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From: Andre Przywara <andre.przywara@arm.com>
To: Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Rob Herring <robh@kernel.org>, Icenowy Zheng <icenowy@aosc.io>,
	Samuel Holland <samuel@sholland.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-sunxi@googlegroups.com, linux-sunxi@lists.linux.dev,
	linux-kernel@vger.kernel.org, Ondrej Jirman <megous@megous.com>,
	Alessandro Zummo <a.zummo@towertech.it>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	linux-rtc@vger.kernel.org
Subject: [PATCH v9 03/11] rtc: sun6i: Fix time overflow handling
Date: Mon,  2 Aug 2021 01:39:44 +0100	[thread overview]
Message-ID: <20210802003952.19942-4-andre.przywara@arm.com> (raw)
In-Reply-To: <20210802003952.19942-1-andre.przywara@arm.com>

Using "unsigned long" for UNIX timestamps is never a good idea, and
comparing the value of such a variable against U32_MAX does not do
anything useful on 32-bit systems.

Use the proper time64_t type when dealing with timestamps, and avoid
cutting down the time range unnecessarily. This also fixes the flawed
check for the alarm time being too far into the future.

The check for this condition is actually somewhat theoretical, as the
RTC counts till 2033 only anyways, and 2^32 seconds from now is not
before the year 2157 - at which point I hope nobody will be using this
hardware anymore.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
---
 drivers/rtc/rtc-sun6i.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index adec1b14a8de..c551ebf0ac00 100644
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -138,7 +138,7 @@ struct sun6i_rtc_dev {
 	const struct sun6i_rtc_clk_data *data;
 	void __iomem *base;
 	int irq;
-	unsigned long alarm;
+	time64_t alarm;
 
 	struct clk_hw hw;
 	struct clk_hw *int_osc;
@@ -510,10 +510,8 @@ 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;
-	unsigned long time_now = 0;
-	unsigned long time_set = 0;
-	unsigned long time_gap = 0;
-	int ret = 0;
+	time64_t time_now, time_set;
+	int ret;
 
 	ret = sun6i_rtc_gettime(dev, &tm_now);
 	if (ret < 0) {
@@ -528,9 +526,7 @@ static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 		return -EINVAL;
 	}
 
-	time_gap = time_set - time_now;
-
-	if (time_gap > U32_MAX) {
+	if ((time_set - time_now) > U32_MAX) {
 		dev_err(dev, "Date too far in the future\n");
 		return -EINVAL;
 	}
@@ -539,7 +535,7 @@ static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
 	writel(0, chip->base + SUN6I_ALRM_COUNTER);
 	usleep_range(100, 300);
 
-	writel(time_gap, chip->base + SUN6I_ALRM_COUNTER);
+	writel(time_set - time_now, chip->base + SUN6I_ALRM_COUNTER);
 	chip->alarm = time_set;
 
 	sun6i_rtc_setaie(wkalrm->enabled, chip);
-- 
2.17.6


  parent reply	other threads:[~2021-08-02  0:40 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02  0:39 [PATCH v9 00/11] arm64: sunxi: Initial Allwinner H616 SoC support Andre Przywara
2021-08-02  0:39 ` [PATCH v9 01/11] dt-bindings: mfd: axp20x: Add AXP305 compatible (plus optional IRQ) Andre Przywara
2021-08-02  7:40   ` Lee Jones
2021-08-02  0:39 ` [PATCH v9 02/11] dt-bindings: rtc: sun6i: Add H616 compatible string Andre Przywara
2021-08-18  8:15   ` Maxime Ripard
2021-08-02  0:39 ` Andre Przywara [this message]
2021-08-02  0:39 ` [PATCH v9 04/11] rtc: sun6i: Add support for linear day storage Andre Przywara
2021-08-02  0:39 ` [PATCH v9 05/11] rtc: sun6i: Add support for broken-down alarm registers Andre Przywara
2021-08-02  0:39 ` [PATCH v9 06/11] rtc: sun6i: Add support for RTCs without external LOSCs Andre Przywara
2021-08-02  0:39 ` [PATCH v9 07/11] rtc: sun6i: Add Allwinner H616 support Andre Przywara
2021-08-02  0:39 ` [PATCH v9 08/11] arm64: dts: allwinner: Add Allwinner H616 .dtsi file Andre Przywara
2021-09-11  4:13   ` Samuel Holland
2021-08-02  0:39 ` [PATCH v9 09/11] dt-bindings: arm: sunxi: Add two H616 board compatible strings Andre Przywara
2021-08-02  0:39 ` [PATCH v9 10/11] arm64: dts: allwinner: h616: Add OrangePi Zero 2 board support Andre Przywara
2021-08-02  0:39 ` [PATCH v9 11/11] arm64: dts: allwinner: h616: Add X96 Mate TV box support Andre Przywara

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