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/cp15.h>
17
cpu_enter_lowpower(void)18 static inline void cpu_enter_lowpower(void)
19 {
20 unsigned int v;
21
22 flush_cache_all();
23 asm volatile(
24 " mcr p15, 0, %1, c7, c5, 0\n"
25 " mcr p15, 0, %1, c7, c10, 4\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");
38 }
39
cpu_leave_lowpower(void)40 static inline void cpu_leave_lowpower(void)
41 {
42 unsigned int v;
43
44 asm volatile(
45 "mrc p15, 0, %0, c1, c0, 0\n"
46 " orr %0, %0, %1\n"
47 " mcr p15, 0, %0, c1, c0, 0\n"
48 " mrc p15, 0, %0, c1, c0, 1\n"
49 " orr %0, %0, #0x20\n"
50 " mcr p15, 0, %0, c1, c0, 1\n"
51 : "=&r" (v)
52 : "Ir" (CR_C)
53 : "cc");
54 }
55
platform_do_lowpower(unsigned int cpu,int * spurious)56 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
57 {
58 /*
59 * there is no power-control hardware on this platform, so all
60 * we can do is put the core into WFI; this is safe as the calling
61 * code will have already disabled interrupts
62 */
63 for (;;) {
64 /*
65 * here's the WFI
66 */
67 asm(".word 0xe320f003\n"
68 :
69 :
70 : "memory", "cc");
71
72 /*if (pen_release == cpu) {*/
73 /*
74 * OK, proper wakeup, we're done
75 */
76 break;
77 /*}*/
78
79 /*
80 * Getting here, means that we have come out of WFI without
81 * having been woken up - this shouldn't happen
82 *
83 * Just note it happening - when we're woken, we can report
84 * its occurrence.
85 */
86 (*spurious)++;
87 }
88 }
89
platform_cpu_kill(unsigned int cpu)90 int platform_cpu_kill(unsigned int cpu)
91 {
92 return 1;
93 }
94
95 /*
96 * platform-specific code to shutdown a CPU
97 *
98 * Called with IRQs disabled
99 */
platform_cpu_die(unsigned int cpu)100 void platform_cpu_die(unsigned int cpu)
101 {
102 int spurious = 0;
103
104 /*
105 * we're ready for shutdown now, so do it
106 */
107 cpu_enter_lowpower();
108 platform_do_lowpower(cpu, &spurious);
109
110 /*
111 * bring this CPU back into the world of cache
112 * coherency, and then restore interrupts
113 */
114 cpu_leave_lowpower();
115
116 if (spurious)
117 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
118 }
119
platform_cpu_disable(unsigned int cpu)120 int platform_cpu_disable(unsigned int cpu)
121 {
122 /*
123 * we don't allow CPU 0 to be shutdown (it is still too special
124 * e.g. clock tick interrupts)
125 */
126 return cpu == 0 ? -EPERM : 0;
127 }
128