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>

It's found that the HPET timer prevents the platform from entering
Low Power S0 on some new Intel platforms.

This means that
1. users can still use RTC wake Alarm for suspend-to-idle, but the system
   never enters Low Power S0, which is a waste of power.
or
2. if users want to put the system into Low Power S0, they can not use
   RTC as the wakeup source.

To fix this, we need to stop using the HPET timer for wake alarm.
But disabling CONFIG_HPET_EMULATE_RTC is not an option because HPET
emulates PIT at the same time, and this is needed on some of these
platforms.

Thus, introduce a new mode (use_acpi_alarm) to the rtc_cmos driver,
so that, even with CONFIG_HPET_EMULATE_RTC enabled, it's still possible to
use ACPI SCI for RTC Alarm, including UIE/AIE/wkalrm, instead of HPET.

Only necessary changes are made for the new "use_acpi_alarm" mode, including
1. drop all the calls to HPET emulation code, including the HPET irq
   handler for rtc interrupt.
2. enabling/disabling ACPI RTC Fixed event upon RTC UIE/AIE request.
3. acknowledge the RTC Alarm in ACPI RTC Fixed event handler.

There is no functional change made in this patch if the new mode is not
enabled.

Note: this "use_acpi_alarm" mode is made based on the assumption that
ACPI RTC Fixed event is reliable both at runtime and during system wakeup.
And this has been verified on a couple of platforms I have, including
a MS Surface Pro 4 (SKL), a Lenovo Yoga 900 (SKL), and a HP 9360 (KBL).
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Pull more btrfs updates from David Sterba:
 "We have queued a few more fixes (error handling, log replay,
  softlockup) and the rest is SPDX updates that touche almost all files
  so the diffstat is long"

* tag 'for-4.17-part2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: Only check first key for committed tree blocks
  btrfs: add SPDX header to Kconfig
  btrfs: replace GPL boilerplate by SPDX -- sources
  btrfs: replace GPL boilerplate by SPDX -- headers
  Btrfs: fix loss of prealloc extents past i_size after fsync log replay
  Btrfs: clean up resources during umount after trans is aborted
  btrfs: Fix possible softlock on single core machines
  Btrfs: bail out on error during replay_dir_deletes
  Btrfs: fix NULL pointer dereference in log_dir_items

Pull cifs fixes from Steve French:
 "SMB3 fixes, a few for stable, and some important cleanup work from
  Ronnie of the smb3 transport code"

* tag '4.17-rc1SMB3-Fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: change validate_buf to validate_iov
  cifs: remove rfc1002 hardcoded constants from cifs_discard_remaining_data()
  cifs: Change SMB2_open to return an iov for the error parameter
  cifs: add resp_buf_size to the mid_q_entry structure
  smb3.11: replace a 4 with server->vals->header_preamble_size
  cifs: replace a 4 with server->vals->header_preamble_size
  cifs: add pdu_size to the TCP_Server_Info structure
  SMB311: Improve checking of negotiate security contexts
  SMB3: Fix length checking of SMB3.11 negotiate request
  CIFS: add ONCE flag for cifs_dbg type
  cifs: Use ULL suffix for 64-bit constant
  SMB3: Log at least once if tree connect fails during reconnect
  cifs: smb2pdu: Fix potential NULL pointer dereference