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Diffstat (limited to 'include/asm-arm/delay.h')
| -rw-r--r-- | include/asm-arm/delay.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/include/asm-arm/delay.h b/include/asm-arm/delay.h new file mode 100644 index 00000000000..1704360e969 --- /dev/null +++ b/include/asm-arm/delay.h @@ -0,0 +1,42 @@ +/* + * Copyright (C) 1995-2004 Russell King + * + * Delay routines, using a pre-computed "loops_per_second" value. + */ +#ifndef __ASM_ARM_DELAY_H +#define __ASM_ARM_DELAY_H + +extern void __delay(int loops); + +/* + * This function intentionally does not exist; if you see references to + * it, it means that you're calling udelay() with an out of range value. + * + * With currently imposed limits, this means that we support a max delay + * of 2000us and 671 bogomips + */ +extern void __bad_udelay(void); + +/* + * division by multiplication: you don't have to worry about + * loss of precision. + * + * Use only for very small delays ( < 1 msec). Should probably use a + * lookup table, really, as the multiplications take much too long with + * short delays. This is a "reasonable" implementation, though (and the + * first constant multiplications gets optimized away if the delay is + * a constant) + */ +extern void __udelay(unsigned long usecs); +extern void __const_udelay(unsigned long); + +#define MAX_UDELAY_MS 2 + +#define udelay(n) \ + (__builtin_constant_p(n) ? \ + ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ + __const_udelay((n) * 0x68dbul)) : \ + __udelay(n)) + +#endif /* defined(_ARM_DELAY_H) */ + |