Re: [PATCH 2/2] iio: accel: Add driver support for ADXL313

[Alexandru Ardelean <ardeleanalex@gmail.com>]

On Sun, Aug 1, 2021 at 9:09 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sat, 31 Jul 2021 17:36:48 -0300
> Lucas Stankus <lucas.p.stankus@gmail.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@gmail.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@vger.kernel.org
> >  S:   Maintained
> >  F:   drivers/platform/x86/adv_swbutton.c
> >
> > +ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
> > +M:   Lucas Stankus <lucas.p.stankus@gmail.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@analog.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@gmail.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@gmail.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()

This is a recurring theme in some ADI chips, where the chip supports
both 3wire and 4wire SPI modes.

But this has some tendency to create confusion and a bit duplication.
Because "spi-3wire" is also valid in `drivers/spi/spi.c` in the SPI framework.
So, it gets parsed [only for OF] by the SPI framework [hence the duplication].
But, then,if the SPI controller doesn't support 3wire mode, this
setting gets invalidated inside the SPI framework; the chip remains in
3wire mode anyway.

[if the above happens] This setting can work if there is a passive
SPI-mode converter [from 4wire to 3wire]
Which is not a great way to describe the HW, but it's the best we can
do for now.

This comes back to an older discussion about overriding spi-cpol &
spi-cpha in the DT in case there are some weird board designs.
The driver would specify some mode, but the DT could override it, in
case it is needed.
I had a plan to do a general approach for this, but did not get to it.

>
> > +             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@gmail.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@gmail.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@gmail.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@gmail.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@gmail.com>");
> > +MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
> > +MODULE_LICENSE("GPL v2");
>