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

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Hi,

On 02.12.2021 18:21, Sebastian Reichel wrote:
On Fri, Nov 12, 2021 at 04:32:48PM -0600, Rob Herring wrote:
On Fri, Nov 12, 2021 at 4:23 PM Rafał Miłecki <zajec5@xxxxxxxxx> wrote:

On 12.11.2021 23:18, Rob Herring wrote:
On Tue, Nov 2, 2021 at 10:22 AM Rafał Miłecki <zajec5@xxxxxxxxx> wrote:

From: Rafał Miłecki <rafal@xxxxxxxxxx>

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?

All the DT address functions give you translated addresses. It's the
latter that doesn't exist that I'm aware of offhand. It's just
of_address_to_resource() on the child and parent nodes and then
calculate the offset.

Has a new version beent sent with this change, that I missed?

Not yet, I was sidetracked by pinctrl & OpenWrt stuff.



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