linux-kernel - Re: [PATCH v2 4/5] rtc: mt6397: Add BBPU alarm status reset and shutdown handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <76325c39-ea88-48fe-b32d-00c1e0d31024@collabora.com>
Date: Thu, 20 Nov 2025 15:42:10 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: ot_shunxi.zhang@...iatek.com, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Matthias Brugger <matthias.bgg@...il.com>,
 Eddie Huang <eddie.huang@...iatek.com>, Sean Wang <sean.wang@...iatek.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>, Lee Jones
 <lee@...nel.org>, Vince-WL.Liu@...iatek.com, sirius.wang@...iatek.com,
 Jh.Hsu@...iatek.com
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2 4/5] rtc: mt6397: Add BBPU alarm status reset and
 shutdown handling

Il 20/11/25 13:18, ot_shunxi.zhang@...iatek.com ha scritto:
> From: Shunxi Zhang <ot_shunxi.zhang@...iatek.com>
> 
> Function "mtk_rtc_reset_bbpu_alarm_status" is added to address the
> issue that the RTC BBPU alarm state remains after the RTC alarm
> has occurred.
> 
> Additionally, function "mtk_rtc_shutdown" is added to address the
> issue of the platform being powered on again after shutdown because
> the RTC_BBPU alarm state was not cleared.
> 
> Signed-off-by: Shunxi Zhang <ot_shunxi.zhang@...iatek.com>
> ---
>   drivers/rtc/rtc-mt6397.c | 30 ++++++++++++++++++++++++++++++
>   1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c
> index b8f44a00de5d..8bf7e0822ef0 100644
> --- a/drivers/rtc/rtc-mt6397.c
> +++ b/drivers/rtc/rtc-mt6397.c
> @@ -37,6 +37,21 @@ static int mtk_rtc_write_trigger(struct mt6397_rtc *rtc)
>   	return ret;
>   }
>   
> +static void mtk_rtc_reset_bbpu_alarm_status(struct mt6397_rtc *rtc)
> +{
> +	u32 bbpu = RTC_BBPU_KEY | RTC_BBPU_PWREN | RTC_BBPU_RESET_AL;
> +	int ret;
> +
> +	ret = regmap_write(rtc->regmap, rtc->addr_base + RTC_BBPU, bbpu);
> +	if (ret < 0) {
> +		dev_err(rtc->rtc_dev->dev.parent, "%s: write rtc bbpu error\n",
> +			__func__);
> +		return;
> +	}
> +
> +	mtk_rtc_write_trigger(rtc);
> +}
> +
>   static irqreturn_t mtk_rtc_irq_handler_thread(int irq, void *data)
>   {
>   	struct mt6397_rtc *rtc = data;
> @@ -51,6 +66,9 @@ static irqreturn_t mtk_rtc_irq_handler_thread(int irq, void *data)
>   		if (regmap_write(rtc->regmap, rtc->addr_base + RTC_IRQ_EN,
>   				 irqen) == 0)
>   			mtk_rtc_write_trigger(rtc);
> +
> +		if (rtc->alarm_sta_supported)
> +			mtk_rtc_reset_bbpu_alarm_status(rtc);
>   		mutex_unlock(&rtc->lock);
>   
>   		return IRQ_HANDLED;
> @@ -249,6 +267,7 @@ static int mtk_rtc_probe(struct platform_device *pdev)
>   	struct resource *res;
>   	struct mt6397_chip *mt6397_chip = dev_get_drvdata(pdev->dev.parent);
>   	struct mt6397_rtc *rtc;
> +	struct device_node *np = pdev->dev.of_node;
>   	int ret;
>   
>   	rtc = devm_kzalloc(&pdev->dev, sizeof(struct mt6397_rtc), GFP_KERNEL);
> @@ -275,6 +294,8 @@ static int mtk_rtc_probe(struct platform_device *pdev)
>   	if (IS_ERR(rtc->rtc_dev))
>   		return PTR_ERR(rtc->rtc_dev);
>   
> +	rtc->alarm_sta_supported = of_property_read_bool(np, "mediatek,alarm-sta-supported");

You don't need a DT property - the PMIC dictates support for that, not the board.

This means that you also don't need the alarm_sta_supported variable, and you
don't need to check for it.

Just execute the mtk_rtc_reset_bbpu_alarm_status() function when you have to,
without any check.

Cheers,
Angelo

> +
>   	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
>   					mtk_rtc_irq_handler_thread,
>   					IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
> @@ -297,6 +318,14 @@ static int mtk_rtc_probe(struct platform_device *pdev)
>   	return devm_rtc_register_device(rtc->rtc_dev);
>   }
>   
> +static void mtk_rtc_shutdown(struct platform_device *pdev)
> +{
> +	struct mt6397_rtc *rtc = platform_get_drvdata(pdev);
> +
> +	if (rtc->alarm_sta_supported)
> +		mtk_rtc_reset_bbpu_alarm_status(rtc);
> +}
> +
>   #ifdef CONFIG_PM_SLEEP
>   static int mt6397_rtc_suspend(struct device *dev)
>   {
> @@ -346,6 +375,7 @@ static struct platform_driver mtk_rtc_driver = {
>   		.pm = &mt6397_pm_ops,
>   	},
>   	.probe = mtk_rtc_probe,
> +	.shutdown = mtk_rtc_shutdown,
>   };
>   
>   module_platform_driver(mtk_rtc_driver);