Out-of-tree driver - Zephyr (freestanding app)

RE: Out-of-tree driver - Zephyr (freestanding app)

Fisherdude — Thu, 01 Aug 2024 15:47:19 GMT

Thanks for this! Another nugget I found along the way:

The driver's CMakeLists.txt must include zephyr_library_add_dependencies(offsets_h), or the Zephyr file linker-defs.h may not compile on a clean build because its #include <offsets.h> doesn't find the file.

RE: Out-of-tree driver - Zephyr (freestanding app)

Mirco — Mon, 10 Jun 2024 08:23:45 GMT

You are my savior!

RE: Out-of-tree driver - Zephyr (freestanding app)

Vignesh R — Sun, 28 Apr 2024 05:22:04 GMT

Hey Hi!

I tried the above and with some references , i could able to build out of tree driver for my application.

But, i cannot able to access the rtc.h (in your case) from pcf85063a.c ,if rtc.h is placed in include/app/drivers/rtc.h.

i moved it to the pcf85063a.c folder and accessed it by "#include "rtc.h"" directly,

but i cant access if it is in the include directory, how to include the rtc.h if placed there?

should i need to add some line in cmakelists to include them??

or anyother way to include them??

RE: Out-of-tree driver - Zephyr (freestanding app)

Cammie — Thu, 21 Mar 2024 21:55:56 GMT

OK - I'm going to give this a whirl - thanks!

RE: Out-of-tree driver - Zephyr (freestanding app)

pixbroker — Thu, 21 Mar 2024 19:53:46 GMT

Thank you!

RE: Out-of-tree driver - Zephyr (freestanding app)

ElectRocnic — Thu, 21 Mar 2024 17:51:55 GMT

The name of the server is "zephyrproject"
This link is only valid for 7 days :(
https://discord.gg/sTDQeVDD

The post I found was from 13. dezember 2022 and was answered by the user Archie.
As soon as you are on this server, my original link should work tho.

RE: Out-of-tree driver - Zephyr (freestanding app)

pixbroker — Thu, 21 Mar 2024 14:33:30 GMT

Thank you. Could you share the Discord server/channel you found the answer at? The link is not working for me.

RE: Out-of-tree driver - Zephyr (freestanding app)

ElectRocnic — Wed, 21 Jun 2023 13:12:21 GMT

I have found a working solution to this now, thanks to this dicord answer:

The problem is indeed, that Zephyr does not seem to clearly document freestanding+out-of-tree applications:
You have to include your out-of-tree driver inside your freestanding app root folder like this:

├── drivers
│   ├── CMakeLists.txt
│   ├── Kconfig
│   ├── rtc
│   │   ├── CMakeLists.txt
│   │   ├── Kconfig
│   │   ├── pcf85063a_util.h
│   │   └── pcf85063a.c
│   └── zephyr
│       └── module.yml
├── dts
│   └── bindings
│       └── rtc
│           └── nxp,pcf85063a.yaml
├── include
│     └── app
│       └── drivers
│           └── rtc.h
├── src
└── proj.conf

and your driver is actually a so-called "module" which needs the drivers/zephyr/module.yml file with the following content:

build:
  cmake: .
  kconfig: Kconfig

Next, you need to include this in your app's root CMakeLists.txt before you find the zephyr package (I don't know why, but I got it running this way):

list(APPEND ZEPHYR_EXTRA_MODULES
  ${CMAKE_CURRENT_SOURCE_DIR}/drivers
)

This is needed instead of the previously (likely, as in my case) used

add_subdirectory(drivers)

so I removed the latter line in my repo and replaced it with the list command above.

Hope, you will find that this solution also works in your case!

Kind regards.

RE: Out-of-tree driver - Zephyr (freestanding app)

ElectRocnic — Tue, 20 Jun 2023 13:47:37 GMT

First little check I made, was to verify that it is indeed a problem with the application type (out-of-tree vs. in-tree), and I did this by duplication an existing driver in the zephyr ncs:

1. Duplicate the folder .../ncs/v2.4.0/zephyr/drivers/sensor/bmi270 to .../bmi271. For simplicity, the new folder can be added to the workspace in VS Code and then use "find in directory" to replace all case-sensitive instances of bmi270 with bmi271, and all BMI270 with BMI271. In the .../ncs/v2.4.0/zephyr/drivers/sensor/CMakeLists.txt file, I also had to duplicate the line for BMI270:

add_subdirectory_ifdef(CONFIG_BMI270		bmi270)
add_subdirectory_ifdef(CONFIG_BMI271		bmi271)

In the .../ncs/v2.4.0/zephyr/drivers/sensor/Kconfig file too:

source "drivers/sensor/bmi270/Kconfig"
source "drivers/sensor/bmi271/Kconfig"

In ncs/v2.4.0/zephyr/dts/bindings/sensor, duplicate the 3 Bosch bindings and rename them (both filename and all strings within the files).

bosch,bmi270-i2c.yaml
bosch,bmi270-spi.yaml
bosch,bmi270.yaml
bosch,bmi271-i2c.yaml
bosch,bmi271-spi.yaml
bosch,bmi271.yaml

In the main.c of the sample project, the app.overlay now needs to be adjusted. For this, I created a second spi node, which looks as follows:

imu: &spi1 {
    compatible = "nordic,nrf-spim";
    status = "okay";
    cs-gpios = <&gpio0 18 0>;
    
    fake_sensor: bmi271@0 {
        compatible = "bosch,bmi271";
        reg = <0>;
        spi-max-frequency = <10000000>;
    };
};

What's relevant is the compatible string and then the location in main.c:

const struct device *const accel_sensor = DEVICE_DT_GET_ONE(bosch_bmi271);
if (!device_is_ready(accel_sensor)) {
		printf("Device %s is not ready\n", accel_sensor->name);
		return 0;
}

char msg_accel[100];  // size might need to be adjusted based on your needs
snprintf(msg_accel, sizeof(msg_accel), "Device %p name is %s", accel_sensor, accel_sensor->name);

Note that I already had a Bosch BMI270 in my app.overlay at spi0 and it worked with the above code already. But I wanted to add an Kionix which is not in the Zephyr device tree and it did not work so far.
My next steps are for now to use this workaround in-tree to get my own PoC for the Kionix, after that I can look into this problem again because I need my Kionix Driver to work out-of-tree anyways.

Until then, kind regards.

RE: Out-of-tree driver - Zephyr (freestanding app)

ElectRocnic — Mon, 19 Jun 2023 16:33:37 GMT

I tried to get this example driver code running in a freestanding fresh hello-world sample in VS Code.
https://github.com/nobodyguy/HX711_zephyr_driver

Getting the error main.c:61: undefined reference to `__device_dts_ord_8'

Even had to add one line in my main Kconfig to get it so far:

source "Kconfig.zephyr" # this one
rsource "drivers/Kconfig"

apparently freestanding apps have major problems easily compared to in-tree apps?
Or I am just too stupid to acknowledge the very basics of Zephyr.

My CMakeLists.txt for the app looks like this:

cmake_minimum_required(VERSION 3.20.0)

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
project(hello_world)

# Point to this project's root directory.
set(HX711_DIR ${CMAKE_CURRENT_LIST_DIR} CACHE PATH "HX711 module root directory")

# Subdirectories
add_subdirectory(drivers)

# Include headers
zephyr_include_directories(drivers)

target_sources(app PRIVATE src/main.c)

I now also tried https://github.com/jeremyherbert/zephyr_testrepo with no luck after I read https://github.com/zephyrproject-rtos/zephyr/issues/41677 where Jeremy seemingly got it working. (Had to adapt a few things like adding "zephyr" to each #include statement before the header names). Also, this repo does not even define an overlay.

RE: Out-of-tree driver - Zephyr (freestanding app)

ElectRocnic — Mon, 19 Jun 2023 14:54:49 GMT

I have the exact same problem right now and am trying to find a solution. My approach is to go deep into the Zephyr theory, looked into a lot of docs from docs.zephyrproject.org and watched youtube talks about writing custom drivers.
I think the problem might be to the difference between freestanding projects vs. in-tree or in-workspace projects in combination with the Kconfig and west yaml.

I will come back if I find a solution.

RE: Out-of-tree driver - Zephyr (freestanding app)

Cammie — Thu, 15 Jun 2023 14:11:22 GMT

2.3.0

RE: Out-of-tree driver - Zephyr (freestanding app)

Hakon — Thu, 15 Jun 2023 14:10:43 GMT

Hello,

what version of NCS are you trying to build this with?