ARM: S5PV310: Add CPU hotplug support for S5PV310

/* linux arch/arm/mach-s5pv310/hotplug.c

 *

 *  Cloned from linux/arch/arm/mach-realview/hotplug.c

 *

 *  Copyright (C) 2002 ARM Ltd.

 *  All Rights Reserved

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

*/

#include <linux/kernel.h>

#include <linux/errno.h>

#include <linux/smp.h>

#include <linux/completion.h>

#include <asm/cacheflush.h>

extern volatile int pen_release;

static DECLARE_COMPLETION(cpu_killed);

static inline void cpu_enter_lowpower(void)

{

	unsigned int v;

	flush_cache_all();

	asm volatile(

	"	mcr	p15, 0, %1, c7, c5, 0\n"

	"	mcr	p15, 0, %1, c7, c10, 4\n"

	/*

	 * Turn off coherency

	 */

	"	mrc	p15, 0, %0, c1, c0, 1\n"

	"	bic	%0, %0, #0x20\n"

	"	mcr	p15, 0, %0, c1, c0, 1\n"

	"	mrc	p15, 0, %0, c1, c0, 0\n"

	"	bic	%0, %0, #0x04\n"

	"	mcr	p15, 0, %0, c1, c0, 0\n"

	  : "=&r" (v)

	  : "r" (0)

	  : "cc");

}

static inline void cpu_leave_lowpower(void)

{

	unsigned int v;

	asm volatile(

	"mrc	p15, 0, %0, c1, c0, 0\n"

	"	orr	%0, %0, #0x04\n"

	"	mcr	p15, 0, %0, c1, c0, 0\n"

	"	mrc	p15, 0, %0, c1, c0, 1\n"

	"	orr	%0, %0, #0x20\n"

	"	mcr	p15, 0, %0, c1, c0, 1\n"

	  : "=&r" (v)

	  :

	  : "cc");

}

static inline void platform_do_lowpower(unsigned int cpu)

{

	/*

	 * there is no power-control hardware on this platform, so all

	 * we can do is put the core into WFI; this is safe as the calling

	 * code will have already disabled interrupts

	 */

	for (;;) {

		/*

		 * here's the WFI

		 */

		asm(".word	0xe320f003\n"

		    :

		    :

		    : "memory", "cc");

		if (pen_release == cpu) {

			/*

			 * OK, proper wakeup, we're done

			 */

			break;

		}

		/*

		 * getting here, means that we have come out of WFI without

		 * having been woken up - this shouldn't happen

		 *

		 * The trouble is, letting people know about this is not really

		 * possible, since we are currently running incoherently, and

		 * therefore cannot safely call printk() or anything else

		 */

#ifdef DEBUG

		printk(KERN_WARN "CPU%u: spurious wakeup call\n", cpu);

#endif

	}

}

int platform_cpu_kill(unsigned int cpu)

{

	return wait_for_completion_timeout(&cpu_killed, 5000);

}

/*

 * platform-specific code to shutdown a CPU

 *

 * Called with IRQs disabled

 */

void platform_cpu_die(unsigned int cpu)

{

#ifdef DEBUG

	unsigned int this_cpu = hard_smp_processor_id();

	if (cpu != this_cpu) {

		printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",

			   this_cpu, cpu);

		BUG();

	}

#endif

	printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);

	complete(&cpu_killed);

	/*

	 * we're ready for shutdown now, so do it

	 */

	cpu_enter_lowpower();

	platform_do_lowpower(cpu);

	/*

	 * bring this CPU back into the world of cache

	 * coherency, and then restore interrupts

	 */

	cpu_leave_lowpower();

}

int platform_cpu_disable(unsigned int cpu)

{

	/*

	 * we don't allow CPU 0 to be shutdown (it is still too special

	 * e.g. clock tick interrupts)

	 */

	return cpu == 0 ? -EPERM : 0;

}