rtc: stm32: Use NOIRQ_SYSTEM_SLEEP_PM_OPS()

After the switch to SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() and a subsequent
fix, stm32_rtc_{suspend,resume}() are unused when CONFIG_PM_SLEEP is not
set because SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() is a no-op in that
configuration:

drivers/rtc/rtc-stm32.c:904:12: error: 'stm32_rtc_resume' defined but not used [-Werror=unused-function]
904 | static int stm32_rtc_resume(struct device *dev)
| ^~~~~~~~~~~~~~~~
drivers/rtc/rtc-stm32.c:894:12: error: 'stm32_rtc_suspend' defined but not used [-Werror=unused-function]
894 | static int stm32_rtc_suspend(struct device *dev)
| ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

The non-"SET_" version of this macro, NOIRQ_SYSTEM_SLEEP_PM_OPS(), is
designed to handle this situation by only assigning the callbacks when
CONFIG_PM_SLEEP is set while allowing the functions to appear used to
the compiler. Switch to that macro to resolve the warnings. There is no
functional change with this, as SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() is
defined using NOIRQ_SYSTEM_SLEEP_PM_OPS() when CONFIG_PM_SLEEP is set.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230815-rtc-stm32-unused-pm-funcs-v1-1-82eb8e02d903@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: remove incorrect #ifdef check

After a previous commit changed the driver over to
SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(), the suspend/resume
functions must no longer be hidden behind an #ifdef:

In file included from include/linux/clk.h:13,
from drivers/rtc/rtc-stm32.c:8:
drivers/rtc/rtc-stm32.c:927:39: error: 'stm32_rtc_suspend' undeclared here (not in a function); did you mean 'stm32_rtc_probe'?
927 | SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(stm32_rtc_suspend, stm32_rtc_resume)
| ^~~~~~~~~~~~~~~~~
include/linux/kernel.h:58:44: note: in definition of macro 'PTR_IF'
58 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:329:26: note: in expansion of macro 'pm_sleep_ptr'
329 | .suspend_noirq = pm_sleep_ptr(suspend_fn), \
| ^~~~~~~~~~~~

Fixes: fb9a7e5360dc8 ("rtc: stm32: change PM callbacks to "_noirq()"")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230801105932.3738430-1-arnd@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230724205456.767430-1-robh@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: fix unnecessary parentheses

Fix a few style issues reported by checkpatch.pl:
- Unnecessary parentheses
- Lines should not end with a '('

Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-8-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: fix issues of stm32_rtc_valid_alrm function

stm32_rtc_valid_alrm function has some issues :
- arithmetical operations are impossible on BCD values
- "cur_mon + 1" can overflow
- the use case with the next month, the same day/hour/minutes went wrong

To solve that, we prefer to use timestamp comparison.
e.g. : On 5 Dec. 2021, the alarm limit is 5 Jan. 2022 (+31 days)
On 31 Jan 2021, the alarm limit is 28 Feb. 2022 (+28 days)

Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-7-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: change PM callbacks to "_noirq()"

The RTC driver stops the RTCAPB clock during suspend, but the
irq handler from RTC is called before starting clock. Then we are
blocked while accessing RTC registers.

We changes PM callbacks to '_no_irq()' to disable irq during
resume callback and so irq handler will be called after the enable
of RTCAPB clock.

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-6-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: don't print an error on probe deferral

Change stm32-rtc driver to not generate an error message when
device probe operation is deferred for a clock.

Signed-off-by: Etienne Carriere <etienne.carriere@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-5-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: improve rtc precision

The rtc is used to update the stgen counter on wake up from
low power modes, so it needs to be as much accurate as possible.

The maximization of asynchronous divider leads to a 4ms rtc
precision clock.
By decreasing pred_a to 0, it will have pred_s=32767 (when
need_accuracy is true), so stgen clock becomes more accurate
with 30us precision.
Nevertheless this will leads to an increase of power consumption.

Signed-off-by: Christophe Guibout <christophe.guibout@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-4-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: don't stop time counter if not needed

RTC counters are stopped when INIT bit in ISR register is set and
start counting from the (eventual) new value when INIT is reset.

In stm32_rtc_init(), called during probe, the INIT bit is set to
program the prescaler and the 24h mode. This halts the RTC counter
at each probe tentative causing the RTC time to loose from 0.3s to
0.8s at each kernel boot.
If the RTC is battery powered, both prescaler value and 24h mode
are kept during power cycle and there is no need to program them
again.

Check if the desired prescaler value and the 24h mode are already
programmed, then skip reprogramming them to avoid halting the time
counter.

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-3-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: use the proper register sequence to read date/time

Date and time are read from two separate RTC registers.
To ensure consistency between the two registers, reading the time
register locks the values in the shadow date register until the
date register is read.
Thus, the whole date/time read requires reading the time register
first, followed by reading the date register.
If the reads are done in reversed order, the shadow date register
will remain locked until a future read operation. The future read
will read the former date value that could be already invalid.

Fix the read order of date/time registers in stm32_rtc_valid_alrm()

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230705174357.353616-2-valentin.caron@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: remove dedicated wakeup management

There is no more needs to use a dedicated wake up interrupt for RTC as
EXTI block manages by itself now all interrupt lines.

Dedicated wakeup interrupt has been introduced with STM32 MP1 support
commit b72252b6580c ("rtc: stm32: add stm32mp1 rtc support") because GIC &
EXTI interrupts were not yet linked in EXTI driver.

Removing this interrupt won't break compatibility with device trees which
do use two interrupts entries: it could only prevent wakeup from low power
modes on STM32MP1x, but platform power management is not yet available.

Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20230531122732.1515594-1-amelie.delaunay@foss.st.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230304133028.2135435-33-u.kleine-koenig@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: Fix unbalanced clk_disable_unprepare() on probe error path

The STM32MP1 RTC may have 2 clocks, the pclk and the rtc_ck.

If clk_prepare_enable() fails for the second clock (rtc_ck) we must only
call clk_disable_unprepare() for the first clock (pclk) but currently we
call it on both leading to a WARN:

[ 15.629568] WARNING: CPU: 0 PID: 146 at drivers/clk/clk.c:958 clk_core_disable+0xb0/0xc8
[ 15.637620] ck_rtc already disabled
[ 15.663322] CPU: 0 PID: 146 Comm: systemd-udevd Not tainted 5.4.77-pknbsp-svn5759-atag-v5.4.77-204-gea4235203137-dirty #2413
[ 15.674510] Hardware name: STM32 (Device Tree Support)
[ 15.679658] [<c0111148>] (unwind_backtrace) from [<c010c0b8>] (show_stack+0x10/0x14)
[ 15.687371] [<c010c0b8>] (show_stack) from [<c0ab3d28>] (dump_stack+0xc0/0xe0)
[ 15.694574] [<c0ab3d28>] (dump_stack) from [<c012360c>] (__warn+0xc8/0xf0)
[ 15.701428] [<c012360c>] (__warn) from [<c0123694>] (warn_slowpath_fmt+0x60/0x94)
[ 15.708894] [<c0123694>] (warn_slowpath_fmt) from [<c053b518>] (clk_core_disable+0xb0/0xc8)
[ 15.717230] [<c053b518>] (clk_core_disable) from [<c053c190>] (clk_core_disable_lock+0x18/0x24)
[ 15.725924] [<c053c190>] (clk_core_disable_lock) from [<bf0adc44>] (stm32_rtc_probe+0x124/0x5e4 [rtc_stm32])
[ 15.735739] [<bf0adc44>] (stm32_rtc_probe [rtc_stm32]) from [<c05f7d4c>] (platform_drv_probe+0x48/0x98)
[ 15.745095] [<c05f7d4c>] (platform_drv_probe) from [<c05f5cec>] (really_probe+0x1f0/0x458)
[ 15.753338] [<c05f5cec>] (really_probe) from [<c05f61c4>] (driver_probe_device+0x70/0x1c4)
[ 15.761584] [<c05f61c4>] (driver_probe_device) from [<c05f6580>] (device_driver_attach+0x58/0x60)
[ 15.770439] [<c05f6580>] (device_driver_attach) from [<c05f6654>] (__driver_attach+0xcc/0x170)
[ 15.779032] [<c05f6654>] (__driver_attach) from [<c05f40d8>] (bus_for_each_dev+0x58/0x7c)
[ 15.787191] [<c05f40d8>] (bus_for_each_dev) from [<c05f4ffc>] (bus_add_driver+0xdc/0x1f8)
[ 15.795352] [<c05f4ffc>] (bus_add_driver) from [<c05f6ed8>] (driver_register+0x7c/0x110)
[ 15.803425] [<c05f6ed8>] (driver_register) from [<c01027bc>] (do_one_initcall+0x70/0x1b8)
[ 15.811588] [<c01027bc>] (do_one_initcall) from [<c01a1094>] (do_init_module+0x58/0x1f8)
[ 15.819660] [<c01a1094>] (do_init_module) from [<c01a0074>] (load_module+0x1e58/0x23c8)
[ 15.827646] [<c01a0074>] (load_module) from [<c01a0860>] (sys_finit_module+0xa0/0xd4)
[ 15.835459] [<c01a0860>] (sys_finit_module) from [<c01011e0>] (__sys_trace_return+0x0/0x20)

Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Fixes: 4e64350f42e2 ("rtc: add STM32 RTC driver")
Cc: stable@vger.kernel.org
Reviewed-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1623087421-19722-1-git-send-email-martin.fuzzey@flowbird.group

rtc: stm32: use rtc_lock/rtc_unlock

Avoid accessing directly rtc->ops_lock and use the RTC core helpers.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210119220653.677750-14-alexandre.belloni@bootlin.com

rtc: stm32: add missed clk_disable_unprepare in error path of resume

The resume() forgets to call clk_disable_unprepare() when failed.
Add the missed call to fix it.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Reviewed-by: Amelie Delaunay <amelie.delaunay@st.com>
Link: https://lore.kernel.org/r/20191205160655.32188-1-hslester96@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: use devm_platform_ioremap_resource() to simplify code

Use devm_platform_ioremap_resource() to simplify the code a bit.
This is detected by coccinelle.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20191006102953.57536-2-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-3-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-4-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-5-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-6-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-7-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-8-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-9-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-10-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-11-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-12-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-13-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-14-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-15-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-16-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-17-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-18-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-19-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-20-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-21-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-22-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-23-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-24-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-25-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-26-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-27-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-28-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-29-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-30-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-31-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-32-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-33-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-34-yuehaibing@huawei.com
Link: https://lore.kernel.org/r/20191006102953.57536-35-yuehaibing@huawei.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: Remove dev_err() usage after platform_get_irq()

We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.

// <smpl>
@@
expression ret;
struct platform_device *E;
@@

ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);

if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>

While we're here, remove braces on if statements that only have one
statement (manually).

Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: linux-rtc@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20190730181557.90391-40-swboyd@chromium.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: remove one condition check in stm32_rtc_set_alarm()

A condition check was repeated in this function implementation despite of
a corresponding check in the stm32_rtc_alarm_irq_enable() function.
Thus delete redundant source code here.

This issue was detected by using the Coccinelle software.

Suggested-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Amelie Delaunay <amelie.delaunay@st.com>
Link: https://lore.kernel.org/r/4da614a4-83c6-548c-a112-033b846c561b@web.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: manage the get_irq probe defer case

Manage the -EPROBE_DEFER error case for the wake IRQ.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Acked-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: add stm32mp1 rtc support

This patch adds support for stm32mp1 RTC.
Some common registers with previous RTC version have a different offset.
It is the case for Control Register (CR) and ALaRMA Register (ALRMAR).
There are also new registers regarding event flags: now, Alarm event flag
is in Status Register (SR) and write 1 in Status Clear Register (SCR) is
required to clear the event.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: rework register management to prepare other version of RTC

This patch reworks register/bits management because next version of RTC
uses the same way of working but with different register's offset or bits
moved in new registers.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: fix misspelling and misalignment issues

This patch cleans the following checkpatch complaints:

CHECK: 'initalized' may be misspelled - perhaps 'initialized'?
#644: FILE: drivers/rtc/rtc-stm32.c:644:
+ * the calendar has been initalized or not. INITS flag is reset by a

CHECK: Alignment should match open parenthesis
#669: FILE: drivers/rtc/rtc-stm32.c:669:
+ rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
+ &stm32_rtc_ops, THIS_MODULE);

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: get DBP register and mask from DT st, syscfg property

RTC driver should not be aware of the PWR registers offset and bits
position. Furthermore, we can imagine that DBP relative register and bit
mask could change depending on the SoC.
So this patch introduces 2 parameters, dbp_reg and dbp_mask, allowing to
get PWR_CR and PWR_CR_DBP from device tree. And it prepares next RTC
version, backup domain write protection is disabled only if needed.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: fix alarm interrupt flags by removing IRQF_TRIGGER_RISING

RTC alarm interrupt is active high and already configured by device tree.
So remove IRQF_TRIGGER_RISING from driver.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: fix copyright and adopt SPDX identifier

Fix copyright by removing "SA" and "for STMicroelectronics", not required.
Adopt SPDX identifier.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: stm32: Fix copyright

Uniformize STMicroelectronics copyrights header

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
CC: Amelie Delaunay <amelie.delaunay@st.com>
Acked-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: stm32: add STM32H7 RTC support

This patch adds support for STM32H7 RTC. On STM32H7, the RTC bus interface
clock (APB clock) needs to be enabled.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: stm32: fix comparison warnings

This patches fixes comparison between signed and unsigned values as it
could produce an incorrect result when the signed value is converted to
unsigned:

drivers/rtc/rtc-stm32.c: In function 'stm32_rtc_valid_alrm':
drivers/rtc/rtc-stm32.c:404:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
if ((((tm->tm_year > cur_year) &&
...

It also fixes comparison always true or false due to the fact that unsigned
value is compared against zero with >= or <:

drivers/rtc/rtc-stm32.c: In function 'stm32_rtc_init':
drivers/rtc/rtc-stm32.c:514:35: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
for (pred_a = pred_a_max; pred_a >= 0; pred_a-- ) {

drivers/rtc/rtc-stm32.c:530:44: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
(rate - ((pred_a + 1) * (pred_s + 1)) < 0) ?

Fixes: 4e64350f42e2 ("rtc: add STM32 RTC driver")
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: stm32: use 0 instead of ~PWR_CR_DBP in regmap_update_bits

Using the ~ operator on a BIT() constant results in a large 'unsigned long'
constant that won't fit into an 'unsigned int' function argument on 64-bit
architectures, resulting in a harmless build warning in x86 allmodconfig:

drivers/rtc/rtc-stm32.c: In function 'stm32_rtc_probe':
drivers/rtc/rtc-stm32.c:651:51: error: large integer implicitly truncated to unsigned type [-Werror=overflow]
regmap_update_bits(rtc->dbp, PWR_CR, PWR_CR_DBP, ~PWR_CR_DBP);

As PWR_CR_DBP mask prevents other bits to be cleared, replace all
~PWR_CR_DBP by 0.

Fixes: 4e64350f42e2 ("rtc: add STM32 RTC driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: stm32: fix building without CONFIG_OF

The new driver has a stray #ifdef in it that causes a build error:

drivers/rtc/rtc-stm32.c:718:21: error: 'stm32_rtc_of_match' undeclared here (not in a function); did you mean 'stm32_rtc_pm_ops'?

As the #ifdef serves no purpose here, let's just remove it.

Fixes: 4e64350f42e2 ("rtc: add STM32 RTC driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: stm32: remove __exit annotation on remove callback

The remove function can be called at runtime for a manual 'unbind'
operation and must not be left out from a built-in driver, as kbuild
complains:

`stm32_rtc_remove' referenced in section `.data.stm32_rtc_driver' of drivers/rtc/rtc-stm32.o: defined in discarded section `.exit.text' of drivers/rtc/rtc-stm32.o

This removes the extraneous annotation.

Fixes: 4e64350f42e2 ("rtc: add STM32 RTC driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: add STM32 RTC driver

This patch adds support for the STM32 RTC.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>