How to connect adc driver in dts with libiio - stm32mp1

[MWoło.2]

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]

Unfortunately, the result is the same. But I have an additional question. After writing my new image to sd card or in my case emmc what I should do after the first login? Maybe here is the problem, maybe additional configuration is needed?

[MWoło.2]

When I issue lsmod I get

Module                  Size  Used by
cfg80211              626688  0
usb_f_rndis            24576  2
u_ether                20480  1 usb_f_rndis
libcomposite           49152  10 usb_f_rndis
galcore               520192  0
dwmac_stm32            16384  0
stmmac_platform        20480  1 dwmac_stm32
stm32_adc_core         20480  0
spi_stm32              24576  0
stm32_timers           16384  0
sch_fq_codel           20480  3
ip_tables              24576  0
x_tables               24576  1 ip_tables
ipv6                  503808  42

 on dk board, I see something different

stm32_adc              32768  0
stm32_timer_trigger    20480  1 stm32_adc
stm32_lptimer_trigger    16384  1 stm32_adc

The above means that timers use adc.

Where I should bind the timer with adc and how?

[Tomáš Juřena]

I have tried to unload the stm32_adc module and the adc devices were removed to. So try to execute modprobe stm32_adc. If this helps add a stm32-adc.conf to the /etc/modules-load.d/. This could help.

[MWoło.2]

Now I'm able to achieve this

stm32_adc              32768  0
stm32_timer_trigger    20480  1 stm32_adc
stm32_lptimer_trigger    16384  1 stm32_adc

but after going to "/sys/bus/iio/devices" still empty

[MWoło.2]

on disco I have

root@stm32mp13-disco:/sys/bus/iio/devices# ls                  
 
iio:device0 

on my board

nothing

[MWoło.2]

I just see that I have a snapshot distro

ST OpenSTLinux - Weston - (A Yocto Project Based Distro) 4.0.4-snapshot

I try to repo sync and check.

[Tomáš Juřena]

Can you post dmesg, full device tree and check if there is anything interesting in /proc/device-tree/soc/adc@48003000/?

[MWoło.2]

Hi,

.../sys/firmware/devicetree/base/soc/adc@48003000/adc@0# ls

I have

'#address-cells'      compatible   interrupt-parent   reg
'#io-channel-cells'   dma-names    interrupts         status
'#size-cells'         dmas         name

[MWoło.2 · Accepted solution]

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

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