arch/arm/mach-exynos4/hotplug.c

   1 /* linux arch/arm/mach-exynos4/hotplug.c
   2  *
   3  *  Cloned from linux/arch/arm/mach-realview/hotplug.c
   4  *
   5  *  Copyright (C) 2002 ARM Ltd.
   6  *  All Rights Reserved
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11 */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/smp.h>
  16
  17 #include <asm/cacheflush.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, %3\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), "Ir" (0x40)
  40           : "cc");
  41 }
  42
  43 static inline void cpu_leave_lowpower(void)
  44 {
  45         unsigned int v;
  46
  47         asm volatile(
  48         "mrc    p15, 0, %0, c1, c0, 0\n"
  49         "       orr     %0, %0, %1\n"
  50         "       mcr     p15, 0, %0, c1, c0, 0\n"
  51         "       mrc     p15, 0, %0, c1, c0, 1\n"
  52         "       orr     %0, %0, %2\n"
  53         "       mcr     p15, 0, %0, c1, c0, 1\n"
  54           : "=&r" (v)
  55           : "Ir" (CR_C), "Ir" (0x40)
  56           : "cc");
  57 }
  58
  59 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  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                  * Just note it happening - when we're woken, we can report
  87                  * its occurrence.
  88                  */
  89                 (*spurious)++;
  90         }
  91 }
  92
  93 int platform_cpu_kill(unsigned int cpu)
  94 {
  95         return 1;
  96 }
  97
  98 /*
  99  * platform-specific code to shutdown a CPU
 100  *
 101  * Called with IRQs disabled
 102  */
 103 void platform_cpu_die(unsigned int cpu)
 104 {
 105         int spurious = 0;
 106
 107         /*
 108          * we're ready for shutdown now, so do it
 109          */
 110         cpu_enter_lowpower();
 111         platform_do_lowpower(cpu, &spurious);
 112
 113         /*
 114          * bring this CPU back into the world of cache
 115          * coherency, and then restore interrupts
 116          */
 117         cpu_leave_lowpower();
 118
 119         if (spurious)
 120                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 121 }
 122
 123 int platform_cpu_disable(unsigned int cpu)
 124 {
 125         /*
 126          * we don't allow CPU 0 to be shutdown (it is still too special
 127          * e.g. clock tick interrupts)
 128          */
 129         return cpu == 0 ? -EPERM : 0;
 130 }