diff options
Diffstat (limited to 'arch/arm/lib/delay-loop.S')
| -rw-r--r-- | arch/arm/lib/delay-loop.S | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/arch/arm/lib/delay-loop.S b/arch/arm/lib/delay-loop.S new file mode 100644 index 000000000..c766694e9 --- /dev/null +++ b/arch/arm/lib/delay-loop.S @@ -0,0 +1,62 @@ +/* + * linux/arch/arm/lib/delay.S + * + * Copyright (C) 1995, 1996 Russell King + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/delay.h> + + .text + +.LC0: .word loops_per_jiffy +.LC1: .word UDELAY_MULT + +/* + * loops = r0 * HZ * loops_per_jiffy / 1000000 + * + * r0 <= 2000 + * HZ <= 1000 + */ + +ENTRY(__loop_udelay) + ldr r2, .LC1 + mul r0, r2, r0 @ r0 = delay_us * UDELAY_MULT +ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0xfffffaf0 + ldr r2, .LC0 + ldr r2, [r2] + umull r1, r0, r2, r0 @ r0-r1 = r0 * loops_per_jiffy + adds r1, r1, #0xffffffff @ rounding up ... + adcs r0, r0, r0 @ and right shift by 31 + reteq lr + + .align 3 + +@ Delay routine +ENTRY(__loop_delay) + subs r0, r0, #1 +#if 0 + retls lr + subs r0, r0, #1 + retls lr + subs r0, r0, #1 + retls lr + subs r0, r0, #1 + retls lr + subs r0, r0, #1 + retls lr + subs r0, r0, #1 + retls lr + subs r0, r0, #1 + retls lr + subs r0, r0, #1 +#endif + bhi __loop_delay + ret lr +ENDPROC(__loop_udelay) +ENDPROC(__loop_const_udelay) +ENDPROC(__loop_delay) |