iio: pressure: add driver and bindings for adp810

Add driver for Aosong adp810 differential pressure and temperature sensor. This sensor provides an I2C interface for reading data. Calculate CRC of the data received using standard crc8 library to verify data integrity.

Tested on TI am62x sk board with sensor connected at i2c-2.

Signed-off-by Akhilesh Patil <[email protected]>

drivers/iio/pressure/Makefile +2 -0

index 6482288e07ee..a21443e992b9 100644
@@ -5,6 +5,7 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ABP060MG) += abp060mg.o
+obj-$(CONFIG_ADP810) += adp810.o
 obj-$(CONFIG_ROHM_BM1390) += rohm-bm1390.o
 obj-$(CONFIG_BMP280) += bmp280.o
 bmp280-objs := bmp280-core.o bmp280-regmap.o

@@ -15,6 +16,7 @@ obj-$(CONFIG_DPS310) += dps310.o
 obj-$(CONFIG_IIO_CROS_EC_BARO) += cros_ec_baro.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_HP03) += hp03.o
+obj-$(CONFIG_HP206C) += hp206c.o
 obj-$(CONFIG_HSC030PA) += hsc030pa.o
 obj-$(CONFIG_HSC030PA_I2C) += hsc030pa_i2c.o
 obj-$(CONFIG_HSC030PA_SPI) += hsc030pa_spi.o

drivers/iio/pressure/Makefile +0 -3

 obj-$(CONFIG_ZPA2326) += zpa2326.o
 obj-$(CONFIG_ZPA2326_I2C) += zpa2326_i2c.o
 obj-$(CONFIG_ZPA2326_SPI) += zpa2326_spi.o
-
-obj-$(CONFIG_IIO_ST_PRESS_I2C) += st_pressure_i2c.o
-obj-$(CONFIG_IIO_ST_PRESS_SPI) += st_pressure_spi.o

drivers/iio/pressure/adp810.c new file +4 -0

new file mode 100644
index 000000000000..c2f3b5f7a1f9
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2025 Akhilesh Patil <[email protected]>
+ *

drivers/iio/pressure/adp810.c new file +4 -0

+	if (ret < 0) {
+		dev_err(dev, "Error sending trigger command\n");
+		return ret;
+	}

drivers/iio/pressure/adp810.c new file +21 -0

+		dev_err(dev, "Error reading from sensor\n");
+		return ret;
+	}
+
+	/* CRC checks */
+	crc8_populate_msb(crc_table, ADP810_CRC8_POLYNOMIAL);
+	if (buf->dp_crc != crc8(crc_table, (u8 *)&buf->dp, 0x2, CRC8_INIT_VALUE)) {
+		dev_err(dev, "CRC error for pressure\n");
+		return -EIO;
+	}
+
+	if (buf->tmp_crc != crc8(crc_table, (u8 *)&buf->tmp, 0x2, CRC8_INIT_VALUE)) {
+		dev_err(dev, "CRC error for temperature\n");
+		return -EIO;
+	}
+
+	if (buf->sf_crc != crc8(crc_table, (u8 *)&buf->sf, 0x2, CRC8_INIT_VALUE)) {
+		dev_err(dev, "CRC error for scale\n");
+		return -EIO;
+	}
+

drivers/iio/pressure/adp810.c new file +37 -0

+	int ret;
+
+	scoped_guard(mutex, &data->lock) {
+		ret = adp810_measure(data, &buf);
+		if (ret) {
+			dev_err(dev, "Failed to read from device\n");
+			return ret;
+		}
+	}
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			*val = get_unaligned_be16(&buf.dp);
+			return IIO_VAL_INT;
+		case IIO_TEMP:
+			*val = get_unaligned_be16(&buf.tmp);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_PRESSURE:
+			*val = get_unaligned_be16(&buf.sf);
+			return IIO_VAL_INT;
+		case IIO_TEMP:
+			*val = 200;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}

Quoted 7 lines · On Mon, 13 Oct 2025 22:32:35 +0530 Akhilesh Patil <[email protected]>…

Add driver for Aosong adp810 differential pressure and temperature sensor. This sensor provides an I2C interface for reading data. Calculate CRC of the data received using standard crc8 library to verify data integrity.

Tested on TI am62x sk board with sensor connected at i2c-2.

Quoted 1 line

Signed-off-by Akhilesh Patil <[email protected]>

A few comments inline and it seems your rebase when wrong and you've picked up unrelated build file changes.

Thanks

Jonathan

Quoted 23 lines

drivers/iio/pressure/Makefile +2 -0

index 6482288e07ee..a21443e992b9 100644
@@ -5,6 +5,7 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ABP060MG) += abp060mg.o
+obj-$(CONFIG_ADP810) += adp810.o
 obj-$(CONFIG_ROHM_BM1390) += rohm-bm1390.o
 obj-$(CONFIG_BMP280) += bmp280.o
 bmp280-objs := bmp280-core.o bmp280-regmap.o

@@ -15,6 +16,7 @@ obj-$(CONFIG_DPS310) += dps310.o
 obj-$(CONFIG_IIO_CROS_EC_BARO) += cros_ec_baro.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_HP03) += hp03.o
+obj-$(CONFIG_HP206C) += hp206c.o
 obj-$(CONFIG_HSC030PA) += hsc030pa.o
 obj-$(CONFIG_HSC030PA_I2C) += hsc030pa_i2c.o
 obj-$(CONFIG_HSC030PA_SPI) += hsc030pa_spi.o

@@ -34,11 +36,9 @@ obj-$(CONFIG_SDP500) += sdp500.o
 obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o

drivers/iio/pressure/Makefile obj-$(CONFIG_SDP500) += sdp500.o · line 38

Quoted 6 lines

drivers/iio/pressure/Makefile +2 -1

 st_pressure-y := st_pressure_core.o
 st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o
+obj-$(CONFIG_IIO_ST_PRESS_I2C) += st_pressure_i2c.o
+obj-$(CONFIG_IIO_ST_PRESS_SPI) += st_pressure_spi.o
 obj-$(CONFIG_T5403) += t5403.o
-obj-$(CONFIG_HP206C) += hp206c.o

Rebase gone wrong I assume.

Quoted 23 lines

drivers/iio/pressure/Makefile +0 -3

 obj-$(CONFIG_ZPA2326) += zpa2326.o
 obj-$(CONFIG_ZPA2326_I2C) += zpa2326_i2c.o
 obj-$(CONFIG_ZPA2326_SPI) += zpa2326_spi.o
-
-obj-$(CONFIG_IIO_ST_PRESS_I2C) += st_pressure_i2c.o
-obj-$(CONFIG_IIO_ST_PRESS_SPI) += st_pressure_spi.o

drivers/iio/pressure/adp810.c new file +10 -0

new file mode 100644
index 000000000000..c2f3b5f7a1f9
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2025 Akhilesh Patil <[email protected]>
+ *
+ * Driver for adp810 pressure and temperature sensor
+ * Datasheet:
+ *   https://aosong.com/userfiles/files/media/Datasheet%20ADP810-Digital.pdf
+ */
+
+#include <linux/crc8.h>

drivers/iio/pressure/adp810.c line 14

Quoted 4 lines

drivers/iio/pressure/adp810.c new file +4 -0

+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/unaligned.h>

This is a very small set of includes. Please follow include what you use (IWYU) principles (loosely - there are a few headers that never make sense to include directly). So I'd definitely expect things like mutex.h here. dev_printk.h etc.

Quoted 4 lines

drivers/iio/pressure/adp810.c new file +2 -0

+
+#include <linux/iio/iio.h>
 

drivers/iio/pressure/adp810.c line 56

Quoted 10 lines

drivers/iio/pressure/adp810.c new file +10 -0

+
+static int adp810_measure(struct adp810_data *data, struct adp810_read_buf *buf)
+{
+	struct i2c_client *client = data->client;
+	struct device *dev = &client->dev;
+	int ret;
+	u16 trig_cmd = ADP810_TRIGGER_COMMAND;
+
+	/* Send trigger to the sensor for measurement */
+	ret = i2c_master_send(client, (char *)&trig_cmd, sizeof(u16));

sizeof(trig_cmd)

I think it is vanishingly unlikely to matter but in theory i2c_master_send() could return 1 and only one byte made it to device.
So it's common to have

	if (ret < 0)...
		....
	if (ret != sizeof(trig_cmd))
		....

Quoted 4 lines

drivers/iio/pressure/adp810.c new file +4 -0

+	if (ret < 0) {
+		dev_err(dev, "Error sending trigger command\n");
+		return ret;
+	}

drivers/iio/pressure/adp810.c line 70

Quoted 10 lines

drivers/iio/pressure/adp810.c new file +10 -0

+
+	/*
+	 * Wait for the sensor to acquire data. As per datasheet section 5.3.1,
+	 * wait for at least 10ms before reading measurements from the sensor.
+	 */
+	msleep(ADP810_MEASURE_LATENCY_MS);
+
+	/* Read sensor values */
+	ret = i2c_master_recv(client, (char *)buf, sizeof(*buf));
+	if (ret < 0) {

Same potential issue for short reads as for the write above.

I don't recall seeing anything to say we either got full length or error code but maybe that changed at somepoint to make this interface easier to use.

Quoted 27 lines

drivers/iio/pressure/adp810.c new file +25 -0

+		dev_err(dev, "Error reading from sensor\n");
+		return ret;
+	}
+
+	/* CRC checks */
+	crc8_populate_msb(crc_table, ADP810_CRC8_POLYNOMIAL);
+	if (buf->dp_crc != crc8(crc_table, (u8 *)&buf->dp, 0x2, CRC8_INIT_VALUE)) {
+		dev_err(dev, "CRC error for pressure\n");
+		return -EIO;
+	}
+
+	if (buf->tmp_crc != crc8(crc_table, (u8 *)&buf->tmp, 0x2, CRC8_INIT_VALUE)) {
+		dev_err(dev, "CRC error for temperature\n");
+		return -EIO;
+	}
+
+	if (buf->sf_crc != crc8(crc_table, (u8 *)&buf->sf, 0x2, CRC8_INIT_VALUE)) {
+		dev_err(dev, "CRC error for scale\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int adp810_read_raw(struct iio_dev *indio_dev,

drivers/iio/pressure/adp810.c line 101

Quoted 6 lines

drivers/iio/pressure/adp810.c new file +6 -0

+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct adp810_data *data = iio_priv(indio_dev);
+	struct device *dev = &data->client->dev;
+	struct adp810_read_buf buf = {0};

Not a big thing but slight preference for { }.

It's a messy thing wrt to the c spec which never talked about holes and this construct until recently. However the kernel has build tests that verify that all compilers will zero the holes with the { } syntax and that is what the C standards folk have put in the spec now as meaning whole structure including holes.

Quoted 12 lines

drivers/iio/pressure/adp810.c new file +11 -0

+	int ret;
+
+	scoped_guard(mutex, &data->lock) {
+		ret = adp810_measure(data, &buf);
+		if (ret) {
+			dev_err(dev, "Failed to read from device\n");
+			return ret;
+		}
+	}
+
+	switch (mask) {

Quoted 10 lines · Jonathan Cameron

Quoted 7 lines · On Mon, 13 Oct 2025 22:32:35 +0530 Akhilesh Patil <[email protected]>…

Add driver for Aosong adp810 differential pressure and temperature sensor. This sensor provides an I2C interface for reading data. Calculate CRC of the data received using standard crc8 library to verify data integrity.

Tested on TI am62x sk board with sensor connected at i2c-2.

Quoted 8 lines

Quoted 1 line

Signed-off-by Akhilesh Patil <[email protected]>

A few comments inline and it seems your rebase when wrong and you've picked up unrelated build file changes.

Thanks

Jonathan

Hi Jonathan, Thanks for the review, I will share v3 addressing these comments.

Regards,
Akhilesh

Quoted 23 lines

Quoted 23 lines

drivers/iio/pressure/Makefile +2 -0

index 6482288e07ee..a21443e992b9 100644
@@ -5,6 +5,7 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ABP060MG) += abp060mg.o
+obj-$(CONFIG_ADP810) += adp810.o
 obj-$(CONFIG_ROHM_BM1390) += rohm-bm1390.o
 obj-$(CONFIG_BMP280) += bmp280.o
 bmp280-objs := bmp280-core.o bmp280-regmap.o

@@ -15,6 +16,7 @@ obj-$(CONFIG_DPS310) += dps310.o
 obj-$(CONFIG_IIO_CROS_EC_BARO) += cros_ec_baro.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_HP03) += hp03.o
+obj-$(CONFIG_HP206C) += hp206c.o
 obj-$(CONFIG_HSC030PA) += hsc030pa.o
 obj-$(CONFIG_HSC030PA_I2C) += hsc030pa_i2c.o
 obj-$(CONFIG_HSC030PA_SPI) += hsc030pa_spi.o

@@ -34,11 +36,9 @@ obj-$(CONFIG_SDP500) += sdp500.o
 obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o

Quoted 8 lines

drivers/iio/pressure/Makefile obj-$(CONFIG_SDP500) += sdp500.o · line 38

Quoted 6 lines

drivers/iio/pressure/Makefile +2 -1

 st_pressure-y := st_pressure_core.o
 st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o
+obj-$(CONFIG_IIO_ST_PRESS_I2C) += st_pressure_i2c.o
+obj-$(CONFIG_IIO_ST_PRESS_SPI) += st_pressure_spi.o
 obj-$(CONFIG_T5403) += t5403.o
-obj-$(CONFIG_HP206C) += hp206c.o  

Rebase gone wrong I assume.

These are intentional changes.

This addresses Andy's suggestion in v1, to keep entries alphabetically arranged in Makefile. Along with adp810 location, fixed other files as well hp206 and st_pressure_* to make entries alphabetically arranged in the entire Makefile.