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/cacheflush.h>
  14 #include <asm/smp_plat.h>
  15
  16 #include "common.h"
  17
  18 static inline void cpu_enter_lowpower(void)
  19 {
  20         /* Just flush the cache. Changing the coherency is not yet
  21          * available on msm. */
  22         flush_cache_all();
  23 }
  24
  25 static inline void cpu_leave_lowpower(void)
  26 {
  27 }
  28
  29 static inline void platform_do_lowpower(unsigned int cpu)
  30 {
  31         /* Just enter wfi for now. TODO: Properly shut off the cpu. */
  32         for (;;) {
  33                 /*
  34                  * here's the WFI
  35                  */
  36                 asm("wfi"
  37                     :
  38                     :
  39                     : "memory", "cc");
  40
  41                 if (pen_release == cpu_logical_map(cpu)) {
  42                         /*
  43                          * OK, proper wakeup, we're done
  44                          */
  45                         break;
  46                 }
  47
  48                 /*
  49                  * getting here, means that we have come out of WFI without
  50                  * having been woken up - this shouldn't happen
  51                  *
  52                  * The trouble is, letting people know about this is not really
  53                  * possible, since we are currently running incoherently, and
  54                  * therefore cannot safely call printk() or anything else
  55                  */
  56                 pr_debug("CPU%u: spurious wakeup call\n", cpu);
  57         }
  58 }
  59
  60 /*
  61  * platform-specific code to shutdown a CPU
  62  *
  63  * Called with IRQs disabled
  64  */
  65 void __ref msm_cpu_die(unsigned int cpu)
  66 {
  67         /*
  68          * we're ready for shutdown now, so do it
  69          */
  70         cpu_enter_lowpower();
  71         platform_do_lowpower(cpu);
  72
  73         /*
  74          * bring this CPU back into the world of cache
  75          * coherency, and then restore interrupts
  76          */
  77         cpu_leave_lowpower();
  78 }