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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> |
14 | #include <linux/completion.h> |
15 | |
16 | #include <asm/cacheflush.h> |
17 | |
18 | static DECLARE_COMPLETION(cpu_killed); |
19 | |
20 | static inline void cpu_enter_lowpower(void) |
21 | { |
22 | unsigned int v; |
23 | |
24 | flush_cache_all(); |
25 | asm volatile( |
26 | " mcr p15, 0, %1, c7, c5, 0\n" |
27 | " mcr p15, 0, %1, c7, c10, 4\n" |
28 | /* |
29 | * Turn off coherency |
30 | */ |
31 | " mrc p15, 0, %0, c1, c0, 1\n" |
32 | " bic %0, %0, #0x20\n" |
33 | " mcr p15, 0, %0, c1, c0, 1\n" |
34 | " mrc p15, 0, %0, c1, c0, 0\n" |
35 | " bic %0, %0, #0x04\n" |
36 | " mcr p15, 0, %0, c1, c0, 0\n" |
37 | : "=&r" (v) |
38 | : "r" (0) |
39 | : "cc"); |
40 | } |
41 | |
42 | static inline void cpu_leave_lowpower(void) |
43 | { |
44 | unsigned int v; |
45 | |
46 | asm volatile( |
47 | "mrc p15, 0, %0, c1, c0, 0\n" |
48 | " orr %0, %0, #0x04\n" |
49 | " mcr p15, 0, %0, c1, c0, 0\n" |
50 | " mrc p15, 0, %0, c1, c0, 1\n" |
51 | " orr %0, %0, #0x20\n" |
52 | " mcr p15, 0, %0, c1, c0, 1\n" |
53 | : "=&r" (v) |
54 | : |
55 | : "cc"); |
56 | } |
57 | |
58 | static inline void platform_do_lowpower(unsigned int cpu) |
59 | { |
60 | /* |
61 | * there is no power-control hardware on this platform, so all |
62 | * we can do is put the core into WFI; this is safe as the calling |
63 | * code will have already disabled interrupts |
64 | */ |
65 | for (;;) { |
66 | /* |
67 | * here's the WFI |
68 | */ |
69 | asm(".word 0xe320f003\n" |
70 | : |
71 | : |
72 | : "memory", "cc"); |
73 | |
74 | /*if (pen_release == cpu) {*/ |
75 | /* |
76 | * OK, proper wakeup, we're done |
77 | */ |
78 | break; |
79 | /*}*/ |
80 | |
81 | /* |
82 | * getting here, means that we have come out of WFI without |
83 | * having been woken up - this shouldn't happen |
84 | * |
85 | * The trouble is, letting people know about this is not really |
86 | * possible, since we are currently running incoherently, and |
87 | * therefore cannot safely call printk() or anything else |
88 | */ |
89 | #ifdef DEBUG |
90 | printk(KERN_WARN "CPU%u: spurious wakeup call\n", cpu); |
91 | #endif |
92 | } |
93 | } |
94 | |
95 | int platform_cpu_kill(unsigned int cpu) |
96 | { |
97 | return wait_for_completion_timeout(&cpu_killed, 5000); |
98 | } |
99 | |
100 | /* |
101 | * platform-specific code to shutdown a CPU |
102 | * |
103 | * Called with IRQs disabled |
104 | */ |
105 | void platform_cpu_die(unsigned int cpu) |
106 | { |
107 | #ifdef DEBUG |
108 | unsigned int this_cpu = hard_smp_processor_id(); |
109 | |
110 | if (cpu != this_cpu) { |
111 | printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n", |
112 | this_cpu, cpu); |
113 | BUG(); |
114 | } |
115 | #endif |
116 | |
117 | printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); |
118 | complete(&cpu_killed); |
119 | |
120 | /* |
121 | * we're ready for shutdown now, so do it |
122 | */ |
123 | cpu_enter_lowpower(); |
124 | platform_do_lowpower(cpu); |
125 | |
126 | /* |
127 | * bring this CPU back into the world of cache |
128 | * coherency, and then restore interrupts |
129 | */ |
130 | cpu_leave_lowpower(); |
131 | } |
132 | |
133 | int platform_cpu_disable(unsigned int cpu) |
134 | { |
135 | /* |
136 | * we don't allow CPU 0 to be shutdown (it is still too special |
137 | * e.g. clock tick interrupts) |
138 | */ |
139 | return cpu == 0 ? -EPERM : 0; |
140 | } |
141 |
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