rtc_register_device() is a managed interface but it doesn't use devres
by itself - instead it marks an rtc_device as "registered" and the devres
callback for devm_rtc_allocate_device() takes care of resource release.

This doesn't correspond with the design behind devres where managed
structures should not be aware of being managed. The correct solution
here is to register a separate devres callback for unregistering the
device.

While at it: rename rtc_register_device() to devm_rtc_register_device()
and add it to the list of managed interfaces in devres.rst. This way we
can avoid any potential confusion of driver developers who may expect
there to exist a corresponding unregister function.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201109163409.24301-8-brgl@bgdev.pl

Converting from hardware to host endiannes was done using reassignment
to the same variable which makes sparse unhappy as it can not verify
the endiannes handling properly. To allow sparse to verify endiannes
handling an explicit __le32 is introduced. Note that this patch does
not change the generated binary (x86_64 and ppc64 binary diff).

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Use devm_add_action_or_reset to simplify .probe and remove .remove

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

There is only one ds2404_chip_ops struct that is implemented, remove the
unnecessary indirection.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Use SPDX-License-Identifier instead of a verbose license text.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Use .set_time instead of the deprecated .set_mmss.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Call the 64bit version of rtc_time_to_tm now that the range is enforced by
the core.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The real-time clock is a 5-byte binary counter. It is incremented 256 times
per second. The least significant byte is a count of fractional seconds.
The upper four bytes are a count of seconds. The realtime clock can
accumulate 136 years of seconds before rolling over.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The RTC core is always calling rtc_valid_tm after the read_time callback.
It is not necessary to call it just before returning from the callback.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc-ds2404.h belongs to include/linux/platform_data/

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>