[S390] rework idle code

Whenever the cpu loads an enabled wait PSW it will appear as idle to the
underlying host system. The code in default_idle calls vtime_stop_cpu
which does the necessary voodoo to get the cpu time accounting right.
The udelay code just loads an enabled wait PSW. To correct this rework
the vtime_stop_cpu/vtime_start_cpu logic and move the difficult parts
to entry[64].S, vtime_stop_cpu can now be called from anywhere and
vtime_start_cpu is gone. The correction of the cpu time during wakeup
from an enabled wait PSW is done with a critical section in entry[64].S.
As vtime_start_cpu is gone, s390_idle_check can be removed as well.

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

1 files changed, 14 insertions, 17 deletions

diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index db92f044024c..9f1f71e85778 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -13,6 +13,7 @@
 #include <linux/irqflags.h>
 #include <linux/interrupt.h>
 #include <asm/div64.h>
+#include <asm/timer.h>
 
 void __delay(unsigned long loops)
 {
@@ -28,36 +29,33 @@ void __delay(unsigned long loops)
 
 static void __udelay_disabled(unsigned long long usecs)
 {
-        unsigned long mask, cr0, cr0_saved;
-        u64 clock_saved;
-        u64 end;
+        unsigned long cr0, cr6, new;
+        u64 clock_saved, end;
 
-        mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_WAIT |
-                PSW_MASK_EXT | PSW_MASK_MCHECK;
         end = get_clock() + (usecs << 12);
         clock_saved = local_tick_disable();
-        __ctl_store(cr0_saved, 0, 0);
-        cr0 = (cr0_saved & 0xffff00e0) | 0x00000800;
-        __ctl_load(cr0 , 0, 0);
+        __ctl_store(cr0, 0, 0);
+        __ctl_store(cr6, 6, 6);
+        new = (cr0 &  0xffff00e0) | 0x00000800;
+        __ctl_load(new , 0, 0);
+        new = 0;
+        __ctl_load(new, 6, 6);
         lockdep_off();
         do {
                 set_clock_comparator(end);
-                trace_hardirqs_on();
-                __load_psw_mask(mask);
+                vtime_stop_cpu();
                 local_irq_disable();
         } while (get_clock() < end);
         lockdep_on();
-        __ctl_load(cr0_saved, 0, 0);
+        __ctl_load(cr0, 0, 0);
+        __ctl_load(cr6, 6, 6);
         local_tick_enable(clock_saved);
 }
 
 static void __udelay_enabled(unsigned long long usecs)
 {
-        unsigned long mask;
-        u64 clock_saved;
-        u64 end;
+        u64 clock_saved, end;
 
-        mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
         end = get_clock() + (usecs << 12);
         do {
                 clock_saved = 0;
@@ -65,8 +63,7 @@ static void __udelay_enabled(unsigned long long usecs)
                         clock_saved = local_tick_disable();
                         set_clock_comparator(end);
                 }
-                trace_hardirqs_on();
-                __load_psw_mask(mask);
+                vtime_stop_cpu();
                 local_irq_disable();
                 if (clock_saved)
                         local_tick_enable(clock_saved);