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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/s390/lib/delay.c | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
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.c | 51 |
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); +} |