Date:   Sun, 1 Aug 2021 19:12:10 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Lucas Stankus <lucas.p.stankus@...il.com>
Cc:     lars@...afoo.de, Michael.Hennerich@...log.com, robh+dt@...nel.org,
        Dragos.Bogdan@...log.com, Darius.Berghe@...log.com,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] iio: accel: Add driver support for ADXL313

On Sat, 31 Jul 2021 17:36:48 -0300
Lucas Stankus <lucas.p.stankus@...il.com> wrote:

> ADXL313 is a small, thin, low power, 3-axis accelerometer with high
> resolution measurement up to +/-4g. It includes an integrated 32-level
> FIFO and has activity and inactivity sensing capabilities.
> 
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> 
> Signed-off-by: Lucas Stankus <lucas.p.stankus@...il.com>

Very nice.  A few really minor things inline.

Jonathan

> ---
>  MAINTAINERS                      |   9 +
>  drivers/iio/accel/Kconfig        |  29 +++
>  drivers/iio/accel/Makefile       |   3 +
>  drivers/iio/accel/adxl313.h      |  60 ++++++
>  drivers/iio/accel/adxl313_core.c | 323 +++++++++++++++++++++++++++++++
>  drivers/iio/accel/adxl313_i2c.c  |  65 +++++++
>  drivers/iio/accel/adxl313_spi.c  |  74 +++++++
>  7 files changed, 563 insertions(+)
>  create mode 100644 drivers/iio/accel/adxl313.h
>  create mode 100644 drivers/iio/accel/adxl313_core.c
>  create mode 100644 drivers/iio/accel/adxl313_i2c.c
>  create mode 100644 drivers/iio/accel/adxl313_spi.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a61f4f3b78a9..1fc88723e632 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -585,6 +585,15 @@ L:	platform-driver-x86@...r.kernel.org
>  S:	Maintained
>  F:	drivers/platform/x86/adv_swbutton.c
>  
> +ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
> +M:	Lucas Stankus <lucas.p.stankus@...il.com>
> +S:	Supported
> +F:	Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml
> +F:	drivers/iio/accel/adxl313.h
> +F:	drivers/iio/accel/adxl313_core.c
> +F:	drivers/iio/accel/adxl313_i2c.c
> +F:	drivers/iio/accel/adxl313_spi.c
> +
>  ADXL34X THREE-AXIS DIGITAL ACCELEROMETER DRIVER (ADXL345/ADXL346)
>  M:	Michael Hennerich <michael.hennerich@...log.com>
>  S:	Supported
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 0e56ace61103..ae621532e716 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -30,6 +30,35 @@ config ADIS16209
>  	  To compile this driver as a module, say M here: the module will be
>  	  called adis16209.
>  
> +config ADXL313
> +	tristate
> +
> +config ADXL313_I2C
> +	tristate "Analog Devices ADXL313 3-Axis Digital Accelerometer I2C Driver"
> +	depends on I2C
> +	select ADXL313
> +	select REGMAP_I2C
> +	help
> +	  Say Y here if you want to build i2c support for the Analog Devices
> +	  ADXL313 3-axis digital accelerometer.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called adxl313_i2c and you will also get adxl313_core
> +	  for the core module.
> +
> +config ADXL313_SPI
> +	tristate "Analog Devices ADXL313 3-Axis Digital Accelerometer SPI Driver"
> +	depends on SPI
> +	select ADXL313
> +	select REGMAP_SPI
> +	help
> +	  Say Y here if you want to build spi support for the Analog Devices
> +	  ADXL313 3-axis digital accelerometer.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called adxl313_spi and you will also get adxl313_core
> +	  for the core module.
> +
>  config ADXL345
>  	tristate
>  
> diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
> index 89280e823bcd..fadc92816e24 100644
> --- a/drivers/iio/accel/Makefile
> +++ b/drivers/iio/accel/Makefile
> @@ -6,6 +6,9 @@
>  # When adding new entries keep the list in alphabetical order
>  obj-$(CONFIG_ADIS16201) += adis16201.o
>  obj-$(CONFIG_ADIS16209) += adis16209.o
> +obj-$(CONFIG_ADXL313) += adxl313_core.o
> +obj-$(CONFIG_ADXL313_I2C) += adxl313_i2c.o
> +obj-$(CONFIG_ADXL313_SPI) += adxl313_spi.o
>  obj-$(CONFIG_ADXL345) += adxl345_core.o
>  obj-$(CONFIG_ADXL345_I2C) += adxl345_i2c.o
>  obj-$(CONFIG_ADXL345_SPI) += adxl345_spi.o
> diff --git a/drivers/iio/accel/adxl313.h b/drivers/iio/accel/adxl313.h
> new file mode 100644
> index 000000000000..72f268e02a80
> --- /dev/null
> +++ b/drivers/iio/accel/adxl313.h
> @@ -0,0 +1,60 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * ADXL313 3-Axis Digital Accelerometer
> + *
> + * Copyright (c) 2021 Lucas Stankus <lucas.p.stankus@...il.com>
> + */
> +
> +#ifndef _ADXL313_H_
> +#define _ADXL313_H_
> +
> +/* ADXL313 register definitions */

If these are only used in the c file, push them down there. Better to
keep what is in the header to absolute minimum.
however I suggest below moving some of this so that won't be true any more,
so maybe you do want to keep them here!


> +#define ADXL313_REG_DEVID0		0x00
> +#define ADXL313_REG_DEVID1		0x01
> +#define ADXL313_REG_PARTID		0x02
> +#define ADXL313_REG_XID			0x04
> +#define ADXL313_REG_SOFT_RESET		0x18
> +#define ADXL313_REG_OFS_AXIS(index)	(0x1E + (index))
> +#define ADXL313_REG_THRESH_ACT		0x24
> +#define ADXL313_REG_ACT_INACT_CTL	0x27
> +#define ADXL313_REG_BW_RATE		0x2C
> +#define ADXL313_REG_POWER_CTL		0x2D
> +#define ADXL313_REG_INT_MAP		0x2F
> +#define ADXL313_REG_DATA_FORMAT		0x31
> +#define ADXL313_REG_DATAX		0x32
> +#define ADXL313_REG_DATAY		0x34
> +#define ADXL313_REG_DATAZ		0x36
> +#define ADXL313_REG_FIFO_CTL		0x38
> +#define ADXL313_REG_FIFO_STATUS		0x39
> +
> +#define ADXL313_DEVID0			0xAD
> +#define ADXL313_DEVID1			0x1D
> +#define ADXL313_PARTID			0xCB
> +#define ADXL313_SOFT_RESET		0x52
> +
> +#define ADXL313_RATE_MSK		GENMASK(3, 0)
> +#define ADXL313_RATE_BASE		6
> +
> +#define ADXL313_POWER_CTL_MSK		GENMASK(3, 2)
> +#define ADXL313_MEASUREMENT_MODE	BIT(3)
> +
> +#define ADXL313_RANGE_MSK		GENMASK(1, 0)
> +#define ADXL313_RANGE_4G		3
> +
> +#define ADXL313_FULL_RES		BIT(3)
> +#define ADXL313_SPI_3WIRE		BIT(6)
> +#define ADXL313_I2C_DISABLE		BIT(6)
> +
> +/*
> + * Scale for any g range is given in datasheet as
> + * 1024 LSB/g = 0.0009765625 * 9.80665 = 0.009576806640625 m/s^2
> + */
> +#define ADXL313_NSCALE 9576806
> +
> +extern const struct regmap_access_table adxl313_readable_regs_table;
> +
> +extern const struct regmap_access_table adxl313_writable_regs_table;
> +
> +int adxl313_core_probe(struct device *dev, struct regmap *regmap,
> +		       const char *name);
> +#endif /* _ADXL313_H_ */
> diff --git a/drivers/iio/accel/adxl313_core.c b/drivers/iio/accel/adxl313_core.c
> new file mode 100644
> index 000000000000..76382ab4f0f4
> --- /dev/null
> +++ b/drivers/iio/accel/adxl313_core.c
> @@ -0,0 +1,323 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ADXL313 3-Axis Digital Accelerometer
> + *
> + * Copyright (c) 2021 Lucas Stankus <lucas.p.stankus@...il.com>
> + *
> + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#include "adxl313.h"
> +
> +const struct regmap_range adxl313_readable_reg_range[] = {
> +	regmap_reg_range(ADXL313_REG_DEVID0, ADXL313_REG_XID),
> +	regmap_reg_range(ADXL313_REG_SOFT_RESET, ADXL313_REG_SOFT_RESET),
> +	regmap_reg_range(ADXL313_REG_OFS_AXIS(0), ADXL313_REG_OFS_AXIS(2)),
> +	regmap_reg_range(ADXL313_REG_THRESH_ACT, ADXL313_REG_ACT_INACT_CTL),
> +	regmap_reg_range(ADXL313_REG_BW_RATE, ADXL313_REG_FIFO_STATUS)
> +};
> +
> +const struct regmap_access_table adxl313_readable_regs_table = {
> +	.yes_ranges = adxl313_readable_reg_range,
> +	.n_yes_ranges = ARRAY_SIZE(adxl313_readable_reg_range)
> +};
> +EXPORT_SYMBOL_GPL(adxl313_readable_regs_table);
> +
> +const struct regmap_range adxl313_writable_reg_range[] = {
> +	regmap_reg_range(ADXL313_REG_SOFT_RESET, ADXL313_REG_SOFT_RESET),
> +	regmap_reg_range(ADXL313_REG_OFS_AXIS(0), ADXL313_REG_OFS_AXIS(2)),
> +	regmap_reg_range(ADXL313_REG_THRESH_ACT, ADXL313_REG_ACT_INACT_CTL),
> +	regmap_reg_range(ADXL313_REG_BW_RATE, ADXL313_REG_INT_MAP),
> +	regmap_reg_range(ADXL313_REG_DATA_FORMAT, ADXL313_REG_DATA_FORMAT),
> +	regmap_reg_range(ADXL313_REG_FIFO_CTL, ADXL313_REG_FIFO_CTL)
> +};
> +
> +const struct regmap_access_table adxl313_writable_regs_table = {
> +	.yes_ranges = adxl313_writable_reg_range,
> +	.n_yes_ranges = ARRAY_SIZE(adxl313_writable_reg_range)
> +};
> +EXPORT_SYMBOL_GPL(adxl313_writable_regs_table);
> +
> +struct adxl313_data {
> +	struct regmap	*regmap;
> +	struct mutex	lock; /* lock to protect transf_buf */
> +	__le16		transf_buf ____cacheline_aligned;
> +};
> +
> +static const int adxl313_odr_freqs[][2] = {
> +	[0] = { 6, 250000 },
> +	[1] = { 12, 500000 },
> +	[2] = { 25, 0 },
> +	[3] = { 50, 0 },
> +	[4] = { 100, 0 },
> +	[5] = { 200, 0 },
> +	[6] = { 400, 0 },
> +	[7] = { 800, 0 },
> +	[8] = { 1600, 0 },
> +	[9] = { 3200, 0 },
> +};
> +
> +#define ADXL313_ACCEL_CHANNEL(index, addr, axis) {			\
> +	.type = IIO_ACCEL,						\
> +	.address = addr,						\
> +	.modified = 1,							\
> +	.channel2 = IIO_MOD_##axis,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
> +			      BIT(IIO_CHAN_INFO_CALIBBIAS),		\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |		\
> +				    BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
> +	.info_mask_shared_by_type_available =				\
> +		BIT(IIO_CHAN_INFO_SAMP_FREQ),				\
> +	.scan_index = index,						\
> +	.scan_type = {							\
> +		.sign = 's',						\
> +		.realbits = 13,						\
> +		.storagebits = 16,					\
> +		.endianness = IIO_LE,					\
> +	},								\
> +}
> +
> +static const struct iio_chan_spec adxl313_channels[] = {
> +	ADXL313_ACCEL_CHANNEL(0, ADXL313_REG_DATAX, X),
> +	ADXL313_ACCEL_CHANNEL(1, ADXL313_REG_DATAY, Y),
> +	ADXL313_ACCEL_CHANNEL(2, ADXL313_REG_DATAZ, Z),
> +};
> +
> +static int adxl313_set_odr(struct adxl313_data *data,
> +			   unsigned int freq1, unsigned int freq2)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(adxl313_odr_freqs); i++) {
> +		if (adxl313_odr_freqs[i][0] == freq1 &&
> +		    adxl313_odr_freqs[i][1] == freq2)
> +			break;
> +	}
> +
> +	if (i == ARRAY_SIZE(adxl313_odr_freqs))
> +		return -EINVAL;
> +
> +	return regmap_update_bits(data->regmap, ADXL313_REG_BW_RATE,
> +				  ADXL313_RATE_MSK,
> +				  FIELD_PREP(ADXL313_RATE_MSK,
> +					     ADXL313_RATE_BASE + i));
> +}
> +
> +static int adxl313_read_axis(struct adxl313_data *data,
> +			     struct iio_chan_spec const *chan)
> +{
> +	int ret;
> +
> +	mutex_lock(&data->lock);
> +
> +	ret = regmap_bulk_read(data->regmap,
> +			       chan->address,
> +			       &data->transf_buf, 2);
> +	if (ret)
> +		goto unlock_ret;
> +
> +	ret = le16_to_cpu(data->transf_buf);
> +
> +unlock_ret:
> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +
> +static int adxl313_read_freq_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_SAMP_FREQ:
> +		*vals = (const int *)adxl313_odr_freqs;
> +		*length = ARRAY_SIZE(adxl313_odr_freqs) * 2;
> +		*type = IIO_VAL_INT_PLUS_MICRO;
> +		return IIO_AVAIL_LIST;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int adxl313_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct adxl313_data *data = iio_priv(indio_dev);
> +	unsigned int regval;
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = adxl313_read_axis(data, chan);
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = sign_extend32(ret, chan->scan_type.realbits - 1);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 0;
> +		*val2 = ADXL313_NSCALE;
> +		return IIO_VAL_INT_PLUS_NANO;
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		ret = regmap_read(data->regmap,
> +				  ADXL313_REG_OFS_AXIS(chan->scan_index),
> +				  &regval);
> +		if (ret)
> +			return ret;
> +
> +		/*
> +		 * 8-bit resolution at +/- 0.5g, that is 4x accel data scale
> +		 * factor at full resolution
> +		 */
> +		*val = sign_extend32(regval, 7) * 4;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = regmap_read(data->regmap, ADXL313_REG_BW_RATE, &regval);
> +		if (ret)
> +			return ret;
> +
> +		ret = FIELD_GET(ADXL313_RATE_MSK, regval) - ADXL313_RATE_BASE;
> +		*val = adxl313_odr_freqs[ret][0];
> +		*val2 = adxl313_odr_freqs[ret][1];
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int adxl313_write_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct adxl313_data *data = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		/*
> +		 * 8-bit resolution at +/- 0.5g, that is 4x accel data scale
> +		 * factor at full resolution
> +		 */
> +		if (val > 127 * 4 || val < -128 * 4)
> +			return -EINVAL;
> +
> +		return regmap_write(data->regmap,
> +				    ADXL313_REG_OFS_AXIS(chan->scan_index),
> +				    val / 4);
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		return adxl313_set_odr(data, val, val2);
> +	}
> +
> +	return -EINVAL;

Put this as a default in the case otherwise you might get warnings saying you
don't handle all the possible values.

> +}
> +
> +static const struct iio_info adxl313_info = {
> +	.read_raw	= adxl313_read_raw,
> +	.write_raw	= adxl313_write_raw,
> +	.read_avail	= adxl313_read_freq_avail
> +};
> +
> +static int adxl313_setup(struct device *dev, struct adxl313_data *data)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	/* Ensures the device is in a consistent state after start up */
> +	ret = regmap_write(data->regmap, ADXL313_REG_SOFT_RESET,
> +			   ADXL313_SOFT_RESET);
> +	if (ret)
> +		return ret;
> +
> +	if (device_property_read_bool(dev, "spi-3wire")) {

Rather odd to see spi specific stuff in here.  Perhaps provide a callback to
common probe if it needs to be done at this point in bringing the device up.
However, I think you can just do this before calling the common_probe()

> +		ret = regmap_write(data->regmap, ADXL313_REG_DATA_FORMAT,
> +				   ADXL313_SPI_3WIRE);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = regmap_read(data->regmap, ADXL313_REG_DEVID0, &regval);
> +	if (ret)
> +		return ret;
> +
> +	if (regval != ADXL313_DEVID0) {
> +		dev_err(dev, "Invalid manufacturer ID: 0x%02x\n", regval);
> +		return -ENODEV;
> +	}
> +
> +	ret = regmap_read(data->regmap, ADXL313_REG_DEVID1, &regval);
> +	if (ret)
> +		return ret;
> +
> +	if (regval != ADXL313_DEVID1) {
> +		dev_err(dev, "Invalid mems ID: 0x%02x\n", regval);
> +		return -ENODEV;
> +	}
> +
> +	ret = regmap_read(data->regmap, ADXL313_REG_PARTID, &regval);
> +	if (ret)
> +		return ret;
> +
> +	if (regval != ADXL313_PARTID) {
> +		dev_err(dev, "Invalid device ID: 0x%02x\n", regval);
> +		return -ENODEV;
> +	}
> +
> +	/* Sets the range to +/- 4g */
> +	ret = regmap_update_bits(data->regmap, ADXL313_REG_DATA_FORMAT,
> +				 ADXL313_RANGE_MSK,
> +				 FIELD_PREP(ADXL313_RANGE_MSK,
> +					    ADXL313_RANGE_4G));
> +	if (ret)
> +		return ret;
> +
> +	/* Enables full resolution */
> +	ret = regmap_update_bits(data->regmap, ADXL313_REG_DATA_FORMAT,
> +				 ADXL313_FULL_RES, ADXL313_FULL_RES);
> +	if (ret)
> +		return ret;
> +
> +	/* Enables measurement mode */
> +	return regmap_update_bits(data->regmap, ADXL313_REG_POWER_CTL,
> +				  ADXL313_POWER_CTL_MSK,
> +				  ADXL313_MEASUREMENT_MODE);
> +}
> +
> +int adxl313_core_probe(struct device *dev, struct regmap *regmap,
> +		       const char *name)
> +{
> +	struct adxl313_data *data;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	data->regmap = regmap;
> +	mutex_init(&data->lock);
> +
> +	indio_dev->name = name;
> +	indio_dev->info = &adxl313_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = adxl313_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(adxl313_channels);
> +
> +	ret = adxl313_setup(dev, data);
> +	if (ret) {
> +		dev_err(dev, "ADXL313 setup failed\n");
> +		return ret;
> +	}
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +EXPORT_SYMBOL_GPL(adxl313_core_probe);
> +
> +MODULE_AUTHOR("Lucas Stankus <lucas.p.stankus@...il.com>");
> +MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/accel/adxl313_i2c.c b/drivers/iio/accel/adxl313_i2c.c
> new file mode 100644
> index 000000000000..65050a2fbd38
> --- /dev/null
> +++ b/drivers/iio/accel/adxl313_i2c.c
> @@ -0,0 +1,65 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ADXL313 3-Axis Digital Accelerometer
> + *
> + * Copyright (c) 2021 Lucas Stankus <lucas.p.stankus@...il.com>
> + *
> + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#include "adxl313.h"
> +
> +static const struct regmap_config adxl313_i2c_regmap_config = {
> +	.reg_bits	= 8,
> +	.val_bits	= 8,
> +	.rd_table	= &adxl313_readable_regs_table,
> +	.wr_table	= &adxl313_writable_regs_table,
> +	.max_register	= 0x39
> +};
> +
> +static int adxl313_i2c_probe(struct i2c_client *client)
> +{
> +	struct regmap *regmap;
> +
> +	regmap = devm_regmap_init_i2c(client, &adxl313_i2c_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(&client->dev, "Error initializing i2c regmap: %ld\n",
> +			PTR_ERR(regmap));
> +		return PTR_ERR(regmap);
> +	}
> +
> +	return adxl313_core_probe(&client->dev, regmap, client->name);
> +}
> +
> +static const struct i2c_device_id adxl313_i2c_id[] = {
> +	{ "adxl313", 0 },

No real need to set the data value if it's just going to be 0.
	{ "adl313 },
is fine.

> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, adxl313_i2c_id);
> +
> +static const struct of_device_id adxl313_of_match[] = {
> +	{ .compatible = "adi,adxl313" },
> +	{ },
> +};
> +
> +MODULE_DEVICE_TABLE(of, adxl313_of_match);
> +
> +static struct i2c_driver adxl313_i2c_driver = {
> +	.driver = {
> +		.name	= "adxl313_i2c",
> +		.of_match_table = adxl313_of_match,
> +	},
> +	.probe_new	= adxl313_i2c_probe,
> +	.id_table	= adxl313_i2c_id,
> +};
> +
> +module_i2c_driver(adxl313_i2c_driver);
> +
> +MODULE_AUTHOR("Lucas Stankus <lucas.p.stankus@...il.com>");
> +MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer I2C driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/accel/adxl313_spi.c b/drivers/iio/accel/adxl313_spi.c
> new file mode 100644
> index 000000000000..7c58c9ff8985
> --- /dev/null
> +++ b/drivers/iio/accel/adxl313_spi.c
> @@ -0,0 +1,74 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ADXL313 3-Axis Digital Accelerometer
> + *
> + * Copyright (c) 2021 Lucas Stankus <lucas.p.stankus@...il.com>
> + *
> + * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
> + */
> +
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/spi/spi.h>
> +
> +#include "adxl313.h"
> +
> +static const struct regmap_config adxl313_spi_regmap_config = {
> +	.reg_bits	= 8,
> +	.val_bits	= 8,
> +	.rd_table	= &adxl313_readable_regs_table,
> +	.wr_table	= &adxl313_writable_regs_table,
> +	.max_register	= 0x39,
> +	 /* Setting bits 7 and 6 enables multiple-byte read */
> +	.read_flag_mask	= BIT(7) | BIT(6)
> +};
> +
> +static int adxl313_spi_probe(struct spi_device *spi)
> +{
> +	const struct spi_device_id *id = spi_get_device_id(spi);
> +	struct regmap *regmap;
> +	int ret;
> +
> +	regmap = devm_regmap_init_spi(spi, &adxl313_spi_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(&spi->dev, "Error initializing spi regmap: %ld\n",
> +			PTR_ERR(regmap));
> +		return PTR_ERR(regmap);
> +	}
> +
> +	ret = adxl313_core_probe(&spi->dev, regmap, id->name);
> +	if (ret < 0)
> +		return ret;
> +
> +	return regmap_update_bits(regmap, ADXL313_REG_POWER_CTL,
> +				  ADXL313_I2C_DISABLE, ADXL313_I2C_DISABLE);

Why is this only done after the rest of probe?  Needs a comment perhaps.
Normally I'd expect the core probe and hence exposure of the device
to userspace etc to be the last thing done.

> +}
> +
> +static const struct spi_device_id adxl313_spi_id[] = {
> +	{ "adxl313", 0 },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(spi, adxl313_spi_id);
> +
> +static const struct of_device_id adxl313_of_match[] = {
> +	{ .compatible = "adi,adxl313" },
> +	{ },
> +};
> +
> +MODULE_DEVICE_TABLE(of, adxl313_of_match);
> +
> +static struct spi_driver adxl313_spi_driver = {
> +	.driver = {
> +		.name	= "adxl313_spi",
> +		.of_match_table = adxl313_of_match,
> +	},
> +	.probe		= adxl313_spi_probe,
> +	.id_table	= adxl313_spi_id,
> +};
> +
> +module_spi_driver(adxl313_spi_driver);
> +
> +MODULE_AUTHOR("Lucas Stankus <lucas.p.stankus@...il.com>");
> +MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
> +MODULE_LICENSE("GPL v2");

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