kernel/linux.git/drivers/rtc/rtc-ds1307.c, branch v6.6.148

rtc: ds1307: Fix off-by-one issue with wday for rx8130

2026-07-24T14:03:23+00:00

[ Upstream commit 6882aab3c66112b33b251be95c09c8ead3e8d580 ] The RTC represent each weekday with a individual bit set in the WDAY register, where the 0th bit represent the first day of the week and the 6th bit represents the last day of the week. For each passed day the chip performs a rotary-left-shift by one to advance the weekday by one. The tm_wday field represent weekdays by a value in the range of 0-6. The fls() function return the bit index of the last bit set. To handle when there are no bits set it will return 0, and if the 0th bit is set it will return 1, and if the 1st bit is set it will return 2, and so on. In order to make the result of the fls() function fall into the expected range of 0-6 (instead of 1-7) this patch subtracts one from the result (which matches how the value is written in ds1307_set_time()). Fixes: 204756f016726 ("rtc: ds1307: Fix wday settings for rx8130") Reviewed-by: Nobuhiro Iwamatsu Signed-off-by: Fredrik M Olsson Link: https://patch.msgid.link/20260520-ds1307-rx8901-add-v2-2-e069ea32e1db@axis.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: handle oscillator stop flag for ds1337/ds1339/ds3231

2026-07-24T14:03:21+00:00

[ Upstream commit a091e1ba3b68cabc9caedafc6f81d9fe9b3b2200 ] Prior to commit 48458654659c ("rtc: ds1307: remove clear of oscillator stop flag (OSF) in probe"), the oscillator stop flag (OSF) bit was checked during device probe for the ds1337, ds1339, ds1341, and ds3231 chips; if it was set, it would be cleared and a warning would be logged saying "SET TIME!". Since that commit, the OSF bit is no longer cleared, but the warning is still printed. Directly following that commit, there was no way to get rid of this warning because nothing cleared the OSF bit on these chips. The commit associated with the previous commit, 523923cfd5d6 ("rtc: ds1307: handle oscillator stop flag (OSF) for ds1341"), made proper use of the OSF when getting and setting the time in the RTC. However, the other RTC variants ds1337, ds1339 and ds3231 didn't have a corresponding change made. Given that the OSF bit is no longer cleared at probe time when it is set, the remaining three chips should have the same handling as the ds1341 chip has for the OSF bit. Fix the issue on the ds1337, ds1339 and ds3231 chips by applying the same logic as the ds1341 has to these chips. Note that any devices brought up between the first referenced commit and this one may begin mistrusting the time reported by the RTC until it is set again, if the bit was never explicitly cleared. Note that only the ds1339 was tested with this change, but the datasheets for the other chips contain essentially identical descriptions of the OSF bit so the same change should work. Signed-off-by: Ronan Dalton Cc: linux-rtc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Alexandre Belloni Cc: Tyler Hicks Cc: Sasha Levin Cc: Meagan Lloyd Cc: Rodolfo Giometti Cc: Chris Packham Fixes: 48458654659c ("rtc: ds1307: remove clear of oscillator stop flag (OSF) in probe") Reviewed-by: Meagan Lloyd Reviewed-by: Tyler Hicks Link: https://patch.msgid.link/20260508032518.3696705-2-ronan.dalton@alliedtelesis.co.nz Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: remove clear of oscillator stop flag (OSF) in probe

2025-08-28T14:28:30+00:00

[ Upstream commit 48458654659c9c2e149c211d86637f1592470da5 ] In using CONFIG_RTC_HCTOSYS, rtc_hctosys() will sync the RTC time to the kernel time as long as rtc_read_time() succeeds. In some power loss situations, our supercapacitor-backed DS1342 RTC comes up with either an unpredictable future time or the default 01/01/00 from the datasheet. The oscillator stop flag (OSF) is set in these scenarios due to the power loss and can be used to determine the validity of the RTC data. Some chip types in the ds1307 driver already have OSF handling to determine whether .read_time provides valid RTC data or returns -EINVAL. This change removes the clear of the OSF in .probe as the OSF needs to be preserved to expand the OSF handling to the ds1341 chip type (note that DS1341 and DS1342 share a datasheet). Signed-off-by: Meagan Lloyd Reviewed-by: Tyler Hicks Acked-by: Rodolfo Giometti Link: https://lore.kernel.org/r/1749665656-30108-2-git-send-email-meaganlloyd@linux.microsoft.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: handle oscillator stop flag (OSF) for ds1341

2025-08-28T14:28:28+00:00

[ Upstream commit 523923cfd5d622b8f4ba893fdaf29fa6adeb8c3e ] In using CONFIG_RTC_HCTOSYS, rtc_hctosys() will sync the RTC time to the kernel time as long as rtc_read_time() succeeds. In some power loss situations, our supercapacitor-backed DS1342 RTC comes up with either an unpredictable future time or the default 01/01/00 from the datasheet. The oscillator stop flag (OSF) is set in these scenarios due to the power loss and can be used to determine the validity of the RTC data. This change expands the oscillator stop flag (OSF) handling that has already been implemented for some chips to the ds1341 chip (DS1341 and DS1342 share a datasheet). This handling manages the validity of the RTC data in .read_time and .set_time based on the OSF. Signed-off-by: Meagan Lloyd Reviewed-by: Tyler Hicks Acked-by: Rodolfo Giometti Link: https://lore.kernel.org/r/1749665656-30108-3-git-send-email-meaganlloyd@linux.microsoft.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: fix incorrect maximum clock rate handling

2025-08-15T10:08:57+00:00

[ Upstream commit cf6eb547a24af7ad7bbd2abe9c5327f956bbeae8 ] When ds3231_clk_sqw_round_rate() is called with a requested rate higher than the highest supported rate, it currently returns 0, which disables the clock. According to the clk API, round_rate() should instead return the highest supported rate. Update the function to return the maximum supported rate in this case. Fixes: 6c6ff145b3346 ("rtc: ds1307: add clock provider support for DS3231") Signed-off-by: Brian Masney Link: https://lore.kernel.org/r/20250710-rtc-clk-round-rate-v1-1-33140bb2278e@redhat.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: stop disabling alarms on probe

2025-06-04T12:42:01+00:00

[ Upstream commit dcec12617ee61beed928e889607bf37e145bf86b ] It is a bad practice to disable alarms on probe or remove as this will prevent alarms across reboots. Link: https://lore.kernel.org/r/20250303223744.1135672-1-alexandre.belloni@bootlin.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: fix Wvoid-pointer-to-enum-cast warning

2023-08-15T23:32:08+00:00

'type' is an enum, thus cast of pointer on 64-bit compile test with W=1 causes: rtc-ds1307.c:1747:18: error: cast to smaller integer type 'enum ds_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast] Signed-off-by: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20230810103902.151145-1-krzysztof.kozlowski@linaro.org Signed-off-by: Alexandre Belloni

rtc: Switch i2c drivers back to use .probe()

2023-06-06T21:29:37+00:00

After commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new() call-back type"), all drivers being converted to .probe_new() and then 03c835f498b5 ("i2c: Switch .probe() to not take an id parameter") convert back to (the new) .probe() to be able to eventually drop .probe_new() from struct i2c_driver. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20230505121136.1185653-1-u.kleine-koenig@pengutronix.de Signed-off-by: Alexandre Belloni

rtc: ds1307: Convert to i2c's .probe_new()

2023-01-09T22:03:56+00:00

.probe_new() doesn't get the i2c_device_id * parameter, so determine that explicitly in the probe function. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20221118224540.619276-561-uwe@kleine-koenig.org Signed-off-by: Alexandre Belloni

rtc: ds1307: use sysfs_emit() to instead of scnprintf()

2022-12-15T22:34:31+00:00

Follow the advice of the Documentation/filesystems/sysfs.rst and show() should only use sysfs_emit() or sysfs_emit_at() when formatting the value to be returned to user space. Signed-off-by: ye xingchen Link: https://lore.kernel.org/r/202212051134455911470@zte.com.cn Signed-off-by: Alexandre Belloni