arch/arm/mach-exynos/hotplug.c

   1 /*
   2  *  Cloned from 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
  12 #include <linux/kernel.h>
  13 #include <linux/errno.h>
  14 #include <linux/smp.h>
  15 #include <linux/io.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/cp15.h>
  19 #include <asm/smp_plat.h>
  20
  21 #include "common.h"
  22 #include "regs-pmu.h"
  23
  24 static inline void cpu_leave_lowpower(void)
  25 {
  26         unsigned int v;
  27
  28         asm volatile(
  29         "mrc    p15, 0, %0, c1, c0, 0\n"
  30         "       orr     %0, %0, %1\n"
  31         "       mcr     p15, 0, %0, c1, c0, 0\n"
  32         "       mrc     p15, 0, %0, c1, c0, 1\n"
  33         "       orr     %0, %0, %2\n"
  34         "       mcr     p15, 0, %0, c1, c0, 1\n"
  35           : "=&r" (v)
  36           : "Ir" (CR_C), "Ir" (0x40)
  37           : "cc");
  38 }
  39
  40 static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  41 {
  42         for (;;) {
  43
  44                 /* make cpu1 to be turned off at next WFI command */
  45                 if (cpu == 1)
  46                         exynos_cpu_power_down(cpu);
  47
  48                 wfi();
  49
  50                 if (pen_release == cpu_logical_map(cpu)) {
  51                         /*
  52                          * OK, proper wakeup, we're done
  53                          */
  54                         break;
  55                 }
  56
  57                 /*
  58                  * Getting here, means that we have come out of WFI without
  59                  * having been woken up - this shouldn't happen
  60                  *
  61                  * Just note it happening - when we're woken, we can report
  62                  * its occurrence.
  63                  */
  64                 (*spurious)++;
  65         }
  66 }
  67
  68 /*
  69  * platform-specific code to shutdown a CPU
  70  *
  71  * Called with IRQs disabled
  72  */
  73 void __ref exynos_cpu_die(unsigned int cpu)
  74 {
  75         int spurious = 0;
  76
  77         v7_exit_coherency_flush(louis);
  78
  79         platform_do_lowpower(cpu, &spurious);
  80
  81         /*
  82          * bring this CPU back into the world of cache
  83          * coherency, and then restore interrupts
  84          */
  85         cpu_leave_lowpower();
  86
  87         if (spurious)
  88                 pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
  89 }