iio: accel: Add support for ADXL313 accelerometer

Add device tree binding documentation for ADXL313 3-axis accelerometer.

Signed-off-by Lucas Stankus <[email protected]>

---
 .../bindings/iio/accel/adi,adxl313.yaml       | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml

Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml new file +24 -0

new file mode 100644
index 000000000000..31f11d7eaaae
@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/accel/adi,adxl313.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices ADXL313 3-Axis Digital Accelerometer
+
+maintainers:
+  - Lucas Stankus <[email protected]>
+
+description: |
+  Analog Devices ADXL313 3-Axis Digital Accelerometer that supports
+  both I2C & SPI interfaces.
+    https://www.analog.com/en/products/adxl313.html
+
+properties:
+  compatible:
+    enum:
+      - adi,adxl313
+
+  reg:
+    maxItems: 1
+

Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml new file +41 -0

+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* Example for a I2C device node */
+        accelerometer@53 {
+            compatible = "adi,adxl313";
+            reg = <0x53>;
+            interrupt-parent = <&gpio0>;
+            interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
+        };
+    };
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* Example for a SPI device node */
+        accelerometer@0 {
+            compatible = "adi,adxl313";
+            reg = <0>;
+            spi-max-frequency = <5000000>;
+            spi-cpol;
+            spi-cpha;
+            interrupt-parent = <&gpio0>;
+            interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
+        };
+    };

Quoted 3 lines · On Sat, 31 Jul 2021 17:36:31 -0300 Lucas Stankus <[email protected]>…

Add device tree binding documentation for ADXL313 3-axis accelerometer.

Signed-off-by Lucas Stankus <[email protected]>

Hi Lucas,

A few minor requests for additions inline, so we include everything that is likely to be used by the driver in the longer term.

Quoted 35 lines

---
 .../bindings/iio/accel/adi,adxl313.yaml       | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml

Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml new file +24 -0

new file mode 100644
index 000000000000..31f11d7eaaae
@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/accel/adi,adxl313.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices ADXL313 3-Axis Digital Accelerometer
+
+maintainers:
+  - Lucas Stankus <[email protected]>
+
+description: |
+  Analog Devices ADXL313 3-Axis Digital Accelerometer that supports
+  both I2C & SPI interfaces.
+    https://www.analog.com/en/products/adxl313.html
+
+properties:
+  compatible:
+    enum:
+      - adi,adxl313
+
+  reg:
+    maxItems: 1
+

Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml line 34

Quoted 10 lines

Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml new file +10 -0

+  spi-3wire: true
+
+  spi-cpha: true
+
+  spi-cpol: true
+
+  spi-max-frequency: true
+
+  interrupts:
+    maxItems: 2

As board designers have an annoying habit of wiring up the second interrupt only, please also provide interrupt-names so we can know which one is connected if it's only one.

From a quick glance at the datasheet, I see this also has two powersupplies. Please include
vddio-supply
vs-supply - annoyingly the s just stands for supply, but v-supply seems a bit to minimal.

Quoted 41 lines

Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml new file +41 -0

+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* Example for a I2C device node */
+        accelerometer@53 {
+            compatible = "adi,adxl313";
+            reg = <0x53>;
+            interrupt-parent = <&gpio0>;
+            interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
+        };
+    };
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* Example for a SPI device node */
+        accelerometer@0 {
+            compatible = "adi,adxl313";
+            reg = <0>;
+            spi-max-frequency = <5000000>;
+            spi-cpol;
+            spi-cpha;
+            interrupt-parent = <&gpio0>;
+            interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
+        };
+    };

Add device tree binding documentation for ADXL313 3-axis accelerometer.

Signed-off-by Lucas Stankus <[email protected]>

---
 .../bindings/iio/accel/adi,adxl313.yaml       | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/accel/adi,adxl313.yaml

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 <[email protected]>

---
 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

MAINTAINERS +9 -0

index a61f4f3b78a9..1fc88723e632 100644
@@ -585,6 +585,15 @@ L:	[email protected]
 S:	Maintained
 F:	drivers/platform/x86/adv_swbutton.c
 
+ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
+M:	Lucas Stankus <[email protected]>
+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 <[email protected]>
 S:	Supported

drivers/iio/accel/Kconfig +29 -0

index 0e56ace61103..ae621532e716 100644
@@ -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
 

drivers/iio/accel/Makefile +3 -0

index 89280e823bcd..fadc92816e24 100644
@@ -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

drivers/iio/accel/adxl313.h new file +1 -0

new file mode 100644
index 000000000000..72f268e02a80
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */

drivers/iio/accel/adxl313.h new file +49 -0

+#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_ */

drivers/iio/accel/adxl313_core.c new file +206 -0

new file mode 100644
index 000000000000..76382ab4f0f4
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)

drivers/iio/accel/adxl313_core.c new file +10 -0

+}
+
+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)
+{

drivers/iio/accel/adxl313_core.c new file +87 -0

+		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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_i2c.c new file +29 -0

new file mode 100644
index 000000000000..65050a2fbd38
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)) {

drivers/iio/accel/adxl313_i2c.c new file +26 -0

+	{ }
+};
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer I2C driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_spi.c new file +34 -0

new file mode 100644
index 000000000000..7c58c9ff8985
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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",

drivers/iio/accel/adxl313_spi.c new file +30 -0

+}
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
+MODULE_LICENSE("GPL v2");

Quoted 7 lines · On Sat, 31 Jul 2021 17:36:48 -0300 Lucas Stankus <[email protected]>…

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 <[email protected]>

Very nice. A few really minor things inline.

Jonathan

Quoted 95 lines

---
 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

MAINTAINERS +9 -0

index a61f4f3b78a9..1fc88723e632 100644
@@ -585,6 +585,15 @@ L:       [email protected]
 S:   Maintained
 F:   drivers/platform/x86/adv_swbutton.c
 
+ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
+M:   Lucas Stankus <[email protected]>
+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 <[email protected]>
 S:   Supported

drivers/iio/accel/Kconfig +29 -0

index 0e56ace61103..ae621532e716 100644
@@ -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
 

drivers/iio/accel/Makefile +3 -0

index 89280e823bcd..fadc92816e24 100644
@@ -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

drivers/iio/accel/adxl313.h new file +1 -0

new file mode 100644
index 000000000000..72f268e02a80
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */

drivers/iio/accel/adxl313.h line 11

Quoted 10 lines

drivers/iio/accel/adxl313.h new file +10 -0

+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ */
+
+#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 261 lines

drivers/iio/accel/adxl313.h new file +49 -0

+#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_ */

drivers/iio/accel/adxl313_core.c new file +206 -0

new file mode 100644
index 000000000000..76382ab4f0f4
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)

drivers/iio/accel/adxl313_core.c line 216

Quoted 10 lines

drivers/iio/accel/adxl313_core.c new file +10 -0

+                     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 16 lines

drivers/iio/accel/adxl313_core.c new file +16 -0

+}
+
+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);

drivers/iio/accel/adxl313_core.c line 236

Quoted 4 lines

drivers/iio/accel/adxl313_core.c new file +4 -0

+     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()

Quoted 123 lines

drivers/iio/accel/adxl313_core.c new file +87 -0

+             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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_i2c.c new file +29 -0

new file mode 100644
index 000000000000..65050a2fbd38
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)) {

drivers/iio/accel/adxl313_i2c.c line 39

Quoted 10 lines

drivers/iio/accel/adxl313_i2c.c new file +10 -0

+             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 66 lines

drivers/iio/accel/adxl313_i2c.c new file +26 -0

+     { }
+};
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer I2C driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_spi.c new file +34 -0

new file mode 100644
index 000000000000..7c58c9ff8985
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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",

drivers/iio/accel/adxl313_spi.c line 44

Quoted 10 lines

drivers/iio/accel/adxl313_spi.c new file +10 -0

+                     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 30 lines

drivers/iio/accel/adxl313_spi.c new file +30 -0

+}
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
+MODULE_LICENSE("GPL v2");

Quoted 419 lines · Jonathan Cameron

Quoted 7 lines · On Sat, 31 Jul 2021 17:36:48 -0300 Lucas Stankus <[email protected]>…

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 <[email protected]>

Very nice. A few really minor things inline.

Jonathan

Quoted 95 lines

---
 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

MAINTAINERS +9 -0

index a61f4f3b78a9..1fc88723e632 100644
@@ -585,6 +585,15 @@ L:       [email protected]
 S:   Maintained
 F:   drivers/platform/x86/adv_swbutton.c
 
+ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
+M:   Lucas Stankus <[email protected]>
+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 <[email protected]>
 S:   Supported

drivers/iio/accel/Kconfig +29 -0

index 0e56ace61103..ae621532e716 100644
@@ -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
 

drivers/iio/accel/Makefile +3 -0

index 89280e823bcd..fadc92816e24 100644
@@ -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

drivers/iio/accel/adxl313.h new file +1 -0

new file mode 100644
index 000000000000..72f268e02a80
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */

drivers/iio/accel/adxl313.h line 11

Quoted 10 lines

drivers/iio/accel/adxl313.h new file +10 -0

+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ */
+
+#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 261 lines

drivers/iio/accel/adxl313.h new file +49 -0

+#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_ */

drivers/iio/accel/adxl313_core.c new file +206 -0

new file mode 100644
index 000000000000..76382ab4f0f4
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)

drivers/iio/accel/adxl313_core.c line 216

Quoted 10 lines

drivers/iio/accel/adxl313_core.c new file +10 -0

+                     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 16 lines

drivers/iio/accel/adxl313_core.c new file +16 -0

+}
+
+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);

Quoted 8 lines

drivers/iio/accel/adxl313_core.c line 236

Quoted 4 lines

drivers/iio/accel/adxl313_core.c new file +4 -0

+     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.

Quoted 250 lines

Quoted 123 lines

drivers/iio/accel/adxl313_core.c new file +87 -0

+             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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_i2c.c new file +29 -0

new file mode 100644
index 000000000000..65050a2fbd38
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)) {

drivers/iio/accel/adxl313_i2c.c line 39

Quoted 10 lines

drivers/iio/accel/adxl313_i2c.c new file +10 -0

+             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 66 lines

drivers/iio/accel/adxl313_i2c.c new file +26 -0

+     { }
+};
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer I2C driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_spi.c new file +34 -0

new file mode 100644
index 000000000000..7c58c9ff8985
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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",

drivers/iio/accel/adxl313_spi.c line 44

Quoted 10 lines

drivers/iio/accel/adxl313_spi.c new file +10 -0

+                     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 30 lines

drivers/iio/accel/adxl313_spi.c new file +30 -0

+}
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
+MODULE_LICENSE("GPL v2");

Quoted 440 lines · Alexandru Ardelean

Quoted 419 lines · Jonathan Cameron

Quoted 7 lines · On Sat, 31 Jul 2021 17:36:48 -0300 Lucas Stankus <[email protected]>…

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 <[email protected]>

Very nice. A few really minor things inline.

Jonathan

Quoted 95 lines

---
 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

MAINTAINERS +9 -0

index a61f4f3b78a9..1fc88723e632 100644
@@ -585,6 +585,15 @@ L:       [email protected]
 S:   Maintained
 F:   drivers/platform/x86/adv_swbutton.c
 
+ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
+M:   Lucas Stankus <[email protected]>
+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 <[email protected]>
 S:   Supported

drivers/iio/accel/Kconfig +29 -0

index 0e56ace61103..ae621532e716 100644
@@ -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
 

drivers/iio/accel/Makefile +3 -0

index 89280e823bcd..fadc92816e24 100644
@@ -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

drivers/iio/accel/adxl313.h new file +1 -0

new file mode 100644
index 000000000000..72f268e02a80
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */

drivers/iio/accel/adxl313.h line 11

Quoted 10 lines

drivers/iio/accel/adxl313.h new file +10 -0

+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ */
+
+#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 261 lines

drivers/iio/accel/adxl313.h new file +49 -0

+#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_ */

drivers/iio/accel/adxl313_core.c new file +206 -0

new file mode 100644
index 000000000000..76382ab4f0f4
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)

drivers/iio/accel/adxl313_core.c line 216

Quoted 10 lines

drivers/iio/accel/adxl313_core.c new file +10 -0

+                     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 16 lines

drivers/iio/accel/adxl313_core.c new file +16 -0

+}
+
+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);

Quoted 8 lines

drivers/iio/accel/adxl313_core.c line 236

Quoted 4 lines

drivers/iio/accel/adxl313_core.c new file +4 -0

+     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.

Quoted 5 lines

[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.

Quoted 257 lines

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 250 lines

Quoted 123 lines

drivers/iio/accel/adxl313_core.c new file +87 -0

+             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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_i2c.c new file +29 -0

new file mode 100644
index 000000000000..65050a2fbd38
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)) {

drivers/iio/accel/adxl313_i2c.c line 39

Quoted 10 lines

drivers/iio/accel/adxl313_i2c.c new file +10 -0

+             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 66 lines

drivers/iio/accel/adxl313_i2c.c new file +26 -0

+     { }
+};
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer I2C driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_spi.c new file +34 -0

new file mode 100644
index 000000000000..7c58c9ff8985
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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",

drivers/iio/accel/adxl313_spi.c line 44

Quoted 10 lines

drivers/iio/accel/adxl313_spi.c new file +10 -0

+                     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 30 lines

drivers/iio/accel/adxl313_spi.c new file +30 -0

+}
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer SPI driver");
+MODULE_LICENSE("GPL v2");

Quoted 4 lines · On Sat, 31 Jul 2021 17:36:48 -0300 Lucas Stankus <[email protected]>…

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.

Quoted 3 lines

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf

Signed-off-by Lucas Stankus <[email protected]>

Very nice. A few really minor things inline.

Jonathan

Quoted 102 lines

---
 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

MAINTAINERS +9 -0

index a61f4f3b78a9..1fc88723e632 100644
@@ -585,6 +585,15 @@ L:       [email protected]
 S:   Maintained
 F:   drivers/platform/x86/adv_swbutton.c
 
+ADXL313 THREE-AXIS DIGITAL ACCELEROMETER DRIVER
+M:   Lucas Stankus <[email protected]>
+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 <[email protected]>
 S:   Supported

drivers/iio/accel/Kconfig +29 -0

index 0e56ace61103..ae621532e716 100644
@@ -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
 

drivers/iio/accel/Makefile +3 -0

index 89280e823bcd..fadc92816e24 100644
@@ -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

drivers/iio/accel/adxl313.h new file +8 -0

new file mode 100644
index 000000000000..72f268e02a80
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ */
+
+#ifndef _ADXL313_H_

drivers/iio/accel/adxl313.h line 11

Quoted 3 lines

drivers/iio/accel/adxl313.h new file +3 -0

+#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 262 lines

drivers/iio/accel/adxl313.h new file +49 -0

+#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_ */

drivers/iio/accel/adxl313_core.c new file +206 -0

new file mode 100644
index 000000000000..76382ab4f0f4
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)

drivers/iio/accel/adxl313_core.c line 216

Quoted 10 lines

drivers/iio/accel/adxl313_core.c new file +10 -0

+                     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 16 lines

drivers/iio/accel/adxl313_core.c new file +16 -0

+}
+
+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);

drivers/iio/accel/adxl313_core.c line 236

Quoted 4 lines

drivers/iio/accel/adxl313_core.c new file +4 -0

+     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()

Quoted 122 lines

drivers/iio/accel/adxl313_core.c new file +87 -0

+             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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer core driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_i2c.c new file +29 -0

new file mode 100644
index 000000000000..65050a2fbd38
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)) {

drivers/iio/accel/adxl313_i2c.c line 39

Quoted 10 lines

drivers/iio/accel/adxl313_i2c.c new file +10 -0

+             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 72 lines

drivers/iio/accel/adxl313_i2c.c new file +26 -0

+     { }
+};
+
+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 <[email protected]>");
+MODULE_DESCRIPTION("ADXL313 3-Axis Digital Accelerometer I2C driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/accel/adxl313_spi.c new file +40 -0

new file mode 100644
index 000000000000..7c58c9ff8985
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADXL313 3-Axis Digital Accelerometer
+ *
+ * Copyright (c) 2021 Lucas Stankus <[email protected]>
+ *
+ * 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)