arch/arm/mach-shmobile/hotplug.c

   1 /*
   2  * SMP support for R-Mobile / SH-Mobile
   3  *
   4  * Copyright (C) 2010  Magnus Damm
   5  *
   6  * Based on realview, Copyright (C) 2002 ARM Ltd, 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 #include <linux/kernel.h>
  13 #include <linux/errno.h>
  14 #include <linux/smp.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/delay.h>
  17 #include <linux/of.h>
  18 #include <mach/common.h>
  19 #include <mach/r8a7779.h>
  20 #include <mach/emev2.h>
  21 #include <asm/cacheflush.h>
  22 #include <asm/mach-types.h>
  23
  24 static cpumask_t dead_cpus;
  25
  26 void shmobile_cpu_die(unsigned int cpu)
  27 {
  28         /* hardware shutdown code running on the CPU that is being offlined */
  29         flush_cache_all();
  30         dsb();
  31
  32         /* notify platform_cpu_kill() that hardware shutdown is finished */
  33         cpumask_set_cpu(cpu, &dead_cpus);
  34
  35         /* wait for SoC code in platform_cpu_kill() to shut off CPU core
  36          * power. CPU bring up starts from the reset vector.
  37          */
  38         while (1) {
  39                 /*
  40                  * here's the WFI
  41                  */
  42                 asm(".word      0xe320f003\n"
  43                     :
  44                     :
  45                     : "memory", "cc");
  46         }
  47 }
  48
  49 int shmobile_cpu_disable(unsigned int cpu)
  50 {
  51         cpumask_clear_cpu(cpu, &dead_cpus);
  52         /*
  53          * we don't allow CPU 0 to be shutdown (it is still too special
  54          * e.g. clock tick interrupts)
  55          */
  56         return cpu == 0 ? -EPERM : 0;
  57 }
  58
  59 int shmobile_cpu_is_dead(unsigned int cpu)
  60 {
  61         return cpumask_test_cpu(cpu, &dead_cpus);
  62 }