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 #include <linux/completion.h>
15
16 #include <asm/cacheflush.h>
17
18 extern volatile int pen_release;
19
20 static DECLARE_COMPLETION(cpu_killed);
21
cpu_enter_lowpower(void)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 " mcr p15, 0, %1, c7, c10, 4\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, #0x04\n"
38 " mcr p15, 0, %0, c1, c0, 0\n"
39 : "=&r" (v)
40 : "r" (0)
41 : "cc");
42 }
43
cpu_leave_lowpower(void)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, #0x04\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 :
56 : "cc");
57 }
58
platform_do_lowpower(unsigned int cpu)59 static inline void platform_do_lowpower(unsigned int cpu)
60 {
61 /*
62 * there is no power-control hardware on this platform, so all
63 * we can do is put the core into WFI; this is safe as the calling
64 * code will have already disabled interrupts
65 */
66 for (;;) {
67 /*
68 * here's the WFI
69 */
70 asm(".word 0xe320f003\n"
71 :
72 :
73 : "memory", "cc");
74
75 if (pen_release == cpu) {
76 /*
77 * OK, proper wakeup, we're done
78 */
79 break;
80 }
81
82 /*
83 * getting here, means that we have come out of WFI without
84 * having been woken up - this shouldn't happen
85 *
86 * The trouble is, letting people know about this is not really
87 * possible, since we are currently running incoherently, and
88 * therefore cannot safely call printk() or anything else
89 */
90 #ifdef DEBUG
91 printk("CPU%u: spurious wakeup call\n", cpu);
92 #endif
93 }
94 }
95
platform_cpu_kill(unsigned int cpu)96 int platform_cpu_kill(unsigned int cpu)
97 {
98 return wait_for_completion_timeout(&cpu_killed, 5000);
99 }
100
101 /*
102 * platform-specific code to shutdown a CPU
103 *
104 * Called with IRQs disabled
105 */
platform_cpu_die(unsigned int cpu)106 void platform_cpu_die(unsigned int cpu)
107 {
108 #ifdef DEBUG
109 unsigned int this_cpu = hard_smp_processor_id();
110
111 if (cpu != this_cpu) {
112 printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",
113 this_cpu, cpu);
114 BUG();
115 }
116 #endif
117
118 printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
119 complete(&cpu_killed);
120
121 /*
122 * we're ready for shutdown now, so do it
123 */
124 cpu_enter_lowpower();
125 platform_do_lowpower(cpu);
126
127 /*
128 * bring this CPU back into the world of cache
129 * coherency, and then restore interrupts
130 */
131 cpu_leave_lowpower();
132 }
133
mach_cpu_disable(unsigned int cpu)134 int mach_cpu_disable(unsigned int cpu)
135 {
136 /*
137 * we don't allow CPU 0 to be shutdown (it is still too special
138 * e.g. clock tick interrupts)
139 */
140 return cpu == 0 ? -EPERM : 0;
141 }
142