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
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, %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
39static 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
55static 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 */
88void 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