I need to connect the DHT22 temperature and humidity sensor to BPi. Obviously, the kernel does not include the corresponding kernel module, but this module exists in sequent releases.
Banana Pi BPI-M2U has the Allwinner R40 chip. This chip does not include a hardware 1-wire interface. But we can implement this data exchange protocol at the software level using the bit bang method. The default Linux kernel (Raspbian Jiessie, 3.10.107) does not include the w1-gpio kernel module. I’ve tried to compile it, but it has many dependencies. I’ve found w1-gpio-cl. This is a Linux kernel-mode driver substitutes w1-gpio 1-wire bus master driver. Contrary to the standard driver, w1-gpio-cl doesn’t need many other kernel modules. Also you may configure this kernel module using command line parameters.
Using BPi for kernel (re)compilation is quite painful because it is very slow for this task. So I configured a virtual machine (VMWare in my case). Now, the kernel can be compiled in 50-80 seconds on my i7-4770. The configuration is easy if you read the following tutorial. I’ve tried several options before and selected this one.