Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 1995-2004 Russell King |
| 3 | * |
| 4 | * Delay routines, using a pre-computed "loops_per_second" value. |
| 5 | */ |
| 6 | #ifndef __ASM_ARM_DELAY_H |
| 7 | #define __ASM_ARM_DELAY_H |
| 8 | |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 9 | #include <asm/memory.h> |
Peter Teichmann | 6d4518d | 2006-03-20 17:10:09 +0000 | [diff] [blame] | 10 | #include <asm/param.h> /* HZ */ |
| 11 | |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 12 | #define MAX_UDELAY_MS 2 |
| 13 | #define UDELAY_MULT ((UL(2199023) * HZ) >> 11) |
| 14 | #define UDELAY_SHIFT 30 |
| 15 | |
| 16 | #ifndef __ASSEMBLY__ |
| 17 | |
Jonathan Austin | 56942fe | 2012-09-21 18:51:44 +0100 | [diff] [blame] | 18 | struct delay_timer { |
| 19 | unsigned long (*read_current_timer)(void); |
| 20 | unsigned long freq; |
| 21 | }; |
| 22 | |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 23 | extern struct arm_delay_ops { |
| 24 | void (*delay)(unsigned long); |
| 25 | void (*const_udelay)(unsigned long); |
| 26 | void (*udelay)(unsigned long); |
| 27 | } arm_delay_ops; |
| 28 | |
| 29 | #define __delay(n) arm_delay_ops.delay(n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | |
| 31 | /* |
| 32 | * This function intentionally does not exist; if you see references to |
| 33 | * it, it means that you're calling udelay() with an out of range value. |
| 34 | * |
| 35 | * With currently imposed limits, this means that we support a max delay |
Peter Teichmann | 6d4518d | 2006-03-20 17:10:09 +0000 | [diff] [blame] | 36 | * of 2000us. Further limits: HZ<=1000 and bogomips<=3355 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | */ |
| 38 | extern void __bad_udelay(void); |
| 39 | |
| 40 | /* |
| 41 | * division by multiplication: you don't have to worry about |
| 42 | * loss of precision. |
| 43 | * |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 44 | * Use only for very small delays ( < 2 msec). Should probably use a |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | * lookup table, really, as the multiplications take much too long with |
| 46 | * short delays. This is a "reasonable" implementation, though (and the |
| 47 | * first constant multiplications gets optimized away if the delay is |
| 48 | * a constant) |
| 49 | */ |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 50 | #define __udelay(n) arm_delay_ops.udelay(n) |
| 51 | #define __const_udelay(n) arm_delay_ops.const_udelay(n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | |
Peter Teichmann | 6d4518d | 2006-03-20 17:10:09 +0000 | [diff] [blame] | 53 | #define udelay(n) \ |
| 54 | (__builtin_constant_p(n) ? \ |
| 55 | ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 56 | __const_udelay((n) * UDELAY_MULT)) : \ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | __udelay(n)) |
| 58 | |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 59 | /* Loop-based definitions for assembly code. */ |
| 60 | extern void __loop_delay(unsigned long loops); |
| 61 | extern void __loop_udelay(unsigned long usecs); |
| 62 | extern void __loop_const_udelay(unsigned long); |
| 63 | |
Jonathan Austin | 56942fe | 2012-09-21 18:51:44 +0100 | [diff] [blame] | 64 | /* Delay-loop timer registration. */ |
| 65 | #define ARCH_HAS_READ_CURRENT_TIMER |
| 66 | extern void register_current_timer_delay(const struct delay_timer *timer); |
| 67 | |
Will Deacon | d0a533b | 2012-07-06 15:47:17 +0100 | [diff] [blame] | 68 | #endif /* __ASSEMBLY__ */ |
| 69 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | #endif /* defined(_ARM_DELAY_H) */ |
| 71 | |