linux-kernel - Re: [PATCH v8 05/11] rtc: sun6i: Add support for broken-down alarm registers

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

Message-ID: <35374855.gLGPhMbAMS@kista>
Date:   Sun, 25 Jul 2021 08:11:49 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Andre Przywara <andre.przywara@....com>
Cc:     Rob Herring <robh@...nel.org>, Icenowy Zheng <icenowy@...c.io>,
        Samuel Holland <samuel@...lland.org>,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...glegroups.com,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Ondrej Jirman <megous@...ous.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        linux-rtc@...r.kernel.org
Subject: Re: [PATCH v8 05/11] rtc: sun6i: Add support for broken-down alarm registers

Hi Andre!

Dne petek, 23. julij 2021 ob 17:38:32 CEST je Andre Przywara napisal(a):
> Newer versions of the Allwinner RTC, for instance as found in the H616
> SoC, not only store the current day as a linear number, but also change
> the way the alarm is handled: There are now two registers, that
> explicitly store the wakeup time, in the same format as the current
> time.
> 
> Add support for that variant by writing the requested wakeup time
> directly into the registers, instead of programming the seconds left, as
> the old SoCs required.
> 
> Signed-off-by: Andre Przywara <andre.przywara@....com>
> ---
>  drivers/rtc/rtc-sun6i.c | 60 +++++++++++++++++++++++++++++------------
>  1 file changed, 43 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> index a02be8bca6f3..f0ee20bfdccb 100644
> --- a/drivers/rtc/rtc-sun6i.c
> +++ b/drivers/rtc/rtc-sun6i.c
> @@ -48,7 +48,8 @@
>  
>  /* Alarm 0 (counter) */
>  #define SUN6I_ALRM_COUNTER			0x0020
> -#define SUN6I_ALRM_CUR_VAL			0x0024
> +/* This holds the remaining alarm seconds on older SoCs (current value) */
> +#define SUN6I_ALRM_COUNTER_HMS			0x0024
>  #define SUN6I_ALRM_EN				0x0028
>  #define SUN6I_ALRM_EN_CNT_EN			BIT(0)
>  #define SUN6I_ALRM_IRQ_EN			0x002c
> @@ -523,32 +524,57 @@ static int sun6i_rtc_setalarm(struct device *dev, 
struct rtc_wkalrm *wkalrm)
>  	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
>  	struct rtc_time *alrm_tm = &wkalrm->time;
>  	struct rtc_time tm_now;
> -	time64_t time_now, time_set;
> +	time64_t time_set;
> +	u32 counter_val, counter_val_hms;
>  	int ret;
>  
> -	ret = sun6i_rtc_gettime(dev, &tm_now);
> -	if (ret < 0) {
> -		dev_err(dev, "Error in getting time\n");
> -		return -EINVAL;
> -	}
> -
>  	time_set = rtc_tm_to_time64(alrm_tm);
> -	time_now = rtc_tm_to_time64(&tm_now);
> -	if (time_set <= time_now) {
> -		dev_err(dev, "Date to set in the past\n");
> -		return -EINVAL;
> -	}
>  
> -	if ((time_set - time_now) > U32_MAX) {
> -		dev_err(dev, "Date too far in the future\n");
> -		return -EINVAL;
> +	if (chip->flags & RTC_LINEAR_DAY) {
> +		time64_t seconds;
> +
> +		/*
> +		 * The alarm registers hold the actual alarm time, 
encoded
> +		 * in the same way (linear day + HMS) as the current 
time.
> +		 */
> +		counter_val_hms = SUN6I_TIME_SET_SEC_VALUE(alrm_tm-
>tm_sec)  |
> +				  
SUN6I_TIME_SET_MIN_VALUE(alrm_tm->tm_min)  |
> +				  
SUN6I_TIME_SET_HOUR_VALUE(alrm_tm->tm_hour);
> +		seconds = mktime64(alrm_tm->tm_year + 1900, alrm_tm-
>tm_mon,
> +				   alrm_tm->tm_mday, 0, 0, 0);

While above line should work, it's confusing why you're adding 1900 to years. 
In my opinion it would be better to use same trick you used in patch 4 - 
rtc_tm_to_time64() with hours, minutes and seconds set to 0. Or maybe you 
don't even need to do that, since division by SECS_PER_DAY will round down 
anyway. In such way you hide RTC internal representation detail which doesn't 
need to be exposed here.

Once fixed:
Reviewed by: Jernej Skrabec <jernej.skrabec@...il.com>

Best regards,
Jernej

> +		counter_val = div_u64(seconds, SECS_PER_DAY);
> +	} else {
> +		/* The alarm register holds the number of seconds left. 
*/
> +		time64_t time_now;
> +
> +		ret = sun6i_rtc_gettime(dev, &tm_now);
> +		if (ret < 0) {
> +			dev_err(dev, "Error in getting time\n");
> +			return -EINVAL;
> +		}
> +
> +		time_now = rtc_tm_to_time64(&tm_now);
> +		if (time_set <= time_now) {
> +			dev_err(dev, "Date to set in the past\n");
> +			return -EINVAL;
> +		}
> +		if ((time_set - time_now) > U32_MAX) {
> +			dev_err(dev, "Date too far in the future\n");
> +			return -EINVAL;
> +		}
> +
> +		counter_val = time_set - time_now;
>  	}
>  
>  	sun6i_rtc_setaie(0, chip);
>  	writel(0, chip->base + SUN6I_ALRM_COUNTER);
> +	if (chip->flags & RTC_LINEAR_DAY)
> +		writel(0, chip->base + SUN6I_ALRM_COUNTER_HMS);
>  	usleep_range(100, 300);
>  
> -	writel(time_set - time_now, chip->base + SUN6I_ALRM_COUNTER);
> +	writel(counter_val, chip->base + SUN6I_ALRM_COUNTER);
> +	if (chip->flags & RTC_LINEAR_DAY)
> +		writel(counter_val_hms, chip->base + 
SUN6I_ALRM_COUNTER_HMS);
>  	chip->alarm = time_set;
>  
>  	sun6i_rtc_setaie(wkalrm->enabled, chip);
> -- 
> 2.17.6
> 
>