LXR linux/arch/arm/mach-realview/hotplug.c

   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#include <linux/completion.h>
  15
  16#include <asm/cacheflush.h>
  17
  18extern volatile int pen_release;
  19
  20static DECLARE_COMPLETION(cpu_killed);
  21
  22static inline void cpu_enter_lowpower(void)
  23{
  24        unsigned int v;
  25
  26        flush_cache_all();
  27        asm volatile(
  28        "       mcr     p15, 0, %1, c7, c5, 0\n"
  29        "       mcr     p15, 0, %1, c7, c10, 4\n"
  30        /*
  31         * Turn off coherency
  32         */
  33        "       mrc     p15, 0, %0, c1, c0, 1\n"
  34        "       bic     %0, %0, #0x20\n"
  35        "       mcr     p15, 0, %0, c1, c0, 1\n"
  36        "       mrc     p15, 0, %0, c1, c0, 0\n"
  37        "       bic     %0, %0, #0x04\n"
  38        "       mcr     p15, 0, %0, c1, c0, 0\n"
  39          : "=&r" (v)
  40          : "r" (0)
  41          : "cc");
  42}
  43
  44static inline void cpu_leave_lowpower(void)
  45{
  46        unsigned int v;
  47
  48        asm volatile(   "mrc    p15, 0, %0, c1, c0, 0\n"
  49        "       orr     %0, %0, #0x04\n"
  50        "       mcr     p15, 0, %0, c1, c0, 0\n"
  51        "       mrc     p15, 0, %0, c1, c0, 1\n"
  52        "       orr     %0, %0, #0x20\n"
  53        "       mcr     p15, 0, %0, c1, c0, 1\n"
  54          : "=&r" (v)
  55          :
  56          : "cc");
  57}
  58
  59static inline void platform_do_lowpower(unsigned int cpu)
  60{
  61        /*
  62         * there is no power-control hardware on this platform, so all
  63         * we can do is put the core into WFI; this is safe as the calling
  64         * code will have already disabled interrupts
  65         */
  66        for (;;) {
  67                /*
  68                 * here's the WFI
  69                 */
  70                asm(".word      0xe320f003\n"
  71                    :
  72                    :
  73                    : "memory", "cc");
  74
  75                if (pen_release == cpu) {
  76                        /*
  77                         * OK, proper wakeup, we're done
  78                         */
  79                        break;
  80                }
  81
  82                /*
  83                 * getting here, means that we have come out of WFI without
  84                 * having been woken up - this shouldn't happen
  85                 *
  86                 * The trouble is, letting people know about this is not really
  87                 * possible, since we are currently running incoherently, and
  88                 * therefore cannot safely call printk() or anything else
  89                 */
  90#ifdef DEBUG
  91                printk("CPU%u: spurious wakeup call\n", cpu);
  92#endif
  93        }
  94}
  95
  96int platform_cpu_kill(unsigned int cpu)
  97{
  98        return wait_for_completion_timeout(&cpu_killed, 5000);
  99}
 100
 101/*
 102 * platform-specific code to shutdown a CPU
 103 *
 104 * Called with IRQs disabled
 105 */
 106void platform_cpu_die(unsigned int cpu)
 107{
 108#ifdef DEBUG
 109        unsigned int this_cpu = hard_smp_processor_id();
 110
 111        if (cpu != this_cpu) {
 112                printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",
 113                           this_cpu, cpu);
 114                BUG();
 115        }
 116#endif
 117
 118        printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
 119        complete(&cpu_killed);
 120
 121        /*
 122         * we're ready for shutdown now, so do it
 123         */
 124        cpu_enter_lowpower();
 125        platform_do_lowpower(cpu);
 126
 127        /*
 128         * bring this CPU back into the world of cache
 129         * coherency, and then restore interrupts
 130         */
 131        cpu_leave_lowpower();
 132}
 133
 134int mach_cpu_disable(unsigned int cpu)
 135{
 136        /*
 137         * we don't allow CPU 0 to be shutdown (it is still too special
 138         * e.g. clock tick interrupts)
 139         */
 140        return cpu == 0 ? -EPERM : 0;
 141}
 142