Message-ID: <20200726131549.02a28962@archlinux>
Date:   Sun, 26 Jul 2020 13:15:49 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Nishant Malpani <nish.malpani25@...il.com>
Cc:     dragos.bogdan@...log.com, darius.berghe@...log.com,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [v3 1/2] iio: gyro: Add driver support for ADXRS290

On Fri, 24 Jul 2020 16:31:59 +0530
Nishant Malpani <nish.malpani25@...il.com> wrote:

> ADXRS290 is a high performance MEMS pitch and roll (dual-axis in-plane)
> angular rate sensor (gyroscope) designed for use in stabilization
> applications. It also features an internal temperature sensor and
> programmable high-pass and low-pass filters.
> 
> Add support for ADXRS290 in direct-access mode for now.
> 
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXRS290.pdf
> Signed-off-by: Nishant Malpani <nish.malpani25@...il.com>

Looks pretty good to me.  A few minor comments seeing as you'll be doing
a v4 anyway to tidy up the bits Andy pointed out.

I've pointed out the locking is probably in excess of what is needed, but
I have no problem with you leaving it as it stands, in the interests of
having less fragile code as you extend the driver futher.

Thanks,

Jonathan

> ---
> 
> Changes in v3:
>   - drop "Link" tag & extra line in commit message
>   - rename cut-off frequencies tables to
>     'adxrs290_{lpf, hpf}_3db_freq_hz_table' to be more descriptive
>   - fix unsigned type errors
>   - add comments on how to scale raw angular velocity and temperature
>     values to appropriate units mentioned in the ABI
>   - re-order declarations in reversed spruce tree order
>   - remove 'indio_dev->dev.parent = &spi->dev' as the iio core handles it
>     during iio_device_alloc()
>   - use plain msleep() instead of the interruptible variant
>   - remove extra terminal comma
> 
> Changes in v2:
>   - append copyright tag with author's info
>   - remove asm/unaligned.h header
>   - remove unnecessary comments about the registers' description
>   - rephrase comment on the usage of mutex_lock
>   - discard the usage of local tx, rx buffers; use DMA-safe buffers
>     provided by the SPI core instead
>   - utilize spi_w8r16 provided by the SPI core instead of writing a
>     wrapper over spi_sync_transfer which semantically does the same
>   - equip spi_write_then_read instead of plain spi_write since the
>     latter requires a DMA-safe buffer
>   - implement exact matching of filter 3db frequencies instead of
>     finding the "closest" match; rounding complexity is left to the
>     userspace
>   - include 'info_mask_shared_by_type_available' when initialising
>     iio_chan_spec instead of explicitly exposing attributes
>     signifying available filter 3db frequencies; with this we can
>     utilize read_avail core callback
> ---
>  MAINTAINERS                 |   6 +
>  drivers/iio/gyro/Kconfig    |  10 +
>  drivers/iio/gyro/Makefile   |   1 +
>  drivers/iio/gyro/adxrs290.c | 446 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 463 insertions(+)
>  create mode 100644 drivers/iio/gyro/adxrs290.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9077411c9890..71ae9b184179 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1098,6 +1098,12 @@ L:	linux-media@...r.kernel.org
>  S:	Maintained
>  F:	drivers/media/i2c/adv7842*
>  
> +ANALOG DEVICES INC ADXRS290 DRIVER
> +M:	Nishant Malpani <nish.malpani25@...il.com>
> +L:	linux-iio@...r.kernel.org
> +S:	Supported
> +F:	drivers/iio/gyro/adxrs290.c
> +
>  ANALOG DEVICES INC ASOC CODEC DRIVERS
>  M:	Lars-Peter Clausen <lars@...afoo.de>
>  M:	Nuno Sá <nuno.sa@...log.com>
> diff --git a/drivers/iio/gyro/Kconfig b/drivers/iio/gyro/Kconfig
> index 6daeddf37f60..024a34139875 100644
> --- a/drivers/iio/gyro/Kconfig
> +++ b/drivers/iio/gyro/Kconfig
> @@ -41,6 +41,16 @@ config ADIS16260
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called adis16260.
>  
> +config ADXRS290
> +	tristate "Analog Devices ADXRS290 Dual-Axis MEMS Gyroscope SPI driver"
> +	depends on SPI
> +	help
> +	  Say yes here to build support for Analog Devices ADXRS290 programmable
> +	  digital output gyroscope.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called adxrs290.
> +
>  config ADXRS450
>  	tristate "Analog Devices ADXRS450/3 Digital Output Gyroscope SPI driver"
>  	depends on SPI
> diff --git a/drivers/iio/gyro/Makefile b/drivers/iio/gyro/Makefile
> index 45cbd5dc644e..0319b397dc3f 100644
> --- a/drivers/iio/gyro/Makefile
> +++ b/drivers/iio/gyro/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_ADIS16080) += adis16080.o
>  obj-$(CONFIG_ADIS16130) += adis16130.o
>  obj-$(CONFIG_ADIS16136) += adis16136.o
>  obj-$(CONFIG_ADIS16260) += adis16260.o
> +obj-$(CONFIG_ADXRS290) += adxrs290.o
>  obj-$(CONFIG_ADXRS450) += adxrs450.o
>  obj-$(CONFIG_BMG160) += bmg160_core.o
>  obj-$(CONFIG_BMG160_I2C) += bmg160_i2c.o
> diff --git a/drivers/iio/gyro/adxrs290.c b/drivers/iio/gyro/adxrs290.c
> new file mode 100644
> index 000000000000..cff1af9211bc
> --- /dev/null
> +++ b/drivers/iio/gyro/adxrs290.c
> @@ -0,0 +1,446 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * ADXRS290 SPI Gyroscope Driver
> + *
> + * Copyright (C) 2020 Nishant Malpani <nish.malpani25@...il.com>
> + * Copyright (C) 2020 Analog Devices, Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define ADXRS290_ADI_ID		0xAD
> +#define ADXRS290_MEMS_ID	0x1D
> +#define ADXRS290_DEV_ID		0x92
> +
> +#define ADXRS290_REG_ADI_ID	0x00
> +#define ADXRS290_REG_MEMS_ID	0x01
> +#define ADXRS290_REG_DEV_ID	0x02
> +#define ADXRS290_REG_REV_ID	0x03
> +#define ADXRS290_REG_SN0	0x04 /* Serial Number Registers, 4 bytes */
> +#define ADXRS290_REG_DATAX0	0x08 /* Roll Rate o/p Data Regs, 2 bytes */
> +#define ADXRS290_REG_DATAY0	0x0A /* Pitch Rate o/p Data Regs, 2 bytes */
> +#define ADXRS290_REG_TEMP0	0x0C
> +#define ADXRS290_REG_POWER_CTL	0x10
> +#define ADXRS290_REG_FILTER	0x11
> +#define ADXRS290_REG_DATA_RDY	0x12
> +
> +#define ADXRS290_READ		BIT(7)
> +#define ADXRS290_TSM		BIT(0)
> +#define ADXRS290_MEASUREMENT	BIT(1)
> +#define ADXRS290_SYNC		GENMASK(1, 0)
> +#define ADXRS290_LPF_MASK	GENMASK(2, 0)
> +#define ADXRS290_LPF(x)		FIELD_PREP(ADXRS290_LPF_MASK, x)
> +#define ADXRS290_HPF_MASK	GENMASK(7, 4)
> +#define ADXRS290_HPF(x)		FIELD_PREP(ADXRS290_HPF_MASK, x)
> +
> +#define ADXRS290_READ_REG(reg)	(ADXRS290_READ | (reg))
> +
> +#define ADXRS290_MAX_TRANSITION_TIME_MS 100
> +
> +enum adxrs290_mode {
> +	STANDBY,
> +	MEASUREMENT,
> +};
> +
> +struct adxrs290_state {
> +	struct spi_device	*spi;
> +	/* Serialize reads and their subsequent processing */
> +	struct mutex		lock;
> +	enum adxrs290_mode	mode;
> +	unsigned int		lpf_3db_freq_idx;
> +	unsigned int		hpf_3db_freq_idx;
> +};
> +
> +/*
> + * Available cut-off frequencies of the low pass filter in Hz.
> + * The integer part and fractional part are represented separately.
> + */
> +static const int adxrs290_lpf_3db_freq_hz_table[][2] = {
> +	[0] = {480, 0},
> +	[1] = {320, 0},
> +	[2] = {160, 0},
> +	[3] = {80, 0},
> +	[4] = {56, 600000},
> +	[5] = {40, 0},
> +	[6] = {28, 300000},
> +	[7] = {20, 0},
> +};
> +
> +/*
> + * Available cut-off frequencies of the high pass filter in Hz.
> + * The integer part and fractional part are represented separately.
> + */
> +static const int adxrs290_hpf_3db_freq_hz_table[][2] = {
> +	[0] = {0, 0},
> +	[1] = {0, 11000},
> +	[2] = {0, 22000},
> +	[3] = {0, 44000},
> +	[4] = {0, 87000},
> +	[5] = {0, 175000},
> +	[6] = {0, 350000},
> +	[7] = {0, 700000},
> +	[8] = {1, 400000},
> +	[9] = {2, 800000},
> +	[10] = {11, 300000},
> +};
> +
> +static int adxrs290_get_rate_data(struct iio_dev *indio_dev, const u8 cmd,
> +				  unsigned int *val)

Why go through the effort of signed to unsigned to signed for val?

> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int ret = 0;
> +	int temp;
> +
> +	mutex_lock(&st->lock);
> +	temp = spi_w8r16(st->spi, cmd);
> +	if (temp < 0) {
> +		ret = temp;
> +		goto err_unlock;
> +	}
> +
> +	*val = temp;
> +
> +err_unlock:
> +	mutex_unlock(&st->lock);
> +	return ret;
> +}
> +
> +static int adxrs290_get_temp_data(struct iio_dev *indio_dev, unsigned int *val)
> +{
> +	const u8 cmd = ADXRS290_READ_REG(ADXRS290_REG_TEMP0);
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int ret = 0;
> +	int temp;
> +
> +	mutex_lock(&st->lock);

Just a quick note here.  I don't think you actually need the lock
(yet) as you aren't doing any read modify write cycles and in this
particular case there is no local cached state to protect.
However, I don't mind if you want to leave them as it may make things
less fragile as you move forwards.

> +	temp = spi_w8r16(st->spi, cmd);
> +	if (temp < 0) {
> +		ret = temp;
> +		goto err_unlock;
> +	}
> +
> +	/* extract lower 12 bits temperature reading */
> +	*val = temp & 0x0FFF;
> +
> +err_unlock:
> +	mutex_unlock(&st->lock);
> +	return ret;
> +}
> +
> +static int adxrs290_get_3db_freq(struct iio_dev *indio_dev, u8 *val, u8 *val2)
> +{
> +	const u8 cmd = ADXRS290_READ_REG(ADXRS290_REG_FILTER);
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int ret = 0;
> +	short temp;
> +
> +	mutex_lock(&st->lock);
> +	temp = spi_w8r8(st->spi, cmd);
> +	if (temp < 0) {
> +		ret = temp;
> +		goto err_unlock;
> +	}
> +
> +	*val = FIELD_GET(ADXRS290_LPF_MASK, temp);
> +	*val2 = FIELD_GET(ADXRS290_HPF_MASK, temp);
> +
> +err_unlock:
> +	mutex_unlock(&st->lock);
> +	return ret;
> +}
> +
> +static int adxrs290_spi_write_reg(struct spi_device *spi, const u8 reg,
> +				  const u8 val)
> +{
> +	u8 buf[2];
> +
> +	buf[0] = reg;
> +	buf[1] = val;
> +
> +	return spi_write_then_read(spi, buf, ARRAY_SIZE(buf), NULL, 0);
> +}
> +
> +static int adxrs290_find_match(const int (*freq_tbl)[2], const int n,
> +			       const int val, const int val2)
> +{
> +	int i;
> +
> +	for (i = 0; i < n; i++) {
> +		if (freq_tbl[i][0] == val && freq_tbl[i][1] == val2)
> +			return i;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int adxrs290_set_filter_freq(struct iio_dev *indio_dev,
> +				    const unsigned int lpf_idx,
> +				    const unsigned int hpf_idx)
> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	u8 val;
> +
> +	val = ADXRS290_HPF(hpf_idx) | ADXRS290_LPF(lpf_idx);
> +
> +	return adxrs290_spi_write_reg(st->spi, ADXRS290_REG_FILTER, val);
> +}
> +
> +static int adxrs290_initial_setup(struct iio_dev *indio_dev)
> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +
> +	st->mode = MEASUREMENT;
> +
> +	return adxrs290_spi_write_reg(st->spi,
> +				      ADXRS290_REG_POWER_CTL,
> +				      ADXRS290_MEASUREMENT | ADXRS290_TSM);
> +}
> +
> +static int adxrs290_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int *val,
> +			     int *val2,
> +			     long mask)
> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	unsigned int t;
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_ANGL_VEL:
> +			ret = adxrs290_get_rate_data(indio_dev,
> +						     ADXRS290_READ_REG(chan->address),
> +						     &t);
> +			if (ret < 0)
> +				return ret;
> +			*val = t;

As mentioned above, you should be fine with using a signed value where you have &t.
As we don't use *val in the error case, it's fine to write directly into it and
avoid the need for the local variable t at all.

> +			return IIO_VAL_INT;
> +		case IIO_TEMP:
> +			ret = adxrs290_get_temp_data(indio_dev, &t);
> +			if (ret < 0)
> +				return ret;
> +			*val = t;
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_ANGL_VEL:
> +			/* 1 LSB = 0.005 degrees/sec */
> +			*val = 0;
> +			*val2 = 87266;
> +			return IIO_VAL_INT_PLUS_NANO;
> +		case IIO_TEMP:
> +			/* 1 LSB = 0.1 degrees Celsius */
> +			*val = 100;
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		switch (chan->type) {
> +		case IIO_ANGL_VEL:
> +			t = st->lpf_3db_freq_idx;
> +			*val = adxrs290_lpf_3db_freq_hz_table[t][0];
> +			*val2 = adxrs290_lpf_3db_freq_hz_table[t][1];
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> +		switch (chan->type) {
> +		case IIO_ANGL_VEL:
> +			t = st->hpf_3db_freq_idx;
> +			*val = adxrs290_hpf_3db_freq_hz_table[t][0];
> +			*val2 = adxrs290_hpf_3db_freq_hz_table[t][1];
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		default:
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int adxrs290_write_raw(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan,
> +			      int val,
> +			      int val2,
> +			      long mask)
> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int lpf_idx, hpf_idx;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		lpf_idx = adxrs290_find_match(adxrs290_lpf_3db_freq_hz_table,
> +					      ARRAY_SIZE(adxrs290_lpf_3db_freq_hz_table),
> +					      val, val2);
> +		if (lpf_idx < 0)
> +			return -EINVAL;
> +		/* caching the updated state of the low-pass filter */
> +		st->lpf_3db_freq_idx = lpf_idx;
> +		/* retrieving the current state of the high-pass filter */
> +		hpf_idx = st->hpf_3db_freq_idx;
> +		return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> +		hpf_idx = adxrs290_find_match(adxrs290_hpf_3db_freq_hz_table,
> +					      ARRAY_SIZE(adxrs290_hpf_3db_freq_hz_table),
> +					      val, val2);
> +		if (hpf_idx < 0)
> +			return -EINVAL;
> +		/* caching the updated state of the high-pass filter */
> +		st->hpf_3db_freq_idx = hpf_idx;
> +		/* retrieving the current state of the low-pass filter */
> +		lpf_idx = st->lpf_3db_freq_idx;
> +		return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int adxrs290_read_avail(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan,
> +			       const int **vals, int *type, int *length,
> +			       long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
> +		*vals = (const int *)adxrs290_lpf_3db_freq_hz_table;
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		/* Values are stored in a 2D matrix */
> +		*length = ARRAY_SIZE(adxrs290_lpf_3db_freq_hz_table) * 2;
> +
> +		return IIO_AVAIL_LIST;
> +	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
> +		*vals = (const int *)adxrs290_hpf_3db_freq_hz_table;
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		/* Values are stored in a 2D matrix */
> +		*length = ARRAY_SIZE(adxrs290_hpf_3db_freq_hz_table) * 2;
> +
> +		return IIO_AVAIL_LIST;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +#define ADXRS290_ANGL_VEL_CHANNEL(reg, axis) {				\
> +	.type = IIO_ANGL_VEL,						\
> +	.address = reg,							\
> +	.modified = 1,							\
> +	.channel2 = IIO_MOD_##axis,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |		\
> +	BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) |		\
> +	BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY),		\
> +	.info_mask_shared_by_type_available =				\
> +	BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) |		\
> +	BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY),		\
> +}
> +
> +static const struct iio_chan_spec adxrs290_channels[] = {
> +	ADXRS290_ANGL_VEL_CHANNEL(ADXRS290_REG_DATAX0, X),
> +	ADXRS290_ANGL_VEL_CHANNEL(ADXRS290_REG_DATAY0, Y),
> +	{
> +		.type = IIO_TEMP,
> +		.address = ADXRS290_REG_TEMP0,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +		BIT(IIO_CHAN_INFO_SCALE),
> +	},
> +};
> +
> +static const struct iio_info adxrs290_info = {
> +	.read_raw = &adxrs290_read_raw,
> +	.write_raw = &adxrs290_write_raw,
> +	.read_avail = &adxrs290_read_avail,
> +};
> +
> +static int adxrs290_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct adxrs290_state *st;
> +	u8 val, val2;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	st->spi = spi;
> +	spi_set_drvdata(spi, indio_dev);

As things currently stand I don't think you ever use this.
So drop it for now and reintroduce it when you need it (probably when
you add power management support).

> +
> +	indio_dev->name = "adxrs290";
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = adxrs290_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(adxrs290_channels);
> +	indio_dev->info = &adxrs290_info;
> +
> +	val = spi_w8r8(spi, ADXRS290_READ_REG(ADXRS290_REG_ADI_ID));
> +	if (val != ADXRS290_ADI_ID) {
> +		dev_err(&spi->dev, "Wrong ADI ID 0x%02x\n", val);
> +		return -ENODEV;
> +	}
> +
> +	val = spi_w8r8(spi, ADXRS290_READ_REG(ADXRS290_REG_MEMS_ID));
> +	if (val != ADXRS290_MEMS_ID) {
> +		dev_err(&spi->dev, "Wrong MEMS ID 0x%02x\n", val);
> +		return -ENODEV;
> +	}
> +
> +	val = spi_w8r8(spi, ADXRS290_READ_REG(ADXRS290_REG_DEV_ID));
> +	if (val != ADXRS290_DEV_ID) {
> +		dev_err(&spi->dev, "Wrong DEV ID 0x%02x\n", val);
> +		return -ENODEV;
> +	}
> +
> +	/* default mode the gyroscope starts in */
> +	st->mode = STANDBY;
> +
> +	/* switch to measurement mode and switch on the temperature sensor */
> +	ret = adxrs290_initial_setup(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* max transition time to measurement mode */
> +	msleep(ADXRS290_MAX_TRANSITION_TIME_MS);
> +
> +	ret = adxrs290_get_3db_freq(indio_dev, &val, &val2);
> +	if (ret < 0)
> +		return ret;
> +
> +	st->lpf_3db_freq_idx = val;
> +	st->hpf_3db_freq_idx = val2;
> +
> +	return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static const struct of_device_id adxrs290_of_match[] = {
> +	{ .compatible = "adi,adxrs290" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, adxrs290_of_match);
> +
> +static struct spi_driver adxrs290_driver = {
> +	.driver = {
> +		.name = "adxrs290",
> +		.of_match_table = adxrs290_of_match,
> +	},
> +	.probe = adxrs290_probe,
> +};
> +module_spi_driver(adxrs290_driver);
> +
> +MODULE_AUTHOR("Nishant Malpani <nish.malpani25@...il.com>");
> +MODULE_DESCRIPTION("Analog Devices ADXRS290 Gyroscope SPI driver");
> +MODULE_LICENSE("GPL");

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