linux-stable.git/drivers/rtc/Makefile, branch linux-5.4.y Linux kernel stable tree rtc: Improve performance of rtc_time64_to_tm(). Add tests. 2025-06-27T10:02:58+00:00 Cassio Neri cassio.neri@gmail.com 2021-06-24T20:13:43+00:00 31d87dda792b819daf028488dcb4dd3206c2a9cd commit 1d1bb12a8b1805ddeef9793ebeb920179fb0fa38 upstream. The current implementation of rtc_time64_to_tm() contains unnecessary loops, branches and look-up tables. The new one uses an arithmetic-based algorithm appeared in [1] and is approximately 4.3 times faster (YMMV). The drawback is that the new code isn't intuitive and contains many 'magic numbers' (not unusual for this type of algorithm). However, [1] justifies all those numbers and, given this function's history, the code is unlikely to need much maintenance, if any at all. Add a KUnit test case that checks every day in a 160,000 years interval starting on 1970-01-01 against the expected result. Add a new config RTC_LIB_KUNIT_TEST symbol to give the option to run this test suite. [1] Neri, Schneider, "Euclidean Affine Functions and Applications to Calendar Algorithms". https://arxiv.org/abs/2102.06959 Signed-off-by: Cassio Neri <cassio.neri@gmail.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Link: https://lore.kernel.org/r/20210624201343.85441-1-cassio.neri@gmail.com Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1d1bb12a8b1805ddeef9793ebeb920179fb0fa38 upstream.

The current implementation of rtc_time64_to_tm() contains unnecessary
loops, branches and look-up tables. The new one uses an arithmetic-based
algorithm appeared in [1] and is approximately 4.3 times faster (YMMV).

The drawback is that the new code isn't intuitive and contains many 'magic
numbers' (not unusual for this type of algorithm). However, [1] justifies
all those numbers and, given this function's history, the code is unlikely
to need much maintenance, if any at all.

Add a KUnit test case that checks every day in a 160,000 years interval
starting on 1970-01-01 against the expected result. Add a new config
RTC_LIB_KUNIT_TEST symbol to give the option to run this test suite.

[1] Neri, Schneider, "Euclidean Affine Functions and Applications to
Calendar Algorithms". https://arxiv.org/abs/2102.06959

Signed-off-by: Cassio Neri <cassio.neri@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210624201343.85441-1-cassio.neri@gmail.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rtc: fsl-ftm-alarm: add FTM alarm driver 2019-08-23T14:20:50+00:00 Biwen Li biwen.li@nxp.com 2019-08-13T03:01:56+00:00 7b0b551dbc1e0acb2a3a6a7fbebc3ab9cf68a050 For the platforms including LS1012A, LS1021A, LS1028A, LS1043A, LS1046A, LS1088A, LS208xA that has the FlexTimer module, implementing alarm functions within RTC subsystem to wakeup the system when system going to sleep (work with RCPM driver). Signed-off-by: Biwen Li <biwen.li@nxp.com> Link: https://lore.kernel.org/r/20190813030157.48590-1-biwen.li@nxp.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> 
For the platforms including LS1012A, LS1021A, LS1028A, LS1043A,
LS1046A, LS1088A, LS208xA that has the FlexTimer
module, implementing alarm functions within RTC subsystem
to wakeup the system when system going to sleep (work with RCPM driver).

Signed-off-by: Biwen Li <biwen.li@nxp.com>
Link: https://lore.kernel.org/r/20190813030157.48590-1-biwen.li@nxp.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
rtc: Add Amlogic Virtual Wake RTC 2019-08-22T21:08:32+00:00 Neil Armstrong narmstrong@baylibre.com 2019-08-12T23:28:50+00:00 6ef35398e827dcf321a012c8f7a4d8d739674db6 The Amlogic Meson GX SoCs uses a special register to store the time in seconds to wakeup after a system suspend. In order to be able to reuse the RTC wakealarm feature, this driver implements a fake RTC device which uses the system time to deduce a suspend delay. Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> [khilman: rebase to v5.3-rc, rework and modernization] Signed-off-by: Kevin Hilman <khilman@baylibre.com> Link: https://lore.kernel.org/r/20190812232850.8016-3-khilman@kernel.org Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> 
The Amlogic Meson GX SoCs uses a special register to store the
time in seconds to wakeup after a system suspend.

In order to be able to reuse the RTC wakealarm feature, this
driver implements a fake RTC device which uses the system time
to deduce a suspend delay.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
[khilman: rebase to v5.3-rc, rework and modernization]
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20190812232850.8016-3-khilman@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
rtc: remove w90x900/nuc900 driver 2019-08-12T20:56:07+00:00 Arnd Bergmann arnd@arndb.de 2019-08-09T20:27:42+00:00 cb3cab06142eaa157bf5666c4e514ef087bf4323 The ARM w90x900 platform is getting removed, so this driver is obsolete. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20190809202749.742267-15-arnd@arndb.de Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> 
The ARM w90x900 platform is getting removed, so this driver is obsolete.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20190809202749.742267-15-arnd@arndb.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
rtc: bd70528: Initial support for ROHM bd70528 RTC 2019-06-27T09:57:24+00:00 Matti Vaittinen matti.vaittinen@fi.rohmeurope.com 2019-06-03T07:27:14+00:00 32a4a4ebf76848828d67f519d07af9eadb6e8300 Support RTC block in ROHM bd70528 power management IC. Support getting and setting the time and date as well as arming an alarm which can also be used to wake the PMIC from standby state. HW supports wake interrupt only for the next 24 hours (sec, minute and hour information only) so we limit also the alarm interrupt to this 24 hours for the sake of consistency. Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Lee Jones <lee.jones@linaro.org> 
Support RTC block in ROHM bd70528 power management IC. Support
getting and setting the time and date as well as arming an alarm
which can also be used to wake the PMIC from standby state.

HW supports wake interrupt only for the next 24 hours (sec, minute
and hour information only) so we limit also the alarm interrupt to
this 24 hours for the sake of consistency.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
rtc: Add ASPEED RTC driver 2019-04-04T08:07:10+00:00 Joel Stanley joel@jms.id.au 2019-03-27T01:02:15+00:00 184a182ed52a9b224cfa081a01e920c6ab1ce0bd Read and writes the time to the non-battery backed RTC in the ASPEED BMC system on chip families. Signed-off-by: Joel Stanley <joel@jms.id.au> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> 
Read and writes the time to the non-battery backed RTC in the ASPEED BMC
system on chip families.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Merge tag 'tag-chrome-platform-for-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux 2019-03-12T16:46:32+00:00 Linus Torvalds torvalds@linux-foundation.org 2019-03-12T16:46:32+00:00 f47d633134f7033e3d0c667419d9f8afd69e308d Pull chrome platform updates from Benson Leung: - SPDX identifier cleanup for platform/chrome - Cleanup series between mfd and chrome/platform, moving cros-ec attributes from mfd/cros_ec_dev to sub-drivers in platform/chrome - Wilco EC driver - Maintainership change to new group repository * tag 'tag-chrome-platform-for-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux: platform/chrome: fix wilco-ec dependencies platform/chrome: wilco_ec: Add RTC driver platform/chrome: wilco_ec: Add support for raw commands in debugfs platform/chrome: Add new driver for Wilco EC platform/chrome: cros_ec: Remove cros_ec dependency in lpc_mec MAINTAINERS: chrome-platform: change the git tree to a chrome-platform group git tree platform/chrome: cros_ec_sysfs: remove pr_fmt() define platform/chrome: cros_ec_lightbar: remove pr_fmt() define platform/chrome: cros_kbd_led_backlight: switch to SPDX identifier platform/chrome: cros_ec_spi: switch to SPDX identifier platform/chrome: cros_ec_proto: switch to SPDX identifier platform/chrome: cros_ec_lpc: switch to SPDX identifier platform/chrome: cros_ec_i2c: switch to SPDX identifier platform/chrome: cros_ec_vbc: switch to SPDX identifier platform/chrome: cros_ec_sysfs: switch to SPDX identifier platform/chrome: cros_ec_lightbar: switch to SPDX identifier platform/chrome: cros_ec_debugfs: switch to SPDX identifier platform/chrome: cromeos_pstore: switch to SPDX identifier 
Pull chrome platform updates from Benson Leung:

 - SPDX identifier cleanup for platform/chrome

 - Cleanup series between mfd and chrome/platform, moving cros-ec
   attributes from mfd/cros_ec_dev to sub-drivers in platform/chrome

 - Wilco EC driver

 - Maintainership change to new group repository

* tag 'tag-chrome-platform-for-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux:
  platform/chrome: fix wilco-ec dependencies
  platform/chrome: wilco_ec: Add RTC driver
  platform/chrome: wilco_ec: Add support for raw commands in debugfs
  platform/chrome: Add new driver for Wilco EC
  platform/chrome: cros_ec: Remove cros_ec dependency in lpc_mec
  MAINTAINERS: chrome-platform: change the git tree to a chrome-platform group git tree
  platform/chrome: cros_ec_sysfs: remove pr_fmt() define
  platform/chrome: cros_ec_lightbar: remove pr_fmt() define
  platform/chrome: cros_kbd_led_backlight: switch to SPDX identifier
  platform/chrome: cros_ec_spi: switch to SPDX identifier
  platform/chrome: cros_ec_proto: switch to SPDX identifier
  platform/chrome: cros_ec_lpc: switch to SPDX identifier
  platform/chrome: cros_ec_i2c: switch to SPDX identifier
  platform/chrome: cros_ec_vbc: switch to SPDX identifier
  platform/chrome: cros_ec_sysfs: switch to SPDX identifier
  platform/chrome: cros_ec_lightbar: switch to SPDX identifier
  platform/chrome: cros_ec_debugfs: switch to SPDX identifier
  platform/chrome: cromeos_pstore: switch to SPDX identifier
platform/chrome: wilco_ec: Add RTC driver 2019-02-21T20:36:53+00:00 Nick Crews ncrews@chromium.org 2019-02-09T00:37:19+00:00 0d2f2a3da1f2a9ebeb66bb03073dd149fccf1bdd This Embedded Controller has an internal RTC that is exposed as a standard RTC class driver with read/write functionality. The driver is added to the drivers/rtc/ so that the maintainer of that directory will be able to comment on this change, as that maintainer is the expert on this system. In addition, the driver code is called indirectly after a corresponding device is registered from core.c, as opposed to core.c registering the driver callbacks directly. To test: > hwclock --show --rtc /dev/rtc1 2007-12-31 16:01:20.460959-08:00 > hwclock --systohc --rtc /dev/rtc1 > hwclock --show --rtc /dev/rtc1 2018-11-29 17:08:00.780793-08:00 > hwclock --show --rtc /dev/rtc1 2007-12-31 16:01:20.460959-08:00 > hwclock --systohc --rtc /dev/rtc1 > hwclock --show --rtc /dev/rtc1 2018-11-29 17:08:00.780793-08:00 Signed-off-by: Duncan Laurie <dlaurie@google.com> Signed-off-by: Nick Crews <ncrews@chromium.org> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> [Fix the sparse warning: symbol 'wilco_ec_rtc_read/write' was not declared] Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> 
This Embedded Controller has an internal RTC that is exposed
as a standard RTC class driver with read/write functionality.

The driver is added to the drivers/rtc/ so that the maintainer of that
directory will be able to comment on this change, as that maintainer is
the expert on this system. In addition, the driver code is called
indirectly after a corresponding device is registered from core.c,
as opposed to core.c registering the driver callbacks directly.

To test:
> hwclock --show --rtc /dev/rtc1
2007-12-31 16:01:20.460959-08:00
> hwclock --systohc --rtc /dev/rtc1
> hwclock --show --rtc /dev/rtc1
2018-11-29 17:08:00.780793-08:00

> hwclock --show --rtc /dev/rtc1
2007-12-31 16:01:20.460959-08:00
> hwclock --systohc --rtc /dev/rtc1
> hwclock --show --rtc /dev/rtc1
2018-11-29 17:08:00.780793-08:00

Signed-off-by: Duncan Laurie <dlaurie@google.com>
Signed-off-by: Nick Crews <ncrews@chromium.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
[Fix the sparse warning: symbol 'wilco_ec_rtc_read/write' was not declared]
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
rtc: add AB-RTCMC-32.768kHz-EOZ9 RTC support 2019-02-18T21:39:30+00:00 Artem Panfilov panfilov.artyom@gmail.com 2019-02-17T18:52:56+00:00 67075b63cce26c9a235986f163ce890e7bb035a7 This patch adds support for AB-RTCMC-32.768kHz-EOZ9 RTC/Calendar module with I2C interface. Signed-off-by: Artem Panfilov <panfilov.artyom@gmail.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> 
This patch adds support for AB-RTCMC-32.768kHz-EOZ9 RTC/Calendar
module with I2C interface.

Signed-off-by: Artem Panfilov <panfilov.artyom@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
rtc: rv3028: add new driver 2019-02-17T20:29:10+00:00 Alexandre Belloni alexandre.belloni@bootlin.com 2019-02-12T23:21:36+00:00 e6e7376cfd7b3f9b63de3a22792f64d9bfb2ab53 Add a driver for the MicroCrystal RV-3028. It is a SMT Real-Time Clock Module that incorporates an integrated CMOS circuit together with an XTAL. It has an i2c interface. The driver handles date/time, alarms, trickle charging, timestamping, frequency offset correction, EEPROM and NVRAM. Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> 
Add a driver for the MicroCrystal RV-3028. It is a SMT Real-Time Clock
Module that incorporates an integrated CMOS circuit together with an XTAL.
It has an i2c interface.

The driver handles date/time, alarms, trickle charging, timestamping,
frequency offset correction, EEPROM and NVRAM.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>