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
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, %3\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), "Ir" (0x40)
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(
44 "mrc p15, 0, %0, c1, c0, 0\n"
45 " orr %0, %0, %1\n"
46 " mcr p15, 0, %0, c1, c0, 0\n"
47 " mrc p15, 0, %0, c1, c0, 1\n"
48 " orr %0, %0, %2\n"
49 " mcr p15, 0, %0, c1, c0, 1\n"
50 : "=&r" (v)
51 : "Ir" (CR_C), "Ir" (0x40)
52 : "cc");
53 }
54
platform_do_lowpower(unsigned int cpu,int * spurious)55 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
56 {
57 /*
58 * there is no power-control hardware on this platform, so all
59 * we can do is put the core into WFI; this is safe as the calling
60 * code will have already disabled interrupts
61 */
62 for (;;) {
63 wfi();
64
65 if (pen_release == cpu_logical_map(cpu)) {
66 /*
67 * OK, proper wakeup, we're done
68 */
69 break;
70 }
71
72 /*
73 * Getting here, means that we have come out of WFI without
74 * having been woken up - this shouldn't happen
75 *
76 * Just note it happening - when we're woken, we can report
77 * its occurrence.
78 */
79 (*spurious)++;
80 }
81 }
82
83 /*
84 * platform-specific code to shutdown a CPU
85 *
86 * Called with IRQs disabled
87 */
vexpress_cpu_die(unsigned int cpu)88 void __ref vexpress_cpu_die(unsigned int cpu)
89 {
90 int spurious = 0;
91
92 /*
93 * we're ready for shutdown now, so do it
94 */
95 cpu_enter_lowpower();
96 platform_do_lowpower(cpu, &spurious);
97
98 /*
99 * bring this CPU back into the world of cache
100 * coherency, and then restore interrupts
101 */
102 cpu_leave_lowpower();
103
104 if (spurious)
105 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
106 }
107