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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-ppc/delay.h | |
download | linux-fsl-qoriq-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-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 'include/asm-ppc/delay.h')
-rw-r--r-- | include/asm-ppc/delay.h | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/include/asm-ppc/delay.h b/include/asm-ppc/delay.h new file mode 100644 index 0000000..badde68 --- /dev/null +++ b/include/asm-ppc/delay.h @@ -0,0 +1,66 @@ +#ifdef __KERNEL__ +#ifndef _PPC_DELAY_H +#define _PPC_DELAY_H + +#include <asm/param.h> + +/* + * Copyright 1996, Paul Mackerras. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +extern unsigned long loops_per_jiffy; + +extern void __delay(unsigned int loops); + +/* + * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so + * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. + * + * The mulhwu instruction gives us loops = (a * b) / 2^32. + * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 + * because this lets us support a wide range of HZ and + * loops_per_jiffy values without either a or b overflowing 2^32. + * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and + * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 + * (which corresponds to ~3800 bogomips at HZ = 100). + * -- paulus + */ +#define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ +#define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ + +extern __inline__ void __udelay(unsigned int x) +{ + unsigned int loops; + + __asm__("mulhwu %0,%1,%2" : "=r" (loops) : + "r" (x), "r" (loops_per_jiffy * 226)); + __delay(loops); +} + +extern __inline__ void __ndelay(unsigned int x) +{ + unsigned int loops; + + __asm__("mulhwu %0,%1,%2" : "=r" (loops) : + "r" (x), "r" (loops_per_jiffy * 5)); + __delay(loops); +} + +extern void __bad_udelay(void); /* deliberately undefined */ +extern void __bad_ndelay(void); /* deliberately undefined */ + +#define udelay(n) (__builtin_constant_p(n)? \ + ((n) > __MAX_UDELAY? __bad_udelay(): __udelay((n) * (19 * HZ))) : \ + __udelay((n) * (19 * HZ))) + +#define ndelay(n) (__builtin_constant_p(n)? \ + ((n) > __MAX_NDELAY? __bad_ndelay(): __ndelay((n) * HZ)) : \ + __ndelay((n) * HZ)) + +#endif /* defined(_PPC_DELAY_H) */ +#endif /* __KERNEL__ */ |