linux-stable.git/drivers/rtc, branch linux-5.16.y

rtc: mc146818-lib: fix signedness bug in mc146818_get_time()

2022-04-13T18:03:24+00:00

commit 7372971c1be5b7d4fdd8ad237798bdc1d1d54162 upstream.

The mc146818_get_time() function returns zero on success or negative
a error code on failure.  It needs to be type int.

Fixes: d35786b3a28d ("rtc: mc146818-lib: change return values of mc146818_get_time()")
Signed-off-by: Dan Carpenter 
Reviewed-by: Mateusz Jończyk 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220111071922.GE11243@kili
Signed-off-by: Greg Kroah-Hartman

rtc: mc146818-lib: fix RTC presence check

2022-04-13T18:03:12+00:00

[ Upstream commit ea6fa4961aab8f90a8aa03575a98b4bda368d4b6 ]

To prevent an infinite loop in mc146818_get_time(),
commit 211e5db19d15 ("rtc: mc146818: Detect and handle broken RTCs")
added a check for RTC availability. Together with a later fix, it
checked if bit 6 in register 0x0d is cleared.

This, however, caused a false negative on a motherboard with an AMD
SB710 southbridge; according to the specification [1], bit 6 of register
0x0d of this chipset is a scratchbit. This caused a regression in Linux
5.11 - the RTC was determined broken by the kernel and not used by
rtc-cmos.c [3]. This problem was also reported in Fedora [4].

As a better alternative, check whether the UIP ("Update-in-progress")
bit is set for longer then 10ms. If that is the case, then apparently
the RTC is either absent (and all register reads return 0xff) or broken.
Also limit the number of loop iterations in mc146818_get_time() to 10 to
prevent an infinite loop there.

The functions mc146818_get_time() and mc146818_does_rtc_work() will be
refactored later in this patch series, in order to fix a separate
problem with reading / setting the RTC alarm time. This is done so to
avoid a confusion about what is being fixed when.

In a previous approach to this problem, I implemented a check whether
the RTC_HOURS register contains a value <= 24. This, however, sometimes
did not work correctly on my Intel Kaby Lake laptop. According to
Intel's documentation [2], "the time and date RAM locations (0-9) are
disconnected from the external bus" during the update cycle so reading
this register without checking the UIP bit is incorrect.

[1] AMD SB700/710/750 Register Reference Guide, page 308,
https://developer.amd.com/wordpress/media/2012/10/43009_sb7xx_rrg_pub_1.00.pdf

[2] 7th Generation Intel ® Processor Family I/O for U/Y Platforms [...] Datasheet
Volume 1 of 2, page 209
Intel's Document Number: 334658-006,
https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/7th-and-8th-gen-core-family-mobile-u-y-processor-lines-i-o-datasheet-vol-1.pdf

[3] Functions in arch/x86/kernel/rtc.c apparently were using it.

[4] https://bugzilla.redhat.com/show_bug.cgi?id=1936688

Fixes: 211e5db19d15 ("rtc: mc146818: Detect and handle broken RTCs")
Fixes: ebb22a059436 ("rtc: mc146818: Dont test for bit 0-5 in Register D")
Signed-off-by: Mateusz Jończyk 
Cc: Thomas Gleixner 
Cc: Alessandro Zummo 
Cc: Alexandre Belloni 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20211210200131.153887-5-mat.jonczyk@o2.pl
Signed-off-by: Sasha Levin

rtc: Check return value from mc146818_get_time()

2022-04-13T18:03:12+00:00

[ Upstream commit 0dd8d6cb9eddfe637bcd821bbfd40ebd5a0737b9 ]

There are 4 users of mc146818_get_time() and none of them was checking
the return value from this function. Change this.

Print the appropriate warnings in callers of mc146818_get_time() instead
of in the function mc146818_get_time() itself, in order not to add
strings to rtc-mc146818-lib.c, which is kind of a library.

The callers of alpha_rtc_read_time() and cmos_read_time() may use the
contents of (struct rtc_time *) even when the functions return a failure
code. Therefore, set the contents of (struct rtc_time *) to 0x00,
which looks more sensible then 0xff and aligns with the (possibly
stale?) comment in cmos_read_time:

	/*
	 * If pm_trace abused the RTC for storage, set the timespec to 0,
	 * which tells the caller that this RTC value is unusable.
	 */

For consistency, do this in mc146818_get_time().

Note: hpet_rtc_interrupt() may call mc146818_get_time() many times a
second. It is very unlikely, though, that the RTC suddenly stops
working and mc146818_get_time() would consistently fail.

Only compile-tested on alpha.

Signed-off-by: Mateusz Jończyk 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: Alessandro Zummo 
Cc: Alexandre Belloni 
Cc: linux-alpha@vger.kernel.org
Cc: x86@kernel.org
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20211210200131.153887-4-mat.jonczyk@o2.pl
Signed-off-by: Sasha Levin

rtc: mc146818-lib: change return values of mc146818_get_time()

2022-04-13T18:03:12+00:00

[ Upstream commit d35786b3a28dee20b12962ae2dd365892a99ed1a ]

No function is checking mc146818_get_time() return values yet, so
correct them to make them more customary.

Signed-off-by: Mateusz Jończyk 
Cc: Alessandro Zummo 
Cc: Alexandre Belloni 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20211210200131.153887-3-mat.jonczyk@o2.pl
Signed-off-by: Sasha Levin

rtc: wm8350: Handle error for wm8350_register_irq

2022-04-13T18:02:56+00:00

[ Upstream commit 43f0269b6b89c1eec4ef83c48035608f4dcdd886 ]

As the potential failure of the wm8350_register_irq(),
it should be better to check it and return error if fails.
Also, it need not free 'wm_rtc->rtc' since it will be freed
automatically.

Fixes: 077eaf5b40ec ("rtc: rtc-wm8350: add support for WM8350 RTC")
Signed-off-by: Jiasheng Jiang 
Acked-by: Charles Keepax 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220303085030.291793-1-jiasheng@iscas.ac.cn
Signed-off-by: Sasha Levin

rtc: check if __rtc_read_time was successful

2022-04-08T12:06:49+00:00

commit 915593a7a663b2ad08b895a5f3ba8b19d89d4ebf upstream.

Clang static analysis reports this issue
interface.c:810:8: warning: Passed-by-value struct
  argument contains uninitialized data
  now = rtc_tm_to_ktime(tm);
      ^~~~~~~~~~~~~~~~~~~

tm is set by a successful call to __rtc_read_time()
but its return status is not checked.  Check if
it was successful before setting the enabled flag.
Move the decl of err to function scope.

Fixes: 2b2f5ff00f63 ("rtc: interface: ignore expired timers when enqueuing new timers")
Signed-off-by: Tom Rix 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220326194236.2916310-1-trix@redhat.com
Signed-off-by: Greg Kroah-Hartman

rtc: pl031: fix rtc features null pointer dereference

2022-04-08T12:05:27+00:00

commit ea6af39f3da50c86367a71eb3cc674ade3ed244c upstream.

When there is no interrupt line, rtc alarm feature is disabled.

The clearing of the alarm feature bit was being done prior to allocations
of ldata->rtc device, resulting in a null pointer dereference.

Clear RTC_FEATURE_ALARM after the rtc device is allocated.

Fixes: d9b0dd54a194 ("rtc: pl031: use RTC_FEATURE_ALARM")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Pouladi 
Signed-off-by: Elliot Berman 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220225161924.274141-1-quic_eberman@quicinc.com
Signed-off-by: Greg Kroah-Hartman

rtc: mc146818-lib: fix locking in mc146818_set_time

2022-04-08T12:05:27+00:00

commit 811f5559270f25c34c338d6eaa2ece2544c3d3bd upstream.

In mc146818_set_time(), CMOS_READ(RTC_CONTROL) was performed without the
rtc_lock taken, which is required for CMOS accesses. Fix this.

Nothing in kernel modifies RTC_DM_BINARY, so a separate critical section
is allowed here.

Fixes: dcf257e92622 ("rtc: mc146818: Reduce spinlock section in mc146818_set_time()")
Signed-off-by: Mateusz Jończyk 
Cc: Alessandro Zummo 
Cc: Alexandre Belloni 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220220090403.153928-1-mat.jonczyk@o2.pl
Signed-off-by: Greg Kroah-Hartman

rtc: cmos: Evaluate century appropriate

2022-02-08T17:35:18+00:00

commit ff164ae39b82ee483b24579c8e22a13a8ce5bd04 upstream.

There's limiting the year to 2069. When setting the rtc year to 2070,
reading it returns 1970. Evaluate century starting from 19 to count the
correct year.

$ sudo date -s 20700106
Mon 06 Jan 2070 12:00:00 AM CST
$ sudo hwclock -w
$ sudo hwclock -r
1970-01-06 12:00:49.604968+08:00

Fixes: 2a4daadd4d3e5071 ("rtc: cmos: ignore bogus century byte")

Signed-off-by: Riwen Lu 
Acked-by: Eric Wong 
Reviewed-by: Mateusz Jończyk 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220106084609.1223688-1-luriwen@kylinos.cn
Signed-off-by: Mateusz Jończyk  # preparation for stable
Signed-off-by: Greg Kroah-Hartman

rtc: pxa: fix null pointer dereference

2022-01-27T11:02:58+00:00

commit 34127b3632b21e5c391756e724b1198eb9917981 upstream.

With the latest stable kernel versions the rtc on the PXA based
Zaurus does not work, when booting I see the following kernel messages:

pxa-rtc pxa-rtc: failed to find rtc clock source
pxa-rtc pxa-rtc: Unable to init SA1100 RTC sub-device
pxa-rtc: probe of pxa-rtc failed with error -2
hctosys: unable to open rtc device (rtc0)

I think this is because commit f2997775b111 ("rtc: sa1100: fix possible
race condition") moved the allocation of the rtc_device struct out of
sa1100_rtc_init and into sa1100_rtc_probe. This means that pxa_rtc_probe
also needs to do allocation for the rtc_device struct, otherwise
sa1100_rtc_init will try to dereference a null pointer. This patch adds
that allocation by copying how sa1100_rtc_probe in
drivers/rtc/rtc-sa1100.c does it; after the IRQs are set up a managed
rtc_device is allocated.

I've tested this patch with `qemu-system-arm -machine akita` and with a
real Zaurus SL-C1000 applied to 4.19, 5.4, and 5.10.

Signed-off-by: Laurence de Bruxelles 
Fixes: f2997775b111 ("rtc: sa1100: fix possible race condition")
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20220101154149.12026-1-lfdebrux@gmail.com
Signed-off-by: Greg Kroah-Hartman