1/* linux arch/arm/mach-exynos4/hotplug.c
2 *
3 *  Cloned from linux/arch/arm/mach-realview/hotplug.c
4 *
5 *  Copyright (C) 2002 ARM Ltd.
6 *  All Rights Reserved
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11*/
12
13#include <linux/kernel.h>
14#include <linux/errno.h>
15#include <linux/smp.h>
16#include <linux/io.h>
17
18#include <asm/cacheflush.h>
19#include <asm/cp15.h>
20#include <asm/smp_plat.h>
21
22#include <mach/regs-pmu.h>
23
24extern volatile int pen_release;
25
26static inline void cpu_enter_lowpower(void)
27{
28	unsigned int v;
29
30	flush_cache_all();
31	asm volatile(
32	"	mcr	p15, 0, %1, c7, c5, 0\n"
33	"	mcr	p15, 0, %1, c7, c10, 4\n"
34	/*
35	 * Turn off coherency
36	 */
37	"	mrc	p15, 0, %0, c1, c0, 1\n"
38	"	bic	%0, %0, %3\n"
39	"	mcr	p15, 0, %0, c1, c0, 1\n"
40	"	mrc	p15, 0, %0, c1, c0, 0\n"
41	"	bic	%0, %0, %2\n"
42	"	mcr	p15, 0, %0, c1, c0, 0\n"
43	  : "=&r" (v)
44	  : "r" (0), "Ir" (CR_C), "Ir" (0x40)
45	  : "cc");
46}
47
48static inline void cpu_leave_lowpower(void)
49{
50	unsigned int v;
51
52	asm volatile(
53	"mrc	p15, 0, %0, c1, c0, 0\n"
54	"	orr	%0, %0, %1\n"
55	"	mcr	p15, 0, %0, c1, c0, 0\n"
56	"	mrc	p15, 0, %0, c1, c0, 1\n"
57	"	orr	%0, %0, %2\n"
58	"	mcr	p15, 0, %0, c1, c0, 1\n"
59	  : "=&r" (v)
60	  : "Ir" (CR_C), "Ir" (0x40)
61	  : "cc");
62}
63
64static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
65{
66	for (;;) {
67
68		/* make cpu1 to be turned off at next WFI command */
69		if (cpu == 1)
70			__raw_writel(0, S5P_ARM_CORE1_CONFIGURATION);
71
72		/*
73		 * here's the WFI
74		 */
75		asm(".word	0xe320f003\n"
76		    :
77		    :
78		    : "memory", "cc");
79
80		if (pen_release == cpu_logical_map(cpu)) {
81			/*
82			 * OK, proper wakeup, we're done
83			 */
84			break;
85		}
86
87		/*
88		 * Getting here, means that we have come out of WFI without
89		 * having been woken up - this shouldn't happen
90		 *
91		 * Just note it happening - when we're woken, we can report
92		 * its occurrence.
93		 */
94		(*spurious)++;
95	}
96}
97
98int platform_cpu_kill(unsigned int cpu)
99{
100	return 1;
101}
102
103/*
104 * platform-specific code to shutdown a CPU
105 *
106 * Called with IRQs disabled
107 */
108void platform_cpu_die(unsigned int cpu)
109{
110	int spurious = 0;
111
112	/*
113	 * we're ready for shutdown now, so do it
114	 */
115	cpu_enter_lowpower();
116	platform_do_lowpower(cpu, &spurious);
117
118	/*
119	 * bring this CPU back into the world of cache
120	 * coherency, and then restore interrupts
121	 */
122	cpu_leave_lowpower();
123
124	if (spurious)
125		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
126}
127
128int platform_cpu_disable(unsigned int cpu)
129{
130	/*
131	 * we don't allow CPU 0 to be shutdown (it is still too special
132	 * e.g. clock tick interrupts)
133	 */
134	return cpu == 0 ? -EPERM : 0;
135}
136