arch/arm/mach-msm/hotplug.c

   1 /*
   2  *  Copyright (C) 2002 ARM Ltd.
   3  *  All Rights Reserved
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9 #include <linux/kernel.h>
  10 #include <linux/errno.h>
  11 #include <linux/smp.h>
  12
  13 #include <asm/smp_plat.h>
  14
  15 #include "common.h"
  16
  17 static inline void cpu_enter_lowpower(void)
  18 {
  19 }
  20
  21 static inline void cpu_leave_lowpower(void)
  22 {
  23 }
  24
  25 static inline void platform_do_lowpower(unsigned int cpu)
  26 {
  27         /* Just enter wfi for now. TODO: Properly shut off the cpu. */
  28         for (;;) {
  29                 /*
  30                  * here's the WFI
  31                  */
  32                 asm("wfi"
  33                     :
  34                     :
  35                     : "memory", "cc");
  36
  37                 if (pen_release == cpu_logical_map(cpu)) {
  38                         /*
  39                          * OK, proper wakeup, we're done
  40                          */
  41                         break;
  42                 }
  43
  44                 /*
  45                  * getting here, means that we have come out of WFI without
  46                  * having been woken up - this shouldn't happen
  47                  *
  48                  * The trouble is, letting people know about this is not really
  49                  * possible, since we are currently running incoherently, and
  50                  * therefore cannot safely call printk() or anything else
  51                  */
  52                 pr_debug("CPU%u: spurious wakeup call\n", cpu);
  53         }
  54 }
  55
  56 /*
  57  * platform-specific code to shutdown a CPU
  58  *
  59  * Called with IRQs disabled
  60  */
  61 void __ref msm_cpu_die(unsigned int cpu)
  62 {
  63         /*
  64          * we're ready for shutdown now, so do it
  65          */
  66         cpu_enter_lowpower();
  67         platform_do_lowpower(cpu);
  68
  69         /*
  70          * bring this CPU back into the world of cache
  71          * coherency, and then restore interrupts
  72          */
  73         cpu_leave_lowpower();
  74 }