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e3978dc7 VK |
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> | |
16 | #include <asm/cacheflush.h> | |
17 | #include <asm/cp15.h> | |
18 | #include <asm/smp_plat.h> | |
19 | ||
20 | extern volatile int pen_release; | |
21 | ||
22 | static inline void cpu_enter_lowpower(void) | |
23 | { | |
24 | unsigned int v; | |
25 | ||
26 | flush_cache_all(); | |
27 | asm volatile( | |
28 | " mcr p15, 0, %1, c7, c5, 0\n" | |
29 | " dsb\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, %2\n" | |
38 | " mcr p15, 0, %0, c1, c0, 0\n" | |
39 | : "=&r" (v) | |
40 | : "r" (0), "Ir" (CR_C) | |
41 | : "cc", "memory"); | |
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, %1\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 | : "Ir" (CR_C) | |
56 | : "cc"); | |
57 | } | |
58 | ||
59 | static inline void platform_do_lowpower(unsigned int cpu, int *spurious) | |
60 | { | |
61 | for (;;) { | |
62 | wfi(); | |
63 | ||
64 | if (pen_release == cpu) { | |
65 | /* | |
66 | * OK, proper wakeup, we're done | |
67 | */ | |
68 | break; | |
69 | } | |
70 | ||
71 | /* | |
72 | * Getting here, means that we have come out of WFI without | |
73 | * having been woken up - this shouldn't happen | |
74 | * | |
75 | * Just note it happening - when we're woken, we can report | |
76 | * its occurrence. | |
77 | */ | |
78 | (*spurious)++; | |
79 | } | |
80 | } | |
81 | ||
82 | int platform_cpu_kill(unsigned int cpu) | |
83 | { | |
84 | return 1; | |
85 | } | |
86 | ||
87 | /* | |
88 | * platform-specific code to shutdown a CPU | |
89 | * | |
90 | * Called with IRQs disabled | |
91 | */ | |
92 | void __cpuinit platform_cpu_die(unsigned int cpu) | |
93 | { | |
94 | int spurious = 0; | |
95 | ||
96 | /* | |
97 | * we're ready for shutdown now, so do it | |
98 | */ | |
99 | cpu_enter_lowpower(); | |
100 | platform_do_lowpower(cpu, &spurious); | |
101 | ||
102 | /* | |
103 | * bring this CPU back into the world of cache | |
104 | * coherency, and then restore interrupts | |
105 | */ | |
106 | cpu_leave_lowpower(); | |
107 | ||
108 | if (spurious) | |
109 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); | |
110 | } | |
111 | ||
112 | int platform_cpu_disable(unsigned int cpu) | |
113 | { | |
114 | /* | |
115 | * we don't allow CPU 0 to be shutdown (it is still too special | |
116 | * e.g. clock tick interrupts) | |
117 | */ | |
118 | return cpu == 0 ? -EPERM : 0; | |
119 | } |