DEPRECATED: Work is moved out of a Linux LKM and into https://github.com/coolbho3k/Linux-Kernel_MiSTer/tree/overclock

MiSTer FPGA cpufreq driver

This is very WIP! It's not fully working yet.

Compile this as a module and the DE10 Nano will be able to scale between 800 MHz and 400 MHz via cpufreq governor.

I have overclocking working in principle, but this driver can't do it yet.

Notes

1. CONFIG_CPU_FREQ needs to be set to y on the kernel.
2. Currently this is set up as a loadable kernel module. I'll try to upstream it into the MiSTer kernel when working well.
3. I'll keep any kernel changes in this driver. I don't think I'll update the socfpga Common Clock Framework unless I can upstream the changes even further.

Helpful resources

Cyclone V docs/code

• Cyclone V Hard Processor System Technical Reference Manual - Everything in the Clock Manager chapter is very helpful.
• u-boot board code cyclone5-socdk | de10-nano | arria5-socdk - Most of the clock setup is done in u-boot. The socdk uses a higher speed grade so comparing the header files was crucial. The Arria V presumably has a similar HPS using different values for PLL registers at a slightly higher frequency and core voltage.
• u-boot clock manager code
• Linux socfpga Common Clock Framework drivers - Not as helpful compared to u-boot.

How to build

• Compiling the Linux kernel for MiSTer
• MISTER CUSTOM WIFI DRIVER COMPILATION GUIDE - how to build as a Linux kernel module