Re: [PATCH 1/2] dt-bindings: reset: introduce toshiba,tc9564-reset.yaml

[Alex Elder <elder@riscstar.com>]

On 10/22/26 1:34 PM, Conor Dooley wrote:
> On Wed, Oct 21, 2026 at 02:50:41PM -0500, Alex Elder wrote:

. . .

>> OK.  Let's see if I understand what you're saying.
>>
>> This approach uses:
>> - A single top-level syscon driver (under drivers/mfd?) which
>>    probes based on a devicetree node compatible string ("toshiba,...")
> 
> I'm not sure if it needs to be under mfd (there's some in soc/foo too)
> but I guess so.

I'll look at both places and will choose the one that seems
most similar to what I end up with.

>> - That compatible string will require a (fairly simple) devicetree
>>    binding
>> - That driver initializes a regmap which will cover the space
>>    defined in its devicetree node (<0x0 0x2000>)
> 
> I don't think the driver has to even do this at all, e.g.
> sg2044-topsys.c doesn't. Whenever someone requests the regmap it will
> get created automatically since you're a syscon.

You're right.

>> - That driver has an array that uses MFD_CELL_NAME() to define
>>    cells for clock and reset
>> - That driver will call some form of mfd_add_devices() using the
>>    MFD cell array
>> - The stmmac driver can refer to this device node with a phandle
>>    property to specify the syscon that provides the regmap it needs
>>
>> And then, for the clock and reset devices:
>> - A clock platform driver (under drivers/clk) will match based
>>    on the driver name (matching what's supplied by MFD_CELL_NAME())
>> - A reset driver will be similar (under drivers/reset)
>> - As you mentioned, these drivers get at the regmap they need using
>>    device_node_to_regmap() (or dev_get_regmap() or something)
> 
> I think "regmap = device_node_to_regmap(pdev->dev.parent->of_node);" is
> the correct way to do it.

     regmap = device_node_to_regmap(dev_of_node(dev->parent));

>> - And despite these being separate drivers (from the syscon driver)
>>    they don't have devicetree nodes, and the syscon node itself
>>    defines the clock-controller and reset-controller properties.
>>
>> Does that sound right?  Am I missing anything?
> 
> Sounds about right.

This is awesome.  I went ahead with this plan and it's working
fine now.

This syscon driver and "sg2044-topsys.c" are awfully trivial,
and they seem like they could be wrapped in something along
the lines of "simple-mfd-i2c.c".

Thank you very much for your help on this Conor.

					-Alex

. . .