Recipe directory structure:
.
├── afrgb-stm32mp1_0.1.bb
└── files
    ├── afrgb-stm32mp1.c
    └── Makefile



afrgb-stm32mp1_0.1.bb:
inherit module

SUMMARY = "Adafruit RGB LED Matrix Driver for STM32MP1xx devices"
LICENSE = "CLOSED"

#SRC_URI = "git://code.technokrat.ch/ecarup/afrgb-stm32mp1.git;protocol=https;branch=rolling"
SRC_URI = "file://Makefile \
           file://afrgb-stm32mp1.c \
          "
S = "${WORKDIR}"
PROVIDES_${PN} += "kernel-module-afrgb-stm32mp1"


afrgb-stm32mp1.c:
#include <linux/module.h>

int init_module(void)
{
    printk(KERN_ALERT "gay\n");
    return 0;
}

void cleanup_module(void)
{
    printk(KERN_ALERT "oh no!\n");
}

MODULE_LICENSE("GPL");



Makefile:
obj-m := afrgb-stm32mp1.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