linux-stable.git/arch/x86/kernel/rtc.c, branch linux-rolling-lts

x86/rtc: Remove unused intel-mid.h

2024-04-03T15:24:48+00:00

The rtc driver used to be disabled with a direct check for Intel MID
platforms.  But that direct check was replaced long ago (see second
link).  Remove the (unused since 2016) include.

[ dhansen: rewrite changelog to include some history ]

Signed-off-by: Andy Shevchenko 
Signed-off-by: Dave Hansen 
Link: https://lore.kernel.org/all/20240305161024.1364098-1-andriy.shevchenko%40linux.intel.com
Link: https://lore.kernel.org/all/1460592286-300-5-git-send-email-mcgrof@kernel.org

rtc: Extend timeout for waiting for UIP to clear to 1s

2023-12-17T21:33:55+00:00

Specs don't say anything about UIP being cleared within 10ms. They
only say that UIP won't occur for another 244uS. If a long NMI occurs
while UIP is still updating it might not be possible to get valid
data in 10ms.

This has been observed in the wild that around s2idle some calls can
take up to 480ms before UIP is clear.

Adjust callers from outside an interrupt context to wait for up to a
1s instead of 10ms.

Cc:   # 6.1.y
Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP")
Reported-by: Carsten Hatger 
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217626
Tested-by: Mateusz Jończyk 
Reviewed-by: Mateusz Jończyk 
Acked-by: Mateusz Jończyk 
Signed-off-by: Mario Limonciello 
Link: https://lore.kernel.org/r/20231128053653.101798-5-mario.limonciello@amd.com
Signed-off-by: Alexandre Belloni

rtc: Add support for configuring the UIP timeout for RTC reads

2023-12-17T21:33:55+00:00

The UIP timeout is hardcoded to 10ms for all RTC reads, but in some
contexts this might not be enough time. Add a timeout parameter to
mc146818_get_time() and mc146818_get_time_callback().

If UIP timeout is configured by caller to be >=100 ms and a call
takes this long, log a warning.

Make all callers use 10ms to ensure no functional changes.

Cc:   # 6.1.y
Fixes: ec5895c0f2d8 ("rtc: mc146818-lib: extract mc146818_avoid_UIP")
Signed-off-by: Mario Limonciello 
Tested-by: Mateusz Jończyk 
Reviewed-by: Mateusz Jończyk 
Acked-by: Mateusz Jończyk 
Link: https://lore.kernel.org/r/20231128053653.101798-4-mario.limonciello@amd.com
Signed-off-by: Alexandre Belloni

x86/rtc: Simplify PNP ids check

2023-01-06T03:22:34+00:00

compare_pnp_id() already iterates over the single linked pnp_ids list
starting with the id past to it.

So there is no need for add_rtc_cmos() to call compare_pnp_id()
for each id on the list.

No change in functionality intended.

Signed-off-by: Hans de Goede 
Signed-off-by: Ingo Molnar 
Acked-by: Rafael J. Wysocki 
Cc: linux-kernel@vger.kernel.org

x86/rtc: Rename mach_set_rtc_mmss() to mach_set_cmos_time()

2022-08-14T09:24:29+00:00

Once upon a time, before this commit in 2013:

   3195ef59cb42 ("x86: Do full rtc synchronization with ntp")

... the mach_set_rtc_mmss() function set only the minutes and seconds
registers of the CMOS RTC - hence the '_mmss' postfix.

This is no longer true, so rename the function to mach_set_cmos_time().

[ mingo: Expanded changelog a bit. ]

Signed-off-by: Mateusz Jończyk 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/r/20220813131034.768527-2-mat.jonczyk@o2.pl

x86/rtc: Rewrite & simplify mach_get_cmos_time() by deleting duplicated functionality

2022-08-14T09:24:08+00:00

There are functions in drivers/rtc/rtc-mc146818-lib.c that handle
reading from / writing to the CMOS RTC clock. mach_get_cmos_time() in
arch/x86/kernel/rtc.c did not use them and was mostly a duplicate of
mc146818_get_time(). Modify mach_get_cmos_time() to use
mc146818_get_time() and remove the duplicated functionality.

mach_get_cmos_time() used a different algorithm than
mc146818_get_time(), but these functions are equivalent. The major
differences are:

- mc146818_get_time() is better refined and handles various edge
  conditions,

- when the UIP ("Update in progress") bit of the RTC is set,
  mach_get_cmos_time() was busy waiting with cpu_relax() while
  mc146818_get_time() is using mdelay(1) in every loop iteration.
  (However, there is my commit merged for Linux 5.20 / 6.0 to decrease
  this period to 100us:
    commit d2a632a8a117 ("rtc: mc146818-lib: reduce RTC_UIP polling period")
  ),

- mach_get_cmos_time() assumed that the RTC year is >= 2000, which
  may not be true on some old boxes with a dead battery,

- mach_get_cmos_time() was holding the rtc_lock for a long time
  and could hang if the RTC is broken or not present.

The RTC writing counterpart, mach_set_rtc_mmss() is already using
mc146818_get_time() from drivers/rtc. This was done in
        commit 3195ef59cb42 ("x86: Do full rtc synchronization with ntp")
It appears that mach_get_cmos_time() was simply forgotten.

mach_get_cmos_time() is really used only in read_persistent_clock64(),
which is called only in a few places in kernel/time/timekeeping.c .

[ mingo: These changes are not supposed to change behavior, but they are
         not identity transformations either, as mc146818_get_time() is a
	 better but different implementation of the same logic - so
	 regressions are possible in principle. ]

Signed-off-by: Mateusz Jończyk 
Signed-off-by: Ingo Molnar 
Acked-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220813131034.768527-1-mat.jonczyk@o2.pl

x86: Convert x86_platform_ops to timespec64

2018-05-19T12:03:14+00:00

The x86 platform operations are fairly isolated, so it's easy to change
them from using timespec to timespec64. It has been checked that all the
users and callers are safe, and there is only one critical function that is
broken beyond 2106:

  pvclock_read_wallclock() uses a 32-bit number of seconds since the epoch
  to communicate the boot time between host and guest in a virtual
  environment. This will work until 2106, but fixing this is outside the
  scope of this change, Add a comment at least.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Boris Ostrovsky 
Acked-by: Radim Krčmář 
Acked-by: Jan Kiszka 
Cc: Juergen Gross 
Cc: jailhouse-dev@googlegroups.com
Cc: Borislav Petkov 
Cc: kvm@vger.kernel.org
Cc: y2038@lists.linaro.org
Cc: "Rafael J. Wysocki" 
Cc: xen-devel@lists.xenproject.org
Cc: John Stultz 
Cc: Andy Lutomirski 
Cc: "H. Peter Anvin" 
Cc: Paolo Bonzini 
Cc: Andy Shevchenko 
Cc: Joao Martins 
Link: https://lkml.kernel.org/r/20180427201435.3194219-1-arnd@arndb.de

x86/rtc: Stop using deprecated functions

2018-03-15T08:47:24+00:00

rtc_time_to_tm() and rtc_tm_to_time() are deprecated because they
rely on 32bits variables and that will make rtc break in y2038/2016.

Use the proper y2038 safe functions.

Signed-off-by: Benjamin Gaignard 
Signed-off-by: John Stultz 
Signed-off-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: Arnd Bergmann 
Cc: Richard Cochran 
Cc: Stephen Boyd 
Cc: Miroslav Lichvar 
Cc: Alexandre Belloni 
Link: https://lkml.kernel.org/r/1520620971-9567-5-git-send-email-john.stultz@linaro.org

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02T10:10:55+00:00

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart 
Reviewed-by: Philippe Ombredanne 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

timekeeping: Ignore the bogus sleep time if pm_trace is enabled

2016-11-29T17:02:58+00:00

Power management suspend/resume tracing (ab)uses the RTC to store
suspend/resume information persistently. As a consequence the RTC value is
clobbered when timekeeping is resumed and tries to inject the sleep time.

Commit a4f8f6667f09 ("timekeeping: Cap array access in timekeeping_debug")
plugged a out of bounds array access in the timekeeping debug code which
was caused by the clobbered RTC value, but we still use the clobbered RTC
value for sleep time injection into kernel timekeeping, which will result
in random adjustments depending on the stored "hash" value.

To prevent this keep track of the RTC clobbering and ignore the invalid RTC
timestamp at resume. If the system resumed successfully clear the flag,
which marks the RTC as unusable, warn the user about the RTC clobber and
recommend to adjust the RTC with 'ntpdate' or 'rdate'.

[jstultz: Fixed up pr_warn formating, and implemented suggestions from Ingo]
[ tglx: Rewrote changelog ]

Originally-from: Thomas Gleixner 
Signed-off-by: Chen Yu 
Signed-off-by: John Stultz 
Acked-by: Pavel Machek 
Acked-by: Thomas Gleixner 
Cc: Prarit Bhargava 
Cc: "Rafael J. Wysocki" 
Cc: Richard Cochran 
Cc: Xunlei Pang 
Cc: Len Brown 
Link: http://lkml.kernel.org/r/1480372524-15181-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner