linux/Documentation/ABI/testing/sysfs-class-rtc
Alexandre Belloni 71db049e73 rtc: Add RTC range
Add a way for drivers to inform the core of the supported date/time range.
The core can then check whether the date/time or alarm is in the range
before calling ->set_time, ->set_mmss or ->set_alarm. It returns -ERANGE
when the time is out of range.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
2018-03-17 14:20:54 +01:00

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What: /sys/class/rtc/
Date: March 2006
KernelVersion: 2.6.17
Contact: linux-rtc@vger.kernel.org
Description:
The rtc/ class subdirectory belongs to the RTC subsystem.
What: /sys/class/rtc/rtcX/
Date: March 2006
KernelVersion: 2.6.17
Contact: linux-rtc@vger.kernel.org
Description:
The /sys/class/rtc/rtc{0,1,2,3,...} directories correspond
to each RTC device.
What: /sys/class/rtc/rtcX/date
Date: March 2006
KernelVersion: 2.6.17
Contact: linux-rtc@vger.kernel.org
Description:
(RO) RTC-provided date in YYYY-MM-DD format
What: /sys/class/rtc/rtcX/hctosys
Date: September 2009
KernelVersion: 2.6.32
Contact: linux-rtc@vger.kernel.org
Description:
(RO) 1 if the RTC provided the system time at boot via the
CONFIG_RTC_HCTOSYS kernel option, 0 otherwise
What: /sys/class/rtc/rtcX/max_user_freq
Date: October 2007
KernelVersion: 2.6.24
Contact: linux-rtc@vger.kernel.org
Description:
(RW) The maximum interrupt rate an unprivileged user may request
from this RTC.
What: /sys/class/rtc/rtcX/name
Date: March 2006
KernelVersion: 2.6.17
Contact: linux-rtc@vger.kernel.org
Description:
(RO) The name of the RTC corresponding to this sysfs directory
What: /sys/class/rtc/rtcX/range
Date: January 2018
KernelVersion: 4.16
Contact: linux-rtc@vger.kernel.org
Description:
Valid time range for the RTC, as seconds from epoch, formatted
as [min, max]
What: /sys/class/rtc/rtcX/since_epoch
Date: March 2006
KernelVersion: 2.6.17
Contact: linux-rtc@vger.kernel.org
Description:
(RO) RTC-provided time as the number of seconds since the epoch
What: /sys/class/rtc/rtcX/time
Date: March 2006
KernelVersion: 2.6.17
Contact: linux-rtc@vger.kernel.org
Description:
(RO) RTC-provided time in 24-hour notation (hh:mm:ss)
What: /sys/class/rtc/rtcX/offset
Date: February 2016
KernelVersion: 4.6
Contact: linux-rtc@vger.kernel.org
Description:
(RW) The amount which the rtc clock has been adjusted in
firmware. Visible only if the driver supports clock offset
adjustment. The unit is parts per billion, i.e. The number of
clock ticks which are added to or removed from the rtc's base
clock per billion ticks. A positive value makes a day pass more
slowly, longer, and a negative value makes a day pass more
quickly.
What: /sys/class/rtc/rtcX/wakealarm
Date: February 2007
KernelVersion: 2.6.20
Contact: linux-rtc@vger.kernel.org
Description:
(RW) The time at which the clock will generate a system wakeup
event. This is a one shot wakeup event, so must be reset after
wake if a daily wakeup is required. Format is seconds since the
epoch by default, or if there's a leading +, seconds in the
future, or if there is a leading +=, seconds ahead of the
current alarm.