[PATCH v3 05/11] IIO: ADC: add stm32 DFSDM support for Sigma delta ADC

Arnaud Pouliquen arnaud.pouliquen at st.com
Fri Mar 17 07:08:18 PDT 2017


Add driver for stm32 DFSDM IP. This IP converts a sigma delta stream
in n bit samples through a low pass filter and an integrator.
stm32-dfsdm-adc driver allows to handle sigma delta ADC.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>
---
V2 -> V3 :
	- Split audio and ADC support in 2 drivers
	- Implement DMA cyclic mode
	- Add SPI bus Trigger for buffer management

 drivers/iio/adc/Kconfig            |  26 ++
 drivers/iio/adc/Makefile           |   2 +
 drivers/iio/adc/stm32-dfsdm-adc.c  | 419 +++++++++++++++++++++++
 drivers/iio/adc/stm32-dfsdm-core.c | 658 +++++++++++++++++++++++++++++++++++++
 drivers/iio/adc/stm32-dfsdm.h      | 372 +++++++++++++++++++++
 5 files changed, 1477 insertions(+)
 create mode 100644 drivers/iio/adc/stm32-dfsdm-adc.c
 create mode 100644 drivers/iio/adc/stm32-dfsdm-core.c
 create mode 100644 drivers/iio/adc/stm32-dfsdm.h

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index d411d66..3e0eb11 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -452,6 +452,32 @@ config STM32_ADC
 	  This driver can also be built as a module.  If so, the module
 	  will be called stm32-adc.
 
+config STM32_DFSDM_CORE
+	tristate "STMicroelectronics STM32 dfsdm core"
+	depends on (ARCH_STM32 && OF) || COMPILE_TEST
+	select REGMAP
+	select REGMAP_MMIO
+	help
+	  Select this option to enable the  driver 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-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_DMAENGINE
+	select IIO_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 X86 && ISA_BUS_API
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index c68819c..161f271 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -43,6 +43,8 @@ obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(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_CORE) += stm32-dfsdm-core.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
 obj-$(CONFIG_TI_ADC12138) += ti-adc12138.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..ebcb3b4
--- /dev/null
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -0,0 +1,419 @@
+/*
+ * 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/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/hw_consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#include "stm32-dfsdm.h"
+
+#define DFSDM_TIMEOUT_US 100000
+#define DFSDM_TIMEOUT (msecs_to_jiffies(DFSDM_TIMEOUT_US / 1000))
+
+struct stm32_dfsdm_adc {
+	struct stm32_dfsdm *dfsdm;
+	unsigned int fl_id;
+	unsigned int ch_id;
+
+	unsigned int oversamp;
+
+	struct completion completion;
+
+	u32 *buffer;
+
+	/* Hardware consumer structure for Front End IIO */
+	struct iio_hw_consumer *hwc;
+};
+
+static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc)
+{
+	int ret;
+
+	ret = stm32_dfsdm_start_dfsdm(adc->dfsdm);
+	if (ret < 0)
+		return ret;
+
+	ret = stm32_dfsdm_start_channel(adc->dfsdm, adc->ch_id);
+	if (ret < 0)
+		goto stop_dfsdm;
+
+	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:
+	stm32_dfsdm_stop_channel(adc->dfsdm, adc->ch_id);
+stop_dfsdm:
+	stm32_dfsdm_stop_dfsdm(adc->dfsdm);
+
+	return ret;
+}
+
+static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc)
+{
+	stm32_dfsdm_stop_filter(adc->dfsdm, adc->fl_id);
+
+	stm32_dfsdm_stop_channel(adc->dfsdm, adc->ch_id);
+
+	stm32_dfsdm_stop_dfsdm(adc->dfsdm);
+}
+
+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;
+
+	/* Unmask IRQ for regular conversion achievement*/
+	ret = regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
+				 DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(1));
+	if (ret < 0)
+		return ret;
+
+	ret = stm32_dfsdm_start_conv(adc);
+	if (ret < 0)
+		return ret;
+
+	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) {
+		dev_warn(&indio_dev->dev, "Conversion timed out!\n");
+		ret = -ETIMEDOUT;
+	} else if (timeout < 0) {
+		ret = timeout;
+	} else {
+		dev_dbg(&indio_dev->dev, "Converted val %#x\n", *res);
+		ret = IIO_VAL_INT;
+	}
+
+	/* 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));
+
+	stm32_dfsdm_stop_conv(adc);
+
+	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);
+		if (ret < 0) {
+			dev_err(&indio_dev->dev,
+				"%s: Conversion failed (channel %d)\n",
+				__func__, chan->channel);
+			return ret;
+		}
+
+		iio_hw_consumer_disable(adc->hwc);
+
+		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,
+	.driver_module = THIS_MODULE,
+};
+
+static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
+{
+	struct stm32_dfsdm_adc *adc = arg;
+	struct regmap *regmap = adc->dfsdm->regmap;
+	unsigned int status;
+
+	regmap_read(regmap, DFSDM_ISR(adc->fl_id), &status);
+
+	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) {
+		regmap_update_bits(regmap, DFSDM_ICR(adc->fl_id),
+				   DFSDM_ICR_CLRROVRF_MASK,
+				   DFSDM_ICR_CLRROVRF_MASK);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
+{
+	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
+
+	return stm32_dfsdm_start_conv(adc);
+}
+
+static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
+{
+	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
+
+	stm32_dfsdm_stop_conv(adc);
+	return 0;
+}
+
+static const struct iio_buffer_setup_ops stm32_dfsdm_buffer_setup_ops = {
+	.postenable = &stm32_dfsdm_postenable,
+	.predisable = &stm32_dfsdm_predisable,
+};
+
+static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev,
+					 struct iio_chan_spec *chan,
+					 int ch_idx)
+{
+	struct iio_chan_spec *ch = &chan[ch_idx];
+	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
+	int ret;
+
+	ret = stm32_dfsdm_channel_parse_of(adc->dfsdm, indio_dev, chan, ch_idx);
+
+	ch->type = IIO_VOLTAGE;
+	ch->indexed = 1;
+	ch->scan_index = ch_idx;
+
+	/*
+	 * 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) |
+				 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_chan_init(struct iio_dev *indio_dev)
+{
+	struct iio_chan_spec *channels;
+	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
+	unsigned int num_ch;
+	int ret, chan_idx;
+
+	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;
+	}
+
+	/*
+	 * Number of channel per filter is temporary limited to 1.
+	 * Restriction should be cleaned with scan mode
+	 */
+	if (num_ch > 1) {
+		dev_err(&indio_dev->dev, "Multi channel not yet supported\n");
+		return -EINVAL;
+	}
+
+	/* Bind to SD modulator IIO device */
+	adc->hwc = iio_hw_consumer_alloc(&indio_dev->dev);
+	if (IS_ERR(adc->hwc))
+		return -EPROBE_DEFER;
+
+	channels = devm_kcalloc(&indio_dev->dev, num_ch, sizeof(*channels),
+				GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	for (chan_idx = 0; chan_idx < num_ch; chan_idx++) {
+		ret = stm32_dfsdm_adc_chan_init_one(indio_dev, channels,
+						    chan_idx);
+		if (ret < 0)
+			goto free_hwc;
+	}
+
+	indio_dev->num_channels = num_ch;
+	indio_dev->channels = channels;
+
+	return 0;
+
+free_hwc:
+	iio_hw_consumer_free(adc->hwc);
+	return ret;
+}
+
+static const struct of_device_id stm32_dfsdm_adc_match[] = {
+	{ .compatible = "st,stm32-dfsdm-adc"},
+	{}
+};
+
+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;
+	struct iio_dev *iio;
+	char *name;
+	int ret, irq, val;
+
+	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->info = &stm32_dfsdm_info_adc;
+	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 = kzalloc(sizeof("dfsdm-adc0"), GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+	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;
+
+	ret = stm32_dfsdm_adc_chan_init(iio);
+	if (ret < 0)
+		return ret;
+
+	init_completion(&adc->completion);
+
+	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 *iio = iio_priv_to_dev(adc);
+
+	iio_device_unregister(iio);
+
+	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,
+};
+module_platform_driver(stm32_dfsdm_adc_driver);
+
+MODULE_DESCRIPTION("STM32 sigma delta ADC");
+MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen at st.com>");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/adc/stm32-dfsdm-core.c b/drivers/iio/adc/stm32-dfsdm-core.c
new file mode 100644
index 0000000..488e456
--- /dev/null
+++ b/drivers/iio/adc/stm32-dfsdm-core.c
@@ -0,0 +1,658 @@
+/*
+ * This file is part the core part STM32 DFSDM driver
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author(s): Arnaud Pouliquen <arnaud.pouliquen at st.com> for STMicroelectronics.
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include <linux/iio/trigger.h>
+#include <linux/iio/sysfs.h>
+
+#include "stm32-dfsdm.h"
+
+struct stm32_dfsdm_dev_data {
+	unsigned int num_filters;
+	unsigned int num_channels;
+	const struct regmap_config *regmap_cfg;
+};
+
+#define STM32H7_DFSDM_NUM_FILTERS	4
+#define STM32H7_DFSDM_NUM_CHANNELS	8
+
+#define DFSDM_MAX_INT_OVERSAMPLING 256
+
+#define DFSDM_MAX_FL_OVERSAMPLING 1024
+
+#define DFSDM_MAX_RES BIT(31)
+#define DFSDM_DATA_RES BIT(23)
+
+static bool stm32_dfsdm_volatile_reg(struct device *dev, unsigned int reg)
+{
+	if (reg < DFSDM_FILTER_BASE_ADR)
+		return false;
+
+	/*
+	 * Mask is done on register to avoid to list registers of all them
+	 * filter instances.
+	 */
+	switch (reg & DFSDM_FILTER_REG_MASK) {
+	case DFSDM_CR1(0) & DFSDM_FILTER_REG_MASK:
+	case DFSDM_ISR(0) & DFSDM_FILTER_REG_MASK:
+	case DFSDM_JDATAR(0) & DFSDM_FILTER_REG_MASK:
+	case DFSDM_RDATAR(0) & DFSDM_FILTER_REG_MASK:
+		return true;
+	}
+
+	return false;
+}
+
+static const struct regmap_config stm32h7_dfsdm_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = sizeof(u32),
+	.max_register = 0x2B8,
+	.volatile_reg = stm32_dfsdm_volatile_reg,
+	.fast_io = true,
+};
+
+static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_data = {
+	.num_filters = STM32H7_DFSDM_NUM_FILTERS,
+	.num_channels = STM32H7_DFSDM_NUM_CHANNELS,
+	.regmap_cfg = &stm32h7_dfsdm_regmap_cfg,
+};
+
+struct dfsdm_priv {
+	struct platform_device *pdev; /* platform device*/
+
+	struct stm32_dfsdm dfsdm; /* common data exported for all instances */
+
+	unsigned int spi_clk_out_div; /* SPI clkout divider value */
+	atomic_t n_active_ch;	/* number of current active channels */
+
+	/* Clock */
+	struct clk *clk; /* DFSDM clock */
+	struct clk *aclk; /* audio clock */
+};
+
+/**
+ * stm32_dfsdm_set_osrs - compute filter parameters.
+ *
+ * Enable interface if n_active_ch is not null.
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @fast: Fast mode enabled or disabled
+ * @oversamp: Expected oversampling between filtered sample and SD input stream
+ */
+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;
+	}
+
+	/*
+	 * Looks for filter and integrator oversampling ratios which allows
+	 * to reach 24 bits data output resolution.
+	 * Leave at once 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;
+}
+
+/**
+ * stm32_dfsdm_start_dfsdm - start global dfsdm IP interface.
+ *
+ * Enable interface if n_active_ch is not null.
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ */
+int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm)
+{
+	struct dfsdm_priv *priv = container_of(dfsdm, struct dfsdm_priv, dfsdm);
+	struct device *dev = &priv->pdev->dev;
+	unsigned int clk_div = priv->spi_clk_out_div;
+	int ret;
+
+	if (atomic_inc_return(&priv->n_active_ch) == 1) {
+		/* Enable clocks */
+		ret = clk_prepare_enable(priv->clk);
+		if (ret < 0) {
+			dev_err(dev, "Failed to start clock\n");
+			return ret;
+		}
+		if (priv->aclk) {
+			ret = clk_prepare_enable(priv->aclk);
+			if (ret < 0) {
+				dev_err(dev, "Failed to start audio clock\n");
+				goto disable_clk;
+			}
+		}
+
+		/* Output the SPI CLKOUT (if clk_div == 0 clock if OFF) */
+		ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
+					 DFSDM_CHCFGR1_CKOUTDIV_MASK,
+					 DFSDM_CHCFGR1_CKOUTDIV(clk_div));
+		if (ret < 0)
+			goto disable_aclk;
+
+		/* Global enable of DFSDM interface */
+		ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
+					 DFSDM_CHCFGR1_DFSDMEN_MASK,
+					 DFSDM_CHCFGR1_DFSDMEN(1));
+		if (ret < 0)
+			goto disable_aclk;
+	}
+
+	dev_dbg(dev, "%s: n_active_ch %d\n", __func__,
+		atomic_read(&priv->n_active_ch));
+
+	return 0;
+
+disable_aclk:
+	clk_disable_unprepare(priv->aclk);
+disable_clk:
+	clk_disable_unprepare(priv->clk);
+
+	return ret;
+}
+
+/**
+ * stm32_dfsdm_stop_dfsdm - stop global DFSDM IP interface.
+ *
+ * Disable interface if n_active_ch is null
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ */
+int stm32_dfsdm_stop_dfsdm(struct stm32_dfsdm *dfsdm)
+{
+	struct dfsdm_priv *priv = container_of(dfsdm, struct dfsdm_priv, dfsdm);
+	int ret;
+
+	if (atomic_dec_and_test(&priv->n_active_ch)) {
+		/* Global disable of DFSDM interface */
+		ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
+					 DFSDM_CHCFGR1_DFSDMEN_MASK,
+					 DFSDM_CHCFGR1_DFSDMEN(0));
+		if (ret < 0)
+			return ret;
+
+		/* Stop SPI CLKOUT */
+		ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
+					 DFSDM_CHCFGR1_CKOUTDIV_MASK,
+					 DFSDM_CHCFGR1_CKOUTDIV(0));
+		if (ret < 0)
+			return ret;
+
+		/* Disable clocks */
+		clk_disable_unprepare(priv->clk);
+		if (priv->aclk)
+			clk_disable_unprepare(priv->aclk);
+	}
+	dev_dbg(&priv->pdev->dev, "%s: n_active_ch %d\n", __func__,
+		atomic_read(&priv->n_active_ch));
+
+	return 0;
+}
+
+/**
+ * stm32_dfsdm_start_channel
+ *	Start DFSDM IP channels and associated interface.
+ *
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @ch_id: Channel index.
+ */
+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));
+}
+
+/**
+ * stm32_dfsdm_stop_channel
+ *	Stop DFSDM IP channels and associated interface.
+ *
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @ch_id: Channel index.
+ */
+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));
+}
+
+/**
+ * stm32_dfsdm_chan_configure
+ *	Configure DFSDM IP channels and associated interface.
+ *
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @ch_id: channel index.
+ */
+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));
+}
+
+/**
+ * stm32_dfsdm_start_filter - Start DFSDM IP filter conversion.
+ *
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @fl_id: Filter index.
+ */
+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));
+}
+
+/**
+ * stm32_dfsdm_stop_filter - Stop DFSDM IP filter conversion.
+ *
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @fl_id: Filter index.
+ */
+void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm, unsigned int fl_id)
+{
+	/* Mask IRQ for regular conversion achievement*/
+	regmap_update_bits(dfsdm->regmap, DFSDM_CR2(fl_id),
+			   DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(0));
+	/* Disable conversion */
+	regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
+			   DFSDM_CR1_DFEN_MASK, DFSDM_CR1_DFEN(0));
+}
+
+/**
+ * stm32_dfsdm_filter_configure - Configure DFSDM IP filter and associate it
+ *	to channel.
+ *
+ * @dfsdm: Handle used to retrieve dfsdm context.
+ * @fl_id: channel index.
+ * @fl_id: Filter index.
+ */
+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));
+
+	/* Filter order and Oversampling */
+	if (!ret)
+		ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id),
+					 DFSDM_FCR_FOSR_MASK,
+					 DFSDM_FCR_FOSR(fl->fosr));
+
+	if (!ret)
+		ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id),
+					 DFSDM_FCR_FORD_MASK,
+					 DFSDM_FCR_FORD(fl->ford));
+
+	/* If only one channel 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));
+
+	return regmap_update_bits(regmap, DFSDM_CR1(fl_id),
+					 DFSDM_CR1_RSYNC_MASK,
+			  DFSDM_CR1_RSYNC(fl->sync_mode));
+}
+
+static const struct iio_trigger_ops dfsdm_trigger_ops = {
+	.owner = THIS_MODULE,
+};
+
+static int stm32_dfsdm_setup_spi_trigger(struct platform_device *pdev,
+					 struct stm32_dfsdm *dfsdm)
+{
+	/*
+	 * To be able to use buffer consumer interface a trigger is needed.
+	 * As conversion are trigged by PDM samples from SPI bus, that makes
+	 * sense to define the serial interface ( SPI or manchester) as
+	 * trigger source.
+	 */
+
+	struct iio_trigger *trig;
+	int ret;
+
+	trig = devm_iio_trigger_alloc(&pdev->dev, DFSDM_SPI_TRIGGER_NAME);
+	if (!trig)
+		return -ENOMEM;
+
+	trig->dev.parent = pdev->dev.parent;
+	trig->ops = &dfsdm_trigger_ops;
+
+	iio_trigger_set_drvdata(trig, dfsdm);
+
+	ret = devm_iio_trigger_register(&pdev->dev, trig);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
+				 struct iio_dev *indio_dev,
+				 struct iio_chan_spec *chan, int chan_idx)
+{
+	struct iio_chan_spec *ch = &chan[chan_idx];
+	struct stm32_dfsdm_channel *df_ch;
+	const char *of_str;
+	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;
+	}
+
+	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);
+	val  = stm32_dfsdm_str2val(of_str, stm32_dfsdm_chan_type);
+	if (ret < 0 || val < 0)
+		df_ch->type = 0;
+	else
+		df_ch->type = val;
+
+	ret = of_property_read_string_index(indio_dev->dev.of_node,
+					    "st,adc-channel-clk-src", chan_idx,
+					    &of_str);
+	val  = stm32_dfsdm_str2val(of_str, stm32_dfsdm_chan_src);
+	if (ret < 0 || val < 0)
+		df_ch->src = 0;
+	else
+		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_parse_of(struct platform_device *pdev,
+				struct dfsdm_priv *priv)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct resource *res;
+	unsigned long clk_freq;
+	unsigned int spi_freq, rem;
+	int ret;
+
+	if (!node)
+		return -EINVAL;
+
+	/* Get resources */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Failed to get memory resource\n");
+		return -ENODEV;
+	}
+	priv->dfsdm.phys_base = res->start;
+	priv->dfsdm.base = devm_ioremap_resource(&pdev->dev, res);
+
+	/* Source clock */
+	priv->clk = devm_clk_get(&pdev->dev, "dfsdm");
+	if (IS_ERR(priv->clk)) {
+		dev_err(&pdev->dev, "No stm32_dfsdm_clk clock found\n");
+		return -EINVAL;
+	}
+
+	priv->aclk = devm_clk_get(&pdev->dev, "audio");
+	if (IS_ERR(priv->aclk))
+		priv->aclk = NULL;
+
+	if (priv->aclk)
+		clk_freq = clk_get_rate(priv->aclk);
+	else
+		clk_freq = clk_get_rate(priv->clk);
+
+	/* SPI clock freq */
+	ret = of_property_read_u32(pdev->dev.of_node, "spi-max-frequency",
+				   &spi_freq);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to get spi-max-frequency\n");
+		return ret;
+	}
+
+	priv->spi_clk_out_div = div_u64_rem(clk_freq, spi_freq, &rem) - 1;
+	priv->dfsdm.spi_master_freq = spi_freq;
+
+	if (rem) {
+		dev_warn(&pdev->dev, "SPI clock not accurate\n");
+		dev_warn(&pdev->dev, "%ld = %d * %d + %d\n",
+			 clk_freq, spi_freq, priv->spi_clk_out_div + 1, rem);
+	}
+
+	return 0;
+};
+
+static const struct of_device_id stm32_dfsdm_of_match[] = {
+	{
+		.compatible = "st,stm32h7-dfsdm",
+		.data = &stm32h7_dfsdm_data,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, stm32_dfsdm_of_match);
+
+static int stm32_dfsdm_remove(struct platform_device *pdev)
+{
+	of_platform_depopulate(&pdev->dev);
+
+	return 0;
+}
+
+static int stm32_dfsdm_probe(struct platform_device *pdev)
+{
+	struct dfsdm_priv *priv;
+	struct device_node *pnode = pdev->dev.of_node;
+	const struct of_device_id *of_id;
+	const struct stm32_dfsdm_dev_data *dev_data;
+	struct stm32_dfsdm *dfsdm;
+	int ret, i;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->pdev = pdev;
+
+	/* Populate data structure depending on compatibility */
+	of_id = of_match_node(stm32_dfsdm_of_match, pnode);
+	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;
+	dfsdm = &priv->dfsdm;
+	dfsdm->fl_list = devm_kcalloc(&pdev->dev, dev_data->num_filters,
+				      sizeof(*dfsdm->fl_list), GFP_KERNEL);
+	if (!dfsdm->fl_list)
+		return -ENOMEM;
+
+	dfsdm->num_fls = dev_data->num_filters;
+	dfsdm->ch_list = devm_kcalloc(&pdev->dev, dev_data->num_channels,
+				      sizeof(*dfsdm->ch_list),
+				      GFP_KERNEL);
+	if (!dfsdm->ch_list)
+		return -ENOMEM;
+	dfsdm->num_chs = dev_data->num_channels;
+
+	ret = stm32_dfsdm_parse_of(pdev, priv);
+	if (ret < 0)
+		return ret;
+
+	dfsdm->regmap = devm_regmap_init_mmio(&pdev->dev, dfsdm->base,
+					    &stm32h7_dfsdm_regmap_cfg);
+	if (IS_ERR(dfsdm->regmap)) {
+		ret = PTR_ERR(dfsdm->regmap);
+		dev_err(&pdev->dev, "%s: Failed to allocate regmap: %d\n",
+			__func__, ret);
+		return ret;
+	}
+
+	for (i = 0; i < STM32H7_DFSDM_NUM_FILTERS; i++) {
+		struct stm32_dfsdm_filter *fl = &dfsdm->fl_list[i];
+
+		fl->id = i;
+	}
+
+	platform_set_drvdata(pdev, dfsdm);
+
+	ret = stm32_dfsdm_setup_spi_trigger(pdev, dfsdm);
+	if (ret < 0)
+		return ret;
+
+	return of_platform_populate(pnode, NULL, NULL, &pdev->dev);
+}
+
+static struct platform_driver stm32_dfsdm_driver = {
+	.probe = stm32_dfsdm_probe,
+	.remove = stm32_dfsdm_remove,
+	.driver = {
+		.name = "stm32-dfsdm",
+		.of_match_table = stm32_dfsdm_of_match,
+	},
+};
+
+module_platform_driver(stm32_dfsdm_driver);
+
+MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen at st.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32 dfsdm driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/adc/stm32-dfsdm.h b/drivers/iio/adc/stm32-dfsdm.h
new file mode 100644
index 0000000..bb7d74f
--- /dev/null
+++ b/drivers/iio/adc/stm32-dfsdm.h
@@ -0,0 +1,371 @@
+/*
+ * This file is part of STM32 DFSDM driver
+ *
+ * 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 MDF_STM32_DFSDM__H
+#define MDF_STM32_DFSDM__H
+
+#include <linux/bitfield.h>
+
+#include <linux/iio/iio.h>
+/*
+ * STM32 DFSDM - global register map
+ * ________________________________________________________
+ * | Offset |                 Registers block             |
+ * --------------------------------------------------------
+ * | 0x000  |      CHANNEL 0 + COMMON CHANNEL FIELDS      |
+ * --------------------------------------------------------
+ * | 0x020  |                CHANNEL 1                    |
+ * --------------------------------------------------------
+ * | ...    |                .....                        |
+ * --------------------------------------------------------
+ * | 0x0E0  |                CHANNEL 7                    |
+ * --------------------------------------------------------
+ * | 0x100  |      FILTER  0 + COMMON  FILTER FIELDs      |
+ * --------------------------------------------------------
+ * | 0x200  |                FILTER  1                    |
+ * --------------------------------------------------------
+ * | 0x300  |                FILTER  2                    |
+ * --------------------------------------------------------
+ * | 0x400  |                FILTER  3                    |
+ * --------------------------------------------------------
+ */
+
+/*
+ * Channels register definitions
+ */
+#define DFSDM_CHCFGR1(y)  ((y) * 0x20 + 0x00)
+#define DFSDM_CHCFGR2(y)  ((y) * 0x20 + 0x04)
+#define DFSDM_AWSCDR(y)   ((y) * 0x20 + 0x08)
+#define DFSDM_CHWDATR(y)  ((y) * 0x20 + 0x0C)
+#define DFSDM_CHDATINR(y) ((y) * 0x20 + 0x10)
+
+/* CHCFGR1: Channel configuration register 1 */
+#define DFSDM_CHCFGR1_SITP_MASK     GENMASK(1, 0)
+#define DFSDM_CHCFGR1_SITP(v)       FIELD_PREP(DFSDM_CHCFGR1_SITP_MASK, v)
+#define DFSDM_CHCFGR1_SPICKSEL_MASK GENMASK(3, 2)
+#define DFSDM_CHCFGR1_SPICKSEL(v)   FIELD_PREP(DFSDM_CHCFGR1_SPICKSEL_MASK, v)
+#define DFSDM_CHCFGR1_SCDEN_MASK    BIT(5)
+#define DFSDM_CHCFGR1_SCDEN(v)      FIELD_PREP(DFSDM_CHCFGR1_SCDEN_MASK, v)
+#define DFSDM_CHCFGR1_CKABEN_MASK   BIT(6)
+#define DFSDM_CHCFGR1_CKABEN(v)     FIELD_PREP(DFSDM_CHCFGR1_CKABEN_MASK, v)
+#define DFSDM_CHCFGR1_CHEN_MASK     BIT(7)
+#define DFSDM_CHCFGR1_CHEN(v)       FIELD_PREP(DFSDM_CHCFGR1_CHEN_MASK, v)
+#define DFSDM_CHCFGR1_CHINSEL_MASK  BIT(8)
+#define DFSDM_CHCFGR1_CHINSEL(v)    FIELD_PREP(DFSDM_CHCFGR1_CHINSEL_MASK, v)
+#define DFSDM_CHCFGR1_DATMPX_MASK   GENMASK(13, 12)
+#define DFSDM_CHCFGR1_DATMPX(v)     FIELD_PREP(DFSDM_CHCFGR1_DATMPX_MASK, v)
+#define DFSDM_CHCFGR1_DATPACK_MASK  GENMASK(15, 14)
+#define DFSDM_CHCFGR1_DATPACK(v)    FIELD_PREP(DFSDM_CHCFGR1_DATPACK_MASK, v)
+#define DFSDM_CHCFGR1_CKOUTDIV_MASK GENMASK(23, 16)
+#define DFSDM_CHCFGR1_CKOUTDIV(v)   FIELD_PREP(DFSDM_CHCFGR1_CKOUTDIV_MASK, v)
+#define DFSDM_CHCFGR1_CKOUTSRC_MASK BIT(30)
+#define DFSDM_CHCFGR1_CKOUTSRC(v)   FIELD_PREP(DFSDM_CHCFGR1_CKOUTSRC_MASK, v)
+#define DFSDM_CHCFGR1_DFSDMEN_MASK  BIT(31)
+#define DFSDM_CHCFGR1_DFSDMEN(v)    FIELD_PREP(DFSDM_CHCFGR1_DFSDMEN_MASK, v)
+
+/* CHCFGR2: Channel configuration register 2 */
+#define DFSDM_CHCFGR2_DTRBS_MASK    GENMASK(7, 3)
+#define DFSDM_CHCFGR2_DTRBS(v)      FIELD_PREP(DFSDM_CHCFGR2_DTRBS_MASK, v)
+#define DFSDM_CHCFGR2_OFFSET_MASK   GENMASK(31, 8)
+#define DFSDM_CHCFGR2_OFFSET(v)     FIELD_PREP(DFSDM_CHCFGR2_OFFSET_MASK, v)
+
+/* AWSCDR: Channel analog watchdog and short circuit detector */
+#define DFSDM_AWSCDR_SCDT_MASK    GENMASK(7, 0)
+#define DFSDM_AWSCDR_SCDT(v)      FIELD_PREP(DFSDM_AWSCDR_SCDT_MASK, v)
+#define DFSDM_AWSCDR_BKSCD_MASK   GENMASK(15, 12)
+#define DFSDM_AWSCDR_BKSCD(v)	  FIELD_PREP(DFSDM_AWSCDR_BKSCD_MASK, v)
+#define DFSDM_AWSCDR_AWFOSR_MASK  GENMASK(20, 16)
+#define DFSDM_AWSCDR_AWFOSR(v)    FIELD_PREP(DFSDM_AWSCDR_AWFOSR_MASK, v)
+#define DFSDM_AWSCDR_AWFORD_MASK  GENMASK(23, 22)
+#define DFSDM_AWSCDR_AWFORD(v)    FIELD_PREP(DFSDM_AWSCDR_AWFORD_MASK, v)
+
+/*
+ * Filters register definitions
+ */
+#define DFSDM_FILTER_BASE_ADR		0x100
+#define DFSDM_FILTER_REG_MASK		0x7F
+#define DFSDM_FILTER_X_BASE_ADR(x)	((x) * 0x80 + DFSDM_FILTER_BASE_ADR)
+
+#define DFSDM_CR1(x)     (DFSDM_FILTER_X_BASE_ADR(x)  + 0x00)
+#define DFSDM_CR2(x)     (DFSDM_FILTER_X_BASE_ADR(x)  + 0x04)
+#define DFSDM_ISR(x)     (DFSDM_FILTER_X_BASE_ADR(x)  + 0x08)
+#define DFSDM_ICR(x)     (DFSDM_FILTER_X_BASE_ADR(x)  + 0x0C)
+#define DFSDM_JCHGR(x)   (DFSDM_FILTER_X_BASE_ADR(x)  + 0x10)
+#define DFSDM_FCR(x)     (DFSDM_FILTER_X_BASE_ADR(x)  + 0x14)
+#define DFSDM_JDATAR(x)  (DFSDM_FILTER_X_BASE_ADR(x)  + 0x18)
+#define DFSDM_RDATAR(x)  (DFSDM_FILTER_X_BASE_ADR(x)  + 0x1C)
+#define DFSDM_AWHTR(x)   (DFSDM_FILTER_X_BASE_ADR(x)  + 0x20)
+#define DFSDM_AWLTR(x)   (DFSDM_FILTER_X_BASE_ADR(x)  + 0x24)
+#define DFSDM_AWSR(x)    (DFSDM_FILTER_X_BASE_ADR(x)  + 0x28)
+#define DFSDM_AWCFR(x)   (DFSDM_FILTER_X_BASE_ADR(x)  + 0x2C)
+#define DFSDM_EXMAX(x)   (DFSDM_FILTER_X_BASE_ADR(x)  + 0x30)
+#define DFSDM_EXMIN(x)   (DFSDM_FILTER_X_BASE_ADR(x)  + 0x34)
+#define DFSDM_CNVTIMR(x) (DFSDM_FILTER_X_BASE_ADR(x)  + 0x38)
+
+/* CR1 Control register 1 */
+#define DFSDM_CR1_DFEN_MASK	BIT(0)
+#define DFSDM_CR1_DFEN(v)	FIELD_PREP(DFSDM_CR1_DFEN_MASK, v)
+#define DFSDM_CR1_JSWSTART_MASK	BIT(1)
+#define DFSDM_CR1_JSWSTART(v)	FIELD_PREP(DFSDM_CR1_JSWSTART_MASK, v)
+#define DFSDM_CR1_JSYNC_MASK	BIT(3)
+#define DFSDM_CR1_JSYNC(v)	FIELD_PREP(DFSDM_CR1_JSYNC_MASK, v)
+#define DFSDM_CR1_JSCAN_MASK	BIT(4)
+#define DFSDM_CR1_JSCAN(v)	FIELD_PREP(DFSDM_CR1_JSCAN_MASK, v)
+#define DFSDM_CR1_JDMAEN_MASK	BIT(5)
+#define DFSDM_CR1_JDMAEN(v)	FIELD_PREP(DFSDM_CR1_JDMAEN_MASK, v)
+#define DFSDM_CR1_JEXTSEL_MASK	GENMASK(12, 8)
+#define DFSDM_CR1_JEXTSEL(v)	FIELD_PREP(DFSDM_CR1_JEXTSEL_MASK, v)
+#define DFSDM_CR1_JEXTEN_MASK	GENMASK(14, 13)
+#define DFSDM_CR1_JEXTEN(v)	FIELD_PREP(DFSDM_CR1_JEXTEN_MASK, v)
+#define DFSDM_CR1_RSWSTART_MASK	BIT(17)
+#define DFSDM_CR1_RSWSTART(v)	FIELD_PREP(DFSDM_CR1_RSWSTART_MASK, v)
+#define DFSDM_CR1_RCONT_MASK	BIT(18)
+#define DFSDM_CR1_RCONT(v)	FIELD_PREP(DFSDM_CR1_RCONT_MASK, v)
+#define DFSDM_CR1_RSYNC_MASK	BIT(19)
+#define DFSDM_CR1_RSYNC(v)	FIELD_PREP(DFSDM_CR1_RSYNC_MASK, v)
+#define DFSDM_CR1_RDMAEN_MASK	BIT(21)
+#define DFSDM_CR1_RDMAEN(v)	FIELD_PREP(DFSDM_CR1_RDMAEN_MASK, v)
+#define DFSDM_CR1_RCH_MASK	GENMASK(26, 24)
+#define DFSDM_CR1_RCH(v)	FIELD_PREP(DFSDM_CR1_RCH_MASK, v)
+#define DFSDM_CR1_FAST_MASK	BIT(29)
+#define DFSDM_CR1_FAST(v)	FIELD_PREP(DFSDM_CR1_FAST_MASK, v)
+#define DFSDM_CR1_AWFSEL_MASK	BIT(30)
+#define DFSDM_CR1_AWFSEL(v)	FIELD_PREP(DFSDM_CR1_AWFSEL_MASK, v)
+
+/* CR2: Control register 2 */
+#define DFSDM_CR2_IE_MASK	GENMASK(6, 0)
+#define DFSDM_CR2_IE(v)		FIELD_PREP(DFSDM_CR2_IE_MASK, v)
+#define DFSDM_CR2_JEOCIE_MASK	BIT(0)
+#define DFSDM_CR2_JEOCIE(v)	FIELD_PREP(DFSDM_CR2_JEOCIE_MASK, v)
+#define DFSDM_CR2_REOCIE_MASK	BIT(1)
+#define DFSDM_CR2_REOCIE(v)	FIELD_PREP(DFSDM_CR2_REOCIE_MASK, v)
+#define DFSDM_CR2_JOVRIE_MASK	BIT(2)
+#define DFSDM_CR2_JOVRIE(v)	FIELD_PREP(DFSDM_CR2_JOVRIE_MASK, v)
+#define DFSDM_CR2_ROVRIE_MASK	BIT(3)
+#define DFSDM_CR2_ROVRIE(v)	FIELD_PREP(DFSDM_CR2_ROVRIE_MASK, v)
+#define DFSDM_CR2_AWDIE_MASK	BIT(4)
+#define DFSDM_CR2_AWDIE(v)	FIELD_PREP(DFSDM_CR2_AWDIE_MASK, v)
+#define DFSDM_CR2_SCDIE_MASK	BIT(5)
+#define DFSDM_CR2_SCDIE(v)	FIELD_PREP(DFSDM_CR2_SCDIE_MASK, v)
+#define DFSDM_CR2_CKABIE_MASK	BIT(6)
+#define DFSDM_CR2_CKABIE(v)	FIELD_PREP(DFSDM_CR2_CKABIE_MASK, v)
+#define DFSDM_CR2_EXCH_MASK	GENMASK(15, 8)
+#define DFSDM_CR2_EXCH(v)	FIELD_PREP(DFSDM_CR2_EXCH_MASK, v)
+#define DFSDM_CR2_AWDCH_MASK	GENMASK(23, 16)
+#define DFSDM_CR2_AWDCH(v)	FIELD_PREP(DFSDM_CR2_AWDCH_MASK, v)
+
+/* ISR: Interrupt status register */
+#define DFSDM_ISR_JEOCF_MASK	BIT(0)
+#define DFSDM_ISR_JEOCF(v)	FIELD_PREP(DFSDM_ISR_JEOCF_MASK, v)
+#define DFSDM_ISR_REOCF_MASK	BIT(1)
+#define DFSDM_ISR_REOCF(v)	FIELD_PREP(DFSDM_ISR_REOCF_MASK, v)
+#define DFSDM_ISR_JOVRF_MASK	BIT(2)
+#define DFSDM_ISR_JOVRF(v)	FIELD_PREP(DFSDM_ISR_JOVRF_MASK, v)
+#define DFSDM_ISR_ROVRF_MASK	BIT(3)
+#define DFSDM_ISR_ROVRF(v)	FIELD_PREP(DFSDM_ISR_ROVRF_MASK, v)
+#define DFSDM_ISR_AWDF_MASK	BIT(4)
+#define DFSDM_ISR_AWDF(v)	FIELD_PREP(DFSDM_ISR_AWDF_MASK, v)
+#define DFSDM_ISR_JCIP_MASK	BIT(13)
+#define DFSDM_ISR_JCIP(v)	FIELD_PREP(DFSDM_ISR_JCIP_MASK, v)
+#define DFSDM_ISR_RCIP_MASK	BIT(14)
+#define DFSDM_ISR_RCIP(v)	FIELD_PREP(DFSDM_ISR_RCIP, v)
+#define DFSDM_ISR_CKABF_MASK	GENMASK(23, 16)
+#define DFSDM_ISR_CKABF(v)	FIELD_PREP(DFSDM_ISR_CKABF_MASK, v)
+#define DFSDM_ISR_SCDF_MASK	GENMASK(31, 24)
+#define DFSDM_ISR_SCDF(v)	FIELD_PREP(DFSDM_ISR_SCDF_MASK, v)
+
+/* ICR: Interrupt flag clear register */
+#define DFSDM_ICR_CLRJOVRF_MASK	      BIT(2)
+#define DFSDM_ICR_CLRJOVRF(v)	      FIELD_PREP(DFSDM_ICR_CLRJOVRF_MASK, v)
+#define DFSDM_ICR_CLRROVRF_MASK	      BIT(3)
+#define DFSDM_ICR_CLRROVRF(v)	      FIELD_PREP(DFSDM_ICR_CLRROVRF_MASK, v)
+#define DFSDM_ICR_CLRCKABF_MASK	      GENMASK(23, 16)
+#define DFSDM_ICR_CLRCKABF(v)	      FIELD_PREP(DFSDM_ICR_CLRCKABF_MASK, v)
+#define DFSDM_ICR_CLRCKABF_CH_MASK(y) BIT(16 + (y))
+#define DFSDM_ICR_CLRCKABF_CH(v, y)   \
+			   (((v) << (16 + (y))) & DFSDM_ICR_CLRCKABF_CH_MASK(y))
+#define DFSDM_ICR_CLRSCDF_MASK	      GENMASK(31, 24)
+#define DFSDM_ICR_CLRSCDF(v)	      FIELD_PREP(DFSDM_ICR_CLRSCDF_MASK, v)
+#define DFSDM_ICR_CLRSCDF_CH_MASK(y)  BIT(24 + (y))
+#define DFSDM_ICR_CLRSCDF_CH(v, y)    \
+			       (((v) << (24 + (y))) & DFSDM_ICR_CLRSCDF_MASK(y))
+
+/* FCR: Filter control register */
+#define DFSDM_FCR_IOSR_MASK	GENMASK(7, 0)
+#define DFSDM_FCR_IOSR(v)	FIELD_PREP(DFSDM_FCR_IOSR_MASK, v)
+#define DFSDM_FCR_FOSR_MASK	GENMASK(25, 16)
+#define DFSDM_FCR_FOSR(v)	FIELD_PREP(DFSDM_FCR_FOSR_MASK, v)
+#define DFSDM_FCR_FORD_MASK	GENMASK(31, 29)
+#define DFSDM_FCR_FORD(v)	FIELD_PREP(DFSDM_FCR_FORD_MASK, v)
+
+/* RDATAR: Filter data register for regular channel */
+#define DFSDM_DATAR_CH_MASK	GENMASK(2, 0)
+#define DFSDM_DATAR_DATA_OFFSET 8
+#define DFSDM_DATAR_DATA_MASK	GENMASK(31, DFSDM_DATAR_DATA_OFFSET)
+
+/* AWLTR: Filter analog watchdog low threshold register */
+#define DFSDM_AWLTR_BKAWL_MASK	GENMASK(3, 0)
+#define DFSDM_AWLTR_BKAWL(v)	FIELD_PREP(DFSDM_AWLTR_BKAWL_MASK, v)
+#define DFSDM_AWLTR_AWLT_MASK	GENMASK(31, 8)
+#define DFSDM_AWLTR_AWLT(v)	FIELD_PREP(DFSDM_AWLTR_AWLT_MASK, v)
+
+/* AWHTR: Filter analog watchdog low threshold register */
+#define DFSDM_AWHTR_BKAWH_MASK	GENMASK(3, 0)
+#define DFSDM_AWHTR_BKAWH(v)	FIELD_PREP(DFSDM_AWHTR_BKAWH_MASK, v)
+#define DFSDM_AWHTR_AWHT_MASK	GENMASK(31, 8)
+#define DFSDM_AWHTR_AWHT(v)	FIELD_PREP(DFSDM_AWHTR_AWHT_MASK, v)
+
+/* AWSR: Filter watchdog status register */
+#define DFSDM_AWSR_AWLTF_MASK	GENMASK(7, 0)
+#define DFSDM_AWSR_AWLTF(v)	FIELD_PREP(DFSDM_AWSR_AWLTF_MASK, v)
+#define DFSDM_AWSR_AWHTF_MASK	GENMASK(15, 8)
+#define DFSDM_AWSR_AWHTF(v)	FIELD_PREP(DFSDM_AWSR_AWHTF_MASK, v)
+
+/* AWCFR: Filter watchdog status register */
+#define DFSDM_AWCFR_AWLTF_MASK	GENMASK(7, 0)
+#define DFSDM_AWCFR_AWLTF(v)	FIELD_PREP(DFSDM_AWCFR_AWLTF_MASK, v)
+#define DFSDM_AWCFR_AWHTF_MASK	GENMASK(15, 8)
+#define DFSDM_AWCFR_AWHTF(v)	FIELD_PREP(DFSDM_AWCFR_AWHTF_MASK, v)
+
+/* DFSDM filter order  */
+enum stm32_dfsdm_sinc_order {
+	DFSDM_FASTSINC_ORDER, /* FastSinc filter type */
+	DFSDM_SINC1_ORDER,    /* Sinc 1 filter type */
+	DFSDM_SINC2_ORDER,    /* Sinc 2 filter type */
+	DFSDM_SINC3_ORDER,    /* Sinc 3 filter type */
+	DFSDM_SINC4_ORDER,    /* Sinc 4 filter type (N.A. for watchdog) */
+	DFSDM_SINC5_ORDER,    /* Sinc 5 filter type (N.A. for watchdog) */
+	DFSDM_NB_SINC_ORDER,
+};
+
+/**
+ * struct stm32_dfsdm_filter - structure relative to stm32 FDSDM filter
+ * TODO: complete structure.
+ * @id:		filetr ID,
+ */
+struct stm32_dfsdm_filter {
+	unsigned int id;
+	unsigned int iosr; /* integrator oversampling */
+	unsigned int fosr; /* filter oversampling */
+	enum stm32_dfsdm_sinc_order ford;
+	u64 res; /* output sample resolution */
+	unsigned int sync_mode; /* filter suynchronized with filter0 */
+	unsigned int fast; /* filter fast mode */
+};
+
+/**
+ * struct stm32_dfsdm_channel - structure relative to stm32 FDSDM channel
+ * TODO: complete structure.
+ * @id:		filetr ID,
+ */
+struct stm32_dfsdm_channel {
+	unsigned int id;   /* id of the channel */
+	unsigned int type; /* interface type linked to stm32_dfsdm_chan_type */
+	unsigned int src; /* interface type linked to stm32_dfsdm_chan_src */
+	unsigned int alt_si; /* use alternative serial input interface */
+};
+
+/**
+ * struct stm32_dfsdm - stm32 FDSDM driver common data (for all instances)
+ * @base:	control registers base cpu addr
+ * @phys_base:	DFSDM IP register physical address.
+ * @fl_list:	filter resources list
+ * @num_fl:	number of filter resources available
+ * @ch_list:	channel resources list
+ * @num_chs:	number of channel resources available
+ */
+struct stm32_dfsdm {
+	void __iomem	*base;
+	phys_addr_t	phys_base;
+	struct regmap *regmap;
+	struct stm32_dfsdm_filter *fl_list;
+	unsigned int num_fls;
+	struct stm32_dfsdm_channel *ch_list;
+	unsigned int num_chs;
+	unsigned int spi_master_freq;
+};
+
+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 */
+	{ 0, 0},
+};
+
+/* DFSDM channel serial spi clock source */
+enum stm32_dfsdm_spi_clk_src {
+	DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL,
+	DFSDM_CHANNEL_SPI_CLOCK_INTERNAL,
+	DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING,
+	DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING
+};
+
+/* 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 },
+	{ 0, 0 },
+};
+
+/* DFSDM Serial interface trigger name  */
+#define DFSDM_SPI_TRIGGER_NAME "DFSDM_SERIAL_IN"
+
+static inline 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;
+}
+
+int stm32_dfsdm_set_osrs(struct stm32_dfsdm_filter *fl, unsigned int fast,
+			 unsigned int oversamp);
+int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm);
+int stm32_dfsdm_stop_dfsdm(struct stm32_dfsdm *dfsdm);
+
+int stm32_dfsdm_filter_configure(struct stm32_dfsdm *dfsdm, unsigned int fl_id,
+				 unsigned int ch_id);
+int stm32_dfsdm_start_filter(struct stm32_dfsdm *dfsdm, unsigned int fl_id);
+void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm, unsigned int fl_id);
+
+int stm32_dfsdm_chan_configure(struct stm32_dfsdm *dfsdm,
+			       struct stm32_dfsdm_channel *ch);
+int stm32_dfsdm_start_channel(struct stm32_dfsdm *dfsdm, unsigned int ch_id);
+void stm32_dfsdm_stop_channel(struct stm32_dfsdm *dfsdm, unsigned int ch_id);
+
+int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
+				 struct iio_dev *indio_dev,
+				 struct iio_chan_spec *chan, int chan_idx);
+
+#endif
-- 
1.9.1




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