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1 | /* |
2 | * linux/arch/arm/mach-realview/hotplug.c | |
3 | * | |
4 | * Copyright (C) 2002 ARM Ltd. | |
5 | * All Rights Reserved | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/smp.h> | |
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14 | |
15 | #include <asm/cacheflush.h> | |
16 | ||
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17 | static inline void cpu_enter_lowpower(void) |
18 | { | |
19 | unsigned int v; | |
20 | ||
21 | flush_cache_all(); | |
22 | asm volatile( | |
23 | " mcr p15, 0, %1, c7, c5, 0\n" | |
24 | " mcr p15, 0, %1, c7, c10, 4\n" | |
25 | /* | |
26 | * Turn off coherency | |
27 | */ | |
28 | " mrc p15, 0, %0, c1, c0, 1\n" | |
30b99d07 | 29 | " bic %0, %0, #0x20\n" |
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30 | " mcr p15, 0, %0, c1, c0, 1\n" |
31 | " mrc p15, 0, %0, c1, c0, 0\n" | |
30b99d07 | 32 | " bic %0, %0, %2\n" |
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33 | " mcr p15, 0, %0, c1, c0, 0\n" |
34 | : "=&r" (v) | |
e3d9c625 | 35 | : "r" (0), "Ir" (CR_C) |
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36 | : "cc"); |
37 | } | |
38 | ||
39 | static inline void cpu_leave_lowpower(void) | |
40 | { | |
41 | unsigned int v; | |
42 | ||
43 | asm volatile( | |
44 | "mrc p15, 0, %0, c1, c0, 0\n" | |
e3d9c625 | 45 | " orr %0, %0, %1\n" |
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46 | " mcr p15, 0, %0, c1, c0, 0\n" |
47 | " mrc p15, 0, %0, c1, c0, 1\n" | |
48 | " orr %0, %0, #0x20\n" | |
49 | " mcr p15, 0, %0, c1, c0, 1\n" | |
50 | : "=&r" (v) | |
e3d9c625 | 51 | : "Ir" (CR_C) |
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52 | : "cc"); |
53 | } | |
54 | ||
d4450261 | 55 | static inline void platform_do_lowpower(unsigned int cpu, int *spurious) |
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56 | { |
57 | /* | |
58 | * there is no power-control hardware on this platform, so all | |
59 | * we can do is put the core into WFI; this is safe as the calling | |
60 | * code will have already disabled interrupts | |
61 | */ | |
62 | for (;;) { | |
63 | /* | |
64 | * here's the WFI | |
65 | */ | |
66 | asm(".word 0xe320f003\n" | |
67 | : | |
68 | : | |
69 | : "memory", "cc"); | |
70 | ||
71 | /*if (pen_release == cpu) {*/ | |
72 | /* | |
73 | * OK, proper wakeup, we're done | |
74 | */ | |
75 | break; | |
76 | /*}*/ | |
77 | ||
78 | /* | |
d4450261 | 79 | * Getting here, means that we have come out of WFI without |
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80 | * having been woken up - this shouldn't happen |
81 | * | |
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82 | * Just note it happening - when we're woken, we can report |
83 | * its occurrence. | |
1cea7326 | 84 | */ |
d4450261 | 85 | (*spurious)++; |
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86 | } |
87 | } | |
88 | ||
89 | int platform_cpu_kill(unsigned int cpu) | |
90 | { | |
3c030bea | 91 | return 1; |
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92 | } |
93 | ||
94 | /* | |
95 | * platform-specific code to shutdown a CPU | |
96 | * | |
97 | * Called with IRQs disabled | |
98 | */ | |
99 | void platform_cpu_die(unsigned int cpu) | |
100 | { | |
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101 | int spurious = 0; |
102 | ||
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103 | /* |
104 | * we're ready for shutdown now, so do it | |
105 | */ | |
106 | cpu_enter_lowpower(); | |
d4450261 | 107 | platform_do_lowpower(cpu, &spurious); |
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108 | |
109 | /* | |
110 | * bring this CPU back into the world of cache | |
111 | * coherency, and then restore interrupts | |
112 | */ | |
113 | cpu_leave_lowpower(); | |
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114 | |
115 | if (spurious) | |
116 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); | |
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117 | } |
118 | ||
119 | int platform_cpu_disable(unsigned int cpu) | |
120 | { | |
121 | /* | |
122 | * we don't allow CPU 0 to be shutdown (it is still too special | |
123 | * e.g. clock tick interrupts) | |
124 | */ | |
125 | return cpu == 0 ? -EPERM : 0; | |
126 | } |