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/cacheflush.h>
 16
 17extern volatile int pen_release;
 18
 19static inline void cpu_enter_lowpower(void)
 20{
 21	unsigned int v;
 22
 23	flush_cache_all();
 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, #0x20\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)
 38	  : "cc");
 39}
 40
 41static inline void cpu_leave_lowpower(void)
 42{
 43	unsigned int v;
 44
 45	asm volatile(	"mrc	p15, 0, %0, c1, c0, 0\n"
 46	"	orr	%0, %0, %1\n"
 47	"	mcr	p15, 0, %0, c1, c0, 0\n"
 48	"	mrc	p15, 0, %0, c1, c0, 1\n"
 49	"	orr	%0, %0, #0x20\n"
 50	"	mcr	p15, 0, %0, c1, c0, 1\n"
 51	  : "=&r" (v)
 52	  : "Ir" (CR_C)
 53	  : "cc");
 54}
 55
 56static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
 57{
 58	/*
 59	 * there is no power-control hardware on this platform, so all
 60	 * we can do is put the core into WFI; this is safe as the calling
 61	 * code will have already disabled interrupts
 62	 */
 63	for (;;) {
 64		/*
 65		 * here's the WFI
 66		 */
 67		asm(".word	0xe320f003\n"
 68		    :
 69		    :
 70		    : "memory", "cc");
 71
 72		if (pen_release == cpu) {
 73			/*
 74			 * OK, proper wakeup, we're done
 75			 */
 76			break;
 77		}
 78
 79		/*
 80		 * Getting here, means that we have come out of WFI without
 81		 * having been woken up - this shouldn't happen
 82		 *
 83		 * Just note it happening - when we're woken, we can report
 84		 * its occurrence.
 85		 */
 86		(*spurious)++;
 87	}
 88}
 89
 90int platform_cpu_kill(unsigned int cpu)
 91{
 92	return 1;
 93}
 94
 95/*
 96 * platform-specific code to shutdown a CPU
 97 *
 98 * Called with IRQs disabled
 99 */
100void platform_cpu_die(unsigned int cpu)
101{
102	int spurious = 0;
103
104	/*
105	 * we're ready for shutdown now, so do it
106	 */
107	cpu_enter_lowpower();
108	platform_do_lowpower(cpu, &spurious);
109
110	/*
111	 * bring this CPU back into the world of cache
112	 * coherency, and then restore interrupts
113	 */
114	cpu_leave_lowpower();
115
116	if (spurious)
117		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
118}
119
120int platform_cpu_disable(unsigned int cpu)
121{
122	/*
123	 * we don't allow CPU 0 to be shutdown (it is still too special
124	 * e.g. clock tick interrupts)
125	 */
126	return cpu == 0 ? -EPERM : 0;
127}