;
+		break;
+	case SND_SOC_DAIFMT_NB_IF:
+	case SND_SOC_DAIFMT_IB_IF:
+		if (!frame_start_falling_edge)
+			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);
+
+	dev_dbg(dev->dev,
+		"slots: %d width: %d rx mask: 0x%02x tx_mask: 0x%02x\n",
+		slots, slot_width, rx_mask, tx_mask);
+
+	dev_dbg(dev->dev, "frame len: %d sync len: %d data len: %d\n",
+		frame_length, framesync_length, data_length);
+
+	dev_dbg(dev->dev, "rx pos: %d,%d tx pos: %d,%d\n",
+		rx_ch1_pos, rx_ch2_pos, tx_ch1_pos, tx_ch2_pos);
+
+	dev_dbg(dev->dev, "sampling rate: %d bclk rate: %d\n",
+		params_rate(params), bclk_rate);
+
+	dev_dbg(dev->dev, "CLKM: %d CLKI: %d FSM: %d FSI: %d frame start: %s edge\n",
+		!!(mode & BCM2835_I2S_CLKM),
+		!!(mode & BCM2835_I2S_CLKI),
+		!!(mode & BCM2835_I2S_FSM),
+		!!(mode & BCM2835_I2S_FSI),
+		(mode & BCM2835_I2S_FSI) ? "falling" : "rising");
+
+	return ret;
+}
+
+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;
+
+	/*
+	 * 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,
+	.set_tdm_slot	= bcm2835_i2s_set_dai_tdm_slot,
+};
+
+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_CONTINUOUS,
+		.rate_min =	8000,
+		.rate_max =	384000,
+		.formats =	SNDRV_PCM_FMTBIT_S16_LE
+				| SNDRV_PCM_FMTBIT_S24_LE
+				| SNDRV_PCM_FMTBIT_S32_LE
+		},
+	.capture = {
+		.channels_min = 2,
+		.channels_max = 2,
+		.rates =	SNDRV_PCM_RATE_CONTINUOUS,
+		.rate_min =	8000,
+		.rate_max =	384000,
+		.formats =	SNDRV_PCM_FMTBIT_S16_LE
+				| SNDRV_PCM_FMTBIT_S24_LE
+				| SNDRV_PCM_FMTBIT_S32_LE
+		},
+	.ops = &bcm2835_i2s_dai_ops,
+	.symmetric_rates = 1,
+	.symmetric_samplebits = 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 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,
+};
+
+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 ret;
+	struct resource *mem;
+	void __iomem *base;
+	const __be32 *addr;
+	dma_addr_t dma_base;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev),
+			   GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	/* get the clock */
+	dev->clk_prepared = false;
+	dev->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dev->clk)) {
+		dev_err(&pdev->dev, "could not get clk: %ld\n",
+			PTR_ERR(dev->clk));
+		return PTR_ERR(dev->clk);
+	}
+
+	/* Request ioarea */
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	dev->i2s_regmap = devm_regmap_init_mmio(&pdev->dev, base,
+				&bcm2835_regmap_config);
+	if (IS_ERR(dev->i2s_regmap))
+		return PTR_ERR(dev->i2s_regmap);
+
+	/* Set the DMA address - we have to parse DT ourselves */
+	addr = of_get_address(pdev->dev.of_node, 0, NULL, NULL);
+	if (!addr) {
+		dev_err(&pdev->dev, "could not get DMA-register address\n");
+		return -EINVAL;
+	}
+	dma_base = be32_to_cpup(addr);
+
+	dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].addr =
+		dma_base + BCM2835_I2S_FIFO_A_REG;
+
+	dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].addr =
+		dma_base + BCM2835_I2S_FIFO_A_REG;
+
+	/* 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;
+
+	/*
+	 * Set the PACK flag to enable S16_LE support (2 S16_LE values
+	 * packed into 32-bit transfers).
+	 */
+	dev->dma_data[SNDRV_PCM_STREAM_PLAYBACK].flags =
+		SND_DMAENGINE_PCM_DAI_FLAG_PACK;
+	dev->dma_data[SNDRV_PCM_STREAM_CAPTURE].flags =
+		SND_DMAENGINE_PCM_DAI_FLAG_PACK;
+
+	/* 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", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, bcm2835_i2s_of_match);
+
+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");