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
  15 #include <asm/cacheflush.h>
  16 #include <asm/cp15.h>
  17 #include <asm/smp_plat.h>
  18
  19 extern volatile int pen_release;
  20
  21 static inline void cpu_enter_lowpower(void)
  22 {
  23         unsigned int v;
  24
  25         flush_cache_all();
  26         asm volatile(
  27         "       mcr     p15, 0, %1, c7, c5, 0\n"
  28         "       mcr     p15, 0, %1, c7, c10, 4\n"
  29         /*
  30          * Turn off coherency
  31          */
  32         "       mrc     p15, 0, %0, c1, c0, 1\n"
  33         "       bic     %0, %0, #0x20\n"
  34         "       mcr     p15, 0, %0, c1, c0, 1\n"
  35         "       mrc     p15, 0, %0, c1, c0, 0\n"
  36         "       bic     %0, %0, %2\n"
  37         "       mcr     p15, 0, %0, c1, c0, 0\n"
  38           : "=&r" (v)
  39           : "r" (0), "Ir" (CR_C)
  40           : "cc");
  41 }
  42
  43 static inline void cpu_leave_lowpower(void)
  44 {
  45         unsigned int v;
  46
  47         asm volatile(   "mrc    p15, 0, %0, c1, c0, 0\n"
  48         "       orr     %0, %0, %1\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           : "Ir" (CR_C)
  55           : "cc");
  56 }
  57
  58 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  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_logical_map(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                  * Just note it happening - when we're woken, we can report
  86                  * its occurrence.
  87                  */
  88                 (*spurious)++;
  89         }
  90 }
  91
  92 int platform_cpu_kill(unsigned int cpu)
  93 {
  94         return 1;
  95 }
  96
  97 /*
  98  * platform-specific code to shutdown a CPU
  99  *
 100  * Called with IRQs disabled
 101  */
 102 void platform_cpu_die(unsigned int cpu)
 103 {
 104         int spurious = 0;
 105
 106         /*
 107          * we're ready for shutdown now, so do it
 108          */
 109         cpu_enter_lowpower();
 110         platform_do_lowpower(cpu, &spurious);
 111
 112         /*
 113          * bring this CPU back into the world of cache
 114          * coherency, and then restore interrupts
 115          */
 116         cpu_leave_lowpower();
 117
 118         if (spurious)
 119                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 120 }
 121
 122 int platform_cpu_disable(unsigned int cpu)
 123 {
 124         /*
 125          * we don't allow CPU 0 to be shutdown (it is still too special
 126          * e.g. clock tick interrupts)
 127          */
 128         return cpu == 0 ? -EPERM : 0;
 129 }