Rust BCM2835(6/7) HWRNG Linux driver

The driver was implemented as a part of my Diploma Thesis in Computer Engineering.

The aim was to perform a basic evaluation of the advantages and drawbacks of using Rust in Linux kernel modules.

Prerequisites

• Linux tree from Rust-for-Linux team^[1] along with its dependencies.

• This Pull Request: rust: platform: add ioremap_resource and get_resource methods

• If you don't intend to use the configuration file^[2] provided inside modified_linux_files you must make sure that the following options are enabled in your custom .config:

  • CONFIG_RUST
  • CONFIG_COMMON_CLK
  • CONFIG_RESET_CONTROLLER
  • CONFIG_HW_RANDOM
  • CONFIG_RANDOM_TRUST_CPU

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[1] Tested on commit 459035ab65.

[2] It is suited to (and tested in a) Raspberry Pi 3B with a 64bit OS. Because it's pretty minimal some basic -but unneeded- features are disabled e.g. sound support. Graphics and network are enabled.

Building the driver as an Out-of-Tree module

Assuming that you are compiling in a x86_64 computer.

1. Copy the contents of modified_linux_files to linux.

   If you won't use a custom configuration file:

   1.a. Rename config to .config.

2. cd to linux and compile the kernel:

    $ make LLVM=1 ARCH=arm64
   

   It is also recommended to use the -j option.

3. Assuming that the directory tree is as follows:

   • working_directory
     • linux
     • driver

   cd to driver and compile the driver:

    $ make
   

   if the linux tree is in a different location then you must supply make with the tree's path.

    $ make KDIR=<path_to_linux_tree>
   

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The aforementioned steps will only produce a working out-of-tree kernel module. If you want a working kernel you must also compile and install the in-tree kernel modules and if necessary, the dtb that corresponds to your platform.