linux-toradex.git/drivers/rtc/class.c, branch v4.15-rc1

rtc: Allow rtc drivers to specify the tv_nsec value for ntp

2017-10-30T22:03:24+00:00

ntp is currently hardwired to try and call the rtc set when wall clock
tv_nsec is 0.5 seconds. This historical behaviour works well with certain
PC RTCs, but is not universal to all rtc hardware.

Change how this works by introducing the driver specific concept of
set_offset_nsec, the delay between current wall clock time and the target
time to set (with a 0 tv_nsecs).

For x86-style CMOS set_offset_nsec should be -0.5 s which causes the last
second to be written 0.5 s after it has started.

For compat with the old rtc_set_ntp_time, the value is defaulted to
+ 0.5 s, which causes the next second to be written 0.5s before it starts,
as things were before this patch.

Testing shows many non-x86 RTCs would like set_offset_nsec ~= 0,
so ultimately each RTC driver should set the set_offset_nsec according
to its needs, and non x86 architectures should stop using
update_persistent_clock64 in order to access this feature.
Future patches will revise the drivers as needed.

Since CMOS and RTC now have very different handling they are split
into two dedicated code paths, sharing the support code, and ifdefs
are replaced with IS_ENABLED.

Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Miroslav Lichvar 
Cc: Richard Cochran 
Cc: Prarit Bhargava 
Cc: Stephen Boyd 
Signed-off-by: Jason Gunthorpe 
Signed-off-by: John Stultz

rtc: add generic nvmem support

2017-07-07T11:14:14+00:00

Many RTCs have an on board non volatile storage. It can be battery backed
RAM or an EEPROM. Use the nvmem subsystem to export it to both userspace
and in-kernel consumers.

This stays compatible with the previous (non documented) ABI that was using
/sys/class/rtc/rtcx/device/nvram to export that memory. But will warn about
the deprecation.

Signed-off-by: Alexandre Belloni

rtc: introduce new registration method

2017-07-07T11:14:10+00:00

Introduce rtc_register_device() to register an already allocated and
initialized struct rtc_device. It automatically sets up the owner and the
two steps allocation/registration will allow to remove race conditions in
the IRQ handling of some driver. It also allows to properly extend the core
without adding more arguments to rtc_device_register().

Signed-off-by: Alexandre Belloni

rtc: class separate id allocation from registration

2017-07-07T11:14:08+00:00

Create rtc_device_get_id to allocate the id for an RTC.

Signed-off-by: Alexandre Belloni

rtc: class separate device allocation from registration

2017-07-07T11:14:06+00:00

Create rtc_allocate_device to allocate memory for a struct rtc_device and
initialize it.

Signed-off-by: Alexandre Belloni

rtc: remove rtc_device.name

2017-06-03T08:55:36+00:00

rtc->name is only used in messages were it is superfluous. Remove it
completely from the structure.

Signed-off-by: Alexandre Belloni

rtc: utilize new cdev_device_add helper function

2017-03-21T05:44:33+00:00

Mostly straightforward, but we had to remove the rtc_dev_add/del_device
functions as they split up the cdev_add and the device_add.

Doing this also revealed that there was likely another subtle bug:
seeing cdev_add was done after device_register, the cdev probably
was not ready before device_add when the uevent occurs. This would
race with userspace, if it tried to use the device directly after
the uevent. This is fixed just by using the new helper function.

Another weird thing is this driver would, in some error cases, call
cdev_add() without calling cdev_init. This patchset corrects this
by avoiding calling cdev_add if the devt is not set.

Signed-off-by: Logan Gunthorpe 
Acked-by: Alexandre Belloni 
Signed-off-by: Greg Kroah-Hartman

rtc: make class.c explicitly non-modular

2016-03-14T16:08:18+00:00

The Makefile/Kconfig currently controlling compilation of this code is:

obj-$(CONFIG_RTC_CLASS)         += rtc-core.o
rtc-core-y                      := class.o interface.o

drivers/rtc/Kconfig:menuconfig RTC_CLASS
drivers/rtc/Kconfig:    bool "Real Time Clock"

...meaning that it currently is not being built as a module by anyone.

Lets remove the modular code that is essentially orphaned, so that
when reading the code there is no doubt it is builtin-only.

We don't replace module.h with init.h since the file does need
to know what a struct module is.

We also delete the MODULE_LICENSE tag etc. since all that information
is already contained at the top of the file in the comments.

Signed-off-by: Paul Gortmaker 
Signed-off-by: Alexandre Belloni

rtc: switch to using is_visible() to control sysfs attributes

2015-09-05T11:19:07+00:00

Instead of creating wakealarm attribute manually, after the device has been
registered, let's rely on facilities provided by the attribute groups to
control which attributes are visible and which are not. This allows to
create all needed attributes at once, at the same time that we register RTC
class device.

Signed-off-by: Dmitry Torokhov 
Reviewed-by: Krzysztof Kozlowski 
Signed-off-by: Alexandre Belloni

rtc: class: remove unnecessary device_get() in rtc_device_unregister

2015-09-05T11:19:07+00:00

Technically the address of rtc->dev can never be NULL, so get_device()
can never fail. Also caller of rtc_device_unregister() supposed to be
the owner of the device and thus have a valid reference. Therefore
call to get_device() is not needed here.

Signed-off-by: Dmitry Torokhov 
Reviewed-by: Krzysztof Kozlowski 
Signed-off-by: Alexandre Belloni