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
  15 #include <asm/cacheflush.h>
  16
  17 static inline void cpu_enter_lowpower(void)
  18 {
  19         unsigned int v;
  20
  21         flush_cache_all();
  22         asm volatile(
  23         "       mcr     p15, 0, %1, c7, c5, 0\n"
  24         "       mcr     p15, 0, %1, c7, c10, 4\n"
  25         /*
  26          * Turn off coherency
  27          */
  28         "       mrc     p15, 0, %0, c1, c0, 1\n"
  29         "       bic     %0, %0, #0x20\n"
  30         "       mcr     p15, 0, %0, c1, c0, 1\n"
  31         "       mrc     p15, 0, %0, c1, c0, 0\n"
  32         "       bic     %0, %0, %2\n"
  33         "       mcr     p15, 0, %0, c1, c0, 0\n"
  34           : "=&r" (v)
  35           : "r" (0), "Ir" (CR_C)
  36           : "cc");
  37 }
  38
  39 static inline void cpu_leave_lowpower(void)
  40 {
  41         unsigned int v;
  42
  43         asm volatile(
  44         "mrc    p15, 0, %0, c1, c0, 0\n"
  45         "       orr     %0, %0, %1\n"
  46         "       mcr     p15, 0, %0, c1, c0, 0\n"
  47         "       mrc     p15, 0, %0, c1, c0, 1\n"
  48         "       orr     %0, %0, #0x20\n"
  49         "       mcr     p15, 0, %0, c1, c0, 1\n"
  50           : "=&r" (v)
  51           : "Ir" (CR_C)
  52           : "cc");
  53 }
  54
  55 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  56 {
  57         /*
  58          * there is no power-control hardware on this platform, so all
  59          * we can do is put the core into WFI; this is safe as the calling
  60          * code will have already disabled interrupts
  61          */
  62         for (;;) {
  63                 /*
  64                  * here's the WFI
  65                  */
  66                 asm(".word      0xe320f003\n"
  67                     :
  68                     :
  69                     : "memory", "cc");
  70
  71                 /*if (pen_release == cpu) {*/
  72                         /*
  73                          * OK, proper wakeup, we're done
  74                          */
  75                         break;
  76                 /*}*/
  77
  78                 /*
  79                  * Getting here, means that we have come out of WFI without
  80                  * having been woken up - this shouldn't happen
  81                  *
  82                  * Just note it happening - when we're woken, we can report
  83                  * its occurrence.
  84                  */
  85                 (*spurious)++;
  86         }
  87 }
  88
  89 int platform_cpu_kill(unsigned int cpu)
  90 {
  91         return 1;
  92 }
  93
  94 /*
  95  * platform-specific code to shutdown a CPU
  96  *
  97  * Called with IRQs disabled
  98  */
  99 void platform_cpu_die(unsigned int cpu)
 100 {
 101         int spurious = 0;
 102
 103         /*
 104          * we're ready for shutdown now, so do it
 105          */
 106         cpu_enter_lowpower();
 107         platform_do_lowpower(cpu, &spurious);
 108
 109         /*
 110          * bring this CPU back into the world of cache
 111          * coherency, and then restore interrupts
 112          */
 113         cpu_leave_lowpower();
 114
 115         if (spurious)
 116                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 117 }
 118
 119 int platform_cpu_disable(unsigned int cpu)
 120 {
 121         /*
 122          * we don't allow CPU 0 to be shutdown (it is still too special
 123          * e.g. clock tick interrupts)
 124          */
 125         return cpu == 0 ? -EPERM : 0;
 126 }