Yocto Recipe for automatically loading Out of Tree Linux Device Drivers on Start

We can instruct Yocto to automatically start our own Linux Kernel Module on Start.

Steps:

1. Create a folder 'recipes-kernel' in your own custom meta layer if it doesn't exist
$ mkdir recipes-kernel
2. Inside 'recipes-kernel', create a folder 'my-module' for storing recipe and device driver files
$ cd recipes-kernel; mkdir my-module
3. Inside 'my-module', create 'files' folder and copy your device driver files
$ cd my-module; mkdir files
4. Copy this Makefile in the 'files' directory

	obj-m := mymod.o
	SRC := $(shell pwd)
	all:
	$(MAKE) -C $(KERNEL_SRC) M=$(SRC)
	modules_install:
	$(MAKE) -C $(KERNEL_SRC) M=$(SRC) modules_install
	clean:
	rm -f *.o *~ core .depend .*.cmd *.ko *.mod.c
	rm -f Module.markers Module.symvers modules.order
	rm -rf .tmp_versions Modules.symvers

view raw Makefile hosted with ❤ by GitHub

5. Come back to the parent folder (i.e., my-module) and create a recipe for building the module
$ cd .. ; touch my-module_0.1.bb

You should have the following tree after this step.

	SUMMARY = "My Module"
	LICENSE = "GPLv2"
	inherit module
	SRC_URI = "file://Makefile \
	file://mymod.c \
	"
	S = "${WORKDIR}"
	# The inherit of module.bbclass will automatically name module packages with
	# "kernel-module-" prefix as required by the oe-core build environment.
	RPROVIDES_${PN} += "kernel-module-mymod"

view raw my-module_0.1.bb hosted with ❤ by GitHub

6. Add this module into your configuration file (local.conf file or machine.conf)
MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "kernel-module-mymod"
KERNEL_MODULE_AUTOLOAD += "mymod"

MACHINE_ESSENTIAL_EXTRA_RDEPENDS tells yocto to build this module and include it in the build image 

KERNEL_MODULE_AUTOLOAD is to load the module automatically on start