Import genrtc's RTC UIE emulation (CONFIG_GEN_RTC_X) to rtc-dev driver with
slight adjustments/refinements.  This makes UIE-less rtc drivers work
better with programs doing read/poll on /dev/rtc, such as hwclock.  This
emulation should not harm rtc drivers with UIE support, since
rtc_dev_ioctl() calls underlaying rtc driver's ioctl() first.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: NAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Appropriately use -ENOIOCTLCMD and -ENOTTY when the ioctl is not
implemented by a driver.

(akpm: we're not allowed to return -ENOIOCTLCMD to userspace.  This patch does
the right thing).
Signed-off-by: NAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make rtc-dev work well on 64-bit platforms with 32-bit userland.  On those
platforms, users might try to read 32-bit integer value.  This patch make
rtc-dev's read() work well for both "int" and "long" size.  This tweak is came
from genrtc driver.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add the dev interface to the RTC subsystem.

Each RTC will be available under /dev/rtcX .  A symlink from /dev/rtc0 to
/dev/rtc cab be obtained with the following udev rule:

KERNEL=="rtc0", SYMLINK+="rtc"
Signed-off-by: NAlessandro Zummo <a.zummo@towertech.it>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>