Re: [PATCHi v3] iio: add support of the max1027

[trem <tremyfr@xxxxxxxx>]

Hi Jonathan,


On 30/05/14 18:29, Jonathan Cameron wrote:
> On May 29, 2014 10:22:00 PM GMT+01:00, Philippe Reynes<tremyfr@xxxxxxxx>  wrote:
> > This driver add partial support of the
> > maxim 1027/1029/1031. Differential mode is not
> > supported.
> >
> > It was tested on armadeus apf27 board.
> >
> > Signed-off-by: Philippe Reynes<tremyfr@xxxxxxxx>
>
> One last thing from me.
> > ---
> > .../devicetree/bindings/iio/adc/max1027-adc.txt    |   22 +
> > drivers/iio/adc/Kconfig                            |    9 +
> > drivers/iio/adc/Makefile                           |    1 +
> > drivers/iio/adc/max1027.c                          |  518
> > ++++++++++++++++++++
> > 4 files changed, 550 insertions(+), 0 deletions(-)
> > create mode 100644
> > Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
> > create mode 100644 drivers/iio/adc/max1027.c
> >
> > Changelog:
> > v3: (thanks Hartmut Knaack, Lars-Peter Clausen and Jonathan Cameron for
> > the feedback)
> > - move to drivers/iio/adc (was in staging)
> > - clean binding doc
> > - drop empty update_scan_mode callback
> > - add a lock around single channel read code
> > - remove useless wrappers around spi_write and spi_read
> > - fix available scan mask (a bit was missing)
> > - remove useless header
> > - some others little cleanp
> >
> > v2: (thanks Hartmut Knaack and Jonathan Cameron for the feedback)
> > - really use devm_*
> > - use demux magic
> > - use spi_read and spi_write (instead of spi_sync)
> > - use define for register (instead of hardcoded value)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
> > b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
> > new file mode 100644
> > index 0000000..a8770cc
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/adc/max1027-adc.txt
> > @@ -0,0 +1,22 @@
> > +* Maxim 1027/1029/1031 Analog to Digital Converter (ADC)
> > +
> > +Required properties:
> > +  - compatible: Should be "maxim,max1027" or "maxim,max1029" or
> > "maxim,max1031"
> > +  - reg: SPI chip select number for the device
> > +  - interrupt-parent: phandle to the parent interrupt controller
> > +  see:
> > Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
> > +  - interrupts: IRQ line for the ADC
> > +  see:
> > Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
> > +
> > +Recommended properties:
> > +- spi-max-frequency: Definition as per
> > +                     Documentation/devicetree/bindings/spi/spi-bus.txt
> > +
> > +Example:
> > +adc@0 {
> > +	compatible = "maxim,max1027";
> > +	reg =<0>;
> > +	interrupt-parent =<&gpio5>;
> > +	interrupts =<15 IRQ_TYPE_EDGE_RISING>;
> > +	spi-max-frequency =<1000000>;
> > +};
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 24c28e3..517f886 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -119,6 +119,15 @@ config LP8788_ADC
> > 	help
> > 	  Say yes here to build support for TI LP8788 ADC.
> >
> > +config MAX1027
> > +	tristate "Maxim max1027 ADC driver"
> > +	depends on SPI
> > +	select IIO_BUFFER
> > +	select IIO_TRIGGERED_BUFFER
> > +	help
> > +	  Say yes here to build support for Maxim SPI ADC models
> > +	  max1027, max1029 and max1031.
> > +
> > config MAX1363
> > 	tristate "Maxim max1363 ADC driver"
> > 	depends on I2C
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index ab346d8..daac784 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -14,6 +14,7 @@ obj-$(CONFIG_AD7887) += ad7887.o
> > obj-$(CONFIG_AT91_ADC) += at91_adc.o
> > obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
> > obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
> > +obj-$(CONFIG_MAX1027) += max1027.o
> > obj-$(CONFIG_MAX1363) += max1363.o
> > obj-$(CONFIG_MCP320X) += mcp320x.o
> > obj-$(CONFIG_MCP3422) += mcp3422.o
> > diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> > new file mode 100644
> > index 0000000..6323510
> > --- /dev/null
> > +++ b/drivers/iio/adc/max1027.c
> > @@ -0,0 +1,518 @@
> > + /*
> > +  * iio/adc/max1027.c
> > +  * Copyright (C) 2014 Philippe Reynes
> > +  *
> > +  * based on linux/drivers/iio/ad7923.c
> > +  * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
> > +  * Copyright 2012 CS Systemes d'Information
> > +  *
> > +  * 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.
> > +  *
> > +  * max1027.c
> > +  *
> > +  * Partial support for max1027 and similar chips.
> > +  */
> > +
> > +#include<linux/kernel.h>
> > +#include<linux/module.h>
> > +#include<linux/spi/spi.h>
> > +#include<linux/delay.h>
> > +
> > +#include<linux/iio/iio.h>
> > +#include<linux/iio/buffer.h>
> > +#include<linux/iio/trigger.h>
> > +#include<linux/iio/trigger_consumer.h>
> > +#include<linux/iio/triggered_buffer.h>
> > +
> > +#define MAX1027_CONV_REG  0x80
> > +#define MAX1027_SETUP_REG 0x40
> > +#define MAX1027_AVG_REG   0x20
> > +#define MAX1027_RST_REG   0x10
> > +
> > +/* conversion register */
> > +#define MAX1027_TEMP      0x01
> > +#define MAX1027_SCAN_0_N  (0x00<<  1)
> > +#define MAX1027_SCAN_N_M  (0x01<<  1)
> > +#define MAX1027_SCAN_N    (0x02<<  1)
> > +#define MAX1027_NOSCAN    (0x03<<  1)
> > +#define MAX1027_CHAN(n)   ((n)<<  3)
> > +
> > +/* setup register */
> > +#define MAX1027_UNIPOLAR  0x02
> > +#define MAX1027_BIPOLAR   0x03
> > +#define MAX1027_REF_MODE0 (0x00<<  2)
> > +#define MAX1027_REF_MODE1 (0x01<<  2)
> > +#define MAX1027_REF_MODE2 (0x02<<  2)
> > +#define MAX1027_REF_MODE3 (0x03<<  2)
> > +#define MAX1027_CKS_MODE0 (0x00<<  4)
> > +#define MAX1027_CKS_MODE1 (0x01<<  4)
> > +#define MAX1027_CKS_MODE2 (0x02<<  4)
> > +#define MAX1027_CKS_MODE3 (0x03<<  4)
> > +
> > +/* averaging register */
> > +#define MAX1027_NSCAN_4   0x00
> > +#define MAX1027_NSCAN_8   0x01
> > +#define MAX1027_NSCAN_12  0x02
> > +#define MAX1027_NSCAN_16  0x03
> > +#define MAX1027_NAVG_4    (0x00<<  2)
> > +#define MAX1027_NAVG_8    (0x01<<  2)
> > +#define MAX1027_NAVG_16   (0x02<<  2)
> > +#define MAX1027_NAVG_32   (0x03<<  2)
> > +#define MAX1027_AVG_EN    (0x01<<  4)
> > +
> > +enum max1027_id {
> > +	max1027,
> > +	max1029,
> > +	max1031,
> > +};
> > +
> > +static const struct spi_device_id max1027_id[] = {
> > +	{"max1027", max1027},
> > +	{"max1029", max1029},
> > +	{"max1031", max1031},
> > +	{}
> > +};
> > +MODULE_DEVICE_TABLE(spi, max1027_id);
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id max1027_adc_dt_ids[] = {
> > +	{ .compatible = "maxim,max1027" },
> > +	{ .compatible = "maxim,max1029" },
> > +	{ .compatible = "maxim,max1031" },
> > +	{},
> > +};
> > +MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
> > +#endif
> > +
> > +#define MAX1027_V_CHAN(index)						\
> > +	{								\
> > +		.type = IIO_VOLTAGE,					\
> > +		.indexed = 1,						\
> > +		.channel = index,					\
> > +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> > +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> > +		.scan_index = index+1,					\
> > +		.scan_type = {						\
> > +			.sign = 'u',					\
> > +			.realbits = 10,					\
> > +			.storagebits = 16,				\
> > +			.shift = 2,					\
> > +			.endianness = IIO_BE,				\
> > +		},							\
> > +	}
> > +
> > +#define MAX1027_T_CHAN(index)						\
> > +	{								\
> > +		.type = IIO_TEMP,					\
> > +		.channel = index,					\
> > +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> > +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> > +		.scan_index = index,					\
> > +		.scan_type = {						\
> > +			.sign = 'u',					\
> > +			.realbits = 12,					\
> > +			.storagebits = 16,				\
> > +			.endianness = IIO_BE,				\
> > +		},							\
> > +	}
> > +
> > +static const struct iio_chan_spec max1027_channels[] = {
> > +	MAX1027_T_CHAN(0),
> > +	MAX1027_V_CHAN(0),
> > +	MAX1027_V_CHAN(1),
> > +	MAX1027_V_CHAN(2),
> > +	MAX1027_V_CHAN(3),
> > +	MAX1027_V_CHAN(4),
> > +	MAX1027_V_CHAN(5),
> > +	MAX1027_V_CHAN(6),
> > +	MAX1027_V_CHAN(7)
> > +};
> > +
> > +static const struct iio_chan_spec max1029_channels[] = {
> > +	MAX1027_T_CHAN(0),
> > +	MAX1027_V_CHAN(0),
> > +	MAX1027_V_CHAN(1),
> > +	MAX1027_V_CHAN(2),
> > +	MAX1027_V_CHAN(3),
> > +	MAX1027_V_CHAN(4),
> > +	MAX1027_V_CHAN(5),
> > +	MAX1027_V_CHAN(6),
> > +	MAX1027_V_CHAN(7),
> > +	MAX1027_V_CHAN(8),
> > +	MAX1027_V_CHAN(9),
> > +	MAX1027_V_CHAN(10),
> > +	MAX1027_V_CHAN(11)
> > +};
> > +
> > +static const struct iio_chan_spec max1031_channels[] = {
> > +	MAX1027_T_CHAN(0),
> > +	MAX1027_V_CHAN(0),
> > +	MAX1027_V_CHAN(1),
> > +	MAX1027_V_CHAN(2),
> > +	MAX1027_V_CHAN(3),
> > +	MAX1027_V_CHAN(4),
> > +	MAX1027_V_CHAN(5),
> > +	MAX1027_V_CHAN(6),
> > +	MAX1027_V_CHAN(7),
> > +	MAX1027_V_CHAN(8),
> > +	MAX1027_V_CHAN(9),
> > +	MAX1027_V_CHAN(10),
> > +	MAX1027_V_CHAN(11),
> > +	MAX1027_V_CHAN(12),
> > +	MAX1027_V_CHAN(13),
> > +	MAX1027_V_CHAN(14),
> > +	MAX1027_V_CHAN(15)
> > +};
> > +
> > +static unsigned long max1027_available_scan_masks[] = {
> > +	0x000001ff,
> > +	0x00000000,
> > +};
> > +
> > +static unsigned long max1029_available_scan_masks[] = {
> > +	0x00001fff,
> > +	0x00000000,
> > +};
> > +
> > +static unsigned long max1031_available_scan_masks[] = {
> > +	0x0001ffff,
> > +	0x00000000,
> > +};
> > +
> > +struct max1027_chip_info {
> > +	const struct iio_chan_spec *channels;
> > +	unsigned int num_channels;
> > +	unsigned long *available_scan_masks;
> > +};
> > +
> > +static const struct max1027_chip_info max1027_chip_info_tbl[] = {
> > +	[max1027] = {
> > +		.channels = max1027_channels,
> > +		.num_channels = ARRAY_SIZE(max1027_channels),
> > +		.available_scan_masks = max1027_available_scan_masks,
> > +	},
> > +	[max1029] = {
> > +		.channels = max1029_channels,
> > +		.num_channels = ARRAY_SIZE(max1029_channels),
> > +		.available_scan_masks = max1029_available_scan_masks,
> > +	},
> > +	[max1031] = {
> > +		.channels = max1031_channels,
> > +		.num_channels = ARRAY_SIZE(max1031_channels),
> > +		.available_scan_masks = max1031_available_scan_masks,
> > +	},
> > +};
> > +
> > +struct max1027_state {
> > +	struct max1027_chip_info	*info;
> > +	struct spi_device		*spi;
> > +	struct iio_trigger		*trig;
> > +	u16				*buffer;
> > +	struct mutex			lock;
> > +};
> > +
> > +static int max1027_read_single_value(struct iio_dev *indio_dev,
> > +				     struct iio_chan_spec const *chan,
> > +				     int *val)
> > +{
> > +	int ret;
> > +	unsigned char reg;
> > +	struct max1027_state *st = iio_priv(indio_dev);
> > +
> > +	if (iio_buffer_enabled(indio_dev)) {
> > +		dev_warn(&indio_dev->dev, "trigger mode already enabled");
> > +		return -EIO;
> > +	}
> > +
> > +	/* Start acquisition on conversion register write */
> > +	reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2 | MAX1027_CKS_MODE2;
> > +	ret = spi_write(st->spi, (void *)&reg, 1);
> > +	if (ret<  0) {
> > +		dev_err(&indio_dev->dev,
> > +			"Failed to configure setup register\n");
> > +		return ret;
> > +	}
> > +
> > +	/* Configure conversion register with the requested chan */
> > +	reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel)
> > +		| MAX1027_NOSCAN | !!(chan->type == IIO_TEMP);
> > +	ret = spi_write(st->spi, (void *)&reg, 1);
> > +	if (ret<  0) {
> > +		dev_err(&indio_dev->dev,
> > +			"Failed to configure conversion register\n");
> > +		return ret;
> > +	}
> > +
> > +	/*
> > +	 * For an unknown reason, when we use the mode "10" (write
> > +	 * conversion register), the it doesn't occur every time.
> > +	 * So we just wait 1 ms.
> > +	 */
> > +	mdelay(1);
> > +
> > +	/* Read result */
> > +	ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ? 4 :
> > 2);
> > +	if (ret<  0)
> > +		return ret;
> > +
> > +	*val = be16_to_cpu(st->buffer[0]);
> > +
> > +	return IIO_VAL_INT;
> > +}
> > +
> > +static int max1027_read_raw(struct iio_dev *indio_dev,
> > +			    struct iio_chan_spec const *chan,
> > +			    int *val, int *val2, long mask)
> > +{
> > +	int ret = 0;
> > +	struct max1027_state *st = iio_priv(indio_dev);
> > +
> > +	mutex_lock(&st->lock);
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:
> > +		ret = max1027_read_single_value(indio_dev, chan, val);
> > +		break;
> > +	case IIO_CHAN_INFO_SCALE:
> > +		switch (chan->type) {
> > +		case IIO_TEMP:
> > +			*val = 1;
> > +			*val2 = 8;
> > +			ret = IIO_VAL_FRACTIONAL;
> > +			break;
> > +		case IIO_VOLTAGE:
> > +			*val = 2500;
> > +			*val2 = 10;
> > +			ret = IIO_VAL_FRACTIONAL_LOG2;
> > +			break;
> > +		default:
> > +			ret = -EINVAL;
> > +			break;
> > +		};
> > +		break;
> > +	default:
> > +		ret = -EINVAL;
> > +		break;
> > +	};
> > +
> > +	mutex_unlock(&st->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
> > +				  unsigned reg, unsigned writeval,
> > +				  unsigned *readval)
> > +{
> > +	unsigned char val;
> > +	struct max1027_state *st = iio_priv(indio_dev);
> > +
> > +	if (readval != NULL)
> > +		return -EINVAL;
> > +
> > +	val = (unsigned char)writeval;
> > +	return spi_write(st->spi, (void *)&val, 1);
> > +}
> > +
> > +static int max1027_set_trigger_state(struct iio_trigger *trig, bool
> > state)
> > +{
> > +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> > +	struct max1027_state *st = iio_priv(indio_dev);
> > +	unsigned char reg;
> > +	int ret;
> > +
> > +	if (state) {
> > +		/* Start acquisition on cnvst */
> > +		reg = MAX1027_SETUP_REG | MAX1027_CKS_MODE0 | MAX1027_REF_MODE2;
> > +		ret = spi_write(st->spi, (void *)&reg, 1);
> > +		if (ret<  0)
> > +			return ret;
> > +
> > +		/* Scan from 0 to max */
> > +		reg = MAX1027_CONV_REG | MAX1027_CHAN(0)
> > +			| MAX1027_SCAN_N_M | MAX1027_TEMP;
> > +		ret = spi_write(st->spi, (void *)&reg, 1);
> > +		if (ret<  0)
> > +			return ret;
> > +	} else {
> > +		/* Start acquisition on conversion register write */
> > +		reg = MAX1027_SETUP_REG | MAX1027_CKS_MODE2 | MAX1027_REF_MODE2;
> > +		ret = spi_write(st->spi, (void *)&reg, 1);
> > +		if (ret<  0)
> > +			return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
>
> This is a very common case so we have a generic function for it so use that...
>
> iio_trigger_generic_data_poll
> Note that the private data is the trigger structure rather than the iio_Dev

I've done a v4 with iio_trigger_generic_data_rdy_poll.

> Also if this only works of the buffer is enabled you need to enforce that using the relevant call backs... Validate_device and validate_trigger. Probably start by only letting the device and trigger bind.

I'm sorry, I don't see what should be done in those callback (IRQ is always enabled).
May you help/explain me what is expected in those callback please .

For now, I send a v4 without those callback.

> One day we will work out a clean way of falling back to polled reads if using any other trigger!
>
> > +static irqreturn_t max1027_interrupt_handler(int irq, void *private)
> > +{
> > +	struct iio_dev *indio_dev = (struct iio_dev *)private;
> > +
> > +	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
> > +
> > +	if (iio_buffer_enabled(indio_dev))
> > +		iio_trigger_poll(indio_dev->trig, iio_get_time_ns());
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static irqreturn_t max1027_trigger_handler(int irq, void *private)
> > +{
> > +	struct iio_poll_func *pf = (struct iio_poll_func *)private;
> > +	struct iio_dev *indio_dev = pf->indio_dev;
> > +	struct max1027_state *st = iio_priv(indio_dev);
> > +
> > +	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
> > +
> > +	/* fill buffer with all channel */
> > +	spi_read(st->spi, st->buffer, indio_dev->masklength * 2);
> > +
> > +	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,
> > +					   iio_get_time_ns());
> > +
> > +	iio_trigger_notify_done(indio_dev->trig);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static const struct iio_trigger_ops max1027_trigger_ops = {
> > +	.owner = THIS_MODULE,
> > +	.set_trigger_state =&max1027_set_trigger_state,
> > +};
> > +
> > +static const struct iio_info max1027_info = {
> > +	.driver_module = THIS_MODULE,
> > +	.read_raw =&max1027_read_raw,
> > +	.debugfs_reg_access =&max1027_debugfs_reg_access,
> > +};
> > +
> > +static int max1027_probe(struct spi_device *spi)
> > +{
> > +	int err;
> > +	unsigned char reg;
> > +	struct iio_dev *indio_dev;
> > +	struct max1027_state *st;
> > +
> > +	pr_debug("%s: probe(spi = 0x%p)\n", __func__, spi);
> > +
> > +	/* allocate iio device */
> > +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> > +	if (indio_dev == NULL) {
> > +		pr_err("can't allocate iio device\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	spi_set_drvdata(spi, indio_dev);
> > +
> > +	st = iio_priv(indio_dev);
> > +	st->spi = spi;
> > +	st->buffer = NULL;
> > +	st->info = (struct max1027_chip_info *)
> > +		&max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];
> > +
> > +	mutex_init(&st->lock);
> > +
> > +	/* request irq */
> > +	err = devm_request_threaded_irq(&spi->dev, spi->irq,
> > +					max1027_interrupt_handler,
> > +					NULL,
> > +					IRQF_TRIGGER_FALLING,
> > +					spi->dev.driver->name, indio_dev);
> > +	if (err<  0) {
> > +		dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
> > +		return err;
> > +	}
> > +
> > +	indio_dev->name = spi_get_device_id(spi)->name;
> > +	indio_dev->dev.parent =&spi->dev;
> > +	indio_dev->info =&max1027_info;
> > +	indio_dev->modes = INDIO_DIRECT_MODE;
> > +	indio_dev->channels = st->info->channels;
> > +	indio_dev->num_channels = st->info->num_channels;
> > +	indio_dev->available_scan_masks = st->info->available_scan_masks;
> > +
> > +	/* Allocate buffer (data) */
> > +	st->buffer = devm_kmalloc(&indio_dev->dev,
> > +				  indio_dev->num_channels * 2,
> > +				  GFP_KERNEL);
> > +	if (st->buffer == NULL) {
> > +		dev_err(&indio_dev->dev, "Can't allocate bufffer\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	/* Allocate buffer */
> > +	err = iio_triggered_buffer_setup(indio_dev,&iio_pollfunc_store_time,
> > +					&max1027_trigger_handler, NULL);
> > +	if (err<  0) {
> > +		dev_err(&indio_dev->dev, "Failed to setup buffer\n");
> > +		return err;
> > +	}
> > +
> > +	/* Allocate trigger */
> > +	st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
> > +							indio_dev->name);
> > +	if (st->trig == NULL) {
> > +		err = -ENOMEM;
> > +		dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n");
> > +		goto fail_trigger_alloc;
> > +	}
> > +
> > +	/* configure and register trigger */
> > +	st->trig->ops =&max1027_trigger_ops;
> > +	st->trig->dev.parent =&spi->dev;
> > +	iio_trigger_set_drvdata(st->trig, indio_dev);
> > +	iio_trigger_register(st->trig);
> > +
> > +	/* Disable averaging */
> > +	reg = MAX1027_AVG_REG;
> > +	err = spi_write(st->spi, (void *)&reg, 1);
> > +	if (err<  0) {
> > +		dev_err(&indio_dev->dev, "Failed to configure averaging
> > register\n");
> > +		goto fail_dev_register;
> > +	}
> > +
> > +	/* Register the device */
> > +	err = iio_device_register(indio_dev);
> > +	if (err<  0) {
> > +		dev_err(&indio_dev->dev, "Failed to register iio device\n");
> > +		goto fail_dev_register;
> > +	}
> > +
> > +	return 0;
> > +
> > +fail_dev_register:
> > +fail_trigger_alloc:
> > +	iio_triggered_buffer_cleanup(indio_dev);
> > +
> > +	return err;
> > +}
> > +
> > +static int max1027_remove(struct spi_device *spi)
> > +{
> > +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> > +
> > +	pr_debug("%s: remove(spi = 0x%p)\n", __func__, spi);
> > +
> > +	iio_device_unregister(indio_dev);
> > +	iio_triggered_buffer_cleanup(indio_dev);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct spi_driver max1027_driver = {
> > +	.driver = {
> > +		.name	= "max1027",
> > +		.owner	= THIS_MODULE,
> > +	},
> > +	.probe		= max1027_probe,
> > +	.remove		= max1027_remove,
> > +	.id_table	= max1027_id,
> > +};
> > +module_spi_driver(max1027_driver);
> > +
> > +MODULE_AUTHOR("Philippe Reynes<tremyfr@xxxxxxxx>");
> > +MODULE_DESCRIPTION("MAX1027/MAX1029/MAX1031 ADC");
> > +MODULE_LICENSE("GPL v2");

Regards,
Philippe
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