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 #include <asm/system.h>
18
19 extern volatile int pen_release;
20
cpu_enter_lowpower(void)21 static inline void cpu_enter_lowpower(void)
22 {
23 unsigned int v;
24
25 flush_cache_all();
26 asm volatile(
27 "mcr p15, 0, %1, c7, c5, 0\n"
28 " mcr p15, 0, %1, c7, c10, 4\n"
29 /*
30 * Turn off coherency
31 */
32 " mrc p15, 0, %0, c1, c0, 1\n"
33 " bic %0, %0, %3\n"
34 " mcr p15, 0, %0, c1, c0, 1\n"
35 " mrc p15, 0, %0, c1, c0, 0\n"
36 " bic %0, %0, %2\n"
37 " mcr p15, 0, %0, c1, c0, 0\n"
38 : "=&r" (v)
39 : "r" (0), "Ir" (CR_C), "Ir" (0x40)
40 : "cc");
41 }
42
cpu_leave_lowpower(void)43 static inline void cpu_leave_lowpower(void)
44 {
45 unsigned int v;
46
47 asm volatile(
48 "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, %2\n"
53 " mcr p15, 0, %0, c1, c0, 1\n"
54 : "=&r" (v)
55 : "Ir" (CR_C), "Ir" (0x40)
56 : "cc");
57 }
58
platform_do_lowpower(unsigned int cpu,int * spurious)59 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
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 wfi();
68
69 if (pen_release == cpu_logical_map(cpu)) {
70 /*
71 * OK, proper wakeup, we're done
72 */
73 break;
74 }
75
76 /*
77 * Getting here, means that we have come out of WFI without
78 * having been woken up - this shouldn't happen
79 *
80 * Just note it happening - when we're woken, we can report
81 * its occurrence.
82 */
83 (*spurious)++;
84 }
85 }
86
platform_cpu_kill(unsigned int cpu)87 int platform_cpu_kill(unsigned int cpu)
88 {
89 return 1;
90 }
91
92 /*
93 * platform-specific code to shutdown a CPU
94 *
95 * Called with IRQs disabled
96 */
platform_cpu_die(unsigned int cpu)97 void platform_cpu_die(unsigned int cpu)
98 {
99 int spurious = 0;
100
101 /*
102 * we're ready for shutdown now, so do it
103 */
104 cpu_enter_lowpower();
105 platform_do_lowpower(cpu, &spurious);
106
107 /*
108 * bring this CPU back into the world of cache
109 * coherency, and then restore interrupts
110 */
111 cpu_leave_lowpower();
112
113 if (spurious)
114 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
115 }
116
platform_cpu_disable(unsigned int cpu)117 int platform_cpu_disable(unsigned int cpu)
118 {
119 /*
120 * we don't allow CPU 0 to be shutdown (it is still too special
121 * e.g. clock tick interrupts)
122 */
123 return cpu == 0 ? -EPERM : 0;
124 }
125