Message-ID: <20200801173316.0f766cbd@archlinux>
Date:   Sat, 1 Aug 2020 17:33:16 +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,
        Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [v4 1/2] iio: gyro: Add driver support for ADXRS290

On Sun, 26 Jul 2020 19:40:16 +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.

Applied to the togreg branch of iio.git which I'll push out as testing
for the autobuilders to poke at and see if they can find any issues
we've missed.

Trivial note though.  Title of email should be

[PATCH v4 1/2]....

Thanks,

Jonathan

> 
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXRS290.pdf
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Nishant Malpani <nish.malpani25@...il.com>
> ---
> 
> Changes in v4:
>   - reorder header includes lexicographically
>   - add prefix 'ADXRS290_MODE_' to enum 'adxrs290_mode' elements
>   - drop unnecessary type promotions/demotions wherever required by
>     modifying function signatures
>   - avoid the usage of local variables and write directly to *val during a
>     read_raw()
>   - remove spi_set_drvdata() as corresponding spi_get_drvdata() is never
>     used
> 
> 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 | 444 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 461 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..38bab4e3eee9
> --- /dev/null
> +++ b/drivers/iio/gyro/adxrs290.c
> @@ -0,0 +1,444 @@
> +// 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/delay.h>
> +#include <linux/device.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 {
> +	ADXRS290_MODE_STANDBY,
> +	ADXRS290_MODE_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, int *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, 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);
> +	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 = ADXRS290_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),
> +						     val);
> +			if (ret < 0)
> +				return ret;
> +
> +			return IIO_VAL_INT;
> +		case IIO_TEMP:
> +			ret = adxrs290_get_temp_data(indio_dev, val);
> +			if (ret < 0)
> +				return ret;
> +
> +			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;
> +
> +	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 = ADXRS290_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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