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rtc.txt: standardize document format 

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- adjust identation of the titles;
- mark a table as such;
- don't capitalize chapter names.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
This commit is contained in:
Mauro Carvalho Chehab 2017-05-18 22:25:56 -03:00 committed by Alexandre Belloni
parent da96aea0ed
commit a21512c169
1 changed files with 23 additions and 21 deletions
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44
Documentation/rtc.txt
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@ -1,6 +1,6 @@
=======================================
Real Time Clock (RTC) Drivers for Linux Real Time Clock (RTC) Drivers for Linux
======================================= =======================================
When Linux developers talk about a "Real Time Clock", they usually mean When Linux developers talk about a "Real Time Clock", they usually mean
something that tracks wall clock time and is battery backed so that it something that tracks wall clock time and is battery backed so that it
@ -32,8 +32,8 @@ only issue an alarm up to 24 hours in the future, other hardware may
be able to schedule one any time in the upcoming century. be able to schedule one any time in the upcoming century.
Old PC/AT-Compatible driver: /dev/rtc Old PC/AT-Compatible driver: /dev/rtc
-------------------------------------- --------------------------------------
All PCs (even Alpha machines) have a Real Time Clock built into them. All PCs (even Alpha machines) have a Real Time Clock built into them.
Usually they are built into the chipset of the computer, but some may Usually they are built into the chipset of the computer, but some may
@ -105,8 +105,8 @@ that will be using this driver. See the code at the end of this document.
(The original /dev/rtc driver was written by Paul Gortmaker.) (The original /dev/rtc driver was written by Paul Gortmaker.)
New portable "RTC Class" drivers: /dev/rtcN New portable "RTC Class" drivers: /dev/rtcN
-------------------------------------------- --------------------------------------------
Because Linux supports many non-ACPI and non-PC platforms, some of which Because Linux supports many non-ACPI and non-PC platforms, some of which
have more than one RTC style clock, it needed a more portable solution have more than one RTC style clock, it needed a more portable solution
@ -136,35 +136,37 @@ 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 the system clock from the discrete RTC, but use the integrated one for all
other tasks, because of its greater functionality. other tasks, because of its greater functionality.
SYSFS INTERFACE SYSFS interface
--------------- ---------------
The sysfs interface under /sys/class/rtc/rtcN provides access to various The sysfs interface under /sys/class/rtc/rtcN provides access to various
rtc attributes without requiring the use of ioctls. All dates and times rtc attributes without requiring the use of ioctls. All dates and times
are in the RTC's timezone, rather than in system time. 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 date RTC-provided date
hctosys 1 if the RTC provided the system time at boot via the
CONFIG_RTC_HCTOSYS kernel option, 0 otherwise CONFIG_RTC_HCTOSYS kernel option, 0 otherwise
max_user_freq: The maximum interrupt rate an unprivileged user may request max_user_freq The maximum interrupt rate an unprivileged user may request
from this RTC. from this RTC.
name: The name of the RTC corresponding to this sysfs directory name The name of the RTC corresponding to this sysfs directory
since_epoch: The number of seconds since the epoch according to the RTC since_epoch The number of seconds since the epoch according to the RTC
time: RTC-provided time time RTC-provided time
wakealarm: The time at which the clock will generate a system wakeup wakealarm The time at which the clock will generate a system wakeup
event. This is a one shot wakeup event, so must be reset event. This is a one shot wakeup event, so must be reset
after wake if a daily wakeup is required. Format is seconds since after wake if a daily wakeup is required. Format is seconds
the epoch by default, or if there's a leading +, seconds in the since the epoch by default, or if there's a leading +, seconds
future, or if there is a leading +=, seconds ahead of the current in the future, or if there is a leading +=, seconds ahead of
alarm. the current alarm.
offset: The amount which the rtc clock has been adjusted in firmware. offset The amount which the rtc clock has been adjusted in firmware.
Visible only if the driver supports clock offset adjustment. Visible only if the driver supports clock offset adjustment.
The unit is parts per billion, i.e. The number of clock ticks 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 which are added to or removed from the rtc's base clock per
billion ticks. A positive value makes a day pass more slowly, billion ticks. A positive value makes a day pass more slowly,
longer, and a negative value makes a day pass more quickly. longer, and a negative value makes a day pass more quickly.
================ ==============================================================
IOCTL INTERFACE IOCTL interface
--------------- ---------------
The ioctl() calls supported by /dev/rtc are also supported by the RTC class The ioctl() calls supported by /dev/rtc are also supported by the RTC class