rtc: rzn1: Report maximum alarm limit to rtc core

RZN1 only supports alarms up to one week in the future.
Report the limit to the RTC core and use the reported limit
to validate the requested alarm time when setting it.

Cc: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230817225537.4053865-8-linux@roeck-us.net
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: rzn1: 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>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230304133028.2135435-29-u.kleine-koenig@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: rzn1: Check return value in rzn1_rtc_probe

The rzn1_rtc_probe() function utilizes devm_pm_runtime_enable()
but wasn't checking the return value. Fix it by adding missing
check.

Fixes: deeb4b5393e1 ("rtc: rzn1: Add new RTC driver")

Signed-off-by: Yushan Zhou <katrinzhou@tencent.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20221107092544.3721053-1-zys.zljxml@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: rzn1: Fix a variable type

The calculation in ->set_offset() handles both negative and positive
offsets. The 'steps' variable will be checked to be in a specific [-x;
+x] range, which means it must be a signed integer rather than
unsigned.

This also fixes the following smatch warning:

warn: 'steps' 'true' implies 'steps > 0' is 'true'

Fixes: be4a11cf98af ("rtc: rzn1: Add oscillator offset support")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220520082500.489248-1-miquel.raynal@bootlin.com

rtc: rzn1: Fix error code in probe

There is a copy and paste error so this code returns the wrong variable.

Fixes: deeb4b5393e1 ("rtc: rzn1: Add new RTC driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/YoZMg1dmHHSJEfE9@kili

rtc: rzn1: Avoid mixing variables

In the ->set_offset() callback, the 'val' variable is used for two
different purposes at the same time, which is oviously wrong:
- It contains the intermediate value of the SUBU register that must be
written at the end of ->set_offset().
- It is used in the middle of the above calculations to poll the CTL2
register for a specific value.

Let's introduce a 'ctl2' variable just for the readl_poll_timeout()
call and use it there in place of 'var'.

In order to avoid mixing those two variables again, let's rename the
remaining occurences of 'val' into 'subu' and initialize it to 0 to
avoid the uninitialized variable situation reported by Tom Rix and Colin
Ian King already.

Fixes: be4a11cf98af ("rtc: rzn1: Add oscillator offset support")
Reported-by: Tom Rix <trix@redhat.com>
Reported-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220520082221.488849-1-miquel.raynal@bootlin.com

rtc: rzn1: fix platform_no_drv_owner.cocci warning

Remove .owner field if calls are used which set it automatically.
./drivers/rtc/rtc-rzn1.c:411:3-8: No need to set .owner here. The core
will do it.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220518232445.79156-1-yang.lee@linux.alibaba.com

rtc: rzn1: Add oscillator offset support

The RZN1 RTC can compensate the imprecision of the oscillator up to
approximately 190ppm.

Seconds can last slightly shorter or longer depending on the
configuration.

Below ~65ppm of correction, we can change the time spent in a second
every minute, which is the most accurate compensation that the RTC can
offer. Above, the compensation will be active every 20s.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220516082504.33913-5-miquel.raynal@bootlin.com

rtc: rzn1: Add alarm support

The RZN1 RTC can trigger an interrupt when reaching a particular date up
to 7 days ahead. Bring support for this alarm.

One drawback though, the granularity is about a minute.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220516082504.33913-4-miquel.raynal@bootlin.com

rtc: rzn1: Add new RTC driver

Add a basic RTC driver for the RZ/N1.

Signed-off-by: Michel Pollet <michel.pollet@bp.renesas.com>
Co-developed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220516082504.33913-3-miquel.raynal@bootlin.com