Re: [PATCH v2 1/3] dt-bindings: clock: introduce toshiba,tc9564-clock.yaml

[Krzysztof Kozlowski <krzk@kernel.org>]

On 09/10/2026 16:23, Alex Elder wrote:
> On 10/9/26 8:56 AM, Krzysztof Kozlowski wrote:
>> On 09/10/2026 15:44, Alex Elder wrote:
>>> On 10/9/26 4:31 AM, Krzysztof Kozlowski wrote:
>>>> On Mon, Oct 05, 2026 at 06:09:24PM -0500, Alex Elder wrote:
>>>>> Define the binding for the clock controller functionality present in
>>>>> the Toshiba TC9564 SoC.
>>>>>
>>>>> Co-developed-by: Daniel Thompson <daniel@riscstar.com>
>>>>> Signed-off-by: Daniel Thompson <daniel@riscstar.com>
>>>>> Signed-off-by: Alex Elder <elder@riscstar.com>
> 
> . . .
> 
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    const: toshiba,tc9564-clock
>>>>> +
>>>>> +  toshiba,config-syscon:
>>>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>>>> +    description:
>>>>> +      Phandle for the configuration space system controller.
>>>>
>>>> I do not see my previous comment addressed - you have no resources here,
>>>> so this belongs to the parent. You responded something about pci-ep, but
>>>> the parent is not pci-ep. Open your code:
>>>> https://lore.kernel.org/lkml/20260918165234.687224-5-elder@riscstar.com/
>>>>
>>>> I clearly see code like:
>>>>     syscon {
>>>>       clock@ {
>>>>       };
>>>>     };
>>>>
>>>> so I do not understand what pci-ep has anything to do here.
>>>
>>> What I have now (about to send) looks like this:
>>>
>>>       syscon@0 {
>>>           compatible = "syscon", "simple-mfd";
>>>           reg = <0x0 0x2000>;
>>>
>>>           clock {
>>>               compatible = "toshiba,tc9564-clock";
>>>               #clock-cells = <1>;
>>>           };
>>>       };
>>>
>>> A reset node will also go inside the syscon, so there is another
>>> function for that MFD.
>>>
>>> The regmap belongs to the parent, and is looked up this way:
>>>
>>>       regmap = syscon_node_to_regmap(dev_of_node(dev->parent));
>>
>> That's driver code, so irrelevant. So how does this solve my comment
>> from v1?
> 
> I'm trying Krzysztof.

In v1 I asked to fold the node into the parent. v2 did not have it. v3,
which you are preparing, still has no node folded, because they are
separate.

> 
> The clock controller uses two registers, 0x1004 and 0x100c,
> to manage whether a set of clock signals are enabled or not.
> (The reset controller uses two adjacent registers, 0x1008
> and 0x1010, to manage whether a set of reset signals are
> asserted or not.)
> 
> You said "no resources except a small address space" and I
> guess it's not clear to me what size is "big enough" to
> warrant representing something as a separate device.
> 
> *One* of the managed clocks is a 25 MHz clock, exposed
> through a pin on the SoC.  That one clock signal is
> therefore usable by the platform (although on the RB3gen2
> it's not used).
> 
> Rather than expose the register addresses in the clock
> node, a syscon is defined, covering 8 KB, and the actual
> offsets used are just defined in the clock and reset
> driver source code.
> 
> If that's not the right thing to do, please say that.

Nodes should be squashed.

> 
>>>> What's more, I still do not see any usage of these clocks outside. And I
>>>> still did not receive actual answers (or I missed them) how these clocks
>>>> are routed OUTSIDE of the connector. You said for example:
>>>> "Ultimately the TC9564 SoC has a single 25 MHz input clock,"
> . . .
> 
>>> The single exposed clock *might* justify presenting the
>>> clock controller device in devicetree.  There are also
>>> resets exposed externally via GPIOs, and these control
>>> external entities (PHYs).
>>
>> I cannot find any of these exposed. Please point me to DTS code showing
>> this.
> 
> It is not used by this platform, but is available for other
> platforms to use.  Its name is "REFCLKO" and is exposed on
> ball C17 of the SoC, if a platform designer decided to use it.

Yeah, but you do not describe the SoC but PCI EP device, thus my claim
is that clocks cannot be used by the host. The SoC itself for different
hardware uses would have different binding, so that's not an argument to
have anything here, unless these different uses are also documented here.

Best regards,
Krzysztof