aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/rtc.txt
diff options
context:
space:
mode:
authorMauro Carvalho Chehab <mchehab@s-opensource.com>2017-05-19 01:25:56 (GMT)
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2017-05-31 11:15:28 (GMT)
commita21512c1698d8106bcece0d24ff590dc92682678 (patch)
treecc8b5ee0b785681a0c1446020d52b8d91b6ffecd /Documentation/rtc.txt
parentda96aea0ed177105cb13ee83b328f6c61e061d3f (diff)
downloadkernel_replicant_linux-a21512c1698d8106bcece0d24ff590dc92682678.zip
kernel_replicant_linux-a21512c1698d8106bcece0d24ff590dc92682678.tar.gz
kernel_replicant_linux-a21512c1698d8106bcece0d24ff590dc92682678.tar.bz2
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>
Diffstat (limited to 'Documentation/rtc.txt')
-rw-r--r--Documentation/rtc.txt44
1 files changed, 23 insertions, 21 deletions
diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index ddc3660..47feb44 100644
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -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
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.
- 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.
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.)
- 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
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
other tasks, because of its greater functionality.
-SYSFS INTERFACE
+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
+================ ==============================================================
+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
+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
+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.
+ 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.
+================ ==============================================================
-IOCTL INTERFACE
+IOCTL interface
---------------
The ioctl() calls supported by /dev/rtc are also supported by the RTC class