While the year is encoded on 32 bits in SYS_TOYWRITE1i/SYS_TOYREAD1. The
Loongson 1c datasheet states that the range is from 0 to 99.

The current code exceeds this range and seems to be working, I deduce that
the leap year algorithm will fail in 2100.

Anyway, alarm registers only encode the year on 14 bits so with alarm
support, the range will always be limited to 0 to 16383.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The error handling in ls1x_rtc_probe used to release resources but since
it is using devm functions, it only returns a value. Make the code clearer
by returning directly instead of using goto.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

This allows for future improvement of the driver.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Let the core handle offsetting and windowing the RTC range.

The RTC has a 40-bit counter counting at 1024 Hz. So its maximum value is
2^(40-10) - 1. Also, let the core handle the offset instead of coding it in
the callbacks. Keep the default epoch at the beginning of 2009 (this will
fail in 2043).
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The probe function is not allowed to fail after the RTC is registered
because the following may happen:

CPU0:                                CPU1:
sys_load_module()
 do_init_module()
  do_one_initcall()
   cmos_do_probe()
    rtc_device_register()
     __register_chrdev()
     cdev->owner = struct module*
                                     open("/dev/rtc0")
    rtc_device_unregister()
  module_put()
  free_module()
   module_free(mod->module_core)
   /* struct module *module is now
      freed */
                                      chrdev_open()
                                       spin_lock(cdev_lock)
                                       cdev_get()
                                        try_module_get()
                                         module_is_live()
                                         /* dereferences already
                                            freed struct module* */
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The vr41xx RTC is a 48-bit counter counting at 32.768 kHz, giving a maximum
value of 2^(48-15)-1 seconds.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The probe function is not allowed to fail after the RTC is registered
because the following may happen:

CPU0:                                CPU1:
sys_load_module()
 do_init_module()
  do_one_initcall()
   cmos_do_probe()
    rtc_device_register()
     __register_chrdev()
     cdev->owner = struct module*
                                     open("/dev/rtc0")
    rtc_device_unregister()
  module_put()
  free_module()
   module_free(mod->module_core)
   /* struct module *module is now
      freed */
                                      chrdev_open()
                                       spin_lock(cdev_lock)
                                       cdev_get()
                                        try_module_get()
                                         module_is_live()
                                         /* dereferences already
                                            freed struct module* */
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Switch to regmap to simplify handling block read/write.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Return an error when the date is unreliable because the battery is low.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The rx8581_driver forward declaration is useless, remove it.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

rx8581_get_datetime and rx8581_set_datetime are only used after casting dev
to an i2c_client. Remove that useless indirection.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Let the core handle offsetting and windowing the RTC range.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The rx8581 can support dates from 01/01/2000 to 31/12/2099.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

This allows for future improvement of the driver.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The tps65910 RTC can support dates from 01/01/2000 to 31/12/2099.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Currently, the IRQs are disabled when the rtc driver is removed (e.g. when
shutting down the platform).
This means that the RTC will be unable to power up the platform.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler. This may lead to a NULL pointer
dereference.

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The ab-b5ze-s3 RTC is storing the year in an 8bit bcd coded register so it
can handle dates from year 2000 to year 2099.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler. This may lead to a NULL pointer
dereference.

Also, the probe function is not allowed to fail after the RTC is registered
because the following may happen:

CPU0:                                CPU1:
sys_load_module()
 do_init_module()
  do_one_initcall()
   cmos_do_probe()
    rtc_device_register()
     __register_chrdev()
     cdev->owner = struct module*
                                     open("/dev/rtc0")
    rtc_device_unregister()
  module_put()
  free_module()
   module_free(mod->module_core)
   /* struct module *module is now
      freed */
                                      chrdev_open()
                                       spin_lock(cdev_lock)
                                       cdev_get()
                                        try_module_get()
                                         module_is_live()
                                         /* dereferences already
                                            freed struct module* */

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ and register the RTC as late as possible.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Now that the RTC range is properly checked, convert the driver to
rtc_tm_to_time64/rtc_time64_to_tm
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The 88pm80x RTC is storing the time as a 32bit offset from a 32bit counter
so it can handle dates from 0 to U32_MAX.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The IRQ is requested before the struct rtc is allocated and registered, but
this struct is used in the IRQ handler. This may lead to a NULL pointer
dereference.

Switch to devm_rtc_allocate_device/rtc_register_device to allocate the rtc
before requesting the IRQ.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

pm80x_rtc_info.calib_work and pm80x_rtc_info.vrtc are never used, remove
them.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

It doesn't make sense to set the RTC to a default value at probe time. Let
the core handle invalid date and time.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The at91rm9200 RTC can support dates from 1900-01-01 00:00:00 to 2099-12-31
23:59:59.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Avoid reporting an error when RTC_NVMEM is not selected.
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

According to Devicetree Specification v0.2 document:

"The name of a node should be somewhat generic, reflecting the function
of the device and not its precise programming model."

Do as suggested in the binding example.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

RTC driver should not be aware of the PWR registers offset and bits
position. Furthermore, we can imagine that DBP relative register and bit
mask could change depending on the SoC.
So this patch introduces 2 parameters, dbp_reg and dbp_mask, allowing to
get PWR_CR and PWR_CR_DBP from device tree. And it prepares next RTC
version, backup domain write protection is disabled only if needed.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

RTC driver should not be aware of the PWR registers offset and bits
position. Furthermore, we can imagine that Disable Backup Protection (DBP)
relative register and bit mask could change depending on the SoC. So this
patch moves st,syscfg property from single pwrcfg phandle to pwrcfg
phandle/offset/mask triplet.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Acked-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

RTC alarm interrupt is active high and already configured by device tree.
So remove IRQF_TRIGGER_RISING from driver.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Fix copyright by removing "SA" and "for STMicroelectronics", not required.
Adopt SPDX identifier.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The tps6586x use a 64-bit 'epoch_start' value, but then computes that
value using an 'mktime()', which has a smaller range and overflows
in 2106 at the latest. As both the hardware and the subsystem interface
support wider than 32-bit ranges for rtc times here, let's change all
the operations on 'seconds' to time64_t.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The loongson1 platform is 32-bit, so storing a time value in 32 bits
suffers from limited range. In this case it is likely to be correct
until 2106, but it's better to avoid the limitation and just use
the time64_t based mktime64() and rtc_time64_to_tm() interfaces.

The hardware uses a 32-bit year number, and time64_t can cover that
entire range.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

This driver uses mktime() and rtc_time_to_tm() to convert between time
values. This works fine on 64-bit kernels over the whole supported
range, and the vr41xx chip is a 64-bit MIPS implementation, but it is
inconsistent because it doesn't do the same thing on 32-bit kernels that
overflow in 2106 or 2038.

Changing it to use mktime64/rtc_time64_to_tm() should have no visible
impact on vr41xx but gets us closer to removing the 32-bit interfaces.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Add support Dallas DS1340 trickle charger function.
Signed-off-by: Andrea Greco <a.greco@4sigma.it>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

The SC27xx RTC can support dates from 1970-01-01 00:00:00 to 2149-06-06
23:59:59.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

This is a preparation patch, changing to use devm_rtc_allocate_device()
that can allow driver to set 'range_max' and 'range_min' for the RTC
device.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

We should get drvdata from struct device directly. Going via
platform_device is an unneeded step back and forth.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Michal Simek <michal.simek@xilinx.com> (for zynqmp)
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Use ACPI for RTC Alarm only for Intel platforms
1. with Low Power S0 support
2. with HPET RTC emulation enabled
3. no earlier than 2015

Note that, during the test, it is found that this patch
1. works in 4.15-rc kernel
2. hangs the platform after suspend-to-idle for 2 or 3 times, in 4.15.0
3. works again in 4.16-rc3 kernel.
4. works in the latest 4.15.12 stable kernel.

Thus although this patch breaks 4.15.0 kernel for some unknown reason,
still, it is safe for both upstream and backport.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Previously, the RTC alarm is acknowledged either by the cmos rtc irq
handler, or by the hpet rtc irq handler.

When using ACPI RTC Fixed event as the RTC alarm, the RTC alarm is
acknowledged by the ACPI RTC event handler, as addressed in the previous
patch.
But, when resume from suspend-to-ram (ACPI S3), the ACPI SCI is cleared
right after resume, thus the ACPI RTC event handler is not invoked at all,
results in the RTC Alarm unacknowledged.

Handle this by comparing the current time and the RTC Alarm time in the
rtc_cmos driver .resume() callback
1. Assume the wakeup event has already been fired if the RTC Alarm time
   is earlier than/equal to the current time, and ACK the RTC Alarm.
2. Assume the wakeup event has not been fired if the RTC Alarm time
   is later than current time, and re-arm it if needed.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>