[PATCH v3 0/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[PATCH v3 0/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[Hungyu Lin]

Changes in v3:
- Fix commit message based on input from Sanjay Chitroda

Changes in v2:
- Fix commit message to match binding requirements

Hungyu Lin (1):
  dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

 .../bindings/iio/adc/adi,ad7816.yaml          | 94 +++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml

-- 
2.34.1

[PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[Hungyu Lin]

Add Device Tree binding documentation for the Analog Devices
AD7816, AD7817 and AD7818 SPI ADC devices.

The AD7816 provides temperature monitoring only, while the
AD7817 and AD7818 provide analog input channels with an
on-chip temperature sensor.

The devices use control GPIOs for RD/WR and CONVST. BUSY is required for
AD7816 and AD7817 variants.

Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
---
Changes in v3:
- Fix commit message to match binding requirements
- Fix commit message based on input from Sanjay Chitroda
---
 .../bindings/iio/adc/adi,ad7816.yaml          | 94 +++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml
new file mode 100644
index 000000000000..490e5338d7b2
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml
@@ -0,0 +1,94 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad7816.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7816/AD7817/AD7818 ADC
+
+maintainers:
+  - Hungyu Lin <dennylin0707@gmail.com>
+
+description: |
+  Binding for Analog Devices AD7816, AD7817 and AD7818 SPI ADCs
+  with on-chip temperature sensor.
+
+  The AD7816 provides temperature monitoring only.
+  The AD7817 provides up to 4 analog input channels.
+  The AD7818 provides a single analog input channel.
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7816
+      - adi,ad7817
+      - adi,ad7818
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+    description:
+      Optional interrupt line used by the device.
+
+  rdwr-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the RD/WR pin used to control read/write cycles.
+
+  convert-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the CONVST pin used to trigger conversions.
+
+  busy-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the BUSY pin indicating conversion status.
+
+required:
+  - compatible
+  - reg
+  - rdwr-gpios
+  - convert-gpios
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7816
+              - adi,ad7817
+    then:
+      required:
+        - busy-gpios
+    else:
+      properties:
+        busy-gpios: false
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    gpio0: gpio {
+      gpio-controller;
+      #gpio-cells = <2>;
+    };
+
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      adc@0 {
+        compatible = "adi,ad7816";
+        reg = <0>;
+        spi-max-frequency = <5000000>;
+        rdwr-gpios = <&gpio0 1 0>;
+        convert-gpios = <&gpio0 2 0>;
+        busy-gpios = <&gpio0 3 0>;
+      };
+    };
-- 
2.34.1

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[David Lechner]

On 5/8/26 9:27 PM, Hungyu Lin wrote:
> Add Device Tree binding documentation for the Analog Devices
> AD7816, AD7817 and AD7818 SPI ADC devices.
> 
Why are we adding bindings without a driver to use them?

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[Denny Lin]

Hi David,

> Why are we adding bindings without a driver to use them?

There is already a driver for these devices in
drivers/staging/iio/adc/ad7816.c, which includes OF match entries
for "adi,ad7816", "adi,ad7817", and "adi,ad7818".

This binding is intended to document the existing DT interface.

Thanks,
Hungyu

On Sat, May 9, 2026 at 3:13 PM David Lechner <dlechner@baylibre.com> wrote:
>
> On 5/8/26 9:27 PM, Hungyu Lin wrote:
> > Add Device Tree binding documentation for the Analog Devices
> > AD7816, AD7817 and AD7818 SPI ADC devices.
> >
> Why are we adding bindings without a driver to use them?

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[David Lechner]

On 5/9/26 8:37 PM, Denny Lin wrote:
> Hi David,
> 
>> Why are we adding bindings without a driver to use them?
> 
> There is already a driver for these devices in
> drivers/staging/iio/adc/ad7816.c, which includes OF match entries
> for "adi,ad7816", "adi,ad7817", and "adi,ad7818".
> 
> This binding is intended to document the existing DT interface.

Usually, we want to be moving the drivers out of staging when
adding the DT bindings so that it all gets reviewed for correctness
at the same time.

Drivers in staging are usually there because they are doing things
that are not actually acceptable for the final stable mainline
version of a driver and need more work.

> 
> Thanks,
> Hungyu
> 
> On Sat, May 9, 2026 at 3:13 PM David Lechner <dlechner@baylibre.com> wrote:
>>
>> On 5/8/26 9:27 PM, Hungyu Lin wrote:
>>> Add Device Tree binding documentation for the Analog Devices
>>> AD7816, AD7817 and AD7818 SPI ADC devices.
>>>
>> Why are we adding bindings without a driver to use them?

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[Denny Lin]

On Mon, May 11, 2026 at 7:51 AM David Lechner <dlechner@baylibre.com> wrote:
>
> Usually, we want to be moving the drivers out of staging when
> adding the DT bindings so that it all gets reviewed for correctness
> at the same time.
>
> Drivers in staging are usually there because they are doing things
> that are not actually acceptable for the final stable mainline
> version of a driver and need more work.
>

Thanks for the explanation.

I took a look at the driver and noticed it still uses the older
IIO sysfs-based interface rather than the iio_chan_spec + read_raw
model.

Would you recommend updating the driver first, or is it okay to
proceed with the binding separately?

Thanks,
Hungyu

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[David Lechner]

On 5/11/26 11:23 AM, Denny Lin wrote:
> On Mon, May 11, 2026 at 7:51 AM David Lechner <dlechner@baylibre.com> wrote:
>>
>> Usually, we want to be moving the drivers out of staging when
>> adding the DT bindings so that it all gets reviewed for correctness
>> at the same time.
>>
>> Drivers in staging are usually there because they are doing things
>> that are not actually acceptable for the final stable mainline
>> version of a driver and need more work.
>>
> 
> Thanks for the explanation.
> 
> I took a look at the driver and noticed it still uses the older
> IIO sysfs-based interface rather than the iio_chan_spec + read_raw
> model.
> 
> Would you recommend updating the driver first, or is it okay to
> proceed with the binding separately?
> 
> Thanks,
> Hungyu

ADI's website says that these parts are obsolete, so unless anyone is
actually still using these with a mainline kernel, I would suggest that
we drop the driver rather than spending time fixing it up.

In any case, unless you have the hardware for testing, it would be
best not to make significant changes. There is a non-standard "oti"
attribute that we would need to figure out what to do with. This is
likely why the driver is in staging in the first place.

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[Jonathan Cameron]

On Mon, 11 May 2026 11:31:13 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On 5/11/26 11:23 AM, Denny Lin wrote:
> > On Mon, May 11, 2026 at 7:51 AM David Lechner <dlechner@baylibre.com> wrote:  
> >>
> >> Usually, we want to be moving the drivers out of staging when
> >> adding the DT bindings so that it all gets reviewed for correctness
> >> at the same time.
> >>
> >> Drivers in staging are usually there because they are doing things
> >> that are not actually acceptable for the final stable mainline
> >> version of a driver and need more work.
> >>  
> > 
> > Thanks for the explanation.
> > 
> > I took a look at the driver and noticed it still uses the older
> > IIO sysfs-based interface rather than the iio_chan_spec + read_raw
> > model.
> > 
> > Would you recommend updating the driver first, or is it okay to
> > proceed with the binding separately?
> > 
> > Thanks,
> > Hungyu  
> 
> ADI's website says that these parts are obsolete, so unless anyone is
> actually still using these with a mainline kernel, I would suggest that
> we drop the driver rather than spending time fixing it up.

The ad7817 isn't obsolete yet unfortunately - that's the only reason I didn't
drop this last time I checked..

Any Analog folk want to take a view on this one - particularly if you
can check if it will be going obsolete soon.   Good not to waste Denny's
time on this if so!

J

> 
> In any case, unless you have the hardware for testing, it would be
> best not to make significant changes. There is a non-standard "oti"
> attribute that we would need to figure out what to do with. This is
> likely why the driver is in staging in the first place.

Re: [PATCH v3 1/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[Jonathan Cameron]

On Sat,  9 May 2026 02:27:18 +0000
Hungyu Lin <dennylin0707@gmail.com> wrote:

> Add Device Tree binding documentation for the Analog Devices
> AD7816, AD7817 and AD7818 SPI ADC devices.
> 
> The AD7816 provides temperature monitoring only, while the
> AD7817 and AD7818 provide analog input channels with an
> on-chip temperature sensor.
> 
> The devices use control GPIOs for RD/WR and CONVST. BUSY is required for
> AD7816 and AD7817 variants.
> 
> Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>

Subject to the discussion you had with David about us only normally
adding a dt-binding as part of the final series that moves a driver
out of staging.  This looks fine to me.

Note I've been hopefully checking analog.com every 6 months or so for
the ad7817 to go obsolete - (no luck yet!) - hence I haven't deleted
the driver despite no one getting it into a reasonable state for
many years. If you are interested in doing that work then great!
Maybe the Analog devices folk can help you out with testing etc.

Jonathan

Re: [PATCH v3 0/1] dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding

[David Lechner]

On 5/8/26 9:27 PM, Hungyu Lin wrote:
> Changes in v3:
> - Fix commit message based on input from Sanjay Chitroda
> 
> Changes in v2:
> - Fix commit message to match binding requirements
> 
> Hungyu Lin (1):
>   dt-bindings: iio: adc: add AD7816/AD7817/AD7818 binding
> 
>  .../bindings/iio/adc/adi,ad7816.yaml          | 94 +++++++++++++++++++
>  1 file changed, 94 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml
> 

Don't need a cover letter for a single patch. Just put
this after --- in the commit message of the patch.