linux.git/arch/x86/kernel/rtc.c, branch v3.11

x86: Increase precision of x86_platform.get/set_wallclock()

2013-05-28T21:00:59+00:00

All the virtualized platforms (KVM, lguest and Xen) have persistent
wallclocks that have more than one second of precision.

read_persistent_wallclock() and update_persistent_wallclock() allow
for nanosecond precision but their implementation on x86 with
x86_platform.get/set_wallclock() only allows for one second precision.
This means guests may see a wallclock time that is off by up to 1
second.

Make set_wallclock() and get_wallclock() take a struct timespec
parameter (which allows for nanosecond precision) so KVM and Xen
guests may start with a more accurate wallclock time and a Xen dom0
can maintain a more accurate wallclock for guests.

Signed-off-by: David Vrabel 
Signed-off-by: John Stultz

x86: Do full rtc synchronization with ntp

2013-03-15T23:50:26+00:00

Every 11 minutes ntp attempts to update the x86 rtc with the current
system time.  Currently, the x86 code only updates the rtc if the system
time is within +/-15 minutes of the current value of the rtc. This
was done originally to avoid setting the RTC if the RTC was in localtime
mode (common with Windows dualbooting).  Other architectures do a full
synchronization and now that we have better infrastructure to detect
when the RTC is in localtime, there is no reason that x86 should be
software limited to a 30 minute window.

This patch changes the behavior of the kernel to do a full synchronization
(year, month, day, hour, minute, and second) of the rtc when ntp requests
a synchronization between the system time and the rtc.

I've used the RTC library functions in this patchset as they do all the
required bounds checking.

Cc: Thomas Gleixner 
Cc: John Stultz 
Cc: x86@kernel.org
Cc: Matt Fleming 
Cc: David Vrabel 
Cc: Andrew Morton 
Cc: Andi Kleen 
Cc: linux-efi@vger.kernel.org
Signed-off-by: Prarit Bhargava 
[jstultz: Tweak commit message, fold in build fix found by fengguang
Also add select RTC_LIB to X86, per new dependency, as found by prarit]
Signed-off-by: John Stultz

x86/time/rtc: Don't print extended CMOS year when reading RTC

2013-01-24T13:56:35+00:00

We shouldn't print the current century every time we read the
RTC.

Signed-off-by: Bjorn Helgaas 
Acked-by: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20130104224146.15189.14874.stgit@bhelgaas.mtv.corp.google.com
Signed-off-by: Ingo Molnar

x86: Allow tracing of functions in arch/x86/kernel/rtc.c

2012-10-24T11:14:22+00:00

Move native_read_tsc() to tsc.c to allow profiling to be
re-enabled for rtc.c.

Signed-off-by: David Vrabel 
Cc: Peter Zijlstra 
Cc: Frederic Weisbecker 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/1349698050-6560-1-git-send-email-david.vrabel@citrix.com
Signed-off-by: Ingo Molnar

sections: fix section conflicts in arch/x86

2012-10-05T18:04:40+00:00

Signed-off-by: Andi Kleen 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86/rtc, mrst: Don't register a platform RTC device for for Intel MID platforms

2011-12-05T16:09:21+00:00

Intel MID x86 platforms have a memory mapped virtual RTC
instead.  No MID platform have the default ports (and
accessing them may do weird stuff).

Signed-off-by: Mathias Nyman 
Signed-off-by: Alan Cox 
Cc: feng.tang@intel.com
Cc: Feng Tang 
Cc: "H. Peter Anvin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Ingo Molnar

x86: Fix files explicitly requiring export.h for EXPORT_SYMBOL/THIS_MODULE

2011-10-31T23:30:35+00:00

These files were implicitly getting EXPORT_SYMBOL via device.h
which was including module.h, but that will be fixed up shortly.

By fixing these now, we can avoid seeing things like:

arch/x86/kernel/rtc.c:29: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’
arch/x86/kernel/pci-dma.c:20: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL’
arch/x86/kernel/e820.c:69: warning: type defaults to ‘int’ in declaration of ‘EXPORT_SYMBOL_GPL’

[ with input from Randy Dunlap  and also
  from Stephen Rothwell  ]

Signed-off-by: Paul Gortmaker

x86/rtc: Don't recursively acquire rtc_lock

2011-09-21T14:16:09+00:00

A deadlock was introduced on x86 in commit ef68c8f87ed1 ("x86:
Serialize EFI time accesses on rtc_lock") because efi_get_time()
and friends can be called with rtc_lock already held by
read_persistent_time(), e.g.:

 timekeeping_init()
    read_persistent_clock()     <-- acquire rtc_lock
        efi_get_time()
            phys_efi_get_time() <-- acquire rtc_lock 

To fix this let's push the locking down into the get_wallclock()
and set_wallclock() implementations.  Only the clock
implementations that access the x86 RTC directly need to acquire
rtc_lock, so it makes sense to push the locking down into the
rtc, vrtc and efi code.

The virtualization implementations don't require rtc_lock to be
held because they provide their own serialization.

Signed-off-by: Matt Fleming 
Acked-by: Jan Beulich 
Acked-by: Avi Kivity  [for the virtualization aspect]
Cc: "H. Peter Anvin" 
Cc: Zhang Rui 
Cc: Josh Boyer 
Signed-off-by: Andrew Morton 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar

rtc: cmos: Add OF bindings

2011-02-23T21:27:55+00:00

This allows to load the OF driver based informations from the device
tree. Systems without BIOS may need to perform some initialization.
PowerPC creates a PNP device from the OF information and performs this
kind of initialization in their private PCI quirk. This looks more
generic.

This patch also avoids registering the platform RTC driver on X86 if
we have a device tree blob. Otherwise we would setup the device based
on the hardcoded information in arch/x86 rather than the device tree
based one.

[ tglx: Changed "int of_have_populated_dt()" to bool as recommended by
        Grant ]

Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Dirk Brandewie 
Acked-by: Grant Likely 
Cc: sodaville@linutronix.de
Cc: devicetree-discuss@lists.ozlabs.org
Cc: rtc-linux@googlegroups.com
Cc: Alessandro Zummo 
LKML-Reference: <1298405266-1624-12-git-send-email-bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner

set_rtc_mmss: show warning message only once

2011-01-13T16:03:07+00:00

Occasionally the system gets into a state where the CMOS clock has gotten
slightly ahead of current time and the periodic update of RTC fails.  The
message is a nuisance and repeats spamming the log.

  See: http://www.ntp.org/ntpfaq/NTP-s-trbl-spec.htm#Q-LINUX-SET-RTC-MMSS

Rather than just removing the message, make it show only once and reduce
severity since it indicates a normal and non urgent condition.

Signed-off-by: Stephen Hemminger 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Ralf Baechle 
Cc: David Howells 
Cc: Paul Mundt 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds