amiga-news.de - Motorola68k emulation: WiFi development for Emu68 paused

25.Aug.2022 Motorola68k emulation: WiFi development for Emu68 paused
Developer Michal Schulz regularly provides background information and status updates on his Motorola68K emulation Emu68 for the ARM architecture on his Patreon website.

At the beginning of May the developer had announced to start writing a WiFi driver. In a blog entry from two days ago, he now reports that the development had to be stopped for the time being. Read his explanations:

"I got stuck. Literally. The progresss on Wi-Fi driver was slowing down during last weeks until a full stop where I have no idea how to proceed. Let me write a bit about it.

The raspberry pi is using several different chipsets from cypress in order to provide Wi-Fi and (eventually) Bluetooth experience. These chips consist of a tiny ARM core connected with radio interface on one side and with communication interface with host, realized as few functions of SDIO interface. Subsequently, the Wi-Fi module has also few additional signals used as a clock source or Wi-Fi/Bluetooth enable/disable switches. So far so good, so where is the problem?

As always, the problem lies in lack of documentation. The cypress module is hardly documented, at least within freely available docs. Because of that I do not actually know how to drive it properly. Furthermore, I do not know if there are any differences on software side between different cypress modules used on pi3, pi zero 2 and so on. Sure, I can lurk into sources of e.g. Linux, where there is a fully functional code for Wi-Fi on raspberry. But digging through others source code is not always that useful, not to mention licensing differences. There are some open source projects like e.g. zerowi, which provide quite a lot of working code with very liberal licensing, but this very project is focusing on raspi zero and I am not entire,y sure if this one is good for me, because of, you guessed, lack of documentation.

So how far I got it? Basic initialization of SDIO is working flawlessly. I can initialize basic SDIO functions used to talk with Wi-Fi chip. I have successfully uploaded firmware for ARM cup and successfully resettled the arm core. Actually I went that far that’s the very next step should be the arm boot followed by full communication with Wi-Fi. Almost. For some reason the clock of arm is not starting up, at least that much I understood from undocumented registers. Without cpu clock running the arm of Wi-Fi will not start.

I am not giving up on this one, far from it! But for now I will do. Short break from Wi-Fi and will do something else. Otherwise I will sit fully blocked in front of the screen without any sable code written. I will come back to Wi-Fi as soon as I will reset my mind :)

By the way, if any of you has ideas how to get to the necessary documentation please let me know. If necessary, I can sign any NDA needed, provided it will allow me to develop open source Wi-Fi driver (with obfuscated register names if requested). Any help is appreciated." (dr)

[News message: 25. Aug. 2022, 06:38] [Comments: 0]
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