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 "common.h"
  23 #include "regs-pmu.h"
  24
  25 static inline void cpu_leave_lowpower(void)
  26 {
  27         unsigned int v;
  28
  29         asm volatile(
  30         "mrc    p15, 0, %0, c1, c0, 0\n"
  31         "       orr     %0, %0, %1\n"
  32         "       mcr     p15, 0, %0, c1, c0, 0\n"
  33         "       mrc     p15, 0, %0, c1, c0, 1\n"
  34         "       orr     %0, %0, %2\n"
  35         "       mcr     p15, 0, %0, c1, c0, 1\n"
  36           : "=&r" (v)
  37           : "Ir" (CR_C), "Ir" (0x40)
  38           : "cc");
  39 }
  40
  41 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  42 {
  43         for (;;) {
  44
  45                 /* make cpu1 to be turned off at next WFI command */
  46                 if (cpu == 1)
  47                         exynos_cpu_power_down(cpu);
  48
  49                 wfi();
  50
  51                 if (pen_release == cpu_logical_map(cpu)) {
  52                         /*
  53                          * OK, proper wakeup, we're done
  54                          */
  55                         break;
  56                 }
  57
  58                 /*
  59                  * Getting here, means that we have come out of WFI without
  60                  * having been woken up - this shouldn't happen
  61                  *
  62                  * Just note it happening - when we're woken, we can report
  63                  * its occurrence.
  64                  */
  65                 (*spurious)++;
  66         }
  67 }
  68
  69 /*
  70  * platform-specific code to shutdown a CPU
  71  *
  72  * Called with IRQs disabled
  73  */
  74 void __ref exynos_cpu_die(unsigned int cpu)
  75 {
  76         int spurious = 0;
  77
  78         v7_exit_coherency_flush(louis);
  79
  80         platform_do_lowpower(cpu, &spurious);
  81
  82         /*
  83          * bring this CPU back into the world of cache
  84          * coherency, and then restore interrupts
  85          */
  86         cpu_leave_lowpower();
  87
  88         if (spurious)
  89                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
  90 }