How to connect adc driver in dts with libiio - stm32mp1

MWoło.2 · ‎2023-03-16

Hi,

I try to connect ADC channels with libiio for my custom board based on the stm32mp157caa3. I followed the instructions from the link

https://wiki.st.com/stm32mpu/wiki/IIO_libiio

https://wiki.st.com/stm32mpu/wiki/ADC_device_tree_configuration#DT_configuration_examples

but without success. After issuing the console

iio_info

I get

Library version: 0.23 (git tag: 92d6a35)
Compiled with backends: local xml ip usb serial
IIO context created with local backend.
Backend version: 0.23 (git tag: 92d6a35)
Backend description string: Linux stm32mp1-connect-bridge 5.15.67 #1 SMP PREEMPT Thu Sep 8 10:32:54 UTC 2022 armv7l
IIO context has 2 attributes:
	local,kernel: 5.15.67
	uri: local:
IIO context has 0 devices:

The same is in

/sys/bus/iio/devices/

empty, with no devices.

Part of my dts looks

&adc{
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&adc_pins_mx>;
	pinctrl-1 = <&adc_sleep_pins_mx>;
	status = "okay";
 
	/* USER CODE BEGIN adc */
	vdda-supply = <&vdda>;                       /* Example to supply vdda pin by using a PMIC regulator */
	vref-supply = <&vrefbuf>;                    /* Example to use VREFBUF (It needs to be enabled as well) */
	adc1: adc@0 {
		assigned-resolution-bits = <12>;
		/* Single-ended channels */
		channel@0 {
			reg = <0>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@1 {
			reg = <1>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@2 {
			reg = <2>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@3 {
			reg = <3>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@5 {
			reg = <5>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@6 {
			reg = <6>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@9 {
			reg = <9>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@10 {
			reg = <10>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@12 {
			reg = <12>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@13 {
			reg = <13>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@15 {
			reg = <15>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
		channel@17 {
			reg = <17>;
			st,min-sample-time-ns = <10000>;  /* 10µs sampling time */
		};
	};
	/* USER CODE END adc */
};

In the Kernel configuration, I also marked

Device Drivers --->
 
  <*> Industrial I/O support --->
 
   Analog to digital converters --->
 
     <*> STMicroelectronics STM32 adc core
 
     <*> STMicroelectronics STM32 adc

It must be something I missed.

Thanks in advance for the hints.

BR Michal

MWoło.2 · ‎2023-05-08

After some break and rechecking everything I discover a correct dts configuration.

First I used as reference AVDD(external) and according to this I have configurations like

The Kernel

&adc {
	/* ANA0, ANA1 are dedicated pins and don't need pinctrl: only in6. */
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&adc_pins_mx>;
	pinctrl-1 = <&adc_sleep_pins_mx>;
	vdd-supply = <&vdd>;
	vdda-supply = <&vdda>;
	vref-supply = <&vdda>;
	status = "okay";
	adc1: adc@0 {
		#address-cells = <1>;
		#size-cells = <0>;
		status = "okay";
		channel@0 {
			reg = <0>;
			/* 16.5 ck_cycles sampling time */
			st,min-sample-time-ns = <5000>;
		};
		channel@1 {
			reg = <1>;
			st,min-sample-time-ns = <5000>;
		};
		channel@3 {
			reg = <3>;
			st,min-sample-time-ns = <5000>;
		};
		channel@5 {
			reg = <5>;
			st,min-sample-time-ns = <5000>;
		};
		channel@6 {
			reg = <6>;
			st,min-sample-time-ns = <5000>;
		};
		channel@9 {
			reg = <9>;
			st,min-sample-time-ns = <5000>;
		};
		channel@10 {
			reg = <10>;
			st,min-sample-time-ns = <5000>;
		};
		channel@13 {
			reg = <13>;
			st,min-sample-time-ns = <5000>;
		};
		channel@15 {
			reg = <15>;
			st,min-sample-time-ns = <5000>;
		};
	};
};

The U-Boot

&adc {
	/* ANA0, ANA1 are dedicated pins and don't need pinctrl: only in6. */
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&adc_pins_mx>;
	pinctrl-1 = <&adc_sleep_pins_mx>;
	vdd-supply = <&vdd>;
	vdda-supply = <&vdda>;
	vref-supply = <&vdda>;
	status = "okay";
	adc1: adc@0 {
		#address-cells = <1>;
		#size-cells = <0>;
		status = "okay";
		channel@0 {
			reg = <0>;
			/* 16.5 ck_cycles sampling time */
			st,min-sample-time-ns = <5000>;
		};
		channel@1 {
			reg = <1>;
			st,min-sample-time-ns = <5000>;
		};
		channel@3 {
			reg = <3>;
			st,min-sample-time-ns = <5000>;
		};
		channel@5 {
			reg = <5>;
			st,min-sample-time-ns = <5000>;
		};
		channel@6 {
			reg = <6>;
			st,min-sample-time-ns = <5000>;
		};
		channel@9 {
			reg = <9>;
			st,min-sample-time-ns = <5000>;
		};
		channel@10 {
			reg = <10>;
			st,min-sample-time-ns = <5000>;
		};
		channel@13 {
			reg = <13>;
			st,min-sample-time-ns = <5000>;
		};
		channel@15 {
			reg = <15>;
			st,min-sample-time-ns = <5000>;
		};
	};
};

Finally T-Fa

&etzpc{
	status = "okay";
	st,decprot = <
        /*"Non Secured" peripherals*/
        DECPROT(STM32MP1_ETZPC_ADC_ID, DECPROT_NS_RW, DECPROT_UNLOCK)
        ...
}
and
&rcc{
...
CLK_ADC_PLL4R
pll4:st,pll@3 {
	compatible = "st,stm32mp1-pll";
	reg = <3>;
	cfg = < 3 98 5 6 5 PQR(1,1,1) >;
};

This works for me and maybe will be suitable for someone else.

Thanks for any help

Topic can be closed.

View solution in original post

OlivierK · ‎2023-03-17

Hi MWoło.2 (Community Member)

According to https://www.kernel.org/doc/Documentation/devicetree/bindings/iio/iio-bindings.txt

It seems that you may have missed the #io-channel-cells = <1>; property in the ADC node.

from : linux-5.15.67/arch/arm/boot/dts/stm32mp151.dtsi

adc: adc@48003000 {

compatible = "st,stm32mp1-adc-core";

reg = <0x48003000 0x400>;

...

adc1: adc@0 {

compatible = "st,stm32mp1-adc";

#io-channel-cells = <1>;

...

Regards,

Olivier

MWoło.2 · ‎2023-03-17

Hi OlivierK,

thanks for the hint, unfortunately, it doesn't work. It is curious to that my configuration works for the DK2 board, in DK2 I see iio devices. The difference between my custom and dk2 is that dk2 not uses cube mx.

MWoło.2 · ‎2023-03-17

In my opinion, the system doesn't bind adc driver with iio. How to force the system to bind adc with iio?

OlivierK · ‎2023-03-17

Hi MWoło.2 (Community Member)

Regarding the bindings, you can use CubeMx and generate MP15-DK2 dts and compare with your settings. Normally if the IIO is enabled in the kernel I don't see why it shouldn't work.

MWoło.2 · ‎2023-03-17

OK,

let's compare

after issue

grep -H "" /sys/bus/iio/devices/*/name | grep adc

I get on my board

grep: /sys/bus/iio/devices/*/name: No such file or directory

and on disco

/sys/bus/iio/devices/iio:device0/name:48003000.adc:adc@0

What do the above means? If I get "No such file ...." it means not configured something in the kernel config or missing something in dts?

MWoło.2 · ‎2023-03-17

The configuration of both board

I can't find only the U-Boot drivers

Do U-Boot configuration (dts+driver) significant?

OlivierK · ‎2023-03-17

Hi MWoło.2 (Community Member)

What about the diff between CubeMX DTS generation for the MP15-DK2 vs your board?

Tomáš Juřena · ‎2023-03-17

Hi,

you can try something like this

&adc1 {
	st,min-sample-time-nsecs = <10000000>;
 
	st,adc-channels = <9 19>;
	assigned-resolution-bits = <12>;
	status = "okay";
};

This works for me on STe4.1.

MWoło.2 · ‎2023-03-17

ok I try, thanks