[PATCH v8 10/13] IIO: ADC: add stm32 DFSDM support for PDM microphone

Jonathan Cameron Jonathan.Cameron at huawei.com
Wed Dec 13 01:18:39 PST 2017


On Wed, 13 Dec 2017 09:42:02 +0100
Arnaud Pouliquen <arnaud.pouliquen at st.com> wrote:

> Hi Jonathan,
> 
> 
> On 12/12/2017 09:27 PM, Jonathan Cameron wrote:
> > On Mon, 11 Dec 2017 11:18:41 +0100
> > Arnaud Pouliquen <arnaud.pouliquen at st.com> wrote:
> >   
> >> This code offers a way to handle PDM audio microphones in
> >> ASOC framework. Audio driver should use consumer API.
> >> A specific management is implemented for DMA, with a
> >> callback, to allows to handle audio buffers efficiently.
> >>
> >> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>  
> 
> 
> > Hi Arnaud,
> > 
> > I raise a few queries on v7 of this patch.
> > 
> > https://marc.info/?l=linux-iio&m=151292965915376&w=2  
> Never received the associated mail (and no in my spam list):( ,I just
> discover it...
> 
> Thanks to have highlighted this and sorry for the inconvenience, I will
> send a v9.
Don't worry about it! Happens to me from time to time as well.

Thanks,

Jonathan

> 
> Regards
> Arnaud
> 
> 
> > 
> > Jonathan
> >   
> >> ---
> >>  .../ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32      |  16 +
> >>  drivers/iio/adc/stm32-dfsdm-adc.c                  | 508 ++++++++++++++++++++-
> >>  include/linux/iio/adc/stm32-dfsdm-adc.h            |  18 +
> >>  3 files changed, 534 insertions(+), 8 deletions(-)
> >>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32
> >>  create mode 100644 include/linux/iio/adc/stm32-dfsdm-adc.h
> >>
> >> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32
> >> new file mode 100644
> >> index 0000000..da98223
> >> --- /dev/null
> >> +++ b/Documentation/ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32
> >> @@ -0,0 +1,16 @@
> >> +What:		/sys/bus/iio/devices/iio:deviceX/in_voltage_spi_clk_freq
> >> +KernelVersion:	4.14
> >> +Contact:	arnaud.pouliquen at st.com
> >> +Description:
> >> +		For audio purpose only.
> >> +		Used by audio driver to set/get the spi input frequency.
> >> +		This is mandatory if DFSDM is slave on SPI bus, to
> >> +		provide information on the SPI clock frequency during runtime
> >> +		Notice that the SPI frequency should be a multiple of sample
> >> +		frequency to ensure the precision.
> >> +		if DFSDM input is SPI master
> >> +			Reading  SPI clkout frequency,
> >> +			error on writing
> >> +		If DFSDM input is SPI Slave:
> >> +			Reading returns value previously set.
> >> +			Writing value before starting conversions.
> >> \ No newline at end of file
> >> diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
> >> index 68b5920..2d6aed5 100644
> >> --- a/drivers/iio/adc/stm32-dfsdm-adc.c
> >> +++ b/drivers/iio/adc/stm32-dfsdm-adc.c
> >> @@ -6,19 +6,25 @@
> >>   * Author: Arnaud Pouliquen <arnaud.pouliquen at st.com>.
> >>   */
> >>  
> >> +#include <linux/dmaengine.h>
> >> +#include <linux/dma-mapping.h>
> >>  #include <linux/interrupt.h>
> >>  #include <linux/iio/buffer.h>
> >>  #include <linux/iio/hw-consumer.h>
> >>  #include <linux/iio/iio.h>
> >>  #include <linux/iio/sysfs.h>
> >> +#include <linux/iio/trigger_consumer.h>
> >> +#include <linux/iio/triggered_buffer.h>
> >>  #include <linux/module.h>
> >> -#include <linux/of.h>
> >> +#include <linux/of_device.h>
> >>  #include <linux/platform_device.h>
> >>  #include <linux/regmap.h>
> >>  #include <linux/slab.h>
> >>  
> >>  #include "stm32-dfsdm.h"
> >>  
> >> +#define DFSDM_DMA_BUFFER_SIZE (4 * PAGE_SIZE)
> >> +
> >>  /* Conversion timeout */
> >>  #define DFSDM_TIMEOUT_US 100000
> >>  #define DFSDM_TIMEOUT (msecs_to_jiffies(DFSDM_TIMEOUT_US / 1000))
> >> @@ -58,6 +64,18 @@ struct stm32_dfsdm_adc {
> >>  	struct completion completion;
> >>  	u32 *buffer;
> >>  
> >> +	/* Audio specific */
> >> +	unsigned int spi_freq;  /* SPI bus clock frequency */
> >> +	unsigned int sample_freq; /* Sample frequency after filter decimation */
> >> +	int (*cb)(const void *data, size_t size, void *cb_priv);
> >> +	void *cb_priv;
> >> +
> >> +	/* DMA */
> >> +	u8 *rx_buf;
> >> +	unsigned int bufi; /* Buffer current position */
> >> +	unsigned int buf_sz; /* Buffer size */
> >> +	struct dma_chan	*dma_chan;
> >> +	dma_addr_t dma_buf;
> >>  };
> >>  
> >>  struct stm32_dfsdm_str2field {
> >> @@ -351,10 +369,63 @@ int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
> >>  	return 0;
> >>  }
> >>  
> >> +static ssize_t dfsdm_adc_audio_get_spiclk(struct iio_dev *indio_dev,
> >> +					  uintptr_t priv,
> >> +					  const struct iio_chan_spec *chan,
> >> +					  char *buf)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +
> >> +	return snprintf(buf, PAGE_SIZE, "%d\n", adc->spi_freq);
> >> +}
> >> +
> >> +static ssize_t dfsdm_adc_audio_set_spiclk(struct iio_dev *indio_dev,
> >> +					  uintptr_t priv,
> >> +					  const struct iio_chan_spec *chan,
> >> +					  const char *buf, size_t len)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
> >> +	struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[adc->ch_id];
> >> +	unsigned int sample_freq = adc->sample_freq;
> >> +	unsigned int spi_freq;
> >> +	int ret;
> >> +
> >> +	dev_err(&indio_dev->dev, "enter %s\n", __func__);
> >> +	/* If DFSDM is master on SPI, SPI freq can not be updated */
> >> +	if (ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
> >> +		return -EPERM;
> >> +
> >> +	ret = kstrtoint(buf, 0, &spi_freq);
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> +	if (!spi_freq)
> >> +		return -EINVAL;
> >> +
> >> +	if (sample_freq) {
> >> +		if (spi_freq % sample_freq)
> >> +			dev_warn(&indio_dev->dev,
> >> +				 "Sampling rate not accurate (%d)\n",
> >> +				 spi_freq / (spi_freq / sample_freq));
> >> +
> >> +		ret = stm32_dfsdm_set_osrs(fl, 0, (spi_freq / sample_freq));
> >> +		if (ret < 0) {
> >> +			dev_err(&indio_dev->dev,
> >> +				"No filter parameters that match!\n");
> >> +			return ret;
> >> +		}
> >> +	}
> >> +	adc->spi_freq = spi_freq;
> >> +
> >> +	return len;
> >> +}
> >> +
> >>  static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc, bool dma)
> >>  {
> >>  	struct regmap *regmap = adc->dfsdm->regmap;
> >>  	int ret;
> >> +	unsigned int dma_en = 0, cont_en = 0;
> >>  
> >>  	ret = stm32_dfsdm_start_channel(adc->dfsdm, adc->ch_id);
> >>  	if (ret < 0)
> >> @@ -365,6 +436,24 @@ static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc, bool dma)
> >>  	if (ret < 0)
> >>  		goto stop_channels;
> >>  
> >> +	if (dma) {
> >> +		/* Enable DMA transfer*/
> >> +		dma_en =  DFSDM_CR1_RDMAEN(1);
> >> +		/* Enable conversion triggered by SPI clock*/
> >> +		cont_en = DFSDM_CR1_RCONT(1);
> >> +	}
> >> +	/* Enable DMA transfer*/
> >> +	ret = regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
> >> +				 DFSDM_CR1_RDMAEN_MASK, dma_en);
> >> +	if (ret < 0)
> >> +		goto stop_channels;
> >> +
> >> +	/* Enable conversion triggered by SPI clock*/
> >> +	ret = regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
> >> +				 DFSDM_CR1_RCONT_MASK, cont_en);
> >> +	if (ret < 0)
> >> +		goto stop_channels;
> >> +
> >>  	ret = stm32_dfsdm_start_filter(adc->dfsdm, adc->fl_id);
> >>  	if (ret < 0)
> >>  		goto stop_channels;
> >> @@ -398,6 +487,231 @@ static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc)
> >>  	stm32_dfsdm_stop_channel(adc->dfsdm, adc->ch_id);
> >>  }
> >>  
> >> +static int stm32_dfsdm_set_watermark(struct iio_dev *indio_dev,
> >> +				     unsigned int val)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	unsigned int watermark = DFSDM_DMA_BUFFER_SIZE / 2;
> >> +
> >> +	/*
> >> +	 * DMA cyclic transfers are used, buffer is split into two periods.
> >> +	 * There should be :
> >> +	 * - always one buffer (period) DMA is working on
> >> +	 * - one buffer (period) driver pushed to ASoC side.
> >> +	 */
> >> +	watermark = min(watermark, val * (unsigned int)(sizeof(u32)));
> >> +	adc->buf_sz = watermark * 2;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static unsigned int stm32_dfsdm_adc_dma_residue(struct stm32_dfsdm_adc *adc)
> >> +{
> >> +	struct dma_tx_state state;
> >> +	enum dma_status status;
> >> +
> >> +	status = dmaengine_tx_status(adc->dma_chan,
> >> +				     adc->dma_chan->cookie,
> >> +				     &state);
> >> +	if (status == DMA_IN_PROGRESS) {
> >> +		/* Residue is size in bytes from end of buffer */
> >> +		unsigned int i = adc->buf_sz - state.residue;
> >> +		unsigned int size;
> >> +
> >> +		/* Return available bytes */
> >> +		if (i >= adc->bufi)
> >> +			size = i - adc->bufi;
> >> +		else
> >> +			size = adc->buf_sz + i - adc->bufi;
> >> +
> >> +		return size;
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void stm32_dfsdm_audio_dma_buffer_done(void *data)
> >> +{
> >> +	struct iio_dev *indio_dev = data;
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	int available = stm32_dfsdm_adc_dma_residue(adc);
> >> +	size_t old_pos;
> >> +
> >> +	/*
> >> +	 * FIXME: In Kernel interface does not support cyclic DMA buffer,and
> >> +	 * offers only an interface to push data samples per samples.
> >> +	 * For this reason IIO buffer interface is not used and interface is
> >> +	 * bypassed using a private callback registered by ASoC.
> >> +	 * This should be a temporary solution waiting a cyclic DMA engine
> >> +	 * support in IIO.
> >> +	 */
> >> +
> >> +	dev_dbg(&indio_dev->dev, "%s: pos = %d, available = %d\n", __func__,
> >> +		adc->bufi, available);
> >> +	old_pos = adc->bufi;
> >> +
> >> +	while (available >= indio_dev->scan_bytes) {
> >> +		u32 *buffer = (u32 *)&adc->rx_buf[adc->bufi];
> >> +
> >> +		/* Mask 8 LSB that contains the channel ID */
> >> +		*buffer = (*buffer & 0xFFFFFF00) << 8;
> >> +		available -= indio_dev->scan_bytes;
> >> +		adc->bufi += indio_dev->scan_bytes;
> >> +		if (adc->bufi >= adc->buf_sz) {
> >> +			if (adc->cb)
> >> +				adc->cb(&adc->rx_buf[old_pos],
> >> +					 adc->buf_sz - old_pos, adc->cb_priv);
> >> +			adc->bufi = 0;
> >> +			old_pos = 0;
> >> +		}
> >> +	}
> >> +	if (adc->cb)
> >> +		adc->cb(&adc->rx_buf[old_pos], adc->bufi - old_pos,
> >> +			adc->cb_priv);
> >> +}
> >> +
> >> +static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	struct dma_async_tx_descriptor *desc;
> >> +	dma_cookie_t cookie;
> >> +	int ret;
> >> +
> >> +	if (!adc->dma_chan)
> >> +		return -EINVAL;
> >> +
> >> +	dev_dbg(&indio_dev->dev, "%s size=%d watermark=%d\n", __func__,
> >> +		adc->buf_sz, adc->buf_sz / 2);
> >> +
> >> +	/* Prepare a DMA cyclic transaction */
> >> +	desc = dmaengine_prep_dma_cyclic(adc->dma_chan,
> >> +					 adc->dma_buf,
> >> +					 adc->buf_sz, adc->buf_sz / 2,
> >> +					 DMA_DEV_TO_MEM,
> >> +					 DMA_PREP_INTERRUPT);
> >> +	if (!desc)
> >> +		return -EBUSY;
> >> +
> >> +	desc->callback = stm32_dfsdm_audio_dma_buffer_done;
> >> +	desc->callback_param = indio_dev;
> >> +
> >> +	cookie = dmaengine_submit(desc);
> >> +	ret = dma_submit_error(cookie);
> >> +	if (ret) {
> >> +		dmaengine_terminate_all(adc->dma_chan);
> >> +		return ret;
> >> +	}
> >> +
> >> +	/* Issue pending DMA requests */
> >> +	dma_async_issue_pending(adc->dma_chan);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	int ret;
> >> +
> >> +	/* Reset adc buffer index */
> >> +	adc->bufi = 0;
> >> +
> >> +	ret = stm32_dfsdm_start_dfsdm(adc->dfsdm);
> >> +	if (ret < 0)
> >> +		return ret;
> >> +
> >> +	ret = stm32_dfsdm_start_conv(adc, true);
> >> +	if (ret) {
> >> +		dev_err(&indio_dev->dev, "Can't start conversion\n");
> >> +		goto stop_dfsdm;
> >> +	}
> >> +
> >> +	if (adc->dma_chan) {
> >> +		ret = stm32_dfsdm_adc_dma_start(indio_dev);
> >> +		if (ret) {
> >> +			dev_err(&indio_dev->dev, "Can't start DMA\n");
> >> +			goto err_stop_conv;
> >> +		}
> >> +	}
> >> +
> >> +	return 0;
> >> +
> >> +err_stop_conv:
> >> +	stm32_dfsdm_stop_conv(adc);
> >> +stop_dfsdm:
> >> +	stm32_dfsdm_stop_dfsdm(adc->dfsdm);
> >> +
> >> +	return ret;
> >> +}
> >> +
> >> +static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +
> >> +	if (adc->dma_chan)
> >> +		dmaengine_terminate_all(adc->dma_chan);
> >> +
> >> +	stm32_dfsdm_stop_conv(adc);
> >> +
> >> +	stm32_dfsdm_stop_dfsdm(adc->dfsdm);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static const struct iio_buffer_setup_ops stm32_dfsdm_buffer_setup_ops = {
> >> +	.postenable = &stm32_dfsdm_postenable,
> >> +	.predisable = &stm32_dfsdm_predisable,
> >> +};
> >> +
> >> +/**
> >> + * stm32_dfsdm_get_buff_cb() - register a callback that will be called when
> >> + *                             DMA transfer period is achieved.
> >> + *
> >> + * @iio_dev: Handle to IIO device.
> >> + * @cb: Pointer to callback function:
> >> + *      - data: pointer to data buffer
> >> + *      - size: size in byte of the data buffer
> >> + *      - private: pointer to consumer private structure.
> >> + * @private: Pointer to consumer private structure.
> >> + */
> >> +int stm32_dfsdm_get_buff_cb(struct iio_dev *iio_dev,
> >> +			    int (*cb)(const void *data, size_t size,
> >> +				      void *private),
> >> +			    void *private)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc;
> >> +
> >> +	if (!iio_dev)
> >> +		return -EINVAL;
> >> +	adc = iio_priv(iio_dev);
> >> +
> >> +	adc->cb = cb;
> >> +	adc->cb_priv = private;
> >> +
> >> +	return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(stm32_dfsdm_get_buff_cb);
> >> +
> >> +/**
> >> + * stm32_dfsdm_release_buff_cb - unregister buffer callback
> >> + *
> >> + * @iio_dev: Handle to IIO device.
> >> + */
> >> +int stm32_dfsdm_release_buff_cb(struct iio_dev *iio_dev)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc;
> >> +
> >> +	if (!iio_dev)
> >> +		return -EINVAL;
> >> +	adc = iio_priv(iio_dev);
> >> +
> >> +	adc->cb = NULL;
> >> +	adc->cb_priv = NULL;
> >> +
> >> +	return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(stm32_dfsdm_release_buff_cb);
> >> +
> >>  static int stm32_dfsdm_single_conv(struct iio_dev *indio_dev,
> >>  				   const struct iio_chan_spec *chan, int *res)
> >>  {
> >> @@ -453,15 +767,41 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
> >>  {
> >>  	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >>  	struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
> >> +	struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[adc->ch_id];
> >> +	unsigned int spi_freq = adc->spi_freq;
> >>  	int ret = -EINVAL;
> >>  
> >> -	if (mask == IIO_CHAN_INFO_OVERSAMPLING_RATIO) {
> >> +	switch (mask) {
> >> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> >>  		ret = stm32_dfsdm_set_osrs(fl, 0, val);
> >>  		if (!ret)
> >>  			adc->oversamp = val;
> >> +
> >> +		return ret;
> >> +
> >> +	case IIO_CHAN_INFO_SAMP_FREQ:
> >> +		if (!val)
> >> +			return -EINVAL;
> >> +		if (ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
> >> +			spi_freq = adc->dfsdm->spi_master_freq;
> >> +
> >> +		if (spi_freq % val)
> >> +			dev_warn(&indio_dev->dev,
> >> +				 "Sampling rate not accurate (%d)\n",
> >> +				 spi_freq / (spi_freq / val));
> >> +
> >> +		ret = stm32_dfsdm_set_osrs(fl, 0, (spi_freq / val));
> >> +		if (ret < 0) {
> >> +			dev_err(&indio_dev->dev,
> >> +				"Not able to find parameter that match!\n");
> >> +			return ret;
> >> +		}
> >> +		adc->sample_freq = val;
> >> +
> >> +		return 0;
> >>  	}
> >>  
> >> -	return ret;
> >> +	return -EINVAL;
> >>  }
> >>  
> >>  static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev,
> >> @@ -494,11 +834,22 @@ static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev,
> >>  		*val = adc->oversamp;
> >>  
> >>  		return IIO_VAL_INT;
> >> +
> >> +	case IIO_CHAN_INFO_SAMP_FREQ:
> >> +		*val = adc->sample_freq;
> >> +
> >> +		return IIO_VAL_INT;
> >>  	}
> >>  
> >>  	return -EINVAL;
> >>  }
> >>  
> >> +static const struct iio_info stm32_dfsdm_info_audio = {
> >> +	.hwfifo_set_watermark = stm32_dfsdm_set_watermark,
> >> +	.read_raw = stm32_dfsdm_read_raw,
> >> +	.write_raw = stm32_dfsdm_write_raw,
> >> +};
> >> +
> >>  static const struct iio_info stm32_dfsdm_info_adc = {
> >>  	.read_raw = stm32_dfsdm_read_raw,
> >>  	.write_raw = stm32_dfsdm_write_raw,
> >> @@ -531,6 +882,60 @@ static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
> >>  	return IRQ_HANDLED;
> >>  }
> >>  
> >> +/*
> >> + * Define external info for SPI Frequency and audio sampling rate that can be
> >> + * configured by ASoC driver through consumer.h API
> >> + */
> >> +static const struct iio_chan_spec_ext_info dfsdm_adc_audio_ext_info[] = {
> >> +	/* spi_clk_freq : clock freq on SPI/manchester bus used by channel */
> >> +	{
> >> +		.name = "spi_clk_freq",
> >> +		.shared = IIO_SHARED_BY_TYPE,
> >> +		.read = dfsdm_adc_audio_get_spiclk,
> >> +		.write = dfsdm_adc_audio_set_spiclk,
> >> +	},
> >> +	{},
> >> +};
> >> +
> >> +static int stm32_dfsdm_dma_request(struct iio_dev *indio_dev)
> >> +{
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	struct dma_slave_config config;
> >> +	int ret;
> >> +
> >> +	adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
> >> +	if (!adc->dma_chan)
> >> +		return -EINVAL;
> >> +
> >> +	adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
> >> +					 DFSDM_DMA_BUFFER_SIZE,
> >> +					 &adc->dma_buf, GFP_KERNEL);
> >> +	if (!adc->rx_buf) {
> >> +		ret = -ENOMEM;
> >> +		goto err_release;
> >> +	}
> >> +
> >> +	/* Configure DMA channel to read data register */
> >> +	memset(&config, 0, sizeof(config));
> >> +	config.src_addr = (dma_addr_t)adc->dfsdm->phys_base;
> >> +	config.src_addr += DFSDM_RDATAR(adc->fl_id);
> >> +	config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> >> +
> >> +	ret = dmaengine_slave_config(adc->dma_chan, &config);
> >> +	if (ret)
> >> +		goto err_free;
> >> +
> >> +	return 0;
> >> +
> >> +err_free:
> >> +	dma_free_coherent(adc->dma_chan->device->dev, DFSDM_DMA_BUFFER_SIZE,
> >> +			  adc->rx_buf, adc->dma_buf);
> >> +err_release:
> >> +	dma_release_channel(adc->dma_chan);
> >> +
> >> +	return ret;
> >> +}
> >> +
> >>  static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev,
> >>  					 struct iio_chan_spec *ch)
> >>  {
> >> @@ -551,7 +956,12 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev,
> >>  	ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> >>  	ch->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO);
> >>  
> >> -	ch->scan_type.sign = 'u';
> >> +	if (adc->dev_data->type == DFSDM_AUDIO) {
> >> +		ch->scan_type.sign = 's';
> >> +		ch->ext_info = dfsdm_adc_audio_ext_info;
> >> +	} else {
> >> +		ch->scan_type.sign = 'u';
> >> +	}
> >>  	ch->scan_type.realbits = 24;
> >>  	ch->scan_type.storagebits = 32;
> >>  	adc->ch_id = ch->channel;
> >> @@ -560,6 +970,64 @@ static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev,
> >>  					  &adc->dfsdm->ch_list[ch->channel]);
> >>  }
> >>  
> >> +static int stm32_dfsdm_audio_init(struct iio_dev *indio_dev)
> >> +{
> >> +	struct iio_chan_spec *ch;
> >> +	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> >> +	struct stm32_dfsdm_channel *d_ch;
> >> +	int ret;
> >> +
> >> +	ret = stm32_dfsdm_dma_request(indio_dev);
> >> +	if (ret) {
> >> +		dev_err(&indio_dev->dev, "DMA request failed\n");
> >> +		return ret;
> >> +	}
> >> +
> >> +	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
> >> +
> >> +	ret = iio_triggered_buffer_setup(indio_dev,
> >> +					 &iio_pollfunc_store_time,
> >> +					 NULL,
> >> +					 &stm32_dfsdm_buffer_setup_ops);
> >> +	if (ret) {
> >> +		dev_err(&indio_dev->dev, "Buffer setup failed\n");
> >> +		goto err_dma_disable;
> >> +	}
> >> +
> >> +	ch = devm_kzalloc(&indio_dev->dev, sizeof(*ch), GFP_KERNEL);
> >> +	if (!ch)
> >> +		return -ENOMEM;
> >> +
> >> +	ch->scan_index = 0;
> >> +	ret = stm32_dfsdm_adc_chan_init_one(indio_dev, ch);
> >> +	if (ret < 0) {
> >> +		dev_err(&indio_dev->dev, "channels init failed\n");
> >> +		goto err_buffer_cleanup;
> >> +	}
> >> +	ch->info_mask_separate = BIT(IIO_CHAN_INFO_SAMP_FREQ);
> >> +
> >> +	d_ch = &adc->dfsdm->ch_list[adc->ch_id];
> >> +	if (d_ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
> >> +		adc->spi_freq = adc->dfsdm->spi_master_freq;
> >> +
> >> +	indio_dev->num_channels = 1;
> >> +	indio_dev->channels = ch;
> >> +
> >> +	return 0;
> >> +
> >> +err_buffer_cleanup:
> >> +	iio_triggered_buffer_cleanup(indio_dev);
> >> +
> >> +err_dma_disable:
> >> +	if (adc->dma_chan) {
> >> +		dma_free_coherent(adc->dma_chan->device->dev,
> >> +				  DFSDM_DMA_BUFFER_SIZE,
> >> +				  adc->rx_buf, adc->dma_buf);
> >> +		dma_release_channel(adc->dma_chan);
> >> +	}
> >> +	return ret;
> >> +}
> >> +
> >>  static int stm32_dfsdm_adc_init(struct iio_dev *indio_dev)
> >>  {
> >>  	struct iio_chan_spec *ch;
> >> @@ -612,11 +1080,20 @@ static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_adc_data = {
> >>  	.init = stm32_dfsdm_adc_init,
> >>  };
> >>  
> >> +static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_audio_data = {
> >> +	.type = DFSDM_AUDIO,
> >> +	.init = stm32_dfsdm_audio_init,
> >> +};
> >> +
> >>  static const struct of_device_id stm32_dfsdm_adc_match[] = {
> >>  	{
> >>  		.compatible = "st,stm32-dfsdm-adc",
> >>  		.data = &stm32h7_dfsdm_adc_data,
> >>  	},
> >> +	{
> >> +		.compatible = "st,stm32-dfsdm-dmic",
> >> +		.data = &stm32h7_dfsdm_audio_data,
> >> +	},
> >>  	{}
> >>  };
> >>  
> >> @@ -667,8 +1144,13 @@ static int stm32_dfsdm_adc_probe(struct platform_device *pdev)
> >>  	name = devm_kzalloc(dev, sizeof("dfsdm-adc0"), GFP_KERNEL);
> >>  	if (!name)
> >>  		return -ENOMEM;
> >> -	iio->info = &stm32_dfsdm_info_adc;
> >> -	snprintf(name, sizeof("dfsdm-adc0"), "dfsdm-adc%d", adc->fl_id);
> >> +	if (dev_data->type == DFSDM_AUDIO) {
> >> +		iio->info = &stm32_dfsdm_info_audio;
> >> +		snprintf(name, sizeof("dfsdm-pdm0"), "dfsdm-pdm%d", adc->fl_id);
> >> +	} else {
> >> +		iio->info = &stm32_dfsdm_info_adc;
> >> +		snprintf(name, sizeof("dfsdm-adc0"), "dfsdm-adc%d", adc->fl_id);
> >> +	}
> >>  	iio->name = name;
> >>  
> >>  	/*
> >> @@ -700,7 +1182,10 @@ static int stm32_dfsdm_adc_probe(struct platform_device *pdev)
> >>  	if (ret < 0)
> >>  		return ret;
> >>  
> >> -	return iio_device_register(iio);
> >> +	iio_device_register(iio);
> >> +	if (dev_data->type == DFSDM_AUDIO)
> >> +		return devm_of_platform_populate(&pdev->dev);
> >> +	return 0;
> >>  }
> >>  
> >>  static int stm32_dfsdm_adc_remove(struct platform_device *pdev)
> >> @@ -709,7 +1194,14 @@ static int stm32_dfsdm_adc_remove(struct platform_device *pdev)
> >>  	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
> >>  
> >>  	iio_device_unregister(indio_dev);
> >> -
> >> +	if (indio_dev->pollfunc)
> >> +		iio_triggered_buffer_cleanup(indio_dev);
> >> +	if (adc->dma_chan) {
> >> +		dma_free_coherent(adc->dma_chan->device->dev,
> >> +				  DFSDM_DMA_BUFFER_SIZE,
> >> +				  adc->rx_buf, adc->dma_buf);
> >> +		dma_release_channel(adc->dma_chan);
> >> +	}
> >>  	return 0;
> >>  }
> >>  
> >> diff --git a/include/linux/iio/adc/stm32-dfsdm-adc.h b/include/linux/iio/adc/stm32-dfsdm-adc.h
> >> new file mode 100644
> >> index 0000000..e7dc7a5
> >> --- /dev/null
> >> +++ b/include/linux/iio/adc/stm32-dfsdm-adc.h
> >> @@ -0,0 +1,18 @@
> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> +/*
> >> + * This file discribe the STM32 DFSDM IIO driver API for audio part
> >> + *
> >> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
> >> + * Author(s): Arnaud Pouliquen <arnaud.pouliquen at st.com>.
> >> + */
> >> +
> >> +#ifndef STM32_DFSDM_ADC_H
> >> +#define STM32_DFSDM_ADC_H
> >> +
> >> +int stm32_dfsdm_get_buff_cb(struct iio_dev *iio_dev,
> >> +			    int (*cb)(const void *data, size_t size,
> >> +				      void *private),
> >> +			    void *private);
> >> +int stm32_dfsdm_release_buff_cb(struct iio_dev *iio_dev);
> >> +
> >> +#endif  
> >   
> 
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