| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [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 | #include <asm/delay.h> |
| 13 | |
| 14 | .text |
| 15 | |
| 16 | .LC0: .word loops_per_jiffy |
| 17 | .LC1: .word UDELAY_MULT |
| 18 | |
| 19 | /* |
| 20 | * loops = r0 * HZ * loops_per_jiffy / 1000000 |
| 21 | * |
| 22 | * r0 <= 2000 |
| 23 | * HZ <= 1000 |
| 24 | */ |
| 25 | |
| 26 | ENTRY(__loop_udelay) |
| 27 | ldr r2, .LC1 |
| 28 | mul r0, r2, r0 @ r0 = delay_us * UDELAY_MULT |
| 29 | ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0xfffffaf0 |
| 30 | ldr r2, .LC0 |
| 31 | ldr r2, [r2] |
| 32 | umull r1, r0, r2, r0 @ r0-r1 = r0 * loops_per_jiffy |
| 33 | adds r1, r1, #0xffffffff @ rounding up ... |
| 34 | adcs r0, r0, r0 @ and right shift by 31 |
| 35 | reteq lr |
| 36 | |
| 37 | .align 3 |
| 38 | |
| 39 | @ Delay routine |
| 40 | ENTRY(__loop_delay) |
| 41 | subs r0, r0, #1 |
| 42 | #if 0 |
| 43 | retls lr |
| 44 | subs r0, r0, #1 |
| 45 | retls lr |
| 46 | subs r0, r0, #1 |
| 47 | retls lr |
| 48 | subs r0, r0, #1 |
| 49 | retls lr |
| 50 | subs r0, r0, #1 |
| 51 | retls lr |
| 52 | subs r0, r0, #1 |
| 53 | retls lr |
| 54 | subs r0, r0, #1 |
| 55 | retls lr |
| 56 | subs r0, r0, #1 |
| 57 | #endif |
| 58 | bhi __loop_delay |
| 59 | ret lr |
| 60 | ENDPROC(__loop_udelay) |
| 61 | ENDPROC(__loop_const_udelay) |
| 62 | ENDPROC(__loop_delay) |