rtc: mpfs: 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: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230304133028.2135435-19-u.kleine-koenig@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: mpfs: Use devm_clk_get_enabled() helper

The devm_clk_get_enabled() helper:
- calls devm_clk_get()
- calls clk_prepare_enable() and registers what is needed in order to
call clk_disable_unprepare() when needed, as a managed resource.

This simplifies the code, the error handling paths and avoid the need of
a dedicated function used with devm_add_action_or_reset().

That said, mpfs_rtc_init_clk() is the same as devm_clk_get_enabled(), so
use this function directly instead.

This also fixes an (unlikely) unchecked devm_add_action_or_reset() error.

Based on my test with allyesconfig, this reduces the .o size from:
text data bss dec hex filename
5330 2208 0 7538 1d72 drivers/rtc/rtc-mpfs.o
down to:
5074 2208 0 7282 1c72 drivers/rtc/rtc-mpfs.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/e55c959f2821a2c367a4c5de529a638b1cc6b8cd.1661329086.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: mpfs: Remove printing of stray CR

During boot, the driver prints out a stray carriage return character.
Remove it, together with the preceding space character.

While at it, change prescaler to "unsigned long", as returned by
clk_get_rate(), to avoid truncating very large clock rates, and update
the format specifiers.

Fixes: 0b31d703598dc199 ("rtc: Add driver for Microchip PolarFire SoC")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/bce2ca405ef96b1363fd1370887409d9e8468422.1660659437.git.geert+renesas@glider.be

rtc: mpfs: remove 'pending' variable from mpfs_rtc_wakeup_irq_handler()

cppcheck reports
[drivers/rtc/rtc-mpfs.c:219]: (style) Variable 'pending' is assigned a value that is never used.

The fetched CONTROL_REG stored in pending is unused and partially
duplicates the functionality of the later call to mpfs_rtc_clear(). This looks
like leftover development code, so remove pending.

Fixes: 0b31d703598d ("rtc: Add driver for Microchip PolarFire SoC")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220627205943.2075043-1-trix@redhat.com

rtc: Add driver for Microchip PolarFire SoC

Add support for the built-in RTC on Microchip PolarFire SoC

Co-Developed-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220601123320.2861043-2-conor.dooley@microchip.com