| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
| 2 | /* |
| 3 | * linux/arch/arm/lib/delay.S |
| 4 | * |
| 5 | * Copyright (C) 1995, 1996 Russell King |
| 6 | */ |
| 7 | #include <linux/linkage.h> |
| 8 | #include <asm/assembler.h> |
| 9 | #include <asm/delay.h> |
| 10 | |
| 11 | .text |
| 12 | |
| 13 | .LC0: .word loops_per_jiffy |
| 14 | .LC1: .word UDELAY_MULT |
| 15 | |
| 16 | /* |
| 17 | * loops = r0 * HZ * loops_per_jiffy / 1000000 |
| 18 | * |
| 19 | * r0 <= 2000 |
| 20 | * HZ <= 1000 |
| 21 | */ |
| 22 | |
| 23 | ENTRY(__loop_udelay) |
| 24 | ldr r2, .LC1 |
| 25 | mul r0, r2, r0 @ r0 = delay_us * UDELAY_MULT |
| 26 | ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0xfffffaf0 |
| 27 | ldr r2, .LC0 |
| 28 | ldr r2, [r2] |
| 29 | umull r1, r0, r2, r0 @ r0-r1 = r0 * loops_per_jiffy |
| 30 | adds r1, r1, #0xffffffff @ rounding up ... |
| 31 | adcs r0, r0, r0 @ and right shift by 31 |
| 32 | reteq lr |
| 33 | |
| 34 | .align 3 |
| 35 | |
| 36 | @ Delay routine |
| 37 | ENTRY(__loop_delay) |
| 38 | subs r0, r0, #1 |
| 39 | #if 0 |
| 40 | retls lr |
| 41 | subs r0, r0, #1 |
| 42 | retls lr |
| 43 | subs r0, r0, #1 |
| 44 | retls lr |
| 45 | subs r0, r0, #1 |
| 46 | retls lr |
| 47 | subs r0, r0, #1 |
| 48 | retls lr |
| 49 | subs r0, r0, #1 |
| 50 | retls lr |
| 51 | subs r0, r0, #1 |
| 52 | retls lr |
| 53 | subs r0, r0, #1 |
| 54 | #endif |
| 55 | bhi __loop_delay |
| 56 | ret lr |
| 57 | ENDPROC(__loop_udelay) |
| 58 | ENDPROC(__loop_const_udelay) |
| 59 | ENDPROC(__loop_delay) |