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/cp15.h>
16 #include <asm/smp_plat.h>
17
cpu_enter_lowpower(void)18 static inline void cpu_enter_lowpower(void)
19 {
20 unsigned int v;
21
22 asm volatile(
23 " mcr p15, 0, %1, c7, c5, 0\n"
24 " mcr p15, 0, %1, c7, c10, 4\n"
25 /*
26 * Turn off coherency
27 */
28 " mrc p15, 0, %0, c1, c0, 1\n"
29 " bic %0, %0, #0x20\n"
30 " mcr p15, 0, %0, c1, c0, 1\n"
31 " mrc p15, 0, %0, c1, c0, 0\n"
32 " bic %0, %0, %2\n"
33 " mcr p15, 0, %0, c1, c0, 0\n"
34 : "=&r" (v)
35 : "r" (0), "Ir" (CR_C)
36 : "cc");
37 }
38
cpu_leave_lowpower(void)39 static inline void cpu_leave_lowpower(void)
40 {
41 unsigned int v;
42
43 asm volatile( "mrc p15, 0, %0, c1, c0, 0\n"
44 " orr %0, %0, %1\n"
45 " mcr p15, 0, %0, c1, c0, 0\n"
46 " mrc p15, 0, %0, c1, c0, 1\n"
47 " orr %0, %0, #0x20\n"
48 " mcr p15, 0, %0, c1, c0, 1\n"
49 : "=&r" (v)
50 : "Ir" (CR_C)
51 : "cc");
52 }
53
platform_do_lowpower(unsigned int cpu,int * spurious)54 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
55 {
56 /*
57 * there is no power-control hardware on this platform, so all
58 * we can do is put the core into WFI; this is safe as the calling
59 * code will have already disabled interrupts
60 */
61 for (;;) {
62 /*
63 * here's the WFI
64 */
65 asm(".word 0xe320f003\n"
66 :
67 :
68 : "memory", "cc");
69
70 if (pen_release == cpu_logical_map(cpu)) {
71 /*
72 * OK, proper wakeup, we're done
73 */
74 break;
75 }
76
77 /*
78 * Getting here, means that we have come out of WFI without
79 * having been woken up - this shouldn't happen
80 *
81 * Just note it happening - when we're woken, we can report
82 * its occurrence.
83 */
84 (*spurious)++;
85 }
86 }
87
88 /*
89 * platform-specific code to shutdown a CPU
90 *
91 * Called with IRQs disabled
92 */
realview_cpu_die(unsigned int cpu)93 void realview_cpu_die(unsigned int cpu)
94 {
95 int spurious = 0;
96
97 /*
98 * we're ready for shutdown now, so do it
99 */
100 cpu_enter_lowpower();
101 platform_do_lowpower(cpu, &spurious);
102
103 /*
104 * bring this CPU back into the world of cache
105 * coherency, and then restore interrupts
106 */
107 cpu_leave_lowpower();
108
109 if (spurious)
110 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
111 }
112