[EXTERNAL] Pi Support Status Question

[Cudmore, Alan P. (GSFC-5820)]

I am not sure about the current state of the Raspberry Pi BSPs, but I can try to explain the differences in the models and how that might affect RTEMS support:

  *   The original single Core Raspberry Pis which include the B, B+, A+ were the target for the original BSP
  *   The Pi Zero is a $5USD variant that has the same single core processor – the original BSP should work on that as well
  *   Support for the Raspberry Pi 2 was added, which has a Quad Core Cortex A7 – this has a basic BSP and SMP should work
All of the above models have the same console UART, so the existing BSP console works.

The Pi 3 models (3B, 3A, 3B+ ) have a couple of differences:

  *   The 3 models are based on a Quad Core A53 processor
  *   The 3 models all have Wi-Fi and Bluetooth. On these models the uart that is normally used for the console, is now used to connect to the Bluetooth device. The console is now a “mini-uart” device on the SoC. So these models break the RTEMS console. We would have to provide a new console driver for those.
  *
The Pi Zero W, is a $10USD variant that has the Wi-fi Bluetooth module, so it needs an RTEMS console uart driver as well.

Finally, the newly released Pi 4 has a Quad Core A72 processor, also with Wi-Fi and Bluetooth. I have not looked at the details of this one yet to know what serial devices it has.

As for libbsd support, is was started under a GSOC project, but I don’t think it ever was completed.

I have not had any time in the past couple of years, to work with the RTEMS BSPs for the Pi. There is a lot of Bare Metal C code out there for just about all of the models if anyone is interested in looking at updating RTEMS support.

Alan

From: devel <devel-bounces at rtems.org> on behalf of Joel Sherrill <joel at rtems.org>
Reply-To: "joel at rtems.org" <joel at rtems.org>
Date: Thursday, October 31, 2019 at 3:39 PM
To: "rtems-devel at rtems.org" <devel at rtems.org>
Subject: [EXTERNAL] Pi Support Status Question

Hi

I got asked a question about the Pi BSP which led me to a couple of more questions.
Help appreciated.

+ Is there support for the Pi3 or Pi4? I recall some comment about the UART base
address changing but nothing useful.

+ I don't see any networking support in rtems-libbsd. I know the controller is on the
USB so we have considered this a barrier but libbsd should support this.

+ I think I recall Alan Cudmore mentioning using the PiZero. Which BSP works on that?

+ Does anyone have Pi code that needs to be merged? <hoping>

Any other Pi questions I should be aware of? :)

Thanks.

-joel
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