Thread (14 messages) 14 messages, 5 authors, 2021-08-03

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

From: Lucas Stankus <lucas.p.stankus@gmail.com>
Date: 2021-08-02 17:29:16
Also in: linux-iio, lkml

On Mon, Aug 2, 2021 at 3:57 AM Alexandru Ardelean
[off-list ref] wrote:
On Sun, Aug 1, 2021 at 9:09 PM Jonathan Cameron [off-list ref] wrote:
quoted
On Sat, 31 Jul 2021 17:36:48 -0300
Lucas Stankus [off-list ref] wrote:
quoted
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
quoted
---
 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!

quoted
+#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.
quoted
+}
+
+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.
Thanks for the insight.

Would it be better to drop 3wire support then? I believe that there
isn't much of a loss in not supporting 3wire when 4wire is already
working, so I think that writing a converter wouldn't be worth the
effort in this case.
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.
quoted
quoted
+             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 [off-list ref]");
+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.
quoted
+     { }
+};
+
+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 [off-list ref]");
+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.
quoted
+}
+
+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 [off-list ref]");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
+MODULE_LICENSE("GPL v2");
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