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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 | ||
8aa2da87 HF |
16 | #include <asm/cacheflush.h> |
17 | ||
97a63ecf RK |
18 | extern volatile int pen_release; |
19 | ||
20 | static DECLARE_COMPLETION(cpu_killed); | |
21 | ||
22 | static inline void cpu_enter_lowpower(void) | |
23 | { | |
24 | unsigned int v; | |
25 | ||
8aa2da87 HF |
26 | flush_cache_all(); |
27 | asm volatile( | |
97a63ecf RK |
28 | " mcr p15, 0, %1, c7, c5, 0\n" |
29 | " mcr p15, 0, %1, c7, c10, 4\n" | |
30 | /* | |
31 | * Turn off coherency | |
32 | */ | |
33 | " mrc p15, 0, %0, c1, c0, 1\n" | |
34 | " bic %0, %0, #0x20\n" | |
35 | " mcr p15, 0, %0, c1, c0, 1\n" | |
36 | " mrc p15, 0, %0, c1, c0, 0\n" | |
37 | " bic %0, %0, #0x04\n" | |
38 | " mcr p15, 0, %0, c1, c0, 0\n" | |
39 | : "=&r" (v) | |
40 | : "r" (0) | |
41 | : "cc"); | |
42 | } | |
43 | ||
44 | static inline void cpu_leave_lowpower(void) | |
45 | { | |
46 | unsigned int v; | |
47 | ||
48 | asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" | |
49 | " orr %0, %0, #0x04\n" | |
50 | " mcr p15, 0, %0, c1, c0, 0\n" | |
51 | " mrc p15, 0, %0, c1, c0, 1\n" | |
52 | " orr %0, %0, #0x20\n" | |
53 | " mcr p15, 0, %0, c1, c0, 1\n" | |
54 | : "=&r" (v) | |
55 | : | |
56 | : "cc"); | |
57 | } | |
58 | ||
59 | static inline void platform_do_lowpower(unsigned int cpu) | |
60 | { | |
61 | /* | |
62 | * there is no power-control hardware on this platform, so all | |
63 | * we can do is put the core into WFI; this is safe as the calling | |
64 | * code will have already disabled interrupts | |
65 | */ | |
66 | for (;;) { | |
67 | /* | |
68 | * here's the WFI | |
69 | */ | |
70 | asm(".word 0xe320f003\n" | |
71 | : | |
72 | : | |
73 | : "memory", "cc"); | |
74 | ||
75 | if (pen_release == cpu) { | |
76 | /* | |
77 | * OK, proper wakeup, we're done | |
78 | */ | |
79 | break; | |
80 | } | |
81 | ||
82 | /* | |
83 | * getting here, means that we have come out of WFI without | |
84 | * having been woken up - this shouldn't happen | |
85 | * | |
86 | * The trouble is, letting people know about this is not really | |
87 | * possible, since we are currently running incoherently, and | |
88 | * therefore cannot safely call printk() or anything else | |
89 | */ | |
90 | #ifdef DEBUG | |
91 | printk("CPU%u: spurious wakeup call\n", cpu); | |
92 | #endif | |
93 | } | |
94 | } | |
95 | ||
96 | int platform_cpu_kill(unsigned int cpu) | |
97 | { | |
98 | return wait_for_completion_timeout(&cpu_killed, 5000); | |
99 | } | |
100 | ||
101 | /* | |
102 | * platform-specific code to shutdown a CPU | |
103 | * | |
104 | * Called with IRQs disabled | |
105 | */ | |
106 | void platform_cpu_die(unsigned int cpu) | |
107 | { | |
108 | #ifdef DEBUG | |
109 | unsigned int this_cpu = hard_smp_processor_id(); | |
110 | ||
111 | if (cpu != this_cpu) { | |
112 | printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n", | |
113 | this_cpu, cpu); | |
114 | BUG(); | |
115 | } | |
116 | #endif | |
117 | ||
118 | printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); | |
119 | complete(&cpu_killed); | |
120 | ||
121 | /* | |
122 | * we're ready for shutdown now, so do it | |
123 | */ | |
124 | cpu_enter_lowpower(); | |
125 | platform_do_lowpower(cpu); | |
126 | ||
127 | /* | |
128 | * bring this CPU back into the world of cache | |
129 | * coherency, and then restore interrupts | |
130 | */ | |
131 | cpu_leave_lowpower(); | |
132 | } | |
133 | ||
134 | int mach_cpu_disable(unsigned int cpu) | |
135 | { | |
136 | /* | |
137 | * we don't allow CPU 0 to be shutdown (it is still too special | |
138 | * e.g. clock tick interrupts) | |
139 | */ | |
140 | return cpu == 0 ? -EPERM : 0; | |
141 | } |