Re: [PATCH v6 09/13] IIO: ADC: add STM32 DFSDM sigma delta ADC support

Jonathan Cameron
2017-12-02T14:58:56Z

On Fri, 1 Dec 2017 18:40:16 +0100
Arnaud Pouliquen <arnaud.pouliquen-qxv4g6HH51o@public.gmane.org> wrote:

> Add DFSDM driver to handle sigma delta ADC.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen-qxv4g6HH51o@public.gmane.org>

A couple of really small nitpicks if you are respinning.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

> ---
> drivers/iio/adc/Kconfig | 13 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/stm32-dfsdm-adc.c | 741 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 755 insertions(+)
> create mode 100644 drivers/iio/adc/stm32-dfsdm-adc.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index b729ae0..98ca30b 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -677,6 +677,19 @@ config STM32_DFSDM_CORE
> This driver can also be built as a module. If so, the module
> will be called stm32-dfsdm-core.
>
> +config STM32_DFSDM_ADC
> + tristate "STMicroelectronics STM32 dfsdm adc"
> + depends on (ARCH_STM32 && OF) || COMPILE_TEST
> + select STM32_DFSDM_CORE
> + select REGMAP_MMIO
> + select IIO_BUFFER_HW_CONSUMER
> + help
> + Select this option to support ADCSigma delta modulator 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-adc.
> +
> config STX104
> tristate "Apex Embedded Systems STX104 driver"
> depends on PC104 && X86 && ISA_BUS_API
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index b52d0a0..c4f5d15 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -64,6 +64,7 @@ obj-$(CONFIG_SUN4I_GPADC) += sun4i-gpadc-iio.o
> obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o
> obj-$(CONFIG_STM32_ADC) += stm32-adc.o
> obj-$(CONFIG_STM32_DFSDM_CORE) += stm32-dfsdm-core.o
> +obj-$(CONFIG_STM32_DFSDM_ADC) += stm32-dfsdm-adc.o
> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
> obj-$(CONFIG_TI_ADC084S021) += ti-adc084s021.o
> diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
> new file mode 100644
> index 0000000..f9419ab
> --- /dev/null
> +++ b/drivers/iio/adc/stm32-dfsdm-adc.c
> @@ -0,0 +1,741 @@
> +/*
> + * This file is the ADC part of the STM32 DFSDM driver
> + *
> + * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
> + * Author: Arnaud Pouliquen <arnaud.pouliquen-qxv4g6HH51o@public.gmane.org>.
> + *
> + * License type: 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.
> + *
> + * 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/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/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +#include "stm32-dfsdm.h"
> +
> +/* Conversion timeout */
> +#define DFSDM_TIMEOUT_US 100000
> +#define DFSDM_TIMEOUT (msecs_to_jiffies(DFSDM_TIMEOUT_US / 1000))
> +
> +/* Oversampling attribute default */
> +#define DFSDM_DEFAULT_OVERSAMPLING 100
> +
> +/* Oversampling max values */
> +#define DFSDM_MAX_INT_OVERSAMPLING 256
> +#define DFSDM_MAX_FL_OVERSAMPLING 1024
> +
> +/* Max sample resolutions */
> +#define DFSDM_MAX_RES BIT(31)
> +#define DFSDM_DATA_RES BIT(23)
> +
> +enum sd_converter_type {
> + DFSDM_AUDIO,
> + DFSDM_IIO,
> +};
> +
> +struct stm32_dfsdm_dev_data {
> + int type;
> + int (*init)(struct iio_dev *indio_dev);
> + unsigned int num_channels;
> + const struct regmap_config *regmap_cfg;
> +};
> +
> +struct stm32_dfsdm_adc {
> + struct stm32_dfsdm *dfsdm;
> + const struct stm32_dfsdm_dev_data *dev_data;
> + unsigned int fl_id;
> + unsigned int ch_id;
> +
> + /* ADC specific */
> + unsigned int oversamp;
> + struct iio_hw_consumer *hwc;
> + struct completion completion;
> + u32 *buffer;
> +
> +};
> +
> +struct stm32_dfsdm_str2field {
> + const char *name;
> + unsigned int val;
> +};
> +
> +/* DFSDM channel serial interface type */
> +static const struct stm32_dfsdm_str2field stm32_dfsdm_chan_type[] = {
> + { "SPI_R", 0 }, /* SPI with data on rising edge */
> + { "SPI_F", 1 }, /* SPI with data on falling edge */
> + { "MANCH_R", 2 }, /* Manchester codec, rising edge = logic 0 */
> + { "MANCH_F", 3 }, /* Manchester codec, falling edge = logic 1 */
> + {},
> +};
> +
> +/* DFSDM channel clock source */
> +static const struct stm32_dfsdm_str2field stm32_dfsdm_chan_src[] = {
> + /* External SPI clock (CLKIN x) */
> + { "CLKIN", DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL },
> + /* Internal SPI clock (CLKOUT) */
> + { "CLKOUT", DFSDM_CHANNEL_SPI_CLOCK_INTERNAL },
> + /* Internal SPI clock divided by 2 (falling edge) */
> + { "CLKOUT_F", DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING },
> + /* Internal SPI clock divided by 2 (falling edge) */
> + { "CLKOUT_R", DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING },
> + {},
> +};
> +
> +static int stm32_dfsdm_str2val(const char *str,
> + const struct stm32_dfsdm_str2field *list)
> +{
> + const struct stm32_dfsdm_str2field *p = list;
> +
> + for (p = list; p && p->name; p++)
> + if (!strcmp(p->name, str))
> + return p->val;
> +
> + return -EINVAL;
> +}
> +
> +static int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl,
> + unsigned int fast, unsigned int oversamp)
> +{
> + unsigned int i, d, fosr, iosr;
> + u64 res;
> + s64 delta;
> + unsigned int m = 1; /* multiplication factor */
> + unsigned int p = fl->ford; /* filter order (ford) */
> +
> + pr_debug("%s: Requested oversampling: %d\n", __func__, oversamp);
> + /*
> + * This function tries to compute filter oversampling and integrator
> + * oversampling, base on oversampling ratio requested by user.
> + *
> + * Decimation d depends on the filter order and the oversampling ratios.
> + * ford: filter order
> + * fosr: filter over sampling ratio
> + * iosr: integrator over sampling ratio
> + */
> + if (fl->ford == DFSDM_FASTSINC_ORDER) {
> + m = 2;
> + p = 2;
> + }
> +
> + /*
> + * Look for filter and integrator oversampling ratios which allows
> + * to reach 24 bits data output resolution.
> + * Leave as soon as if exact resolution if reached.
> + * Otherwise the higher resolution below 32 bits is kept.
> + */
> + for (fosr = 1; fosr <= DFSDM_MAX_FL_OVERSAMPLING; fosr++) {
> + for (iosr = 1; iosr <= DFSDM_MAX_INT_OVERSAMPLING; iosr++) {
> + if (fast)
> + d = fosr * iosr;
> + else if (fl->ford == DFSDM_FASTSINC_ORDER)
> + d = fosr * (iosr + 3) + 2;
> + else
> + d = fosr * (iosr - 1 + p) + p;
> +
> + if (d > oversamp)
> + break;
> + else if (d != oversamp)
> + continue;
> + /*
> + * Check resolution (limited to signed 32 bits)
> + * res <= 2^31
> + * Sincx filters:
> + * res = m * fosr^p x iosr (with m=1, p=ford)
> + * FastSinc filter
> + * res = m * fosr^p x iosr (with m=2, p=2)
> + */
> + res = fosr;
> + for (i = p - 1; i > 0; i--) {
> + res = res * (u64)fosr;
> + if (res > DFSDM_MAX_RES)
> + break;
> + }
> + if (res > DFSDM_MAX_RES)
> + continue;
> + res = res * (u64)m * (u64)iosr;
> + if (res > DFSDM_MAX_RES)
> + continue;
> +
> + delta = res - DFSDM_DATA_RES;
> +
> + if (res >= fl->res) {
> + fl->res = res;
> + fl->fosr = fosr;
> + fl->iosr = iosr;
> + fl->fast = fast;
> + pr_debug("%s: fosr = %d, iosr = %d\n",
> + __func__, fl->fosr, fl->iosr);
> + }
> +
> + if (!delta)
> + return 0;
> + }
> + }
> +
> + if (!fl->fosr)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int stm32_dfsdm_start_channel(struct stm32_dfsdm *dfsdm,
> + unsigned int ch_id)
> +{
> + return regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(ch_id),
> + DFSDM_CHCFGR1_CHEN_MASK,
> + DFSDM_CHCFGR1_CHEN(1));
> +}
> +
> +static void stm32_dfsdm_stop_channel(struct stm32_dfsdm *dfsdm,
> + unsigned int ch_id)
> +{
> + regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(ch_id),
> + DFSDM_CHCFGR1_CHEN_MASK, DFSDM_CHCFGR1_CHEN(0));
> +}
> +
> +static int stm32_dfsdm_chan_configure(struct stm32_dfsdm *dfsdm,
> + struct stm32_dfsdm_channel *ch)
> +{
> + unsigned int id = ch->id;
> + struct regmap *regmap = dfsdm->regmap;
> + int ret;
> +
> + ret = regmap_update_bits(regmap, DFSDM_CHCFGR1(id),
> + DFSDM_CHCFGR1_SITP_MASK,
> + DFSDM_CHCFGR1_SITP(ch->type));
> + if (ret < 0)
> + return ret;
> + ret = regmap_update_bits(regmap, DFSDM_CHCFGR1(id),
> + DFSDM_CHCFGR1_SPICKSEL_MASK,
> + DFSDM_CHCFGR1_SPICKSEL(ch->src));
> + if (ret < 0)
> + return ret;
> + return regmap_update_bits(regmap, DFSDM_CHCFGR1(id),
> + DFSDM_CHCFGR1_CHINSEL_MASK,
> + DFSDM_CHCFGR1_CHINSEL(ch->alt_si));
> +}
> +
> +static int stm32_dfsdm_start_filter(struct stm32_dfsdm *dfsdm,
> + unsigned int fl_id)
> +{
> + int ret;
> +
> + /* Enable filter */
> + ret = regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
> + DFSDM_CR1_DFEN_MASK, DFSDM_CR1_DFEN(1));
> + if (ret < 0)
> + return ret;
> +
> + /* Start conversion */
> + return regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
> + DFSDM_CR1_RSWSTART_MASK,
> + DFSDM_CR1_RSWSTART(1));
> +}
> +
> +void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm, unsigned int fl_id)
> +{
> + /* Disable conversion */
> + regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
> + DFSDM_CR1_DFEN_MASK, DFSDM_CR1_DFEN(0));
> +}
> +
> +static int stm32_dfsdm_filter_configure(struct stm32_dfsdm *dfsdm,
> + unsigned int fl_id, unsigned int ch_id)
> +{
> + struct regmap *regmap = dfsdm->regmap;
> + struct stm32_dfsdm_filter *fl = &dfsdm->fl_list[fl_id];
> + int ret;
> +
> + /* Average integrator oversampling */
> + ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id), DFSDM_FCR_IOSR_MASK,
> + DFSDM_FCR_IOSR(fl->iosr - 1));
> + if (ret)
> + return ret;
> +
> + /* Filter order and Oversampling */
> + ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id), DFSDM_FCR_FOSR_MASK,
> + DFSDM_FCR_FOSR(fl->fosr - 1));
> + if (ret)
> + return ret;
> +
> + ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id), DFSDM_FCR_FORD_MASK,
> + DFSDM_FCR_FORD(fl->ford));
> + if (ret)
> + return ret;
> +
> + /* No scan mode supported for the moment */
> + ret = regmap_update_bits(regmap, DFSDM_CR1(fl_id), DFSDM_CR1_RCH_MASK,
> + DFSDM_CR1_RCH(ch_id));
> + if (ret)
> + return ret;
> +
> + return regmap_update_bits(regmap, DFSDM_CR1(fl_id),
> + DFSDM_CR1_RSYNC_MASK,
> + DFSDM_CR1_RSYNC(fl->sync_mode));
> +}
> +
> +int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
> + struct iio_dev *indio_dev,
> + struct iio_chan_spec *ch)
> +{
> + struct stm32_dfsdm_channel *df_ch;
> + const char *of_str;
> + int chan_idx = ch->scan_index;
> + int ret, val;
> +
> + ret = of_property_read_u32_index(indio_dev->dev.of_node,
> + "st,adc-channels", chan_idx,
> + &ch->channel);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev,
> + " Error parsing 'st,adc-channels' for idx %d\n",
> + chan_idx);
> + return ret;
> + }
> + if (ch->channel >= dfsdm->num_chs) {
> + dev_err(&indio_dev->dev,
> + " Error bad channel number %d (max = %d)\n",
> + ch->channel, dfsdm->num_chs);
> + return -EINVAL;
> + }
> +
> + ret = of_property_read_string_index(indio_dev->dev.of_node,
> + "st,adc-channel-names", chan_idx,
> + &ch->datasheet_name);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev,
> + " Error parsing 'st,adc-channel-names' for idx %d\n",
> + chan_idx);
> + return ret;
> + }
> +
> + df_ch = &dfsdm->ch_list[ch->channel];
> + df_ch->id = ch->channel;
> +
> + ret = of_property_read_string_index(indio_dev->dev.of_node,
> + "st,adc-channel-types", chan_idx,
> + &of_str);
> + if (!ret) {
> + val = stm32_dfsdm_str2val(of_str, stm32_dfsdm_chan_type);
> + if (val < 0)
> + return val;
> + } else {
> + val = 0;
> + }
> + df_ch->type = val;
> +
> + ret = of_property_read_string_index(indio_dev->dev.of_node,
> + "st,adc-channel-clk-src", chan_idx,
> + &of_str);
> + if (!ret) {
> + val = stm32_dfsdm_str2val(of_str, stm32_dfsdm_chan_src);
> + if (val < 0)
> + return val;
> + } else {
> + val = 0;
> + }
> + df_ch->src = val;
> +
> + ret = of_property_read_u32_index(indio_dev->dev.of_node,
> + "st,adc-alt-channel", chan_idx,
> + &df_ch->alt_si);
> + if (ret < 0)
> + df_ch->alt_si = 0;
> +
> + return 0;
> +}
> +
> +static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc, bool dma)
> +{
> + struct regmap *regmap = adc->dfsdm->regmap;
> + int ret;
> +
> + ret = stm32_dfsdm_start_channel(adc->dfsdm, adc->ch_id);
> + if (ret < 0)
> + return ret;
> +
> + ret = stm32_dfsdm_filter_configure(adc->dfsdm, adc->fl_id,
> + adc->ch_id);
> + if (ret < 0)
> + goto stop_channels;
> +
> + ret = stm32_dfsdm_start_filter(adc->dfsdm, adc->fl_id);
> + if (ret < 0)
> + goto stop_channels;
> +
> + return 0;
> +
> +stop_channels:
> + regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
> + DFSDM_CR1_RDMAEN_MASK, 0);
> +
> + regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
> + DFSDM_CR1_RCONT_MASK, 0);
> + stm32_dfsdm_stop_channel(adc->dfsdm, adc->fl_id);
> +
> + return ret;
> +}
> +
> +static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc)
> +{
> + struct regmap *regmap = adc->dfsdm->regmap;
> +
> + stm32_dfsdm_stop_filter(adc->dfsdm, adc->fl_id);
> +
> + /* Clean conversion options */
> + regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
> + DFSDM_CR1_RDMAEN_MASK, 0);
> +
> + regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
> + DFSDM_CR1_RCONT_MASK, 0);
> +
> + stm32_dfsdm_stop_channel(adc->dfsdm, adc->ch_id);
> +}
> +
> +static int stm32_dfsdm_single_conv(struct iio_dev *indio_dev,
> + const struct iio_chan_spec *chan, int *res)
> +{
> + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> + long timeout;
> + int ret;
> +
> + reinit_completion(&adc->completion);
> +
> + adc->buffer = res;
> +
> + ret = stm32_dfsdm_start_dfsdm(adc->dfsdm);
> + if (ret < 0)
> + return ret;
> +
> + ret = regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
> + DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(1));
> + if (ret < 0)
> + goto stop_dfsdm;
> +
> + ret = stm32_dfsdm_start_conv(adc, false);
> + if (ret < 0) {
> + regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
> + DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(0));
> + goto stop_dfsdm;
> + }
> +
> + timeout = wait_for_completion_interruptible_timeout(&adc->completion,
> + DFSDM_TIMEOUT);
> +
> + /* Mask IRQ for regular conversion achievement*/
> + regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
> + DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(0));
> +
> + if (timeout == 0)
> + ret = -ETIMEDOUT;
> + else if (timeout < 0)
> + ret = timeout;
> + else
> + ret = IIO_VAL_INT;
> +
> + stm32_dfsdm_stop_conv(adc);
> +
> +stop_dfsdm:
> + stm32_dfsdm_stop_dfsdm(adc->dfsdm);
> +
> + return ret;
> +}
> +
> +static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> + struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
> + int ret = -EINVAL;
> +
> + if (mask == IIO_CHAN_INFO_OVERSAMPLING_RATIO) {
> + ret = stm32_dfsdm_set_osrs(fl, 0, val);
> + if (!ret)
> + adc->oversamp = val;
> + }
> +
> + return ret;
> +}
> +
> +static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int *val,
> + int *val2, long mask)
> +{
> + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = iio_hw_consumer_enable(adc->hwc);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev,
> + "%s: IIO enable failed (channel %d)\n",
> + __func__, chan->channel);
> + return ret;
> + }
> + ret = stm32_dfsdm_single_conv(indio_dev, chan, val);
> + iio_hw_consumer_disable(adc->hwc);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev,
> + "%s: Conversion failed (channel %d)\n",
> + __func__, chan->channel);
> + return ret;
> + }
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + *val = adc->oversamp;
> +
> + return IIO_VAL_INT;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct iio_info stm32_dfsdm_info_adc = {
> + .read_raw = stm32_dfsdm_read_raw,
> + .write_raw = stm32_dfsdm_write_raw,
> +};
> +
> +static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
> +{
> + struct stm32_dfsdm_adc *adc = arg;
> + struct iio_dev *indio_dev = iio_priv_to_dev(adc);
> + struct regmap *regmap = adc->dfsdm->regmap;
> + unsigned int status, int_en;
> +
> + regmap_read(regmap, DFSDM_ISR(adc->fl_id), &status);
> + regmap_read(regmap, DFSDM_CR2(adc->fl_id), &int_en);
> +
> + if (status & DFSDM_ISR_REOCF_MASK) {
> + /* Read the data register clean the IRQ status */
> + regmap_read(regmap, DFSDM_RDATAR(adc->fl_id), adc->buffer);
> + complete(&adc->completion);
> + }
> +
> + if (status & DFSDM_ISR_ROVRF_MASK) {
> + if (int_en & DFSDM_CR2_ROVRIE_MASK)
> + dev_warn(&indio_dev->dev, "Overrun detected\n");
> + regmap_update_bits(regmap, DFSDM_ICR(adc->fl_id),
> + DFSDM_ICR_CLRROVRF_MASK,
> + DFSDM_ICR_CLRROVRF_MASK);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev,
> + struct iio_chan_spec *ch)
> +{
> + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> + int ret;
> +
> + ret = stm32_dfsdm_channel_parse_of(adc->dfsdm, indio_dev, ch);
> + if (ret < 0)
> + return ret;
> +
> + ch->type = IIO_VOLTAGE;
> + ch->indexed = 1;
> +
> + /*
> + * IIO_CHAN_INFO_RAW: used to compute regular conversion
> + * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling
> + */
> + 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';
> + ch->scan_type.realbits = 24;
> + ch->scan_type.storagebits = 32;
> + adc->ch_id = ch->channel;
> +
> + return stm32_dfsdm_chan_configure(adc->dfsdm,
> + &adc->dfsdm->ch_list[ch->channel]);
> +}
> +
> +static int stm32_dfsdm_adc_init(struct iio_dev *indio_dev)
> +{
> + struct iio_chan_spec *ch;
> + struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
> + int num_ch;
> + int ret, chan_idx;
> +
> + adc->oversamp = DFSDM_DEFAULT_OVERSAMPLING;
> + ret = stm32_dfsdm_set_osrs(&adc->dfsdm->fl_list[adc->fl_id], 0,
> + adc->oversamp);
> + if (ret < 0)
> + return ret;
> +
> + num_ch = of_property_count_u32_elems(indio_dev->dev.of_node,
> + "st,adc-channels");
> + if (num_ch < 0 || num_ch > adc->dfsdm->num_chs) {
> + dev_err(&indio_dev->dev, "Bad st,adc-channels\n");
> + return num_ch < 0 ? num_ch : -EINVAL;
> + }
> +
> + /* Bind to SD modulator IIO device */
> + adc->hwc = devm_iio_hw_consumer_alloc(&indio_dev->dev);
> + if (IS_ERR(adc->hwc))
> + return -EPROBE_DEFER;
> +
> + ch = devm_kcalloc(&indio_dev->dev, num_ch, sizeof(*ch),
> + GFP_KERNEL);
> + if (!ch)
> + return -ENOMEM;
> +
> + for (chan_idx = 0; chan_idx < num_ch; chan_idx++) {
> + ch->scan_index = chan_idx;
> + ret = stm32_dfsdm_adc_chan_init_one(indio_dev, ch);
> + if (ret < 0) {
> + dev_err(&indio_dev->dev, "Channels init failed\n");
> + return ret;
> + }
> + }
> +
> + indio_dev->num_channels = num_ch;
> + indio_dev->channels = ch;
> +
> + init_completion(&adc->completion);
> +
> + return 0;
> +}
> +
> +static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_adc_data = {
> + .type = DFSDM_IIO,
> + .init = stm32_dfsdm_adc_init,
> +};
> +
> +static const struct of_device_id stm32_dfsdm_adc_match[] = {
> + { .compatible = "st,stm32-dfsdm-adc",
Slightly odd alignment, I'd drop .compatible onto a new line as well..

> + .data = &stm32h7_dfsdm_adc_data,
> + },
> + {}
> +};
> +
> +static int stm32_dfsdm_adc_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct stm32_dfsdm_adc *adc;
> + struct device_node *np = dev->of_node;
> + const struct stm32_dfsdm_dev_data *dev_data;
> + struct iio_dev *iio;
> + const struct of_device_id *of_id;
> + char *name;
> + int ret, irq, val;
> +
> + of_id = of_match_node(stm32_dfsdm_adc_match, np);
> + if (!of_id->data) {
> + dev_err(&pdev->dev, "Data associated to device is missing\n");
> + return -EINVAL;
> + }
> +
> + dev_data = (const struct stm32_dfsdm_dev_data *)of_id->data;
> +
> + iio = devm_iio_device_alloc(dev, sizeof(*adc));
> + if (IS_ERR(iio)) {
> + dev_err(dev, "%s: Failed to allocate IIO\n", __func__);
> + return PTR_ERR(iio);
> + }
> +
> + adc = iio_priv(iio);
> + if (IS_ERR(adc)) {
> + dev_err(dev, "%s: Failed to allocate ADC\n", __func__);
> + return PTR_ERR(adc);
> + }
> + adc->dfsdm = dev_get_drvdata(dev->parent);
> +
> + iio->dev.parent = dev;
> + iio->dev.of_node = np;
> + iio->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
> +
> + platform_set_drvdata(pdev, adc);
> +
> + ret = of_property_read_u32(dev->of_node, "reg", &adc->fl_id);
> + if (ret != 0) {
> + dev_err(dev, "Missing reg property\n");
> + return -EINVAL;
> + }
> +
> + 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);
> + 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, adc);
> + 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;
> + }
> +
> + adc->dfsdm->fl_list[adc->fl_id].ford = val;
> +
> + ret = of_property_read_u32(dev->of_node, "st,filter0-sync", &val);
> + if (!ret)
> + adc->dfsdm->fl_list[adc->fl_id].sync_mode = val;
> +
> + adc->dev_data = dev_data;
> + ret = dev_data->init(iio);
> + if (ret < 0)
> + return ret;
> +
> + return iio_device_register(iio);
> +}
> +
> +static int stm32_dfsdm_adc_remove(struct platform_device *pdev)
> +{
> + struct stm32_dfsdm_adc *adc = platform_get_drvdata(pdev);
> + struct iio_dev *indio_dev = iio_priv_to_dev(adc);
> +
> + iio_device_unregister(indio_dev);
> +
> + return 0;
> +}
> +
> +static struct platform_driver stm32_dfsdm_adc_driver = {
> + .driver = {
> + .name = "stm32-dfsdm-adc",
> + .of_match_table = stm32_dfsdm_adc_match,
> + },
> + .probe = stm32_dfsdm_adc_probe,
> + .remove = stm32_dfsdm_adc_remove,
> +

Real nitpick but no blank line here!

> +};
> +module_platform_driver(stm32_dfsdm_adc_driver);
> +
> +MODULE_DESCRIPTION("STM32 sigma delta ADC");
> +MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen-qxv4g6HH51o@public.gmane.org>");
> +MODULE_LICENSE("GPL v2");

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