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1 | /* |
2 | * linux/arch/arm/mach-spear13xx/hotplug.c | |
3 | * | |
4 | * Copyright (C) 2012 ST Microelectronics Ltd. | |
5 | * Deepak Sikri <deepak.sikri@st.com> | |
6 | * | |
7 | * based upon linux/arch/arm/mach-realview/hotplug.c | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
12 | */ | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/errno.h> | |
15 | #include <linux/smp.h> | |
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16 | #include <asm/cp15.h> |
17 | #include <asm/smp_plat.h> | |
18 | ||
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19 | static inline void cpu_enter_lowpower(void) |
20 | { | |
21 | unsigned int v; | |
22 | ||
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23 | asm volatile( |
24 | " mcr p15, 0, %1, c7, c5, 0\n" | |
25 | " dsb\n" | |
26 | /* | |
27 | * Turn off coherency | |
28 | */ | |
29 | " mrc p15, 0, %0, c1, c0, 1\n" | |
30 | " bic %0, %0, #0x20\n" | |
31 | " mcr p15, 0, %0, c1, c0, 1\n" | |
32 | " mrc p15, 0, %0, c1, c0, 0\n" | |
33 | " bic %0, %0, %2\n" | |
34 | " mcr p15, 0, %0, c1, c0, 0\n" | |
35 | : "=&r" (v) | |
36 | : "r" (0), "Ir" (CR_C) | |
37 | : "cc", "memory"); | |
38 | } | |
39 | ||
40 | static inline void cpu_leave_lowpower(void) | |
41 | { | |
42 | unsigned int v; | |
43 | ||
44 | asm volatile("mrc p15, 0, %0, c1, c0, 0\n" | |
45 | " orr %0, %0, %1\n" | |
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) | |
51 | : "Ir" (CR_C) | |
52 | : "cc"); | |
53 | } | |
54 | ||
2d8b21d9 | 55 | static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) |
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56 | { |
57 | for (;;) { | |
58 | wfi(); | |
59 | ||
60 | if (pen_release == cpu) { | |
61 | /* | |
62 | * OK, proper wakeup, we're done | |
63 | */ | |
64 | break; | |
65 | } | |
66 | ||
67 | /* | |
68 | * Getting here, means that we have come out of WFI without | |
69 | * having been woken up - this shouldn't happen | |
70 | * | |
71 | * Just note it happening - when we're woken, we can report | |
72 | * its occurrence. | |
73 | */ | |
74 | (*spurious)++; | |
75 | } | |
76 | } | |
77 | ||
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78 | /* |
79 | * platform-specific code to shutdown a CPU | |
80 | * | |
81 | * Called with IRQs disabled | |
82 | */ | |
2d8b21d9 | 83 | void __ref spear13xx_cpu_die(unsigned int cpu) |
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84 | { |
85 | int spurious = 0; | |
86 | ||
87 | /* | |
88 | * we're ready for shutdown now, so do it | |
89 | */ | |
90 | cpu_enter_lowpower(); | |
2d8b21d9 | 91 | spear13xx_do_lowpower(cpu, &spurious); |
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92 | |
93 | /* | |
94 | * bring this CPU back into the world of cache | |
95 | * coherency, and then restore interrupts | |
96 | */ | |
97 | cpu_leave_lowpower(); | |
98 | ||
99 | if (spurious) | |
100 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); | |
101 | } |