Re: [PATCH RFC 0/3] reset: syscon-reboot: add "reg" property support

["Rafał Miłecki" <zajec5@gmail.com>]

On 12.11.2021 23:18, Rob Herring wrote:
> On Tue, Nov 2, 2021 at 10:22 AM Rafał Miłecki <zajec5@gmail.com> wrote:
>>
>> From: Rafał Miłecki <rafal@milecki.pl>
>>
>> During my work on MFD binding for Broadcom's TWD block I received
>> comment from Rob saying that "syscon-reboot" should use "reg" property.
>> I'm not sure if my understanding & implementation are correct so I'm
>> sending this RFC.
>>
>> What bothers me is non-standard "reg" property usage. Treating it as a
>> simple (unsigned) integer number means different logic when it comes to
>> ranges.
> 
> It shouldn't be. The idea is that 'reg' works like normal. See below.
> 
>> Consider this example:
>>
>> timer@400 {
>>          compatible = "simple-mfd", "syscon";
>>          reg = <0x400 0x3c>;
>>          ranges;
> 
> ranges = <0 0x400 0x100>; // Just guessing for size
> 
>>
>>          #address-cells = <1>;
>>          #size-cells = <1>;
>>
>>          reboot@434 {
> 
> reboot@34
> 
> Just reading 'reg' is fine, but really, Linux should be either getting
> the translated address or have a function to get the offset from the
> parent base. IOW, it should also work if you just changed 'reg' to
> '<0x434 0x4>'.

Are you aware of anyone working on support for getting translated
address? Do you recall any efforts on implementing such a helper?

Thanks a lot for commenting on this concern explicitly.