linux-kernel - Re: [PATCH v15] rtc: sophgo: add rtc support for Sophgo CV1800 SoC

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Message-ID: <4d15d7b363869080da825ddc700e553a68928c85.camel@gmail.com>
Date: Sat, 10 May 2025 16:30:07 +0200
From: Alexander Sverdlin <alexander.sverdlin@...il.com>
To: Inochi Amaoto <inochiama@...il.com>, sophgo@...ts.linux.dev, 
	linux-rtc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH v15] rtc: sophgo: add rtc support for Sophgo CV1800 SoC

Hi Inochi!

On Fri, 2025-05-09 at 06:21 +0800, Inochi Amaoto wrote:
> On Wed, May 07, 2025 at 09:56:20PM +0200, Alexander Sverdlin wrote:
> > From: Jingbao Qiu <qiujingbao.dlmu@...il.com>
> > 
> > Implement the RTC driver for CV1800, which able to provide time alarm.
> > 
> > Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@...il.com>
> > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...il.com>

...

> > +static int cv1800_rtc_probe(struct platform_device *pdev)
> > +{
> > +	struct cv1800_rtc_priv *rtc;
> > +	int ret;
> > +
> > +	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
> > +	if (!rtc)
> > +		return -ENOMEM;
> > +
> > +	rtc->rtc_map = device_node_to_regmap(pdev->dev.parent->of_node);
> > +	if (IS_ERR(rtc->rtc_map))
> > +		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_map),
> > +				     "cannot get parent regmap\n");
> > +
> > +	rtc->irq = platform_get_irq(pdev, 0);
> > +	if (rtc->irq < 0)
> > +		return rtc->irq;
> > +
> > +	rtc->clk = devm_clk_get_enabled(pdev->dev.parent, "rtc");
> > +	if (IS_ERR(rtc->clk))
> > +		return dev_err_probe(&pdev->dev, PTR_ERR(rtc->clk),
> > +				     "rtc clk not found\n");
> > +
> > +	platform_set_drvdata(pdev, rtc);
> > +
> > +	device_init_wakeup(&pdev->dev, 1);
> > +
> > +	rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
> > +	if (IS_ERR(rtc->rtc_dev))
> > +		return PTR_ERR(rtc->rtc_dev);
> > +
> > +	rtc->rtc_dev->ops = &cv1800_rtc_ops;
> > +	rtc->rtc_dev->range_max = U32_MAX;
> > +
> > +	ret = devm_request_irq(&pdev->dev, rtc->irq, cv1800_rtc_irq_handler,
> > +			       IRQF_TRIGGER_HIGH, "rtc alarm", rtc);
> > +	if (ret)
> > +		return dev_err_probe(&pdev->dev, ret,
> > +				     "cannot register interrupt handler\n");
> > +
> > +	return devm_rtc_register_device(rtc->rtc_dev);
> > +}
> > +
> 
> I wonder whether the rtc driver may need reset (maybe optional) for this?
> If so, please add it.

I'm not sure which reset you are referring to... RTC module can carry out
system-wide resets, but cannot be reset itself (as I understand).

Initially I was thinking about providing a reboot driver for Linux utilizing
the RTC module but it turns out PSCI interface is not optional on ARM64, which
means PSCI reset interface has to be provided by the firmware (I'm thinking
about U-Boot) and Linux will rely on PSCI reboot.

-- 
Alexander Sverdlin.