Re: [PATCH v4 09/12] IIO: ADC: add stm32 DFSDM support for PDM microphone

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On 11/19/2017 03:18 PM, Jonathan Cameron wrote:
> On Thu, 9 Nov 2017 11:12:31 +0100
> Arnaud Pouliquen <arnaud.pouliquen@xxxxxx> 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@xxxxxx>
> 
> A few minor points inline.  I'm not sure I really 'like' the
> solution we've ended up with currently but if it works it will
> do just fine for now :)
> 
> Jonathan
> 
> 
>> ---
>> V3 -> V4 changes:
>>  - Merge audio implementation in stm32-dfsdm-adc.c instead of creating separate file
>>  - Add sysfs document for exported attributes
>> 
>>  .../ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32      |  22 +
>>  drivers/iio/adc/stm32-dfsdm-adc.c                  | 517 ++++++++++++++++++++-
>>  include/linux/iio/adc/stm32-dfsdm-adc.h            |  27 ++
>>  3 files changed, 562 insertions(+), 4 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..0ce5508
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32
>> @@ -0,0 +1,22 @@
>> +What:                /sys/bus/iio/devices/iio:deviceX/in_voltage_audio_sampling_rate
>> +KernelVersion:       4.14
>> +Contact:     arnaud.pouliquen@xxxxxx
>> +Description:
>> +             For audio purpose only.
>> +             Used by audio driver to set/get the audio sampling rate.
>> +             Reading returns current audio sample frequency.
>> +             Writing value before starting conversions.
> 
> I would like to see a note here on why sampling_frequency can't be used for
> this purpose.
The IIO_CHAN_INFO_SAMP_FREQ can not be used because consumer API allows
only to access to ext_info attributes.
An alternate is to export channel attribute functions the consumer API.
- iio_read_channel_attribute (already exist)
- iio_write_channel_attribute

Please, tell me your preference.
> 
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/in_voltage_spi_clk_freq
>> +KernelVersion:       4.14
>> +Contact:     arnaud.pouliquen@xxxxxx
>> +Description:
>> +             For audio purpose only.
>> +             Used by audio driver to set/get the spi input frequency
>> +             when DFSDM SPI input channel is in slave mode.
>> +             if DFSDM input is SPI master
>> +                     Reading  0,
>> +                     error on writing
>> +             If DFSDM input is SPI Slave:
>> +             Reading returns value previously set.
>> +             Writing value before starting conversions.
> 
> I'd like a brief note here on why we might change this at runtime.
Sure, i will add it, output audio sample frequency is computed from the
SPI_clock bus. User can need to change it depending on the Audio
frequency configured for the audio card. This configuration occurs after
audio driver probing.
> 
>> diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
>> index f9419ab..f0952e26 100644
>> --- a/drivers/iio/adc/stm32-dfsdm-adc.c
>> +++ b/drivers/iio/adc/stm32-dfsdm-adc.c
>> @@ -19,11 +19,15 @@
>>   * this program. If not, see <http://www.gnu.org/licenses/>.
>>   */
>
>> +#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/platform_device.h>
>> @@ -32,6 +36,8 @@
>
>>  #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))
>> @@ -71,6 +77,18 @@ 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 {
>> @@ -364,10 +382,110 @@ int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
>>        return 0;
>>  }
>
>> +static ssize_t dfsdm_adc_audio_get_rate(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->sample_freq);
>> +}
>> +
>> +static ssize_t dfsdm_adc_audio_set_rate(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 spi_freq = adc->spi_freq;
>> +     unsigned int sample_freq;
>> +     int ret;
>> +
>> +     ret = kstrtoint(buf, 0, &sample_freq);
>> +     if (ret)
>> +             return ret;
>> +     dev_dbg(&indio_dev->dev, "Requested sample_freq :%d\n", sample_freq);
>> +
>> +     if (!sample_freq)
>> +             return -EINVAL;
>> +
>> +     if (ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
>> +             spi_freq = adc->dfsdm->spi_master_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,
>> +                     "Not able to find filter parameter that match!\n");
>> +             return ret;
>> +     }
>> +     adc->sample_freq = sample_freq;
>> +
>> +     return len;
>> +}
>> +
>> +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;
>> +}
> blank line here please.
> 
>>  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)
>> @@ -378,6 +496,24 @@ 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;
>> @@ -411,6 +547,241 @@ 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 const struct iio_info stm32_dfsdm_info_audio = {
>> +     .hwfifo_set_watermark = stm32_dfsdm_set_watermark,
>> +     .driver_module = THIS_MODULE,
> 
> This has gone - now handled by macro magic...
> 
>> +};
>> +
>> +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: Buffer 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.
> More specifically the in kernel interfaces don't support dma cyclic
> buffers.  We can already do them to userspace.  Doesn't really matter
> though!
Ok I will change comment
> 
>> +      */
>> +
>> +     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.
> Please run kernel-doc over this file. I'm fairly sure this isn't
> quite meeting the spec...
Sorry it is not crystal clear for me, could you detail what you would
mean by
"I'm fairly sure this isn't quite meeting the spec.."?

> 
>> + *
>> + * @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);
>> +
>> +     if (iio_dev !=  iio_priv_to_dev(adc))
>> +             return -EINVAL;
> Same as for the case below..
> 
>> +
>> +     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);
>> +
>> +     if (iio_dev !=  iio_priv_to_dev(adc))
>> +             return -EINVAL;
> I can't immediately spot why this could ever fail so we definitely
> need a comment here saying what it is protecting against!
You're right , it is over-protection, i will suppress it

Thanks
Arnaud

> 
>> +     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)
>>  {
>> @@ -544,6 +915,67 @@ 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[] = {
>> +     /* filter oversampling: Post filter oversampling ratio */
>> +     {
>> +             .name = "audio_sampling_rate",
>> +             .shared = IIO_SHARED_BY_TYPE,
>> +             .read = dfsdm_adc_audio_get_rate,
>> +             .write = dfsdm_adc_audio_set_rate,
>> +     },
>> +     /* data_right_bit_shift : Filter output data shifting */
>> +     {
>> +             .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)
>>  {
>> @@ -564,7 +996,12 @@ 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;
>> @@ -573,6 +1010,58 @@ 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);
>> +     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;
>> +     }
>> +
>> +     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;
>> @@ -625,10 +1114,18 @@ 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,
>> +     },
>>        {}
>>  };
>
>> @@ -679,8 +1176,13 @@ 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;
>
>>        /*
>> @@ -721,7 +1223,14 @@ 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..6885645
>> --- /dev/null
>> +++ b/include/linux/iio/adc/stm32-dfsdm-adc.h
>> @@ -0,0 +1,27 @@
>> +/*
>> + * 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@xxxxxx>.
>> + *
>> + * License terms: GPL V2.0.
>> + *
>> + * 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.
>> + */
>> +#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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