target/linux/oxnas/files/arch/arm/mach-oxnas/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/cp15.h>
  16 #include <asm/smp_plat.h>
  17 #include <mach/smp.h>
  18
  19 static inline void cpu_enter_lowpower(void)
  20 {
  21         unsigned int v;
  22
  23         asm volatile(
  24         "       mcr     p15, 0, %1, c7, c5, 0\n"
  25         "       mcr     p15, 0, %1, c7, c10, 4\n"
  26         /*
  27          * Turn off coherency
  28          */
  29         "       mrc     p15, 0, %0, c1, c0, 1\n"
  30         "       bic     %0, %0, #0x20\n"
  31         "       mcr     p15, 0, %0, c1, c0, 1\n"
  32         "       mrc     p15, 0, %0, c1, c0, 0\n"
  33         "       bic     %0, %0, %2\n"
  34         "       mcr     p15, 0, %0, c1, c0, 0\n"
  35           : "=&r" (v)
  36           : "r" (0), "Ir" (CR_C)
  37           : "cc");
  38 }
  39
  40 static inline void cpu_leave_lowpower(void)
  41 {
  42         unsigned int v;
  43
  44         asm volatile("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 (read_pen_release() == cpu_logical_map(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 /*
  90  * platform-specific code to shutdown a CPU
  91  *
  92  * Called with IRQs disabled
  93  */
  94 void __ref ox820_cpu_die(unsigned int cpu)
  95 {
  96         int spurious = 0;
  97
  98         /*
  99          * we're ready for shutdown now, so do it
 100          */
 101         cpu_enter_lowpower();
 102         platform_do_lowpower(cpu, &spurious);
 103
 104         /*
 105          * bring this CPU back into the world of cache
 106          * coherency, and then restore interrupts
 107          */
 108         cpu_leave_lowpower();
 109
 110         if (spurious)
 111                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 112 }