arch/arm/mach-oxnas/hotplug.c

   1 /*
   2  *  Copyright (C) 2002 ARM Ltd.
   3  *  All Rights Reserved
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9 #include <linux/kernel.h>
  10 #include <linux/errno.h>
  11 #include <linux/smp.h>
  12
  13 #include <asm/cp15.h>
  14 #include <asm/smp_plat.h>
  15
  16 static inline void cpu_enter_lowpower(void)
  17 {
  18         unsigned int v;
  19
  20         asm volatile(
  21         "       mcr     p15, 0, %1, c7, c5, 0\n"
  22         "       mcr     p15, 0, %1, c7, c10, 4\n"
  23         /*
  24          * Turn off coherency
  25          */
  26         "       mrc     p15, 0, %0, c1, c0, 1\n"
  27         "       bic     %0, %0, #0x20\n"
  28         "       mcr     p15, 0, %0, c1, c0, 1\n"
  29         "       mrc     p15, 0, %0, c1, c0, 0\n"
  30         "       bic     %0, %0, %2\n"
  31         "       mcr     p15, 0, %0, c1, c0, 0\n"
  32           : "=&r" (v)
  33           : "r" (0), "Ir" (CR_C)
  34           : "cc");
  35 }
  36
  37 static inline void cpu_leave_lowpower(void)
  38 {
  39         unsigned int v;
  40
  41         asm volatile(   "mrc    p15, 0, %0, c1, c0, 0\n"
  42         "       orr     %0, %0, %1\n"
  43         "       mcr     p15, 0, %0, c1, c0, 0\n"
  44         "       mrc     p15, 0, %0, c1, c0, 1\n"
  45         "       orr     %0, %0, #0x20\n"
  46         "       mcr     p15, 0, %0, c1, c0, 1\n"
  47           : "=&r" (v)
  48           : "Ir" (CR_C)
  49           : "cc");
  50 }
  51
  52 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  53 {
  54         /*
  55          * there is no power-control hardware on this platform, so all
  56          * we can do is put the core into WFI; this is safe as the calling
  57          * code will have already disabled interrupts
  58          */
  59         for (;;) {
  60                 /*
  61                  * here's the WFI
  62                  */
  63                 asm(".word      0xe320f003\n"
  64                     :
  65                     :
  66                     : "memory", "cc");
  67
  68                 if (pen_release == cpu_logical_map(cpu)) {
  69                         /*
  70                          * OK, proper wakeup, we're done
  71                          */
  72                         break;
  73                 }
  74
  75                 /*
  76                  * Getting here, means that we have come out of WFI without
  77                  * having been woken up - this shouldn't happen
  78                  *
  79                  * Just note it happening - when we're woken, we can report
  80                  * its occurrence.
  81                  */
  82                 (*spurious)++;
  83         }
  84 }
  85
  86 /*
  87  * platform-specific code to shutdown a CPU
  88  *
  89  * Called with IRQs disabled
  90  */
  91 void ox820_cpu_die(unsigned int cpu)
  92 {
  93         int spurious = 0;
  94
  95         /*
  96          * we're ready for shutdown now, so do it
  97          */
  98         cpu_enter_lowpower();
  99         platform_do_lowpower(cpu, &spurious);
 100
 101         /*
 102          * bring this CPU back into the world of cache
 103          * coherency, and then restore interrupts
 104          */
 105         cpu_leave_lowpower();
 106
 107         if (spurious)
 108                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 109 }