Some code, for example clocksource drivers, may want to use the vDSO
clockmode constants even when CONFIG_GENERIC_GETTIMEOFDAY=n.
But the symbols are completely hidden in that case, making ugly
ifdeffery necessary.

Always provide the enum definitions.

As not all architectures provide asm/vdso/clocksource.h,
provide an empty stub in asm-generic for it.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260724-vdso-arch-clockmodes-v4-2-ddbe447be860@linutronix.de

CONFIG_GENERIC_GETTIMEOFDAY is a sufficient condition to verify if an
architecture implements asm/vdso/clocksource.h or not. The current
implementation wrongly assumes that the same is true for the config
option CONFIG_ARCH_CLOCKSOURCE_DATA.

This results in a series of build errors on ia64/sparc/sparc64 like this:

  In file included from ./include/linux/clocksource.h:31,
                   from ./include/linux/clockchips.h:14,
                   from ./include/linux/tick.h:8,
                   from fs/proc/stat.c:15:
  ./include/vdso/clocksource.h:9:10: fatal error: asm/vdso/clocksource.h:
  No such file or directory
      9 | #include <asm/vdso/clocksource.h>
        |          ^~~~~~~~~~~~~~~~~~~~~~~~

Fix the issue removing the unneeded config condition.

Fixes: 14ee2ac618e4 ("linux/clocksource.h: Extract common header for vDSO")
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200323133920.46546-1-vincenzo.frascino@arm.com

The vDSO library should only include the necessary headers required for
a userspace library (UAPI and a minimal set of kernel headers). To make
this possible it is necessary to isolate from the kernel headers the
common parts that are strictly necessary to build the library.

Split clocksource.h into linux and common headers to make the latter
suitable for inclusion in the vDSO library.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200320145351.32292-9-vincenzo.frascino@arm.com