rtc: ds1685: drop no_irq

No platforms are currently setting no_irq. Anyway, letting platform_get_irq
fail is fine as this means that there is no IRQ. In that case, clear
RTC_FEATURE_ALARM so the core knows there are no alarms.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220309162301.61679-2-alexandre.belloni@bootlin.com

rtc: ds1685: add indirect access method and remove plat_read/plat_write

SGI Octane (IP30) doesn't have RTC register directly mapped into CPU
address space, but accesses RTC registers with an address and data
register. This is now supported by additional access functions, which
are selected by a new field in platform data. Removed plat_read/plat_write
since there is no user and their usage could introduce lifetime issue,
when functions are placed in different modules.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Acked-by: Joshua Kinard <kumba@gentoo.org>
Reviewed-by: Joshua Kinard <kumba@gentoo.org>
Link: https://lore.kernel.org/r/20191014214621.25257-1-tbogendoerfer@suse.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: ds1685: use devm_platform_ioremap_resource helper

Simplify ioremapping of registers by using devm_platform_ioremap_resource.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Acked-by: Joshua Kinard <kumba@gentoo.org>
Link: https://lore.kernel.org/r/20191011150546.9186-2-tbogendoerfer@suse.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rts: ds1685: remove not needed fields from private struct

A few of the fields in struct ds1685_priv aren't needed at all,
so we can remove it.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Acked-by: Joshua Kinard <kumba@gentoo.org>
Link: https://lore.kernel.org/r/20191011150546.9186-1-tbogendoerfer@suse.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rtc: ds1685: use threaded interrupt

Handling of extended interrupts (kickstart, wake-up, ram-clear) was
moved off to a work queue, but the interrupts aren't acknowledged
in the interrupt handler. This leads to a deadlock, if driver
is used with interrupts. To fix this we use a threaded interrupt, get rid
of the work queue and do locking with just the rtc mutex lock.

Fixes: aaaf5fbf56f1 ("rtc: add driver for DS1685 family of real time clocks")
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: add driver for DS1685 family of real time clocks

This adds a driver for the Dallas/Maxim DS1685-family of RTC chips. It
supports the DS1685/DS1687, DS1688/DS1691, DS1689/DS1693, DS17285/DS17287,
DS17485/DS17487, and DS17885/DS17887 RTC chips. These chips are commonly
found in SGI O2 and SGI Octane systems. It was originally derived from a
driver patch submitted by Matthias Fuchs many years ago for use in
EPPC-405-UC modules, which also used these RTCs. In addition to the
time-keeping functions, this RTC also handles the shutdown mechanism of
the O2 and Octane and acts as a partial NVRAM for the boot PROMS in these
systems.

Verified on both an SGI O2 and an SGI Octane.

Signed-off-by: Joshua Kinard <kumba@gentoo.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>