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rtc: ds1685: arm the wake-up alarm at power-off only if an alarm is set

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ds1685_rtc_poweroff() always sets WIE. The wake-up alarm then compares
the time-of-day and date alarm registers, which hold whatever was last
written to them, and a match powers the machine straight back on.

Set WIE only when AIE is set in Control B, and clear it otherwise.

Fixes: aaaf5fbf56 ("rtc: add driver for DS1685 family of real time clocks")
Signed-off-by: Imre Kaloz <kaloz@kernel.org>
Acked-by: Joshua Kinard <linux@kumba.dev>
Link: https://patch.msgid.link/20261013120208.11268-2-kaloz@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Imre Kaloz 2026-10-13 14:02:06 +02:00 committed by Alexandre Belloni
parent 55bb587749
commit c2373bcd50
1 changed files with 12 additions and 6 deletions
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18
drivers/rtc/rtc-ds1685.c
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@ -1366,7 +1366,7 @@ module_platform_driver(ds1685_rtc_driver);
void __noreturn
ds1685_rtc_poweroff(struct platform_device *pdev)
{
u8 ctrla, ctrl4a, ctrl4b;
u8 ctrla, ctrlb, ctrl4a, ctrl4b;
struct ds1685_priv *rtc;
/* Check for valid RTC data, else, spin forever. */
@ -1393,6 +1393,8 @@ ds1685_rtc_poweroff(struct platform_device *pdev)
ctrla &= ~(RTC_CTRL_A_DV2);
rtc->write(rtc, RTC_CTRL_A, ctrla);
ctrlb = rtc->read(rtc, RTC_CTRL_B);
/*
* Read Control 4A and check the status of the auxillary
* battery. This must be present and working (VRT2 = 1)
@ -1407,13 +1409,17 @@ ds1685_rtc_poweroff(struct platform_device *pdev)
/*
* The auxillary battery is present and working.
* Enable extended functions (ABE=1), enable
* wake-up (WIE=1), and enable kickstart (KSE=1)
* in Control 4B.
* Enable extended functions (ABE=1) and kickstart
* (KSE=1) in Control 4B. Enable wake-up (WIE=1) only
* if an alarm is set, else stale alarm registers
* can power the system back on.
*/
ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
ctrl4b |= (RTC_CTRL_4B_ABE | RTC_CTRL_4B_WIE |
RTC_CTRL_4B_KSE);
ctrl4b |= (RTC_CTRL_4B_ABE | RTC_CTRL_4B_KSE);
if (ctrlb & RTC_CTRL_B_AIE)
ctrl4b |= RTC_CTRL_4B_WIE;
else
ctrl4b &= ~(RTC_CTRL_4B_WIE);
rtc->write(rtc, RTC_EXT_CTRL_4B, ctrl4b);
}