kernel/linux.git/drivers/rtc/rtc-cmos.c, branch v6.18.40

rtc: cmos: unregister HPET IRQ handler on probe failure

2026-07-24T14:16:39+00:00

[ Upstream commit a5bb580df018b5d1c5668f05f7979044fb19e23a ] cmos_do_probe() registers cmos_interrupt() as the HPET RTC IRQ handler before requesting the RTC IRQ and registering the RTC device. If either request_irq() or devm_rtc_register_device() fails afterwards, the error path leaves the HPET RTC IRQ handler installed. This leaves a stale handler behind and make a later hpet_register_irq_handler() fail with -EBUSY. Track whether the HPET handler was registered successfully and undo the registration on the probe error path. Also mask the HPET RTC IRQ bits to match the normal shutdown cleanup. Fixes: 9d8af78b0797 ("rtc: add HPET RTC emulation to RTC_DRV_CMOS") Signed-off-by: Haoxiang Li Link: https://patch.msgid.link/20260623100848.2127281-1-haoxiang_li2024@163.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: cmos: use spin_lock_irqsave in cmos_interrupt

2025-06-23T22:27:51+00:00

cmos_interrupt() can be called in a non-interrupt context, such as in an ACPI event handler (which runs in an interrupt thread). Therefore, usage of spin_lock(&rtc_lock) is insecure. Use spin_lock_irqsave() / spin_unlock_irqrestore() instead. Before a misguided commit 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ") the cmos_interrupt() function used spin_lock_irqsave(). That commit changed it to spin_lock() and broke locking, which was partially fixed in commit 13be2efc390a ("rtc: cmos: Disable irq around direct invocation of cmos_interrupt()") That second commit did not take account of the ACPI fixed event handler pathway, however. It introduced local_irq_disable() workarounds in cmos_check_wkalrm(), which can cause problems on PREEMPT_RT kernels and are now unnecessary. Add an explicit comment so that this change will not be reverted by mistake. Cc: stable@vger.kernel.org Fixes: 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ") Signed-off-by: Mateusz Jończyk Reviewed-by: Sebastian Andrzej Siewior Tested-by: Chris Bainbridge Reported-by: Chris Bainbridge Closes: https://lore.kernel.org/all/aDtJ92foPUYmGheF@debian.local/ Link: https://lore.kernel.org/r/20250607210608.14835-1-mat.jonczyk@o2.pl Signed-off-by: Alexandre Belloni

rtc: Remove hpet_rtc_dropped_irq()

2025-01-13T22:07:18+00:00

hpet_rtc_dropped_irq() has been unused since commit f52ef24be21a ("rtc/alpha: remove legacy rtc driver") Remove it in rtc, and x86 hpet code. Signed-off-by: Dr. David Alan Gilbert Acked-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20241215022356.181625-1-linux@treblig.org Signed-off-by: Alexandre Belloni

rtc: use boolean values with device_init_wakeup()

2025-01-09T17:29:24+00:00

device_init_wakeup() second argument is a bool type. Use proper boolean values when calling it to match the type and to produce unambiguous code which is easier to understand. Signed-off-by: Wolfram Sang Reviewed-by: Charles Keepax Reviewed-by: Andre Przywara Link: https://lore.kernel.org/r/20241217071331.3607-2-wsa+renesas@sang-engineering.com Signed-off-by: Alexandre Belloni

rtc: Switch back to struct platform_driver::remove()

2024-11-10T21:58:28+00:00

After commit 0edb555a65d1 ("platform: Make platform_driver::remove() return void") .remove() is (again) the right callback to implement for platform drivers. Convert all platform drivers below drivers/rtc to use .remove(), with the eventual goal to drop struct platform_driver::remove_new(). As .remove() and .remove_new() have the same prototypes, conversion is done by just changing the structure member name in the driver initializer. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20241007205803.444994-6-u.kleine-koenig@baylibre.com Signed-off-by: Alexandre Belloni

rtc: cmos: avoid taking rtc_lock for extended period of time

2024-10-31T23:19:22+00:00

On my device reading entirety of /sys/devices/pnp0/00:03/cmos_nvram0/nvmem takes about 9 msec during which time interrupts are off on the CPU that does the read and the thread that performs the read can not be migrated or preempted by another higher priority thread (RT or not). Allow readers and writers be preempted by taking and releasing rtc_lock spinlock for each individual byte read or written rather than once per read/write request. Signed-off-by: Dmitry Torokhov Reviewed-by: Mateusz Jończyk Link: https://lore.kernel.org/r/Zxv8QWR21AV4ztC5@google.com Signed-off-by: Alexandre Belloni

rtc: cmos: Fix return value of nvmem callbacks

2024-06-27T22:21:06+00:00

Read/write callbacks registered with nvmem core expect 0 to be returned on success and a negative value to be returned on failure. cmos_nvram_read()/cmos_nvram_write() currently return the number of bytes read or written, fix to return 0 on success and -EIO incase number of bytes requested was not read or written. Fixes: 8b5b7958fd1c ("rtc: cmos: use generic nvmem") Cc: stable@vger.kernel.org Signed-off-by: Joy Chakraborty Reviewed-by: Dan Carpenter Link: https://lore.kernel.org/r/20240612083635.1253039-1-joychakr@google.com Signed-off-by: Alexandre Belloni

rtc: Extend timeout for waiting for UIP to clear to 1s

2023-12-17T21:33:55+00:00

Specs don't say anything about UIP being cleared within 10ms. They only say that UIP won't occur for another 244uS. If a long NMI occurs while UIP is still updating it might not be possible to get valid data in 10ms. This has been observed in the wild that around s2idle some calls can take up to 480ms before UIP is clear. Adjust callers from outside an interrupt context to wait for up to a 1s instead of 10ms. Cc: # 6.1.y Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP") Reported-by: Carsten Hatger Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217626 Tested-by: Mateusz Jończyk Reviewed-by: Mateusz Jończyk Acked-by: Mateusz Jończyk Signed-off-by: Mario Limonciello Link: https://lore.kernel.org/r/20231128053653.101798-5-mario.limonciello@amd.com Signed-off-by: Alexandre Belloni

rtc: Add support for configuring the UIP timeout for RTC reads

2023-12-17T21:33:55+00:00

The UIP timeout is hardcoded to 10ms for all RTC reads, but in some contexts this might not be enough time. Add a timeout parameter to mc146818_get_time() and mc146818_get_time_callback(). If UIP timeout is configured by caller to be >=100 ms and a call takes this long, log a warning. Make all callers use 10ms to ensure no functional changes. Cc: # 6.1.y Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP") Signed-off-by: Mario Limonciello Tested-by: Mateusz Jończyk Reviewed-by: Mateusz Jończyk Acked-by: Mateusz Jończyk Link: https://lore.kernel.org/r/20231128053653.101798-4-mario.limonciello@amd.com Signed-off-by: Alexandre Belloni

rtc: Adjust failure return code for cmos_set_alarm()

2023-12-17T21:33:54+00:00

When mc146818_avoid_UIP() fails to return a valid value, this is because UIP didn't clear in the timeout period. Adjust the return code in this case to -ETIMEDOUT. Tested-by: Mateusz Jończyk Reviewed-by: Mateusz Jończyk Acked-by: Mateusz Jończyk Cc: Fixes: cdedc45c579f ("rtc: cmos: avoid UIP when reading alarm time") Fixes: cd17420ebea5 ("rtc: cmos: avoid UIP when writing alarm time") Signed-off-by: Mario Limonciello Link: https://lore.kernel.org/r/20231128053653.101798-3-mario.limonciello@amd.com Signed-off-by: Alexandre Belloni