| GuanXuetao | 96cf518 | 2011-01-15 18:23:09 +0800 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/unicore32/lib/delay.S |
| 3 | * |
| 4 | * Code specific to PKUnity SoC and UniCore ISA |
| 5 | * |
| 6 | * Copyright (C) 2001-2010 GUAN Xue-tao |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License version 2 as |
| 10 | * published by the Free Software Foundation. |
| 11 | */ |
| 12 | #include <linux/linkage.h> |
| 13 | #include <asm/assembler.h> |
| 14 | #include <asm/param.h> |
| 15 | .text |
| 16 | |
| 17 | .LC0: .word loops_per_jiffy |
| 18 | .LC1: .word (2199023*HZ)>>11 |
| 19 | |
| 20 | /* |
| 21 | * r0 <= 2000 |
| 22 | * lpj <= 0x01ffffff (max. 3355 bogomips) |
| 23 | * HZ <= 1000 |
| 24 | */ |
| 25 | |
| 26 | ENTRY(__udelay) |
| 27 | ldw r2, .LC1 |
| 28 | mul r0, r2, r0 |
| 29 | ENTRY(__const_udelay) @ 0 <= r0 <= 0x7fffff06 |
| 30 | ldw r2, .LC0 |
| 31 | ldw r2, [r2] @ max = 0x01ffffff |
| 32 | mov r0, r0 >> #14 @ max = 0x0001ffff |
| 33 | mov r2, r2 >> #10 @ max = 0x00007fff |
| 34 | mul r0, r2, r0 @ max = 2^32-1 |
| 35 | mov.a r0, r0 >> #6 |
| 36 | cmoveq pc, lr |
| 37 | |
| 38 | /* |
| 39 | * loops = r0 * HZ * loops_per_jiffy / 1000000 |
| 40 | * |
| 41 | * Oh, if only we had a cycle counter... |
| 42 | */ |
| 43 | |
| 44 | @ Delay routine |
| 45 | ENTRY(__delay) |
| 46 | sub.a r0, r0, #2 |
| 47 | bua __delay |
| 48 | mov pc, lr |
| 49 | ENDPROC(__udelay) |
| 50 | ENDPROC(__const_udelay) |
| 51 | ENDPROC(__delay) |