path: root/Documentation/rtc.txt
diff options
authorMatthew Garrett <mjg59@srcf.ucam.org>2009-09-22 23:46:32 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 14:39:46 (GMT)
commitd8c1acb1664d17dd995e34507533321e986d9215 (patch)
tree5c8c8a60bc0da9f16a748c6ef8c3cb98f33d21be /Documentation/rtc.txt
parentea3d1606fd32059461309099e8856c6652888a79 (diff)
rtc: add boot_timesource sysfs attribute
CONFIG_RTC_HCTOSYS allows the kernel to read the system time from the RTC at boot and resume, avoiding the need for userspace to do so. Unfortunately userspace currently has no way to know whether this configuration option is enabled and thus cannot sensibly choose whether to run hwclock itself or not. Add a hctosys sysfs attribute which indicates whether a given RTC set the system clock. Signed-off-by: Matthew Garrett <mjg@redhat.com> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: David Brownell <david-b@pacbell.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/rtc.txt')
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index 2745e81..9104c10 100644
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -143,6 +143,8 @@ 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