Add Support for ADMT4000 #2944

adiceline · 2025-09-19T04:01:43Z

PR Description

This adds driver support and device tree binding for ADMT4000 True Power-On Multiturn Sensor
Datasheet: ADMT4000
Tested on RPI4 using the following demo board: EVAL-ADMT4000

PR Type

Bug fix (a change that fixes an issue)
New feature (a change that adds new functionality)
Breaking change (a change that affects other repos or cause CIs to fail)

PR Checklist

I have conducted a self-review of my own code changes
I have tested the changes on the relevant hardware
I have updated the documentation outside this repo accordingly (if there is the case)

The ADMT4000 is a magnetic turn count sensor that records the rotations of a magnetic system even when powered down. Signed-off-by: adiceline <[email protected]>

Add ABI documentation for ADMT4000 sysfs attributes: - phase and magnitude correction for harmonics - filter enable control Signed-off-by: adiceline <[email protected]>

Add ADI ADMT4000 magnetic turn count sensor driver support Signed-off-by: adiceline <[email protected]>

imply ADMT4000_POS Signed-off-by: adiceline <[email protected]>

jemfgeronimo · 2025-10-20T02:04:41Z

drivers/iio/position/Makefile

 # When adding new entries keep the list in alphabetical order

+obj-$(CONFIG_ADMT4000_POS) += admt4000.o
+obj-$(CONFIG_ADMT4000_ADG714) += adg714.o


Forgot to remove this.

jemfgeronimo · 2025-10-20T02:08:27Z

drivers/iio/position/admt4000.c

+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/*ADMT4000 Registers*/


Suggested change

/*ADMT4000 Registers*/

/* ADMT4000 Registers */

Apply to other comments as well.

jemfgeronimo · 2025-10-20T02:11:21Z

Documentation/ABI/testing/sysfs-bus-iio-position-admt4000

+KernelVersion:	6.6.0
+Contact:	[email protected]
+Description:
+	Enable or disable the device's angle measurement filter.


Add empty line at EOF.

jemfgeronimo · 2025-10-20T02:18:48Z

drivers/iio/position/admt4000.c

+	switch (private) {
+	case ADMT4000_ANGLE_FILT_EN:
+		ret = kstrtobool(buf, &is_en);
+		ret = admt4000_set_angle_filt(st, (bool)is_en);


Suggested change

ret = admt4000_set_angle_filt(st, (bool)is_en);

ret = admt4000_set_angle_filt(st, is_en);

is_en is already bool, no?

jemfgeronimo · 2025-10-20T02:18:58Z

drivers/iio/position/admt4000.c

+	if (ret)
+		return ret;
+
+	*is_filtered = (bool)FIELD_GET(ADMT4000_ANGL_FILT_MASK, temp);


Suggested change

*is_filtered = (bool)FIELD_GET(ADMT4000_ANGL_FILT_MASK, temp);

*is_filtered = !!FIELD_GET(ADMT4000_ANGL_FILT_MASK, temp);

jemfgeronimo · 2025-10-20T02:23:49Z

drivers/iio/position/admt4000.c

+	int turns;
+	u16 angle[2];
+
+	mutex_lock(&st->lock);


I don't think you need locking for scale and offset.

jemfgeronimo · 2025-10-20T02:25:25Z

drivers/iio/position/admt4000.c

+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:


You can use iio_device_claim_direct_mode and iio_device_release_direct_mode for locking and unlocking. Same with IIO_CHAN_INFO_PROCESSED.

jemfgeronimo · 2025-10-20T02:29:37Z

drivers/iio/position/admt4000.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ *


Suggested change

*

* Analog Devices ADMT4000 SPI True Power-On Multiturn Sensor driver

jemfgeronimo · 2025-10-20T02:29:59Z

drivers/iio/position/admt4000.c

+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
+//adg


Still need this?

jemfgeronimo · 2025-10-20T02:31:58Z

drivers/iio/position/admt4000.c

+	if (value)
+		code[(eff_pos >> 3)] |= BIT(eff_pos & 0x7);
+
+	*ecc |= (value << i);


Fix alignment.

jemfgeronimo · 2025-10-20T02:36:03Z

drivers/iio/position/admt4000.c

+	int turns;
+	u16 angle[2];
+
+	mutex_lock(&st->lock);


Suggested change

mutex_lock(&st->lock);

guard(mutex)(&st->lock);

Then you don't need to call mutex_unlock(&st->lock); later. Apply to other mutex_lock(&st->lock);

jemfgeronimo · 2025-10-20T02:38:35Z

drivers/iio/position/admt4000.c

+			*val2 = 1632;
+			if (st->ext_vdd == ADMT4000_3P3V)
+				*val2 = 1632;
+			else if (st->ext_vdd == ADMT4000_5V)
+				*val2 = 1627;


Suggested change

*val2 = 1632;

if (st->ext_vdd == ADMT4000_3P3V)

*val2 = 1632;

else if (st->ext_vdd == ADMT4000_5V)

*val2 = 1627;

if (st->ext_vdd == ADMT4000_5V)

*val2 = 1627;

else

*val2 = 1632;

adiceline requested review from CiprianRegus, amiclaus, btogorean, buha, chegbeli, danmois, dbogdan, machschmitt, mhennerich, nunojsa and rbolboac as code owners September 19, 2025 04:01

adiceline marked this pull request as draft September 19, 2025 04:04

adiceline force-pushed the dev/admt4000 branch 13 times, most recently from 5372162 to 68a67ca Compare September 19, 2025 06:57

adiceline added 2 commits September 19, 2025 15:00

dt-bindings: iio: position: Document ADMT4000

1774b9a

The ADMT4000 is a magnetic turn count sensor that records the rotations of a magnetic system even when powered down. Signed-off-by: adiceline <[email protected]>

ABI: Add angular correction and filter attributes

6792eb0

Add ABI documentation for ADMT4000 sysfs attributes: - phase and magnitude correction for harmonics - filter enable control Signed-off-by: adiceline <[email protected]>

adiceline force-pushed the dev/admt4000 branch 3 times, most recently from 6858ddb to 4c9a4b7 Compare September 19, 2025 07:46

adiceline force-pushed the dev/admt4000 branch from de29f9d to b699a29 Compare September 19, 2025 07:55

adiceline added 2 commits September 19, 2025 16:17

iio: position: Add driver for ADMT4000

44a33b4

Add ADI ADMT4000 magnetic turn count sensor driver support Signed-off-by: adiceline <[email protected]>

kconfig.adi: Add ADMT4000

75cdd19

imply ADMT4000_POS Signed-off-by: adiceline <[email protected]>

adiceline force-pushed the dev/admt4000 branch from b699a29 to 75cdd19 Compare September 19, 2025 08:17

adiceline marked this pull request as ready for review October 20, 2025 01:18

jemfgeronimo reviewed Oct 20, 2025

View reviewed changes

	ret = admt4000_set_angle_filt(st, (bool)is_en);
	ret = admt4000_set_angle_filt(st, is_en);

	*is_filtered = (bool)FIELD_GET(ADMT4000_ANGL_FILT_MASK, temp);
	*is_filtered = !!FIELD_GET(ADMT4000_ANGL_FILT_MASK, temp);

	*
	* Analog Devices ADMT4000 SPI True Power-On Multiturn Sensor driver

Add Support for ADMT4000 #2944

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adiceline commented Sep 19, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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jemfgeronimo Oct 20, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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adiceline commented Sep 19, 2025 •

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jemfgeronimo Oct 20, 2025 •

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