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Date: Tue, 16 Jan 2024 16:25:26 +0100
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Subject: Re: [PATCH v6 3/3] riscv: dts: sophgo: add rtc dt node for CV1800
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To: Jingbao Qiu <qiujingbao.dlmu@gmail.com>
Cc: alexandre.belloni@bootlin.com, robh+dt@kernel.org,
 krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, chao.wei@sophgo.com,
 unicorn_wang@outlook.com, paul.walmsley@sifive.com, palmer@dabbelt.com,
 aou@eecs.berkeley.edu, linux-rtc@vger.kernel.org,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-riscv@lists.infradead.org, dlan@gentoo.org, inochiama@outlook.com
References: <20240115160600.5444-1-qiujingbao.dlmu@gmail.com>
 <20240115160600.5444-4-qiujingbao.dlmu@gmail.com>
 <f2b3dff2-ce0d-4ddb-ad61-74abf2c3022d@linaro.org>
 <CAJRtX8QFLoWnJBkepZrbneHX8qZdde=aw+zbdErVC91B=u==MA@mail.gmail.com>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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On 16/01/2024 15:41, Jingbao Qiu wrote:
> On Tue, Jan 16, 2024 at 3:44 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> On 15/01/2024 17:06, Jingbao Qiu wrote:
>>> Add the rtc device tree node to cv1800 SoC.
>>>
>>> Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@gmail.com>
>>> ---
>>>  arch/riscv/boot/dts/sophgo/cv1800b.dtsi | 12 ++++++++++++
>>>  1 file changed, 12 insertions(+)
>>>
>>> diff --git a/arch/riscv/boot/dts/sophgo/cv1800b.dtsi b/arch/riscv/boot/dts/sophgo/cv1800b.dtsi
>>> index df40e87ee063..66bb4a752b91 100644
>>> --- a/arch/riscv/boot/dts/sophgo/cv1800b.dtsi
>>> +++ b/arch/riscv/boot/dts/sophgo/cv1800b.dtsi
>>> @@ -119,5 +119,17 @@ clint: timer@74000000 {
>>>                       reg = <0x74000000 0x10000>;
>>>                       interrupts-extended = <&cpu0_intc 3>, <&cpu0_intc 7>;
>>>               };
>>> +
>>> +             rtc: rtc@5025000 {
>>> +                     compatible = "sophgo,cv1800-rtc", "syscon";
>>> +                     reg = <0x5025000 0x2000>;
>>> +                     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
>>> +                     clocks = <&osc>;
>>> +             };
>>> +
>>> +             por {
>>> +                     compatible = "sophgo,cv1800-por";
>>
>> What is this? Why is it here, how did it even appear? It misses unit
>> address and reg or is clearly placed in wrong place. It seems you
>> entirely ignored out previous discussion.
>>
>> NAK
>>
> 
> I'm very sorry for wasting your time. Furthermore, we would like to
> thank you for your patient response.
> Let me realize the rigor of Linux kernel code. I greatly admire
> this.Please allow me to briefly review
> our previous discussions.
> 
> CV1800 is a RISCV based SOC that includes an RTC module. The RTC
> module has an OSC oscillator


I am not going to read pages of description. Please write concise replies.

> and POR submodule inside.This OSC oscillator is only for RTC use, so
> it does not need to be described
> as a dt node. The POR submodule provides power off/on and restart
> functions for CV1800. So I need
> two drivers corresponding to RTC and POR respectively. RTC requires

This is DTS, not drivers. Please do not mix it.

> the use of irq and clk resources
> in addition to registers, while POR only requires Reg resources. The
> current problem is how to describe
> the relationship between RTC and POR, and how to make registers shared
> by these two drivers.
> 
> In v3, I thought RTC was an MFD device because it not only had RTC
> functionality but also restart and
> power on/off capabilities.So my example is shown below.
> 
> syscon@5025000 {
>   compatible = "sophgo,cv1800b-subsys", "syscon", "simple-mfd";
>   reg = <0x05025000 0x2000>;
>   rtc {
>     compatible = "sophgo,cv1800b-rtc";
>     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
>     clocks = <&clk CLK_RTC_25M>;
>   };
> }
> 
> There were two suggestions you made at the time. Firstly, I only
> described RTC and did not describe
> the POR submodule. Secondly, regarding the name issue, system
> controllers should not be placed
> in the mfd file.Afterwards, I released the 4th version, in which I
> described the POR submodule, which
> is included side by side with RTC in the misc device. Then, by sharing
> the register, both RTC and
> POR drivers can access the registers.
> 
> misc@5025000 {
>   compatible = "sophgo,cv1800-misc", "syscon", "simple-mfd";
>   reg = <0x05025000 0x2000>;
>   rtc  {
>     compatible = "sophgo,cv1800-rtc";
>     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
>     clocks = <&clk 15>;
>   };
>   por  {
>     compatible = "sophgo,cv1800-por";
>   };
> };
> 
> Your suggestion is, firstly, the por submodule does not have any
> resources, so it should be deleted.

So where did you delete it? I still see it in this patch.

> The second issue is still the name, misc is any device.
> Afterwards, I released the 5th edition. In this version, I removed the
> POR submodule in RTC.
> 
> rtc@5025000 {
>     compatible = "sophgo,cv1800-rtc", "syscon";
>     reg = <0x5025000 0x2000>;
>     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
>     clocks = <&clk 15>;
> };
> 
> The question you raised is why syscon child nodes are used.
> In this version, I will try the following methods.

"Will" is the future tense, so about which patch are we talking?

> 
> rtc: rtc@5025000 {
>                     compatible = "sophgo,cv1800-rtc", "syscon";
>                     reg = <0x5025000 0x2000>;
>                     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
>                     clocks = <&osc>;
> };
> por {
>                     compatible = "sophgo,cv1800-por";
>                     sophgo,rtc-sysreg = <&rtc>;
> };

NAK, because:

"so it should be deleted."


> 
> My idea is that this register can be accessed through the syscon tag,
> RTC driver, and reboot driver.

Again, what drivers have anything to do here?

> Then complete their functions.
> I'm sorry if it was due to language differences that caused my misunderstanding.
> Perhaps I can accomplish it through the following methods.
> rtc: rtc@5025000 {
>                     compatible = "sophgo,cv1800-rtc", "sophgo,cv1800-por";

Device is only one thing, not two.

>                     reg = <0x5025000 0x2000>;
>                     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
>                     clocks = <&osc>;
> };
> However, in reality, the POR submodule does not use IRQ and CLK.
> Please do not hesitate to teach. Thanks.

I expect one device node. How many drivers you have does not matter: you
can instantiate 100 Linux devices in 100 Linux device drivers.

Best regards,
Krzysztof