summaryrefslogtreecommitdiff
path: root/arch/s390/lib/delay.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/s390/lib/delay.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/s390/lib/delay.c')
-rw-r--r--arch/s390/lib/delay.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
new file mode 100644
index 000000000000..e96c35bddac7
--- /dev/null
+++ b/arch/s390/lib/delay.c
@@ -0,0 +1,51 @@
+/*
+ * arch/s390/kernel/delay.c
+ * Precise Delay Loops for S390
+ *
+ * S390 version
+ * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
+ *
+ * Derived from "arch/i386/lib/delay.c"
+ * Copyright (C) 1993 Linus Torvalds
+ * Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
+ */
+
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+
+#ifdef CONFIG_SMP
+#include <asm/smp.h>
+#endif
+
+void __delay(unsigned long loops)
+{
+ /*
+ * To end the bloody studid and useless discussion about the
+ * BogoMips number I took the liberty to define the __delay
+ * function in a way that that resulting BogoMips number will
+ * yield the megahertz number of the cpu. The important function
+ * is udelay and that is done using the tod clock. -- martin.
+ */
+ __asm__ __volatile__(
+ "0: brct %0,0b"
+ : /* no outputs */ : "r" (loops/2) );
+}
+
+/*
+ * Waits for 'usecs' microseconds using the tod clock, giving up the time slice
+ * of the virtual PU inbetween to avoid congestion.
+ */
+void __udelay(unsigned long usecs)
+{
+ uint64_t start_cc, end_cc;
+
+ if (usecs == 0)
+ return;
+ asm volatile ("STCK %0" : "=m" (start_cc));
+ do {
+ cpu_relax();
+ asm volatile ("STCK %0" : "=m" (end_cc));
+ } while (((end_cc - start_cc)/4096) < usecs);
+}