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This version (15 May 2019 16:01) was approved by aardelean.

Building for Raspberry PI

The Analog Devices kernel can be built to run on the Raspberry PI boards. Unfortunately, these changes are not in master, because they diverge too much (at this point in time) from the changes in both Xilinx & ADI kernel.

Because of this, there are special branches in the repository that should be built to run on the Raspberry PI. They contain several drivers that are not upstreamed yet. These are mostly used for internal testing, and they also contain device-tree overlays for some of these drivers.

The Raspberry PI branches do not contain all of the changes in master. They contain only a set of them, typically for simple ADCs & DACs. The more complex drivers are in master and are typically tested/running on Xilinx & Intel boards using FPGA parts. These FPGA parts are needed for some reference designs/boards supported by Analog Devices.

The Raspberry PI branches are:

  • rpi-4.9.y - this is an older branch, when Raspberry PI's default kernel version was at 4.9 ; it's kept around for some older boards/setups
  • rpi-4.14.y - the current default Raspberry PI branch, also the official version of Raspbian at this point in time
  • There maybe be a few other branches that start with rpi-xxx ; these should not be used, they will be removed in the future, and were used to test things sometime in the past.

Initial setup

The initial setup is to get an SD-card image from here: https://www.raspberrypi.org/downloads/raspbian/ It does not matter which distribution is used/preferred.

Instructions on writing to SD-card are here: https://www.raspberrypi.org/documentation/installation/installing-images/README.md

At the time of this writing Raspbian's kernel version is 4.14.

Getting the ADI kernel

git clone https://github.com/analogdevicesinc/linux
git checkout rpi-4.14.y

Building the ADI kernel - manual cross-compiling

Get an ARM compiler for cross-compiling.

ARCH=arm make adi_bcm2709_defconfig
ARCH=arm CROSS_COMPILE=<path-to-arm-toolchain> make

Building the ADI kernel - script method

Download this script (and make it executable): https://github.com/analogdevicesinc/wiki-scripts/blob/master/linux/build_rpi_kernel_image.sh

Run it:

./build_rpi_kernel_image.sh linux
The linux directory in the above example is optional. If unspecified, a linux-adi directory will be cloned

Adding the generated file on the SD-card

First backup the kernel7.img file on the SD-card.

The generated arch/arm/boot/zImage file should be copied to the /boot to overwrite the kernel7.img.

Always remember to run sudo sync or un-mount the SD-card safely so that whatever is copied on it, actually gets flushed to it.

Customizing the kernel/adding-drivers

For Raspberry-PI, a way to add a driver (and usually in IIO), is to build it into the kernel7.img and add a device-tree overlay.

Adding drivers is done via make menuconfig, and selecting the [y] option.

Device-tree overlays are covered in these docs:

Some examples of DT overlays for drivers written for ADI parts can be found at this link: https://github.com/analogdevicesinc/linux/commits/rpi-4.14.y/arch/arm/boot/dts/overlays

resources/tools-software/linux-build/generic/raspberrypi.txt · Last modified: 15 May 2019 16:01 by aardelean