[S390] Use CONFIG_GENERIC_TIME and define TOD clock source.

Fix too slow clock by using CONFIG_GENERIC_TIME and adding a
clock source for the s390 time-of-day clock. As added benefit
we get rid of the s390 specific definition of do_gettimeofday
and do_settimeofday.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 24 insertions, 68 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 51c2dfe89c62..608193cfe43f 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -30,6 +30,9 @@ config GENERIC_CALIBRATE_DELAY
         bool
         default y
 
+config GENERIC_TIME
+        def_bool y
+
 config GENERIC_BUST_SPINLOCK
         bool
 
diff --git a/arch/s390/defconfig b/arch/s390/defconfig
index b6cad75fd1f4..a3257398ea8d 100644
--- a/arch/s390/defconfig
+++ b/arch/s390/defconfig
@@ -9,6 +9,7 @@ CONFIG_STACKTRACE_SUPPORT=y
 CONFIG_RWSEM_XCHGADD_ALGORITHM=y
 CONFIG_GENERIC_HWEIGHT=y
 CONFIG_GENERIC_CALIBRATE_DELAY=y
+CONFIG_GENERIC_TIME=y
 CONFIG_S390=y
 CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
 
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 2c8c690688cb..6cceed4df73e 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -28,6 +28,7 @@
 #include <linux/profile.h>
 #include <linux/timex.h>
 #include <linux/notifier.h>
+#include <linux/clocksource.h>
 
 #include <asm/uaccess.h>
 #include <asm/delay.h>
@@ -82,74 +83,6 @@ void tod_to_timeval(__u64 todval, struct timespec *xtime)
         xtime->tv_nsec = ((todval * 1000) >> 12);
 }
 
-static inline unsigned long do_gettimeoffset(void) 
-{
-        __u64 now;
-
-        now = (get_clock() - jiffies_timer_cc) >> 12;
-        now -= (__u64) jiffies * USECS_PER_JIFFY;
-        return (unsigned long) now;
-}
-
-/*
- * This version of gettimeofday has microsecond resolution.
- */
-void do_gettimeofday(struct timeval *tv)
-{
-        unsigned long flags;
-        unsigned long seq;
-        unsigned long usec, sec;
-
-        do {
-                seq = read_seqbegin_irqsave(&xtime_lock, flags);
-
-                sec = xtime.tv_sec;
-                usec = xtime.tv_nsec / 1000 + do_gettimeoffset();
-        } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
-
-        while (usec >= 1000000) {
-                usec -= 1000000;
-                sec++;
-        }
-
-        tv->tv_sec = sec;
-        tv->tv_usec = usec;
-}
-
-EXPORT_SYMBOL(do_gettimeofday);
-
-int do_settimeofday(struct timespec *tv)
-{
-        time_t wtm_sec, sec = tv->tv_sec;
-        long wtm_nsec, nsec = tv->tv_nsec;
-
-        if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
-                return -EINVAL;
-
-        write_seqlock_irq(&xtime_lock);
-        /* This is revolting. We need to set the xtime.tv_nsec
-         * correctly. However, the value in this location is
-         * is value at the last tick.
-         * Discover what correction gettimeofday
-         * would have done, and then undo it!
-         */
-        nsec -= do_gettimeoffset() * 1000;
-
-        wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
-        wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
-
-        set_normalized_timespec(&xtime, sec, nsec);
-        set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
-
-        ntp_clear();
-        write_sequnlock_irq(&xtime_lock);
-        clock_was_set();
-        return 0;
-}
-
-EXPORT_SYMBOL(do_settimeofday);
-
-
 #ifdef CONFIG_PROFILING
 #define s390_do_profile()       profile_tick(CPU_PROFILING)
 #else
@@ -340,6 +273,22 @@ void init_cpu_timer(void)
 
 extern void vtime_init(void);
 
+static cycle_t read_tod_clock(void)
+{
+        return get_clock();
+}
+
+static struct clocksource clocksource_tod = {
+        .name           = "tod",
+        .rating         = 100,
+        .read           = read_tod_clock,
+        .mask           = -1ULL,
+        .mult           = 1000,
+        .shift          = 12,
+        .is_continuous  = 1,
+};
+
+
 /*
  * Initialize the TOD clock and the CPU timer of
  * the boot cpu.
@@ -384,6 +333,9 @@ void __init time_init(void)
                                               &ext_int_info_cc) != 0)
                 panic("Couldn't request external interrupt 0x1004");
 
+        if (clocksource_register(&clocksource_tod) != 0)
+                panic("Could not register TOD clock source");
+
         init_cpu_timer();
 
 #ifdef CONFIG_NO_IDLE_HZ