arch/arm/mach-exynos/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 #include <asm/smp_plat.h>
  20
  21 #include <mach/regs-pmu.h>
  22
  23 extern volatile int pen_release;
  24
  25 static inline void cpu_enter_lowpower(void)
  26 {
  27         unsigned int v;
  28
  29         flush_cache_all();
  30         asm volatile(
  31         "       mcr     p15, 0, %1, c7, c5, 0\n"
  32         "       mcr     p15, 0, %1, c7, c10, 4\n"
  33         /*
  34          * Turn off coherency
  35          */
  36         "       mrc     p15, 0, %0, c1, c0, 1\n"
  37         "       bic     %0, %0, %3\n"
  38         "       mcr     p15, 0, %0, c1, c0, 1\n"
  39         "       mrc     p15, 0, %0, c1, c0, 0\n"
  40         "       bic     %0, %0, %2\n"
  41         "       mcr     p15, 0, %0, c1, c0, 0\n"
  42           : "=&r" (v)
  43           : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  44           : "cc");
  45 }
  46
  47 static inline void cpu_leave_lowpower(void)
  48 {
  49         unsigned int v;
  50
  51         asm volatile(
  52         "mrc    p15, 0, %0, c1, c0, 0\n"
  53         "       orr     %0, %0, %1\n"
  54         "       mcr     p15, 0, %0, c1, c0, 0\n"
  55         "       mrc     p15, 0, %0, c1, c0, 1\n"
  56         "       orr     %0, %0, %2\n"
  57         "       mcr     p15, 0, %0, c1, c0, 1\n"
  58           : "=&r" (v)
  59           : "Ir" (CR_C), "Ir" (0x40)
  60           : "cc");
  61 }
  62
  63 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  64 {
  65         for (;;) {
  66
  67                 /* make cpu1 to be turned off at next WFI command */
  68                 if (cpu == 1)
  69                         __raw_writel(0, S5P_ARM_CORE1_CONFIGURATION);
  70
  71                 /*
  72                  * here's the WFI
  73                  */
  74                 asm(".word      0xe320f003\n"
  75                     :
  76                     :
  77                     : "memory", "cc");
  78
  79                 if (pen_release == cpu_logical_map(cpu)) {
  80                         /*
  81                          * OK, proper wakeup, we're done
  82                          */
  83                         break;
  84                 }
  85
  86                 /*
  87                  * Getting here, means that we have come out of WFI without
  88                  * having been woken up - this shouldn't happen
  89                  *
  90                  * Just note it happening - when we're woken, we can report
  91                  * its occurrence.
  92                  */
  93                 (*spurious)++;
  94         }
  95 }
  96
  97 int platform_cpu_kill(unsigned int cpu)
  98 {
  99         return 1;
 100 }
 101
 102 /*
 103  * platform-specific code to shutdown a CPU
 104  *
 105  * Called with IRQs disabled
 106  */
 107 void platform_cpu_die(unsigned int cpu)
 108 {
 109         int spurious = 0;
 110
 111         /*
 112          * we're ready for shutdown now, so do it
 113          */
 114         cpu_enter_lowpower();
 115         platform_do_lowpower(cpu, &spurious);
 116
 117         /*
 118          * bring this CPU back into the world of cache
 119          * coherency, and then restore interrupts
 120          */
 121         cpu_leave_lowpower();
 122
 123         if (spurious)
 124                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 125 }
 126
 127 int platform_cpu_disable(unsigned int cpu)
 128 {
 129         /*
 130          * we don't allow CPU 0 to be shutdown (it is still too special
 131          * e.g. clock tick interrupts)
 132          */
 133         return cpu == 0 ? -EPERM : 0;
 134 }