[PATCH v3 06/11] IIO: ADC: add stm32 DFSDM support for PDM microphone
Arnaud Pouliquen
arnaud.pouliquen at st.com
Tue Mar 28 00:45:51 PDT 2017
On 03/25/2017 04:59 PM, Jonathan Cameron wrote:
> On 20/03/17 11:29, Arnaud Pouliquen wrote:
>> Please find my comments in-line
>>
>> Thanks and Regards,
>> Arnaud
>>
>> On 03/19/2017 11:38 PM, Jonathan Cameron wrote:
>>> On 17/03/17 14:08, Arnaud Pouliquen wrote:
>>>> Add DFSDM driver to handle PDM audio microphones.
>>>>
>>>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>
>>> So key element here is that we really need to have a proper way of
>>> doing DMA buffer consumers from IIO (as you said in your cover letter).
>>>
>>> Not entirely obvious how to do this. Would like some input from Lars
>>> if possible. I'm afraid I don't have an suitable hardware to try anything
>>> out on (or the time really!). This will obviously be quite different from
>>> the single scan stuff you have seen is there at the moment.
>> I saw 2 other drivers ti_am335x_adc.c and stm32_adc.c) that use cyclic
>> DMA. I suppose that problematics are similar. Perhaps the extra
>> constrains in DFSDM is the in-kernel API used to get the data.
> Absolutely. Cyclic dma is becoming more and more common on SoC ADCs.
> There are a few more fpga based ones in Analog devices tree as well -
> most of those actually do the dma buffer route rather than pushing through
> the normal buffer interface (kfifo effectively). Right now we just
> don't have any means of accessing these dma buffers in kernel.
>
> Unlike the normal consumer interface, I doubt we'll want to do demuxing
> of the stream for this sort of usecase - feels like exclusive use is more
> likely.
>>
>>>
>>> Whether this whole approach makes sense vs doing the dma in the alsa driver
>>> isn't clear to me.
>>>
>>> On the plus side, presumably we'll get love dma ADC support for free
>>> as part of doing it this way ;)
>>>
>>> It's been a while since I looked at the IIO dma buffer stuff at all. Will
>>> try and refresh my memory sometime this week.
>>
>> Ok, i will wait your feedback (and Lars's one) before updating my code
>> for next version.
> It may well be the case that it will take us sometime (when I say us, I mean
> you and Lars ;) to pin down how to do dma buffer consumers, so it may be
> a case of taking the driver in a state close to the current one with the
> intent to switch to a generic way of handling it later.
I had a short discussion with Lars on IIO IRC, seems that he also does
not see a straightforward solution for this IP.
The Fact that audio part is in a separate file should help to rework it
in a generic way.
So i will propose a V4 for upstream, integrating discussed fixes.
Thanks
Arnaud
>
> As long as bindings and userspace don't change we can of course mess with
> anything we like.
>
> Jonathan
>>>
>>> Jonathan
>>>> ---
>>>> drivers/iio/adc/Kconfig | 13 +
>>>> drivers/iio/adc/Makefile | 1 +
>>>> drivers/iio/adc/stm32-dfsdm-audio.c | 720 ++++++++++++++++++++++++++++++
>>>> include/linux/iio/adc/stm32-dfsdm-audio.h | 41 ++
>>>> 4 files changed, 775 insertions(+)
>>>> create mode 100644 drivers/iio/adc/stm32-dfsdm-audio.c
>>>> create mode 100644 include/linux/iio/adc/stm32-dfsdm-audio.h
>>>>
>>>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>>>> index 3e0eb11..c108933 100644
>>>> --- a/drivers/iio/adc/Kconfig
>>>> +++ b/drivers/iio/adc/Kconfig
>>>> @@ -478,6 +478,19 @@ config STM32_DFSDM_ADC
>>>> This driver can also be built as a module. If so, the module
>>>> will be called stm32-dfsdm-adc.
>>>>
>>>> +config STM32_DFSDM_AUDIO
>>>> + tristate "STMicroelectronics STM32 dfsdm audio
>>>> + depends on (ARCH_STM32 && OF) || COMPILE_TEST
>>>> + select STM32_DFSDM_CORE
>>>> + select REGMAP_MMIO
>>>> + select IIO_BUFFER_DMAENGINE
>>>> + help
>>>> + Select this option to support Audio PDM micophone for
>>>> + STMicroelectronics STM32 digital filter for sigma delta converter.
>>>> +
>>>> + This driver can also be built as a module. If so, the module
>>>> + will be called stm32-dfsdm-audio.
>>>> +
>>>> config STX104
>>>> tristate "Apex Embedded Systems STX104 driver"
>>>> depends on X86 && ISA_BUS_API
>>>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>>>> index 161f271..79f975d 100644
>>>> --- a/drivers/iio/adc/Makefile
>>>> +++ b/drivers/iio/adc/Makefile
>>>> @@ -44,6 +44,7 @@ obj-$(CONFIG_STX104) += stx104.o
>>>> obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o
>>>> obj-$(CONFIG_STM32_ADC) += stm32-adc.o
>>>> obj-$(CONFIG_STM32_DFSDM_ADC) += stm32-dfsdm-adc.o
>>>> +obj-$(CONFIG_STM32_DFSDM_AUDIO) += stm32-dfsdm-audio.o
>>>> obj-$(CONFIG_STM32_DFSDM_CORE) += stm32-dfsdm-core.o
>>>> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>>>> obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
>>>> diff --git a/drivers/iio/adc/stm32-dfsdm-audio.c b/drivers/iio/adc/stm32-dfsdm-audio.c
>>>> new file mode 100644
>>>> index 0000000..115ef8f
>>>> --- /dev/null
>>>> +++ b/drivers/iio/adc/stm32-dfsdm-audio.c
>>>> @@ -0,0 +1,720 @@
>>>> +/*
>>>> + * This file is the ADC part of of the STM32 DFSDM driver
>>>> + *
>>>> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
>>>> + * Author: Arnaud Pouliquen <arnaud.pouliquen at st.com>.
>>>> + *
>>>> + * License type: GPLv2
>>>> + *
>>>> + * This program is free software; you can redistribute it and/or modify it
>>>> + * under the terms of the GNU General Public License version 2 as published by
>>>> + * the Free Software Foundation.
>>>> + *
>>>> + * This program is distributed in the hope that it will be useful, but
>>>> + * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
>>>> + * or FITNESS FOR A PARTICULAR PURPOSE.
>>>> + * See the GNU General Public License for more details.
>>>> + *
>>>> + * You should have received a copy of the GNU General Public License along with
>>>> + * this program. If not, see <http://www.gnu.org/licenses/>.
>>>> + */
>>>> +
>>>> +#include <linux/dmaengine.h>
>>>> +#include <linux/dma-mapping.h>
>>>> +#include <linux/interrupt.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/regmap.h>
>>>> +#include <linux/slab.h>
>>>> +
>>>> +#include <linux/iio/buffer.h>
>>>> +#include <linux/iio/hw_consumer.h>
>>>> +#include <linux/iio/sysfs.h>
>>>> +#include <linux/iio/trigger.h>
>>>> +#include <linux/iio/trigger_consumer.h>
>>>> +#include <linux/iio/triggered_buffer.h>
>>>> +
>>>> +#include "stm32-dfsdm.h"
>>>> +
>>>> +#define DFSDM_DMA_BUFFER_SIZE (4 * PAGE_SIZE)
>>>> +
>>>> +struct stm32_dfsdm_audio {
>>>> + struct stm32_dfsdm *dfsdm;
>>>> + unsigned int fl_id;
>>>> + unsigned int ch_id;
>>>> + unsigned int spi_freq; /* SPI bus clock frequency */
>>>> + unsigned int sample_freq; /* Sample frequency after filter decimation */
>>>> +
>>>> + 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;
>>>> +
>>>> + int (*cb)(const void *data, size_t size, void *cb_priv);
>>>> + void *cb_priv;
>>>> +};
>>>> +
>>>> +const char *stm32_dfsdm_spi_trigger = DFSDM_SPI_TRIGGER_NAME;
>>>> +
>>>> +static ssize_t dfsdm_audio_get_rate(struct iio_dev *indio_dev, uintptr_t priv,
>>>> + const struct iio_chan_spec *chan, char *buf)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> +
>>>> + return snprintf(buf, PAGE_SIZE, "%d\n", pdmc->sample_freq);
>>>> +}
>>>> +
>>>> +static ssize_t dfsdm_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_audio *pdmc = iio_priv(indio_dev);
>>>> + struct stm32_dfsdm_filter *fl = &pdmc->dfsdm->fl_list[pdmc->fl_id];
>>>> + struct stm32_dfsdm_channel *ch = &pdmc->dfsdm->ch_list[pdmc->ch_id];
>>>> + unsigned int spi_freq = pdmc->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 = pdmc->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;
>>>> + }
>>>> + pdmc->sample_freq = sample_freq;
>>>> +
>>>> + return len;
>>>> +}
>>>> +
>>>> +static ssize_t dfsdm_audio_get_spiclk(struct iio_dev *indio_dev, uintptr_t priv,
>>>> + const struct iio_chan_spec *chan,
>>>> + char *buf)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> +
>>>> + return snprintf(buf, PAGE_SIZE, "%d\n", pdmc->spi_freq);
>>>> +}
>>>> +
>>>> +static ssize_t dfsdm_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_audio *pdmc = iio_priv(indio_dev);
>>>> + struct stm32_dfsdm_filter *fl = &pdmc->dfsdm->fl_list[pdmc->fl_id];
>>>> + struct stm32_dfsdm_channel *ch = &pdmc->dfsdm->ch_list[pdmc->ch_id];
>>>> + unsigned int sample_freq = pdmc->sample_freq;
>>>> + unsigned int spi_freq;
>>>> + int ret;
>>>> +
>>>> + /* 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;
>>>> +
>>>> + dev_dbg(&indio_dev->dev, "Requested frequency :%d\n", spi_freq);
>>>> + 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;
>>>> + }
>>>> + }
>>>> + pdmc->spi_freq = spi_freq;
>>>> +
>>>> + return len;
>>>> +}
>>>> +
>>>> +/*
>>>> + * 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_ext_info[] = {
>>>> + /* filter oversampling: Post filter oversampling ratio */
>>>> + {
>>>> + .name = "audio_sampling_rate",
>>>> + .shared = IIO_SHARED_BY_TYPE,
>>>> + .read = dfsdm_audio_get_rate,
>>>> + .write = dfsdm_audio_set_rate,
>>>> + },
>>>> + /* data_right_bit_shift : Filter output data shifting */
>>>> + {
>>>> + .name = "spi_clk_freq",
>>>> + .shared = IIO_SHARED_BY_TYPE,
>>>> + .read = dfsdm_audio_get_spiclk,
>>>> + .write = dfsdm_audio_set_spiclk,
>>>> + },
>>>> + {},
>>>> +};
>>>> +
>>>> +static int stm32_dfsdm_start_conv(struct stm32_dfsdm_audio *pdmc, bool single)
>>>> +{
>>>> + struct regmap *regmap = pdmc->dfsdm->regmap;
>>>> + int ret;
>>>> +
>>>> + ret = stm32_dfsdm_start_dfsdm(pdmc->dfsdm);
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + ret = stm32_dfsdm_start_channel(pdmc->dfsdm, pdmc->ch_id);
>>>> + if (ret < 0)
>>>> + goto stop_dfsdm;
>>>> +
>>>> + ret = stm32_dfsdm_filter_configure(pdmc->dfsdm, pdmc->fl_id,
>>>> + pdmc->ch_id);
>>>> + if (ret < 0)
>>>> + goto stop_channels;
>>>> +
>>>> + /* Enable DMA transfer*/
>>>> + ret = regmap_update_bits(regmap, DFSDM_CR1(pdmc->fl_id),
>>>> + DFSDM_CR1_RDMAEN_MASK, DFSDM_CR1_RDMAEN(1));
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + /* Enable conversion triggered by SPI clock*/
>>>> + ret = regmap_update_bits(regmap, DFSDM_CR1(pdmc->fl_id),
>>>> + DFSDM_CR1_RCONT_MASK, DFSDM_CR1_RCONT(1));
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + ret = stm32_dfsdm_start_filter(pdmc->dfsdm, pdmc->fl_id);
>>>> + if (ret < 0)
>>>> + goto stop_channels;
>>>> +
>>>> + return 0;
>>>> +
>>>> +stop_channels:
>>>> + stm32_dfsdm_stop_channel(pdmc->dfsdm, pdmc->fl_id);
>>>> +stop_dfsdm:
>>>> + stm32_dfsdm_stop_dfsdm(pdmc->dfsdm);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_audio *pdmc)
>>>> +{
>>>> + stm32_dfsdm_stop_filter(pdmc->dfsdm, pdmc->fl_id);
>>>> +
>>>> + stm32_dfsdm_stop_channel(pdmc->dfsdm, pdmc->ch_id);
>>>> +
>>>> + stm32_dfsdm_stop_dfsdm(pdmc->dfsdm);
>>>> +}
>>>> +
>>>> +static int stm32_dfsdm_set_watermark(struct iio_dev *indio_dev,
>>>> + unsigned int val)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = 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)));
>>>> + pdmc->buf_sz = watermark * 2;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +int stm32_dfsdm_validate_trigger(struct iio_dev *indio_dev,
>>>> + struct iio_trigger *trig)
>>>> +{
>>>> + if (!strcmp(stm32_dfsdm_spi_trigger, trig->name))
>>>> + return 0;
>>>> +
>>>> + return -EINVAL;
>>>> +}
>>>> +
>>>> +static const struct iio_info stm32_dfsdm_info_pdmc = {
>>>> + .hwfifo_set_watermark = stm32_dfsdm_set_watermark,
>>>> + .driver_module = THIS_MODULE,
>>>> + .validate_trigger = stm32_dfsdm_validate_trigger,
>>>> +};
>>>> +
>>>> +static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = arg;
>>>> + struct iio_dev *indio_dev = iio_priv_to_dev(pdmc);
>>>> + struct regmap *regmap = pdmc->dfsdm->regmap;
>>>> + unsigned int status;
>>>> +
>>>> + regmap_read(regmap, DFSDM_ISR(pdmc->fl_id), &status);
>>>> +
>>>> + if (status & DFSDM_ISR_ROVRF_MASK) {
>>>> + dev_err(&indio_dev->dev, "Unexpected Conversion overflow\n");
>>>> + regmap_update_bits(regmap, DFSDM_ICR(pdmc->fl_id),
>>>> + DFSDM_ICR_CLRROVRF_MASK,
>>>> + DFSDM_ICR_CLRROVRF_MASK);
>>>> + }
>>>> +
>>>> + return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static unsigned int stm32_dfsdm_audio_avail_data(struct stm32_dfsdm_audio *pdmc)
>>>> +{
>>>> + struct dma_tx_state state;
>>>> + enum dma_status status;
>>>> +
>>>> + status = dmaengine_tx_status(pdmc->dma_chan,
>>>> + pdmc->dma_chan->cookie,
>>>> + &state);
>>>> + if (status == DMA_IN_PROGRESS) {
>>>> + /* Residue is size in bytes from end of buffer */
>>>> + unsigned int i = pdmc->buf_sz - state.residue;
>>>> + unsigned int size;
>>>> +
>>>> + /* Return available bytes */
>>>> + if (i >= pdmc->bufi)
>>>> + size = i - pdmc->bufi;
>>>> + else
>>>> + size = pdmc->buf_sz + i - pdmc->bufi;
>>>> +
>>>> + return size;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static void stm32_dfsdm_audio_dma_buffer_done(void *data)
>>>> +{
>>>> + struct iio_dev *indio_dev = data;
>>>> +
>>>> + iio_trigger_poll_chained(indio_dev->trig);
>>> This shouldn't be going through the trigger infrastructure at all really.
>>> I'm not 100% sure what doing so is gaining you...
>> Yes i will clean trigger part and call directly the ASoC callback here.
>>>> +}
>>>> +
>>>> +static int stm32_dfsdm_audio_dma_start(struct iio_dev *indio_dev)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> + struct dma_async_tx_descriptor *desc;
>>>> + dma_cookie_t cookie;
>>>> + int ret;
>>>> +
>>>> + if (!pdmc->dma_chan)
>>>> + return -EINVAL;
>>>> +
>>>> + dev_dbg(&indio_dev->dev, "%s size=%d watermark=%d\n", __func__,
>>>> + pdmc->buf_sz, pdmc->buf_sz / 2);
>>>> +
>>>> + /* Prepare a DMA cyclic transaction */
>>>> + desc = dmaengine_prep_dma_cyclic(pdmc->dma_chan,
>>>> + pdmc->dma_buf,
>>>> + pdmc->buf_sz, pdmc->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(pdmc->dma_chan);
>>>> + return ret;
>>>> + }
>>>> +
>>>> + /* Issue pending DMA requests */
>>>> + dma_async_issue_pending(pdmc->dma_chan);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> + int ret;
>>>> +
>>>> + dev_dbg(&indio_dev->dev, "%s\n", __func__);
>>>> + /* Reset pdmc buffer index */
>>>> + pdmc->bufi = 0;
>>>> +
>>>> + ret = stm32_dfsdm_start_conv(pdmc, false);
>>>> + if (ret) {
>>>> + dev_err(&indio_dev->dev, "Can't start conversion\n");
>>>> + return ret;
>>>> + }
>>>> +
>>>> + ret = stm32_dfsdm_audio_dma_start(indio_dev);
>>>> + if (ret) {
>>>> + dev_err(&indio_dev->dev, "Can't start DMA\n");
>>>> + goto err_stop_conv;
>>>> + }
>>>> +
>>>> + ret = iio_triggered_buffer_postenable(indio_dev);
>>>> + if (ret < 0) {
>>>> + dev_err(&indio_dev->dev, "%s :%d\n", __func__, __LINE__);
>>>> + goto err_stop_dma;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +
>>>> +err_stop_dma:
>>>> + if (pdmc->dma_chan)
>>>> + dmaengine_terminate_all(pdmc->dma_chan);
>>>> +err_stop_conv:
>>>> + stm32_dfsdm_stop_conv(pdmc);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> + int ret;
>>>> +
>>>> + dev_dbg(&indio_dev->dev, "%s\n", __func__);
>>>> + ret = iio_triggered_buffer_predisable(indio_dev);
>>>> + if (ret < 0)
>>>> + dev_err(&indio_dev->dev, "Predisable failed\n");
>>>> +
>>>> + if (pdmc->dma_chan)
>>>> + dmaengine_terminate_all(pdmc->dma_chan);
>>>> +
>>>> + stm32_dfsdm_stop_conv(pdmc);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static const struct iio_buffer_setup_ops stm32_dfsdm_buffer_setup_ops = {
>>>> + .postenable = &stm32_dfsdm_postenable,
>>>> + .predisable = &stm32_dfsdm_predisable,
>>>> +};
>>>> +
>>>> +static irqreturn_t stm32_dfsdm_audio_trigger_handler(int irq, void *p)
>>>> +{
>>> OK. So now I kind of understand what the trigger provided in the adc driver
>>> was about. hmm. Triggers are supposed to be per sample so this is indeed
>>> a hack. We need fullblown DMA buffer consumers to do this right.
>> Yes exactly.
>>>
>>> Probably best person to comment on that is Lars.
>>>> + struct iio_poll_func *pf = p;
>>>> + struct iio_dev *indio_dev = pf->indio_dev;
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> + size_t old_pos;
>>>> + int available = stm32_dfsdm_audio_avail_data(pdmc);
>>>> +
>>>> + /*
>>>> + * Buffer interface is not support cyclic DMA buffer,and offer only
>>>> + * an interface to push data samples per samples.
>>>> + * For this reason iio_push_to_buffers_with_timestamp in not used
>>>> + * and interface is hacked 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__,
>>>> + pdmc->bufi, available);
>>>> + old_pos = pdmc->bufi;
>>>> + while (available >= indio_dev->scan_bytes) {
>>>> + u32 *buffer = (u32 *)&pdmc->rx_buf[pdmc->bufi];
>>>> +
>>>> + /* Mask 8 LSB that contains the channel ID */
>>>> + *buffer &= 0xFFFFFF00;
>>>> + available -= indio_dev->scan_bytes;
>>>> + pdmc->bufi += indio_dev->scan_bytes;
>>>> + if (pdmc->bufi >= pdmc->buf_sz) {
>>>> + if (pdmc->cb)
>>>> + pdmc->cb(&pdmc->rx_buf[old_pos],
>>>> + pdmc->buf_sz - old_pos, pdmc->cb_priv);
>>>> + pdmc->bufi = 0;
>>>> + old_pos = 0;
>>>> + }
>>>> + }
>>>> + if (pdmc->cb)
>>>> + pdmc->cb(&pdmc->rx_buf[old_pos], pdmc->bufi - old_pos,
>>>> + pdmc->cb_priv);
>>>> +
>>>> + iio_trigger_notify_done(indio_dev->trig);
>>>> +
>>>> + return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +/**
>>>> + * 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_audio *pdmc;
>>>> +
>>>> + if (!iio_dev)
>>>> + return -EINVAL;
>>>> + pdmc = iio_priv(iio_dev);
>>>> +
>>>> + if (iio_dev != iio_priv_to_dev(pdmc))
>>>> + return -EINVAL;
>>>> +
>>>> + pdmc->cb = cb;
>>>> + pdmc->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_audio *pdmc;
>>>> +
>>>> + if (!iio_dev)
>>>> + return -EINVAL;
>>>> + pdmc = iio_priv(iio_dev);
>>>> +
>>>> + if (iio_dev != iio_priv_to_dev(pdmc))
>>>> + return -EINVAL;
>>>> + pdmc->cb = NULL;
>>>> + pdmc->cb_priv = NULL;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(stm32_dfsdm_release_buff_cb);
>>>> +
>>>> +static int stm32_dfsdm_audio_chan_init(struct iio_dev *indio_dev)
>>>> +{
>>>> + struct iio_chan_spec *ch;
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> + int ret;
>>>> +
>>>> + ch = devm_kzalloc(&indio_dev->dev, sizeof(*ch), GFP_KERNEL);
>>>> + if (!ch)
>>>> + return -ENOMEM;
>>>> +
>>>> + ret = stm32_dfsdm_channel_parse_of(pdmc->dfsdm, indio_dev, ch, 0);
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + ch->type = IIO_VOLTAGE;
>>>> + ch->indexed = 1;
>>>> + ch->scan_index = 0;
>>>> + ch->ext_info = dfsdm_adc_ext_info;
>>>> +
>>>> + ch->scan_type.sign = 's';
>>>> + ch->scan_type.realbits = 24;
>>>> + ch->scan_type.storagebits = 32;
>>>> +
>>>> + pdmc->ch_id = ch->channel;
>>>> + ret = stm32_dfsdm_chan_configure(pdmc->dfsdm,
>>>> + &pdmc->dfsdm->ch_list[ch->channel]);
>>>> +
>>>> + indio_dev->num_channels = 1;
>>>> + indio_dev->channels = ch;
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static const struct of_device_id stm32_dfsdm_audio_match[] = {
>>>> + { .compatible = "st,stm32-dfsdm-audio"},
>>>> + {}
>>>> +};
>>>> +
>>>> +static int stm32_dfsdm_audio_dma_request(struct iio_dev *indio_dev)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = iio_priv(indio_dev);
>>>> + struct dma_slave_config config;
>>>> + int ret;
>>>> +
>>>> + pdmc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
>>>> + if (!pdmc->dma_chan)
>>>> + return -EINVAL;
>>>> +
>>>> + pdmc->rx_buf = dma_alloc_coherent(pdmc->dma_chan->device->dev,
>>>> + DFSDM_DMA_BUFFER_SIZE,
>>>> + &pdmc->dma_buf, GFP_KERNEL);
>>>> + if (!pdmc->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)pdmc->dfsdm->phys_base;
>>>> + config.src_addr += DFSDM_RDATAR(pdmc->fl_id);
>>>> + config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
>>>> +
>>>> + ret = dmaengine_slave_config(pdmc->dma_chan, &config);
>>>> + if (ret)
>>>> + goto err_free;
>>>> +
>>>> + return 0;
>>>> +
>>>> +err_free:
>>>> + dma_free_coherent(pdmc->dma_chan->device->dev, DFSDM_DMA_BUFFER_SIZE,
>>>> + pdmc->rx_buf, pdmc->dma_buf);
>>>> +err_release:
>>>> + dma_release_channel(pdmc->dma_chan);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int stm32_dfsdm_audio_probe(struct platform_device *pdev)
>>>> +{
>>>> + struct device *dev = &pdev->dev;
>>>> + struct stm32_dfsdm_audio *pdmc;
>>>> + struct device_node *np = dev->of_node;
>>>> + struct iio_dev *iio;
>>>> + char *name;
>>>> + int ret, irq, val;
>>>> +
>>>> + iio = devm_iio_device_alloc(dev, sizeof(*pdmc));
>>>> + if (IS_ERR(iio)) {
>>>> + dev_err(dev, "%s: Failed to allocate IIO\n", __func__);
>>>> + return PTR_ERR(iio);
>>>> + }
>>>> +
>>>> + pdmc = iio_priv(iio);
>>>> + if (IS_ERR(pdmc)) {
>>>> + dev_err(dev, "%s: Failed to allocate ADC\n", __func__);
>>>> + return PTR_ERR(pdmc);
>>>> + }
>>>> + pdmc->dfsdm = dev_get_drvdata(dev->parent);
>>>> +
>>>> + iio->name = np->name;
>>>> + iio->dev.parent = dev;
>>>> + iio->dev.of_node = np;
>>>> + iio->info = &stm32_dfsdm_info_pdmc;
>>>> + iio->modes = INDIO_DIRECT_MODE;
>>>> +
>>>> + platform_set_drvdata(pdev, pdmc);
>>>> +
>>>> + ret = of_property_read_u32(dev->of_node, "reg", &pdmc->fl_id);
>>>> + if (ret != 0) {
>>>> + dev_err(dev, "Missing reg property\n");
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> + name = kzalloc(sizeof("dfsdm-pdm0"), GFP_KERNEL);
>>>> + if (!name)
>>>> + return -ENOMEM;
>>>> + snprintf(name, sizeof("dfsdm-pdm0"), "dfsdm-pdm%d", pdmc->fl_id);
>>>> + iio->name = name;
>>>> +
>>>> + /*
>>>> + * In a first step IRQs generated for channels are not treated.
>>>> + * So IRQ associated to filter instance 0 is dedicated to the Filter 0.
>>>> + */
>>>> + irq = platform_get_irq(pdev, 0);
>>>> + ret = devm_request_irq(dev, irq, stm32_dfsdm_irq,
>>>> + 0, pdev->name, pdmc);
>>>> + if (ret < 0) {
>>>> + dev_err(dev, "Failed to request IRQ\n");
>>>> + return ret;
>>>> + }
>>>> +
>>>> + ret = of_property_read_u32(dev->of_node, "st,filter-order", &val);
>>>> + if (ret < 0) {
>>>> + dev_err(dev, "Failed to set filter order\n");
>>>> + return ret;
>>>> + }
>>>> + pdmc->dfsdm->fl_list[pdmc->fl_id].ford = val;
>>>> +
>>>> + ret = of_property_read_u32(dev->of_node, "st,filter0-sync", &val);
>>>> + if (!ret)
>>>> + pdmc->dfsdm->fl_list[pdmc->fl_id].sync_mode = val;
>>>> +
>>>> + ret = stm32_dfsdm_audio_chan_init(iio);
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + ret = stm32_dfsdm_audio_dma_request(iio);
>>>> + if (ret) {
>>>> + dev_err(&pdev->dev, "DMA request failed\n");
>>>> + return ret;
>>>> + }
>>>> +
>>>> + iio->modes |= INDIO_BUFFER_SOFTWARE;
>>>> +
>>>> + ret = iio_triggered_buffer_setup(iio,
>>>> + &iio_pollfunc_store_time,
>>>> + &stm32_dfsdm_audio_trigger_handler,
>>>> + &stm32_dfsdm_buffer_setup_ops);
>>>> + if (ret) {
>>>> + dev_err(&pdev->dev, "Buffer setup failed\n");
>>>> + goto err_dma_disable;
>>>> + }
>>>> +
>>>> + ret = iio_device_register(iio);
>>>> + if (ret) {
>>>> + dev_err(&pdev->dev, "IIO dev register failed\n");
>>>> + goto err_buffer_cleanup;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +
>>>> +err_buffer_cleanup:
>>>> + iio_triggered_buffer_cleanup(iio);
>>>> +
>>>> +err_dma_disable:
>>>> + if (pdmc->dma_chan) {
>>>> + dma_free_coherent(pdmc->dma_chan->device->dev,
>>>> + DFSDM_DMA_BUFFER_SIZE,
>>>> + pdmc->rx_buf, pdmc->dma_buf);
>>>> + dma_release_channel(pdmc->dma_chan);
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int stm32_dfsdm_audio_remove(struct platform_device *pdev)
>>>> +{
>>>> + struct stm32_dfsdm_audio *pdmc = platform_get_drvdata(pdev);
>>>> + struct iio_dev *iio = iio_priv_to_dev(pdmc);
>>>> +
>>>> + iio_device_unregister(iio);
>>> Same as in the other driver. Can just use the devm_iio_device_register
>>> version and drop remove.
>> oops missing the previous comment... sorry.
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static struct platform_driver stm32_dfsdm_audio_driver = {
>>>> + .driver = {
>>>> + .name = "stm32-dfsdm-audio",
>>>> + .of_match_table = stm32_dfsdm_audio_match,
>>>> + },
>>>> + .probe = stm32_dfsdm_audio_probe,
>>>> + .remove = stm32_dfsdm_audio_remove,
>>>> +};
>>>> +module_platform_driver(stm32_dfsdm_audio_driver);
>>>> +
>>>> +MODULE_DESCRIPTION("STM32 sigma delta converter for PDM microphone");
>>>> +MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen at st.com>");
>>>> +MODULE_LICENSE("GPL v2");
>>>> diff --git a/include/linux/iio/adc/stm32-dfsdm-audio.h b/include/linux/iio/adc/stm32-dfsdm-audio.h
>>>> new file mode 100644
>>>> index 0000000..9b41b28
>>>> --- /dev/null
>>>> +++ b/include/linux/iio/adc/stm32-dfsdm-audio.h
>>>> @@ -0,0 +1,41 @@
>>>> +/*
>>>> + * 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>.
>>>> + *
>>>> + * 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_AUDIO_H
>>>> +#define STM32_DFSDM_AUDIO_H
>>>> +
>>>> +/**
>>>> + * stm32_dfsdm_get_buff_cb() - register callback for capture buffer period.
>>>> + * @dev: Pointer to client device.
>>>> + * @indio_dev: Device on which the channel exists.
>>>> + * @cb: Callback function.
>>>> + * @data: pointer to data buffer
>>>> + * @size: size of the data buffer in bytes
>>>> + * @private: Private data passed to callback.
>>>> + *
>>>> + */
>>>> +int stm32_dfsdm_get_buff_cb(struct iio_dev *iio_dev,
>>>> + int (*cb)(const void *data, size_t size,
>>>> + void *private),
>>>> + void *private);
>>>> +/**
>>>> + * stm32_dfsdm_get_buff_cb() - release callback for capture buffer period.
>>>> + * @indio_dev: Device on which the channel exists.
>>>> + */
>>>> +int stm32_dfsdm_release_buff_cb(struct iio_dev *iio_dev);
>>>> +
>>>> +#endif
>>>>
>>>
>> --
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