kernel/linux.git/drivers/rtc/rtc-ds1307.c, branch v6.12.80

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

2025-08-20T16:30:50+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

2025-08-20T16:30:46+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

2025-08-15T10:13:59+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

2025-05-29T09:02:27+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: Clamp year to valid BCD (0-99) in `set_time()`

2024-07-06T22:39:27+00:00

`tm_year` may go up to 299 if the device supports the century bit. Therefore, subtracting may not give us a valid 2-digit number, but modulo does. Co-developed-by: Szentendrei, Tamás Signed-off-by: Szentendrei, Tamás Signed-off-by: Csókás, Bence Link: https://lore.kernel.org/r/20240611072411.671600-2-csokas.bence@prolan.hu Signed-off-by: Alexandre Belloni

rtc: ds1307: Detect oscillator fail on mcp794xx

2024-07-06T22:39:15+00:00

This patch enables the detection of the oscillator failure on mcp794xx chips. Co-developed-by: Szentendrei, Tamás Signed-off-by: Szentendrei, Tamás Signed-off-by: Csókás, Bence Link: https://lore.kernel.org/r/20240611072411.671600-1-csokas.bence@prolan.hu Signed-off-by: Alexandre Belloni

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