Enable real-time-clock support in sandbox.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a driver which communicates with the sandbox I2C emulation RTC device
and permits it to be used in U-Boot. This driver is very simple - it just
reads and writes selected I2C registers in the device.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a sandbox I2C emulation device which emulates a real-time clock. The
clock works off an offset from the current system time, and supports setting
and getting the clock, as well as access to byte-width regisers in the RTC.
It does not support changing the system time.

This device can be used for testing the 'date' command on sandbox, as well
as the RTC uclass.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a uclass for real-time clocks which support getting the current time,
setting it and resetting the chip to a known-working state. Some RTCs have
additional registers which can be used to store settings, so also provide
an interface to these.

Signed-off-by: Simon Glass <sjg@chromium.org>

Most callers unpack the structure and pass each member. It seems better to
pass the whole structure instead, as with the C library. Also add an rtc_
prefix.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

Rename this function so that it is clear that it is provided by the RTC.
Also return an error when it cannot function as expected. This is unlikely
to occur since it works for dates since 1752 and many RTCs do not support
such old dates. Still it is better to be accurate.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

Change this function name to something more descriptive. Also return a
failure code if it cannot calculate a correct value.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

Various files are needlessly rebuilt every time due to the version and
build time changing. As version.h is not actually needed, remove the
include.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Tom Warren <twarren@nvidia.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Macpaul Lin <macpaul@andestech.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: York Sun <yorksun@freescale.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Philippe Reynes <tremyfr@yahoo.fr>
Cc: Eric Jarrige <eric.jarrige@armadeus.org>
Cc: "David Müller" <d.mueller@elsoft.ch>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Robert Baldyga <r.baldyga@samsung.com>
Cc: Torsten Koschorrek <koschorrek@synertronixx.de>
Cc: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Łukasz Majewski <l.majewski@samsung.com>

On x86 we use CMOS RAM to read and write some settings. Add basic support
for this, including access to registers 128-255.

Signed-off-by: Simon Glass <sjg@chromium.org>

These boards are still non-generic boards.

drivers/rtc/ds12887.c should also be removed because it can not
be built without CONFIG_ATC.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Wolfgang Denk <wd@denx.de>