| GuanXuetao | 96cf518 | 2011-01-15 18:23:09 +0800 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/unicore32/include/asm/delay.h |
| 3 | * |
| 4 | * Code specific to PKUnity SoC and UniCore ISA |
| 5 | * |
| 6 | * Copyright (C) 2001-2010 GUAN Xue-tao |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License version 2 as |
| 10 | * published by the Free Software Foundation. |
| 11 | * |
| 12 | * Delay routines, using a pre-computed "loops_per_second" value. |
| 13 | */ |
| 14 | #ifndef __UNICORE_DELAY_H__ |
| 15 | #define __UNICORE_DELAY_H__ |
| 16 | |
| 17 | #include <asm/param.h> /* HZ */ |
| 18 | |
| 19 | extern void __delay(int loops); |
| 20 | |
| 21 | /* |
| 22 | * This function intentionally does not exist; if you see references to |
| 23 | * it, it means that you're calling udelay() with an out of range value. |
| 24 | * |
| 25 | * With currently imposed limits, this means that we support a max delay |
| 26 | * of 2000us. Further limits: HZ<=1000 and bogomips<=3355 |
| 27 | */ |
| 28 | extern void __bad_udelay(void); |
| 29 | |
| 30 | /* |
| 31 | * division by multiplication: you don't have to worry about |
| 32 | * loss of precision. |
| 33 | * |
| 34 | * Use only for very small delays ( < 1 msec). Should probably use a |
| 35 | * lookup table, really, as the multiplications take much too long with |
| 36 | * short delays. This is a "reasonable" implementation, though (and the |
| 37 | * first constant multiplications gets optimized away if the delay is |
| 38 | * a constant) |
| 39 | */ |
| 40 | extern void __udelay(unsigned long usecs); |
| 41 | extern void __const_udelay(unsigned long); |
| 42 | |
| 43 | #define MAX_UDELAY_MS 2 |
| 44 | |
| 45 | #define udelay(n) \ |
| 46 | (__builtin_constant_p(n) ? \ |
| 47 | ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ |
| 48 | __const_udelay((n) * ((2199023U*HZ)>>11))) : \ |
| 49 | __udelay(n)) |
| 50 | |
| 51 | #endif /* __UNICORE_DELAY_H__ */ |
| 52 | |