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From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Jingbao Qiu <qiujingbao.dlmu@gmail.com>
Cc: Inochi Amaoto <inochiama@outlook.com>,
	robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
	conor+dt@kernel.org, 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, dlan@gentoo.org
Subject: Re: [PATCH v8 2/2] rtc: sophgo: add rtc support for Sophgo CV1800 SoC
Date: Wed, 1 May 2024 13:20:01 +0200	[thread overview]
Message-ID: <20240501112001dc47d549@mail.local> (raw)
In-Reply-To: <CAJRtX8Ruh4BethYcGM2RueNBDioXpn8dJ3yvUD4iW_1cmiVFqg@mail.gmail.com>

On 01/05/2024 17:14:43+0800, Jingbao Qiu wrote:
> On Wed, May 1, 2024 at 3:43 PM Inochi Amaoto <inochiama@outlook.com> wrote:
> >
> > On Wed, May 01, 2024 at 01:03:58PM GMT, Jingbao Qiu wrote:
> > > Hi, Inochi
> > >
> > > On Wed, May 1, 2024 at 10:19 AM Inochi Amaoto <inochiama@outlook.com> wrote:
> 
> > > > Another thing is that I do not think is a good way to let the
> > > > rtc driver access RTC_CTRL area directly. You have already
> > > > know there is a 8051 device in the 0x05025000. It is necessary
> > > > to make some room for this device. Maybe you want to implement
> > > > them all in the rtc driver? If so, I do think it is a bad idea.
> > >
> > >
> > > Do you mean that RTC drivers should not directly access the 0x05025000 address?
> > > Because there is an 8051 subsystem on this address.
> >
> > Yes. At least we need some mechanism to share these address between
> > this devices.
> >
> > > Firstly, I do not intend to implement 8051 in the RTC driver,
> > > but the 8051 subsystem is located within a module independently
> > > powered by the RTC.
> > > So if we want to implement the 8051 subsystem in the future, it can be
> > > used as a node in RTC? I'm not sure.
> >
> > Yes, this is what I care about.
> >
> > > Then, Alexandre told me that there are operations related to PM in
> > > RTC, such as the following files.
> > > This matches the description of address 0x05025000.
> > >
> > > drivers/rtc/rtc jz4740. c
> > >
> >
> > I do not think this is something related to the PM. 8051 is more
> > like remoteproc. So it is necessary to arrange them carefully.
> >
> 
> You are right.
> I learned from official documents that 8051 works in the RTC domain.
> Linux does not provide relevant interfaces to operate 8051,
> Just providing a mailbox for communication between them, or through
> interruptions.
> I don't understand how 8051 works, so I shouldn't write to the
> corresponding registers in RTC.
> 
> https://milkv.io/docs/duo/getting-started/8051core

Then you will have to have a driver for the 8051 firmware before being
able to access registers that are outside of the RTC range. However, I
se the firmware is using RTC_INFOx without any form of locking but I
guess this just means Linux will have to ensure it never writes to
those.

> 
> 
> > > > > 2.25.1
> > > > >

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

  reply	other threads:[~2024-05-01 11:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-04  4:41 [PATCH v8 0/2] riscv: rtc: sophgo: add rtc support for CV1800 Jingbao Qiu
2024-02-04  4:41 ` [PATCH v8 1/2] dt-bindings: rtc: sophgo: add RTC support for Sophgo CV1800 series SoC Jingbao Qiu
2024-02-04  4:41 ` [PATCH v8 2/2] rtc: sophgo: add rtc support for Sophgo CV1800 SoC Jingbao Qiu
2024-03-05 10:25   ` Jingbao Qiu
2024-04-17 21:23   ` Alexandre Belloni
2024-04-24  7:35     ` Jingbao Qiu
2024-05-01  2:19   ` Inochi Amaoto
2024-05-01  5:03     ` Jingbao Qiu
2024-05-01  7:43       ` Inochi Amaoto
2024-05-01  9:14         ` Jingbao Qiu
2024-05-01 11:20           ` Alexandre Belloni [this message]
2024-05-02  7:39             ` Jingbao Qiu

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