From mboxrd@z Thu Jan  1 00:00:00 1970
From: baruch@tkos.co.il (Baruch Siach)
Date: Tue, 18 Feb 2014 15:34:42 +0200
Subject: [PATCH] rtc: mv: reset date if after year 2038
In-Reply-To: <1392729966-25394-1-git-send-email-thomas.petazzoni@free-electrons.com>
References: <1392729966-25394-1-git-send-email-thomas.petazzoni@free-electrons.com>
Message-ID: <20140218133442.GW4168@tarshish>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Thomas,

On Tue, Feb 18, 2014 at 02:26:06PM +0100, Thomas Petazzoni wrote:
> Dates after January, 19th 2038 are badly handled by userspace due to
> the time being stored on 32 bits. This causes issues on some Marvell
> platform on which the RTC is initialized by default to a date that's
> beyond 2038, causing a really weird behavior of the RTC.
> 
> In order to avoid that, reset the date to a sane value if the RTC is
> beyond 2038.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> ---
>  drivers/rtc/rtc-mv.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
> index d536c59..f124dc6 100644
> --- a/drivers/rtc/rtc-mv.c
> +++ b/drivers/rtc/rtc-mv.c
> @@ -222,6 +222,7 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
>  	struct resource *res;
>  	struct rtc_plat_data *pdata;
>  	u32 rtc_time;
> +	u32 rtc_date;
>  	int ret = 0;
>  
>  	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> @@ -257,6 +258,17 @@ static int __init mv_rtc_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	/*
> +	 * A date after January 19th, 2038 does not fit on 32 bits and
> +	 * will confuse the kernel and userspace. Reset to a sane date
> +	 * (January 1st, 2013) if we're after 2038.
> +	 */
> +	rtc_date = readl(pdata->ioaddr + RTC_DATE_REG_OFFS);
> +	if (bcd2bin((rtc_date >> RTC_YEAR_OFFS) & 0xff) >= 38) {
> +		dev_info(&pdev->dev, "invalid RTC date, resetting to January, 1st 2013\n");

Misplaced comma?

> +		writel(0x130101, pdata->ioaddr + RTC_DATE_REG_OFFS);
> +	}
> +
>  	pdata->irq = platform_get_irq(pdev, 0);
>  
>  	platform_set_drvdata(pdev, pdata);
> -- 
> 1.8.3.2

baruch

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