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 #include <linux/io.h>
  17
  18 #include <asm/cacheflush.h>
  19
  20 #include <mach/regs-pmu.h>
  21
  22 extern volatile int pen_release;
  23
  24 static inline void cpu_enter_lowpower(void)
  25 {
  26         unsigned int v;
  27
  28         flush_cache_all();
  29         asm volatile(
  30         "       mcr     p15, 0, %1, c7, c5, 0\n"
  31         "       mcr     p15, 0, %1, c7, c10, 4\n"
  32         /*
  33          * Turn off coherency
  34          */
  35         "       mrc     p15, 0, %0, c1, c0, 1\n"
  36         "       bic     %0, %0, %3\n"
  37         "       mcr     p15, 0, %0, c1, c0, 1\n"
  38         "       mrc     p15, 0, %0, c1, c0, 0\n"
  39         "       bic     %0, %0, %2\n"
  40         "       mcr     p15, 0, %0, c1, c0, 0\n"
  41           : "=&r" (v)
  42           : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  43           : "cc");
  44 }
  45
  46 static inline void cpu_leave_lowpower(void)
  47 {
  48         unsigned int v;
  49
  50         asm volatile(
  51         "mrc    p15, 0, %0, c1, c0, 0\n"
  52         "       orr     %0, %0, %1\n"
  53         "       mcr     p15, 0, %0, c1, c0, 0\n"
  54         "       mrc     p15, 0, %0, c1, c0, 1\n"
  55         "       orr     %0, %0, %2\n"
  56         "       mcr     p15, 0, %0, c1, c0, 1\n"
  57           : "=&r" (v)
  58           : "Ir" (CR_C), "Ir" (0x40)
  59           : "cc");
  60 }
  61
  62 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  63 {
  64         for (;;) {
  65
  66                 /* make cpu1 to be turned off at next WFI command */
  67                 if (cpu == 1)
  68                         __raw_writel(0, S5P_ARM_CORE1_CONFIGURATION);
  69
  70                 /*
  71                  * here's the WFI
  72                  */
  73                 asm(".word      0xe320f003\n"
  74                     :
  75                     :
  76                     : "memory", "cc");
  77
  78                 if (pen_release == cpu) {
  79                         /*
  80                          * OK, proper wakeup, we're done
  81                          */
  82                         break;
  83                 }
  84
  85                 /*
  86                  * Getting here, means that we have come out of WFI without
  87                  * having been woken up - this shouldn't happen
  88                  *
  89                  * Just note it happening - when we're woken, we can report
  90                  * its occurrence.
  91                  */
  92                 (*spurious)++;
  93         }
  94 }
  95
  96 int platform_cpu_kill(unsigned int cpu)
  97 {
  98         return 1;
  99 }
 100
 101 /*
 102  * platform-specific code to shutdown a CPU
 103  *
 104  * Called with IRQs disabled
 105  */
 106 void platform_cpu_die(unsigned int cpu)
 107 {
 108         int spurious = 0;
 109
 110         /*
 111          * we're ready for shutdown now, so do it
 112          */
 113         cpu_enter_lowpower();
 114         platform_do_lowpower(cpu, &spurious);
 115
 116         /*
 117          * bring this CPU back into the world of cache
 118          * coherency, and then restore interrupts
 119          */
 120         cpu_leave_lowpower();
 121
 122         if (spurious)
 123                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 124 }
 125
 126 int platform_cpu_disable(unsigned int cpu)
 127 {
 128         /*
 129          * we don't allow CPU 0 to be shutdown (it is still too special
 130          * e.g. clock tick interrupts)
 131          */
 132         return cpu == 0 ? -EPERM : 0;
 133 }