rtc: brcmstb-waketimer: support level alarm_irq

Some devices (e.g. BCM72112) use an alarm_irq interrupt that is
connected to a level interrupt controller rather than an edge
interrupt controller. In this case, the interrupt cannot be left
enabled by the irq handler while preserving the hardware wake-up
signal on wake capable devices or an interrupt storm will occur.

The alarm_expired flag is introduced to allow the disabling of
the interrupt when an alarm expires and to support balancing the
calls to disable_irq() and enable_irq() in accordance with the
existing design.

Fixes: 24304a87158a ("rtc: brcmstb-waketimer: allow use as non-wake alarm")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230830224747.1663044-1-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: 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/20230304133028.2135435-8-u.kleine-koenig@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: allow use as non-wake alarm

The wake interrupt only fires when the system is in a suspend
state. Fortunately we have another interrupt that fires in a
non-suspend state at the L2 controller UPG_AUX_AON. Add support
for this interrupt line so we can use the alarm in a non-wake
context.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230124201430.2502371-3-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: rename irq to wake_irq

In preparation for adding a second interrupt to service RTC
interrupts, the existing interrupt is renamed from the generic
'irq' to 'wake_irq' to more clearly convey its role.

It is also converted to an unsigned int.

Finally, the driver message that outputs the IRQ number when
registered is removed since devm_rtc_register_device() already
provides a report of registration and the interrupts can be
found in /proc/interrupts.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230120190147.718976-5-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: compensate for lack of wktmr disable

Since the WKTMR hardware block cannot be disabled it is necessary
for the driver to accommodate for associated timing hazards. This
commit targets the following possibilities:

A possible race between clearing a wktmr event and the alarm expiring
is made one-sided by setting the alarm to its maximum value before
clearing the event.

Programming alarm values close to the current time may not trigger
events if the counter advances while the alarm is being programmed.
After programming an alarm, a check is made to ensure that it is
either in the future or an expiration event is pending.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230120190147.718976-4-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: non-functional code changes

These changes are not intended to affect functionality, but
simplify the source code. They are performed here to simplify
review and reduce confusion with other changes in this set.

Since set_alarm includes the alarm_irq_enable functionality call
it directly from that function for simplicity (even though it
does nothing at the moment). The order of the declarations is
changed to prevent the need for a prototype.

The function device_init_wakeup() is used to replace the
functions device_set_wakeup_capable() and device_wakeup_enable()
since it is equivalent.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230120190147.718976-3-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: introduce WKTMR_ALARM_EVENT flag

This commit defines bit 0 as the bit of interest within the
BRCMSTB_WKTMR_EVENT register to make the implementation more
readable.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230120190147.718976-2-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: quiet maybe-unused variable warning

When CONFIG_OF is disabled then the matching table is not referenced.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210202112219.3610853-5-alexandre.belloni@bootlin.com

rtc: rework rtc_register_device() resource management

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

rtc: brcmstb-waketimer: Remove redundant null check before clk_disable_unprepare

Because clk_disable_unprepare() already checked NULL clock parameter,
so the additional check is unnecessary, just remove it.

Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201113074538.65028-1-vulab@iscas.ac.cn

rtc: brcmstb-waketimer: add missed clk_disable_unprepare

This driver forgets to disable and unprepare clock when remove.
Add a call to clk_disable_unprepare to fix it.

Fixes: c4f07ecee22e ("rtc: brcmstb-waketimer: Add Broadcom STB wake-timer")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20191105160043.20018-1-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 superfluous error message

The RTC core now has error messages in case of registration failure, there
is no need to have other messages in the drivers.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20190818220041.17833-2-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174

Based on 1 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
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 655 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070034.575739538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rtc: brcmstb-waketimer: switch to rtc_time64_to_tm

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

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: add range

Let the core handle the range.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: switch to rtc_register_device

Switch to devm_rtc_allocate_device/rtc_register_device.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: Set wktmr prescaler

The HW default is one tick per second, however instead of assuming this,
lets make sure the waketimer is actually one tick per second before
arming the alarm.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rtc: brcmstb-waketimer: fix error handling in brcmstb_waketmr_probe()

brcmstb_waketmr_probe() does not disable timer->clk on error paths.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: c4f07ecee22e ("rtc: brcmstb-waketimer: Add Broadcom STB wake-timer")
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

rtc: brcmstb-waketimer: Add Broadcom STB wake-timer

This adds support for the Broadcom STB wake-timer which is a timer in
the chip's 27Mhz clock domain that offers the ability to wake the system
(wake-up source) from suspend states (S2, S3, S5). It is supported using
the rtc framework allowing us to configure alarms for system wake-up.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>