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
15 #include <asm/cacheflush.h>
16 #include <asm/smp_plat.h>
17
18 extern volatile int pen_release;
19
cpu_enter_lowpower(void)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 " mcr p15, 0, %1, c7, c10, 4\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");
40 }
41
cpu_leave_lowpower(void)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
platform_do_lowpower(unsigned int cpu,int * spurious)57 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
58 {
59 /*
60 * there is no power-control hardware on this platform, so all
61 * we can do is put the core into WFI; this is safe as the calling
62 * code will have already disabled interrupts
63 */
64 for (;;) {
65 /*
66 * here's the WFI
67 */
68 asm(".word 0xe320f003\n"
69 :
70 :
71 : "memory", "cc");
72
73 if (pen_release == cpu_logical_map(cpu)) {
74 /*
75 * OK, proper wakeup, we're done
76 */
77 break;
78 }
79
80 /*
81 * Getting here, means that we have come out of WFI without
82 * having been woken up - this shouldn't happen
83 *
84 * Just note it happening - when we're woken, we can report
85 * its occurrence.
86 */
87 (*spurious)++;
88 }
89 }
90
platform_cpu_kill(unsigned int cpu)91 int platform_cpu_kill(unsigned int cpu)
92 {
93 return 1;
94 }
95
96 /*
97 * platform-specific code to shutdown a CPU
98 *
99 * Called with IRQs disabled
100 */
platform_cpu_die(unsigned int cpu)101 void platform_cpu_die(unsigned int cpu)
102 {
103 int spurious = 0;
104
105 /*
106 * we're ready for shutdown now, so do it
107 */
108 cpu_enter_lowpower();
109 platform_do_lowpower(cpu, &spurious);
110
111 /*
112 * bring this CPU back into the world of cache
113 * coherency, and then restore interrupts
114 */
115 cpu_leave_lowpower();
116
117 if (spurious)
118 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
119 }
120
platform_cpu_disable(unsigned int cpu)121 int platform_cpu_disable(unsigned int cpu)
122 {
123 /*
124 * we don't allow CPU 0 to be shutdown (it is still too special
125 * e.g. clock tick interrupts)
126 */
127 return cpu == 0 ? -EPERM : 0;
128 }
129