Using AD7476A IIO Single Channel Serial ADC Linux Driver with Kuiper Linux for AD7091R

Hi CBellmann ,

I'll contact the product owner and get back to you.

Regards,
Jo

Hello CBellmann ,

Can we get some snapshots on how are you configuring the code based on the tutorial?

Regards,
Jo

Hello NathanT,

thank you for following up.

I started to write the file ad7091r.dts to compile into ad7091r.dtbo.

My Intention is add to the device in /boot/config.txt: dtoverlay=ad7091r.

So far, my ad7091r.dts looks like this: (following lines are inside tics because "code" block of the Forum post cuts away text in <>)

```

// SPDX-License-Identifier: GPL-2.0

/dts-v1/;
/plugin/;

#include <dt-bindings/interrupt-controller/irq.h>
#include <dt-bindings/gpio/gpio.h>

/ {
    compatible = "brcm,bcm2835", "brcm,bcm2711";
};

&gpio {
    ad7091r_pins: ad7091r_pins {
        brcm,pins = <22>; // interrupt
        brcm,function = <0>; // input
    };
};

&gpio {
    ad7091r_reset: ad7091r_reset {
        brcm,pins = <27>; // reset
        brcm,function = <0>; // input
    };
};

&spi0 {
    status = "okay";

    cs-gpios = <&gpio 8 GPIO_ACTIVE_LOW>;

    ad7091r@0 {
        compatible = "adi,ad7091r";
        reg = <0>;
        spi-max-frequency = <1000000>;
        convst-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
        reset-gpios = <&gpio_ad7091r_reset 27 GPIO_ACTIVE_LOW>; // Use the defined GPIO node
        pinctrl-names = "default";
        pinctrl-0 = <&ad7091r_pins>;
        interrupt-parent = <&gpio>;
        interrupts = <22 IRQ_TYPE_EDGE_FALLING>;
    };
};

&spidev0 {
    status = "disabled";
};

&spidev1 {
    status = "disabled";
};

```

For compilation, i did the following, whereas the dtc command failed.

# cd /usr/src
# sudo git clone --depth=1 --branch rpi-6.1.y https://github.com/analogdevicesinc/linux
# cd /home/analog/createDeviceTree
# cpp -nostdinc -I include -I arch -I/usr/src/linux/include -undef -x assembler-with-cpp  ad7091r.dts ad7091r.dts.preprocessed
# dtc -I dts -O dtb -o ad7091r.dtb ad7091r.dts.preprocessed 

The output of the dtc command is:

ad7091r.dts:34.9-19: Warning (reg_format): /fragment@2/__overlay__/ad7091r@0:reg: property has invalid length (4 bytes) (#address-cells == 2, #size-cells == 1)
ad7091r.dtb: Warning (pci_device_reg): Failed prerequisite 'reg_format'
ad7091r.dtb: Warning (pci_device_bus_num): Failed prerequisite 'reg_format'
ad7091r.dtb: Warning (simple_bus_reg): Failed prerequisite 'reg_format'
ad7091r.dtb: Warning (i2c_bus_reg): Failed prerequisite 'reg_format'
ad7091r.dtb: Warning (spi_bus_reg): Failed prerequisite 'reg_format'
ad7091r.dts:32.15-42.7: Warning (avoid_default_addr_size): /fragment@2/__overlay__/ad7091r@0: Relying on default #address-cells value
ad7091r.dts:32.15-42.7: Warning (avoid_default_addr_size): /fragment@2/__overlay__/ad7091r@0: Relying on default #size-cells value
ad7091r.dtb: Warning (avoid_unnecessary_addr_size): Failed prerequisite 'avoid_default_addr_size'
ad7091r.dtb: Warning (unique_unit_address): Failed prerequisite 'avoid_default_addr_size'

From the tutorial i did not understand where the c structs are to be placed (if necessary in my case) so i jumped to creating the device tree overlay file instead.

I am new to device tree, i hope you can help me with setting it up.

Best regards,

Christoph

Hi CBellmann ,

I think these links could help you. Can you try checking at them? Let me know if these links are able to help with your query. So that I could further guide you.

• (+) Is there a linux driver for the AD7091R-8? - Q&A - Precision ADCs - EngineerZone (analog.com)
  
  
• https://github.com/analogdevicesinc/linux/blob/master/drivers/iio/adc/ad7091r-base.c
  
  
• https://github.com/analogdevicesinc/linux/blob/master/drivers/iio/adc/ad7091r5.c
  
  
• https://github.com/analogdevicesinc/linux/blob/master/Documentation/devicetree/bindings/iio/adc/adi%2Cad7091r5.yaml
  
• AD7091R-2/-4/-8 ADC Linux Driver [Analog Devices Wiki]

Regards,
Jo

Hello NathanT,

i see that the development for running these ADCs on linux is fairly new and the infos are quite promising. From what i understand is, the driver in c for the ad7091r is in the linux kernel. Not sure if compiling and running it would help? It is already enabled in the kernel config.

So i went to look at the devicetree documentation to try to create a overlay file. I did make install yamldt and tried the following:

 analog@analog:~/kernel $ yamldt --in-format=yaml linux/Documentation/devicetree/bindings/iio/adc/adi,ad7091r5.yaml -o ad7091r5.dtbo

The output though is:

error: found incompatible YAML document.

It looks like everything is there, but i do not know how to use it. Thanks a lot for your help, i hope you see where i am am stuck and can give me an advice on using the driver.

Best,

Christoph

Hello CBellmann ,

Thank you for your patience. They are currently looking into this query.

Warm regards,
Jo

Dear NathanT ,

thanks a lot! We have four EVAL-CN0336-PMDZ boards on the desk for integration, not in a hurry but waiting.

I am looking forward to your reply,

have a great day,

Christoph

This is still open, could you help please?

Hello CBellmann ,

Thank you for your patience. They are currently looking into this. 

Warm regards,
Jo

I followed the git repo here: https://github.com/karu2003/rpi_ad7476 because it has a dts file provided.

Its for the ad7476a, which is different from the ad7091r. But still i managed to get the output:

analog@analog:~ $ cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw
2207
analog@analog:~ $ cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw
0

First line after reboot is a number, but every other time the value is 0.