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