| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/arm/lib/delay.S |
| 3 | * |
| 4 | * Copyright (C) 1995, 1996 Russell King |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | */ |
| 10 | #include <linux/linkage.h> |
| 11 | #include <asm/assembler.h> |
| 12 | .text |
| 13 | |
| Nicolas Pitre | 8adbb37 | 2005-11-11 21:51:49 +0000 | [diff] [blame^] | 14 | .LC0: .word loops_per_jiffy |
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | |
| 16 | /* |
| 17 | * 0 <= r0 <= 2000 |
| 18 | */ |
| 19 | ENTRY(__udelay) |
| 20 | mov r2, #0x6800 |
| 21 | orr r2, r2, #0x00db |
| 22 | mul r0, r2, r0 |
| 23 | ENTRY(__const_udelay) @ 0 <= r0 <= 0x01ffffff |
| Nicolas Pitre | 8adbb37 | 2005-11-11 21:51:49 +0000 | [diff] [blame^] | 24 | ldr r2, .LC0 |
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | ldr r2, [r2] @ max = 0x0fffffff |
| 26 | mov r0, r0, lsr #11 @ max = 0x00003fff |
| 27 | mov r2, r2, lsr #11 @ max = 0x0003ffff |
| 28 | mul r0, r2, r0 @ max = 2^32-1 |
| 29 | movs r0, r0, lsr #6 |
| 30 | RETINSTR(moveq,pc,lr) |
| 31 | |
| 32 | /* |
| 33 | * loops = (r0 * 0x10c6 * 100 * loops_per_jiffy) / 2^32 |
| 34 | * |
| 35 | * Oh, if only we had a cycle counter... |
| 36 | */ |
| 37 | |
| 38 | @ Delay routine |
| 39 | ENTRY(__delay) |
| 40 | subs r0, r0, #1 |
| 41 | #if 0 |
| 42 | RETINSTR(movls,pc,lr) |
| 43 | subs r0, r0, #1 |
| 44 | RETINSTR(movls,pc,lr) |
| 45 | subs r0, r0, #1 |
| 46 | RETINSTR(movls,pc,lr) |
| 47 | subs r0, r0, #1 |
| 48 | RETINSTR(movls,pc,lr) |
| 49 | subs r0, r0, #1 |
| 50 | RETINSTR(movls,pc,lr) |
| 51 | subs r0, r0, #1 |
| 52 | RETINSTR(movls,pc,lr) |
| 53 | subs r0, r0, #1 |
| 54 | RETINSTR(movls,pc,lr) |
| 55 | subs r0, r0, #1 |
| 56 | #endif |
| 57 | bhi __delay |
| 58 | RETINSTR(mov,pc,lr) |