Re: New remoteproc driver for TI PRU

[Roger Quadros]

On 29/06/18 20:44, David Lechner wrote:
> On 06/29/2018 04:58 AM, Roger Quadros wrote:
>> +Suman & Tero
>>
>> Hi David,
>>
>> On 24/06/18 00:08, David Lechner wrote:
>>>
>>> Date: Sat, 23 Jun 2018 15:43:59 -0500
>>> Subject: [PATCH 0/8] New remoteproc driver for TI PRU
>>>
>>> This series adds a new remoteproc driver for the TI Programmable Runtime Unit
>>> (PRU) that is present in some TI Sitara processors. This code has been tested
>>> working on AM1808 (LEGO MINDSTORMS EV3) and AM3358 (BeagleBone Green).
>>
>> This is great. We have been working on something similar and I think it would
>> be great if we can collaborate to get all our needs addressed.
> 
> Yes, I have used the PRU with the TI kernel on BeagleBone so I've seen the TI
> implementation. My primary interest is in the AM1808, which has a far simpler
> PRU than other SoCs. So, I was hoping I could get away with just implementing
> the basic stuff that I need and let TI add the more complex stuff later.
> 

The PRUSS core is essentially the same thing on most of our SoCs. They might
be varying in amount of RAM and integrated modules though. So PRUSS core support
should be scalable across all SoCs.

It is perfectly fine to get basic support in first and add the rest as we go along.

>>
>> Our primary requirement is that it should be possible for a user (e.g. kernel driver) to
>> - request a specific PRU core load a specific firmware blob and boot/stop the PRU.
> 
> For this, I was thinking of suggesting a generic remoteproc provider/consumer
> binding that is similar to other subsystems. For example:
> 
> Provider node has:
> 
> ÂÂÂÂ#remoteproc-cells = <1>;
> 
> And consumer has:
> 
> ÂÂÂÂremoteprocs = <&pruss 0>, <&pruss 1>;
> ÂÂÂÂremoteproc-names = "pru0", "pru1";
> 
> The consumer device would be responsible for determining the firmware file
> and for calling the rproc boot function.
> 
> 
>> - configure INTC interrupt mapping based on either resource table or DT
>> - use request_irq to request and use an interrupt.
> 
> I didn't consider creating a new interrupt controller in device tree, but
> that makes sense. I will have to look into it some more.
> 
> 
>> - request access to DRAM/SRAM
> 
> Can the existing device tree bindings for reserved-memory be used for this?
> I would expect the consumer nodes to use this and not the PRUSS provider node.
> 
> 
>> - configure gpimode/miirt/xfr (CFG space)
> 
> I have no idea what this stuff is. :-)
> 
> (This is what I was referring to when I said I was hoping that someone
> else could add more later).
> 

-- 
cheers,
-roger

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