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/smp_plat.h>
16 #include <asm/cp15.h>
17
18 #include "core.h"
19
cpu_enter_lowpower(void)20 static inline void cpu_enter_lowpower(void)
21 {
22 unsigned int v;
23
24 asm volatile(
25 "mcr p15, 0, %1, c7, c5, 0\n"
26 " mcr p15, 0, %1, c7, c10, 4\n"
27 /*
28 * Turn off coherency
29 */
30 " mrc p15, 0, %0, c1, c0, 1\n"
31 " bic %0, %0, %3\n"
32 " mcr p15, 0, %0, c1, c0, 1\n"
33 " mrc p15, 0, %0, c1, c0, 0\n"
34 " bic %0, %0, %2\n"
35 " mcr p15, 0, %0, c1, c0, 0\n"
36 : "=&r" (v)
37 : "r" (0), "Ir" (CR_C), "Ir" (0x40)
38 : "cc");
39 }
40
cpu_leave_lowpower(void)41 static inline void cpu_leave_lowpower(void)
42 {
43 unsigned int v;
44
45 asm volatile(
46 "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, %2\n"
51 " mcr p15, 0, %0, c1, c0, 1\n"
52 : "=&r" (v)
53 : "Ir" (CR_C), "Ir" (0x40)
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 wfi();
66
67 if (pen_release == cpu_logical_map(cpu)) {
68 /*
69 * OK, proper wakeup, we're done
70 */
71 break;
72 }
73
74 /*
75 * Getting here, means that we have come out of WFI without
76 * having been woken up - this shouldn't happen
77 *
78 * Just note it happening - when we're woken, we can report
79 * its occurrence.
80 */
81 (*spurious)++;
82 }
83 }
84
85 /*
86 * platform-specific code to shutdown a CPU
87 *
88 * Called with IRQs disabled
89 */
vexpress_cpu_die(unsigned int cpu)90 void vexpress_cpu_die(unsigned int cpu)
91 {
92 int spurious = 0;
93
94 /*
95 * we're ready for shutdown now, so do it
96 */
97 cpu_enter_lowpower();
98 platform_do_lowpower(cpu, &spurious);
99
100 /*
101 * bring this CPU back into the world of cache
102 * coherency, and then restore interrupts
103 */
104 cpu_leave_lowpower();
105
106 if (spurious)
107 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
108 }
109