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) 60