s390/time: Convert MACHINE_HAS_SCC to machine_has_scc()

Use static branch(es) to implement and use machine_has_scc() instead
of a runtime check via MACHINE_HAS_SCC.

This comes with a cleanup of early time initialization: the initial
tod_clock_base value is now passed via the bootdata mechanism, instead
of using absolute lowcore as transport vehicle from the decompressor
to the kernel.

Also the early tod clock initialization is moved to the decompressor
which allows to use a static branch with machine_has_scc() within the
kernel.

Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index e9f47c3a6197..ac58b1db40e6 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -54,10 +54,10 @@
 #include <asm/cio.h>
 #include "entry.h"
 
-union tod_clock tod_clock_base __section(".data");
+union tod_clock __bootdata_preserved(tod_clock_base);
 EXPORT_SYMBOL_GPL(tod_clock_base);
 
-u64 clock_comparator_max = -1ULL;
+u64 __bootdata_preserved(clock_comparator_max);
 EXPORT_SYMBOL_GPL(clock_comparator_max);
 
 static DEFINE_PER_CPU(struct clock_event_device, comparators);