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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> | |
16 | #include <asm/cacheflush.h> | |
17 | #include <asm/cp15.h> | |
18 | #include <asm/smp_plat.h> | |
19 | ||
e3978dc7 VK |
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 | " dsb\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, %2\n" | |
36 | " mcr p15, 0, %0, c1, c0, 0\n" | |
37 | : "=&r" (v) | |
38 | : "r" (0), "Ir" (CR_C) | |
39 | : "cc", "memory"); | |
40 | } | |
41 | ||
42 | static inline void cpu_leave_lowpower(void) | |
43 | { | |
44 | unsigned int v; | |
45 | ||
46 | asm volatile("mrc p15, 0, %0, c1, c0, 0\n" | |
47 | " orr %0, %0, %1\n" | |
48 | " mcr p15, 0, %0, c1, c0, 0\n" | |
49 | " mrc p15, 0, %0, c1, c0, 1\n" | |
50 | " orr %0, %0, #0x20\n" | |
51 | " mcr p15, 0, %0, c1, c0, 1\n" | |
52 | : "=&r" (v) | |
53 | : "Ir" (CR_C) | |
54 | : "cc"); | |
55 | } | |
56 | ||
2d8b21d9 | 57 | static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) |
e3978dc7 VK |
58 | { |
59 | for (;;) { | |
60 | wfi(); | |
61 | ||
62 | if (pen_release == cpu) { | |
63 | /* | |
64 | * OK, proper wakeup, we're done | |
65 | */ | |
66 | break; | |
67 | } | |
68 | ||
69 | /* | |
70 | * Getting here, means that we have come out of WFI without | |
71 | * having been woken up - this shouldn't happen | |
72 | * | |
73 | * Just note it happening - when we're woken, we can report | |
74 | * its occurrence. | |
75 | */ | |
76 | (*spurious)++; | |
77 | } | |
78 | } | |
79 | ||
e3978dc7 VK |
80 | /* |
81 | * platform-specific code to shutdown a CPU | |
82 | * | |
83 | * Called with IRQs disabled | |
84 | */ | |
2d8b21d9 | 85 | void __ref spear13xx_cpu_die(unsigned int cpu) |
e3978dc7 VK |
86 | { |
87 | int spurious = 0; | |
88 | ||
89 | /* | |
90 | * we're ready for shutdown now, so do it | |
91 | */ | |
92 | cpu_enter_lowpower(); | |
2d8b21d9 | 93 | spear13xx_do_lowpower(cpu, &spurious); |
e3978dc7 VK |
94 | |
95 | /* | |
96 | * bring this CPU back into the world of cache | |
97 | * coherency, and then restore interrupts | |
98 | */ | |
99 | cpu_leave_lowpower(); | |
100 | ||
101 | if (spurious) | |
102 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); | |
103 | } |