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Commit 81fdc7af authored by Alexandre Belloni's avatar Alexandre Belloni
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Documentation: rtc: move sysfs documentation to ABI



The sysfs documentation should be located under Documentation/ABI.

Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent db00d38e
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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:
		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:
		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:
		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:
		The name of the RTC corresponding to this sysfs directory

What:		/sys/class/rtc/rtcX/since_epoch
Date:		March 2006
KernelVersion:	2.6.17
Contact:	linux-rtc@vger.kernel.org
Description:
		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:
		RTC-provided time in 24-hour notation (hh:mm:ss)

What:		/sys/class/rtc/rtcX/*/nvmem
Date:		February 2016
KernelVersion:	4.6
Contact:	linux-rtc@vger.kernel.org
Description:
		The non volatile storage exported as a raw file, as described in
		Documentation/nvmem/nvmem.txt

What:		/sys/class/rtc/rtcX/offset
Date:		February 2016
KernelVersion:	4.6
Contact:	linux-rtc@vger.kernel.org
Description:
		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:
		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.
+0 −32
Original line number Diff line number Diff line
@@ -136,38 +136,6 @@ a high functionality RTC is integrated into the SOC. That system might read
the system clock from the discrete RTC, but use the integrated one for all
other tasks, because of its greater functionality.

SYSFS interface
---------------

The sysfs interface under /sys/class/rtc/rtcN provides access to various
rtc attributes without requiring the use of ioctls. All dates and times
are in the RTC's timezone, rather than in system time.

================ ==============================================================
date  	   	 RTC-provided date
hctosys   	 1 if the RTC provided the system time at boot via the
		 CONFIG_RTC_HCTOSYS kernel option, 0 otherwise
max_user_freq	 The maximum interrupt rate an unprivileged user may request
		 from this RTC.
name		 The name of the RTC corresponding to this sysfs directory
since_epoch	 The number of seconds since the epoch according to the RTC
time		 RTC-provided time
wakealarm	 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.
offset		 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.
*/nvmem		 The non volatile storage exported as a raw file, as described
		 in Documentation/nvmem/nvmem.txt
================ ==============================================================

IOCTL interface
---------------