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/cp15.h>
  20 #include <asm/smp_plat.h>
  21
  22 #include <mach/regs-pmu.h>
  23
  24 extern volatile int pen_release;
  25
  26 static inline void cpu_enter_lowpower(void)
  27 {
  28         unsigned int v;
  29
  30         flush_cache_all();
  31         asm volatile(
  32         "       mcr     p15, 0, %1, c7, c5, 0\n"
  33         "       mcr     p15, 0, %1, c7, c10, 4\n"
  34         /*
  35          * Turn off coherency
  36          */
  37         "       mrc     p15, 0, %0, c1, c0, 1\n"
  38         "       bic     %0, %0, %3\n"
  39         "       mcr     p15, 0, %0, c1, c0, 1\n"
  40         "       mrc     p15, 0, %0, c1, c0, 0\n"
  41         "       bic     %0, %0, %2\n"
  42         "       mcr     p15, 0, %0, c1, c0, 0\n"
  43           : "=&r" (v)
  44           : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  45           : "cc");
  46 }
  47
  48 static inline void cpu_leave_lowpower(void)
  49 {
  50         unsigned int v;
  51
  52         asm volatile(
  53         "mrc    p15, 0, %0, c1, c0, 0\n"
  54         "       orr     %0, %0, %1\n"
  55         "       mcr     p15, 0, %0, c1, c0, 0\n"
  56         "       mrc     p15, 0, %0, c1, c0, 1\n"
  57         "       orr     %0, %0, %2\n"
  58         "       mcr     p15, 0, %0, c1, c0, 1\n"
  59           : "=&r" (v)
  60           : "Ir" (CR_C), "Ir" (0x40)
  61           : "cc");
  62 }
  63
  64 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  65 {
  66         for (;;) {
  67
  68                 /* make cpu1 to be turned off at next WFI command */
  69                 if (cpu == 1)
  70                         __raw_writel(0, S5P_ARM_CORE1_CONFIGURATION);
  71
  72                 /*
  73                  * here's the WFI
  74                  */
  75                 asm(".word      0xe320f003\n"
  76                     :
  77                     :
  78                     : "memory", "cc");
  79
  80                 if (pen_release == cpu_logical_map(cpu)) {
  81                         /*
  82                          * OK, proper wakeup, we're done
  83                          */
  84                         break;
  85                 }
  86
  87                 /*
  88                  * Getting here, means that we have come out of WFI without
  89                  * having been woken up - this shouldn't happen
  90                  *
  91                  * Just note it happening - when we're woken, we can report
  92                  * its occurrence.
  93                  */
  94                 (*spurious)++;
  95         }
  96 }
  97
  98 int platform_cpu_kill(unsigned int cpu)
  99 {
 100         return 1;
 101 }
 102
 103 /*
 104  * platform-specific code to shutdown a CPU
 105  *
 106  * Called with IRQs disabled
 107  */
 108 void platform_cpu_die(unsigned int cpu)
 109 {
 110         int spurious = 0;
 111
 112         /*
 113          * we're ready for shutdown now, so do it
 114          */
 115         cpu_enter_lowpower();
 116         platform_do_lowpower(cpu, &spurious);
 117
 118         /*
 119          * bring this CPU back into the world of cache
 120          * coherency, and then restore interrupts
 121          */
 122         cpu_leave_lowpower();
 123
 124         if (spurious)
 125                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
 126 }
 127
 128 int platform_cpu_disable(unsigned int cpu)
 129 {
 130         /*
 131          * we don't allow CPU 0 to be shutdown (it is still too special
 132          * e.g. clock tick interrupts)
 133          */
 134         return cpu == 0 ? -EPERM : 0;
 135 }