kernel/linux.git/drivers/rtc/class.c, branch v5.10.258

rtc: introduce features bitfield

2026-06-01T15:29:41+00:00

[ Upstream commit 7ae41220ef5831674f446baef19bfe1b31358260 ] Introduce a bitfield to allow the drivers to announce the available features for an RTC. The main use case would be to better handle alarms, that could be present or not or have a minute resolution or may need a correct week day to be set. Use the newly introduced RTC_FEATURE_ALARM bit to then test whether alarms are available instead of relying on the presence of ops->set_alarm. Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20210110231752.1418816-2-alexandre.belloni@bootlin.com Stable-dep-of: 0fedce7244e4 ("rtc: abx80x: Disable alarm feature if no interrupt attached") Signed-off-by: Sasha Levin

rtc: Fix offset calculation for .start_secs < 0

2025-06-27T10:04:06+00:00

[ Upstream commit fe9f5f96cfe8b82d0f24cbfa93718925560f4f8d ] The comparison rtc->start_secs > rtc->range_max has a signed left-hand side and an unsigned right-hand side. So the comparison might become true for negative start_secs which is interpreted as a (possibly very large) positive value. As a negative value can never be bigger than an unsigned value the correct representation of the (mathematical) comparison rtc->start_secs > rtc->range_max in C is: rtc->start_secs >= 0 && rtc->start_secs > rtc->range_max Use that to fix the offset calculation currently used in the rtc-mt6397 driver. Fixes: 989515647e783 ("rtc: Add one offset seconds to expand RTC range") Signed-off-by: Alexandre Mergnat Reviewed-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20250428-enable-rtc-v4-2-2b2f7e3f9349@baylibre.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: fix use-after-free on device removal

2022-05-25T07:17:52+00:00

[ Upstream commit c8fa17d9f08a448184f03d352145099b5beb618e ] If the irqwork is still scheduled or running while the RTC device is removed, a use-after-free occurs in rtc_timer_do_work(). Cleanup the timerqueue and ensure the work is stopped to fix this. BUG: KASAN: use-after-free in mutex_lock+0x94/0x110 Write of size 8 at addr ffffff801d846338 by task kworker/3:1/41 Workqueue: events rtc_timer_do_work Call trace: mutex_lock+0x94/0x110 rtc_timer_do_work+0xec/0x630 process_one_work+0x5fc/0x1344 ... Allocated by task 551: kmem_cache_alloc_trace+0x384/0x6e0 devm_rtc_allocate_device+0xf0/0x574 devm_rtc_device_register+0x2c/0x12c ... Freed by task 572: kfree+0x114/0x4d0 rtc_device_release+0x64/0x80 device_release+0x8c/0x1f4 kobject_put+0x1c4/0x4b0 put_device+0x20/0x30 devm_rtc_release_device+0x1c/0x30 devm_action_release+0x54/0x90 release_nodes+0x124/0x310 devres_release_group+0x170/0x240 i2c_device_remove+0xd8/0x314 ... Last potentially related work creation: insert_work+0x5c/0x330 queue_work_on+0xcc/0x154 rtc_set_time+0x188/0x5bc rtc_dev_ioctl+0x2ac/0xbd0 ... Signed-off-by: Vincent Whitchurch Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20211210160951.7718-1-vincent.whitchurch@axis.com Signed-off-by: Sasha Levin

rtc: class: remove redundant assignment to variable err

2020-04-02T16:47:30+00:00

The variable err is being initialized with a value that is never read and it is being updated later with a new value. The initialization is redundant and can be removed. Addresses-Coverity: ("Unused value") Signed-off-by: Colin Ian King Link: https://lore.kernel.org/r/20200402110411.508534-1-colin.king@canonical.com Signed-off-by: Alexandre Belloni

rtc: class: avoid unnecessary lookup in hctosys

2020-03-24T21:48:04+00:00

rtc_hctosys is only called when the relevant RTC is found, avoid looking it up while we already have a pinter to the proper struct rtc_device. Link: https://lore.kernel.org/r/20200323213039.297458-1-alexandre.belloni@bootlin.com Signed-off-by: Alexandre Belloni

rtc: class: support hctosys from modular RTC drivers

2020-03-23T20:14:34+00:00

Due to distribution constraints it may not be possible to statically compile the required RTC driver into the kernel. Expand RTC_HCTOSYS support to cover all RTC devices (statically compiled or not) by checking at the end of RTC device registration whether the time should be synced. Signed-off-by: Steve Muckle Link: https://lore.kernel.org/r/20191106194625.116692-1-smuckle@google.com Signed-off-by: Alexandre Belloni

rtc: class: add debug message when registration fails

2019-08-20T19:44:45+00:00

Add a message when __rtc_register_device fails because rtc->ops is NULL. This may only happen when developing a new driver so use dev_dbg to avoid compiling it in by default. Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20190818220041.17833-1-alexandre.belloni@bootlin.com Signed-off-by: Alexandre Belloni

rtc: core: correct trivial checkpatch warnings

2019-04-04T08:07:08+00:00

Correct trivial checkpatch warnings, mostly whitespace issues and unbalanced braces. Signed-off-by: Alexandre Belloni

rtc: convert core to SPDX identifier

2019-03-18T02:36:01+00:00

Use SPDX-License-Identifier instead of a verbose license text. Also fix the block comment alignment. Signed-off-by: Alexandre Belloni

rtc: class: reimplement devm_rtc_device_register

2018-12-18T21:53:32+00:00

Implement devm_rtc_device_register using devm_rtc_allocate_device and __rtc_register_device so there is only one path left to register rtc devices. Also mark it as deprecated so new drivers will hopefully use devm_rtc_allocate_device and rtc_register_device that are less race prone and allow avoiding the 2038, 2070, 2100 and 2106 bugs properly. Signed-off-by: Alexandre Belloni