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1 | /* |
2 | * Copyright (C) 2002 ARM Ltd. | |
3 | * All Rights Reserved | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License version 2 as | |
7 | * published by the Free Software Foundation. | |
8 | */ | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/errno.h> | |
11 | #include <linux/smp.h> | |
12 | ||
13 | #include <asm/cp15.h> | |
14 | #include <asm/smp_plat.h> | |
15 | ||
16 | static inline void cpu_enter_lowpower(void) | |
17 | { | |
18 | unsigned int v; | |
19 | ||
20 | asm volatile( | |
21 | " mcr p15, 0, %1, c7, c5, 0\n" | |
22 | " mcr p15, 0, %1, c7, c10, 4\n" | |
23 | /* | |
24 | * Turn off coherency | |
25 | */ | |
26 | " mrc p15, 0, %0, c1, c0, 1\n" | |
27 | " bic %0, %0, #0x20\n" | |
28 | " mcr p15, 0, %0, c1, c0, 1\n" | |
29 | " mrc p15, 0, %0, c1, c0, 0\n" | |
30 | " bic %0, %0, %2\n" | |
31 | " mcr p15, 0, %0, c1, c0, 0\n" | |
32 | : "=&r" (v) | |
33 | : "r" (0), "Ir" (CR_C) | |
34 | : "cc"); | |
35 | } | |
36 | ||
37 | static inline void cpu_leave_lowpower(void) | |
38 | { | |
39 | unsigned int v; | |
40 | ||
41 | asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" | |
42 | " orr %0, %0, %1\n" | |
43 | " mcr p15, 0, %0, c1, c0, 0\n" | |
44 | " mrc p15, 0, %0, c1, c0, 1\n" | |
45 | " orr %0, %0, #0x20\n" | |
46 | " mcr p15, 0, %0, c1, c0, 1\n" | |
47 | : "=&r" (v) | |
48 | : "Ir" (CR_C) | |
49 | : "cc"); | |
50 | } | |
51 | ||
52 | static inline void platform_do_lowpower(unsigned int cpu, int *spurious) | |
53 | { | |
54 | /* | |
55 | * there is no power-control hardware on this platform, so all | |
56 | * we can do is put the core into WFI; this is safe as the calling | |
57 | * code will have already disabled interrupts | |
58 | */ | |
59 | for (;;) { | |
60 | /* | |
61 | * here's the WFI | |
62 | */ | |
63 | asm(".word 0xe320f003\n" | |
64 | : | |
65 | : | |
66 | : "memory", "cc"); | |
67 | ||
68 | if (pen_release == cpu_logical_map(cpu)) { | |
69 | /* | |
70 | * OK, proper wakeup, we're done | |
71 | */ | |
72 | break; | |
73 | } | |
74 | ||
75 | /* | |
76 | * Getting here, means that we have come out of WFI without | |
77 | * having been woken up - this shouldn't happen | |
78 | * | |
79 | * Just note it happening - when we're woken, we can report | |
80 | * its occurrence. | |
81 | */ | |
82 | (*spurious)++; | |
83 | } | |
84 | } | |
85 | ||
86 | /* | |
87 | * platform-specific code to shutdown a CPU | |
88 | * | |
89 | * Called with IRQs disabled | |
90 | */ | |
91 | void ox820_cpu_die(unsigned int cpu) | |
92 | { | |
93 | int spurious = 0; | |
94 | ||
95 | /* | |
96 | * we're ready for shutdown now, so do it | |
97 | */ | |
98 | cpu_enter_lowpower(); | |
99 | platform_do_lowpower(cpu, &spurious); | |
100 | ||
101 | /* | |
102 | * bring this CPU back into the world of cache | |
103 | * coherency, and then restore interrupts | |
104 | */ | |
105 | cpu_leave_lowpower(); | |
106 | ||
107 | if (spurious) | |
108 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); | |
109 | } |