OpenWrt – Rev 1

Subversion Repositories:
Rev:
/* linux arch/arm/mach-cns3xxx/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 <asm/cacheflush.h>

extern volatile int pen_release;

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, %3\n"
        "       mcr     p15, 0, %0, c1, c0, 1\n"
        "       mrc     p15, 0, %0, c1, c0, 0\n"
        "       bic     %0, %0, %2\n"
        "       mcr     p15, 0, %0, c1, c0, 0\n"
          : "=&r" (v)
          : "r" (0), "Ir" (CR_C), "Ir" (0x40)
          : "cc");
}

static inline void cpu_leave_lowpower(void)
{
        unsigned int v;

        asm volatile(
        "mrc    p15, 0, %0, c1, c0, 0\n"
        "       orr     %0, %0, %1\n"
        "       mcr     p15, 0, %0, c1, c0, 0\n"
        "       mrc     p15, 0, %0, c1, c0, 1\n"
        "       orr     %0, %0, %2\n"
        "       mcr     p15, 0, %0, c1, c0, 1\n"
          : "=&r" (v)
          : "Ir" (CR_C), "Ir" (0x40)
          : "cc");
}

static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
{
        /*
         * 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
                 *
                 * Just note it happening - when we're woken, we can report
                 * its occurrence.
                 */
                (*spurious)++;
        }
}

int platform_cpu_kill(unsigned int cpu)
{
        return 1;
}

/*
 * platform-specific code to shutdown a CPU
 *
 * Called with IRQs disabled
 */
void platform_cpu_die(unsigned int cpu)
{
        int spurious = 0;

        /*
         * we're ready for shutdown now, so do it
         */
        cpu_enter_lowpower();
        platform_do_lowpower(cpu, &spurious);

        /*
         * bring this CPU back into the world of cache
         * coherency, and then restore interrupts
         */
        cpu_leave_lowpower();

        if (spurious)
                pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
}

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;
}