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0c176fa8 MG |
1 | /* |
2 | * Copied from <file:arch/powerpc/kernel/misc_32.S> | |
3 | * | |
4 | * This file contains miscellaneous low-level functions. | |
5 | * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) | |
6 | * | |
7 | * Largely rewritten by Cort Dougan (cort@cs.nmt.edu) | |
8 | * and Paul Mackerras. | |
9 | * | |
10 | * kexec bits: | |
11 | * Copyright (C) 2002-2003 Eric Biederman <ebiederm@xmission.com> | |
12 | * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz | |
13 | * | |
14 | * This program is free software; you can redistribute it and/or | |
15 | * modify it under the terms of the GNU General Public License | |
16 | * as published by the Free Software Foundation; either version | |
17 | * 2 of the License, or (at your option) any later version. | |
18 | * | |
19 | */ | |
20 | #include "ppc_asm.h" | |
21 | ||
22 | #define SPRN_PVR 0x11F /* Processor Version Register */ | |
23 | ||
24 | .text | |
25 | ||
26 | /* udelay (on non-601 processors) needs to know the period of the | |
27 | * timebase in nanoseconds. This used to be hardcoded to be 60ns | |
28 | * (period of 66MHz/4). Now a variable is used that is initialized to | |
29 | * 60 for backward compatibility, but it can be overridden as necessary | |
30 | * with code something like this: | |
31 | * extern unsigned long timebase_period_ns; | |
32 | * timebase_period_ns = 1000000000 / bd->bi_tbfreq; | |
33 | */ | |
34 | .data | |
35 | .globl timebase_period_ns | |
36 | timebase_period_ns: | |
37 | .long 60 | |
38 | ||
39 | .text | |
40 | /* | |
41 | * Delay for a number of microseconds | |
42 | */ | |
43 | .globl udelay | |
44 | udelay: | |
45 | mfspr r4,SPRN_PVR | |
46 | srwi r4,r4,16 | |
47 | cmpwi 0,r4,1 /* 601 ? */ | |
48 | bne .udelay_not_601 | |
49 | 00: li r0,86 /* Instructions / microsecond? */ | |
50 | mtctr r0 | |
51 | 10: addi r0,r0,0 /* NOP */ | |
52 | bdnz 10b | |
53 | subic. r3,r3,1 | |
54 | bne 00b | |
55 | blr | |
56 | ||
57 | .udelay_not_601: | |
58 | mulli r4,r3,1000 /* nanoseconds */ | |
59 | /* Change r4 to be the number of ticks using: | |
60 | * (nanoseconds + (timebase_period_ns - 1 )) / timebase_period_ns | |
61 | * timebase_period_ns defaults to 60 (16.6MHz) */ | |
62 | mflr r5 | |
63 | bl 0f | |
64 | 0: mflr r6 | |
65 | mtlr r5 | |
66 | lis r5,0b@ha | |
67 | addi r5,r5,0b@l | |
68 | subf r5,r5,r6 /* In case we're relocated */ | |
69 | addis r5,r5,timebase_period_ns@ha | |
70 | lwz r5,timebase_period_ns@l(r5) | |
71 | add r4,r4,r5 | |
72 | addi r4,r4,-1 | |
73 | divw r4,r4,r5 /* BUS ticks */ | |
74 | 1: mftbu r5 | |
75 | mftb r6 | |
76 | mftbu r7 | |
77 | cmpw 0,r5,r7 | |
78 | bne 1b /* Get [synced] base time */ | |
79 | addc r9,r6,r4 /* Compute end time */ | |
80 | addze r8,r5 | |
81 | 2: mftbu r5 | |
82 | cmpw 0,r5,r8 | |
83 | blt 2b | |
84 | bgt 3f | |
85 | mftb r6 | |
86 | cmpw 0,r6,r9 | |
87 | blt 2b | |
88 | 3: blr |