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
18static 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
39static 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
54static 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 */
93void __ref 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