arch/arm/mach-ux500/hotplug.c

   1 /*
   2  * Copyright (C) STMicroelectronics 2009
   3  * Copyright (C) ST-Ericsson SA 2010
   4  *
   5  * License Terms: GNU General Public License v2
   6  *      Based on ARM realview platform
   7  *
   8  * Author: Sundar Iyer <sundar.iyer@stericsson.com>
   9  *
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/errno.h>
  13 #include <linux/smp.h>
  14 #include <linux/completion.h>
  15
  16 #include <asm/cacheflush.h>
  17
  18 extern volatile int pen_release;
  19
  20 static DECLARE_COMPLETION(cpu_killed);
  21
  22 static inline void platform_do_lowpower(unsigned int cpu)
  23 {
  24         flush_cache_all();
  25
  26         /* we put the platform to just WFI */
  27         for (;;) {
  28                 __asm__ __volatile__("dsb\n\t" "wfi\n\t"
  29                                 : : : "memory");
  30                 if (pen_release == cpu) {
  31                         /*
  32                          * OK, proper wakeup, we're done
  33                          */
  34                         break;
  35                 }
  36         }
  37 }
  38
  39 int platform_cpu_kill(unsigned int cpu)
  40 {
  41         return wait_for_completion_timeout(&cpu_killed, 5000);
  42 }
  43
  44 /*
  45  * platform-specific code to shutdown a CPU
  46  *
  47  * Called with IRQs disabled
  48  */
  49 void platform_cpu_die(unsigned int cpu)
  50 {
  51 #ifdef DEBUG
  52         unsigned int this_cpu = hard_smp_processor_id();
  53
  54         if (cpu != this_cpu) {
  55                 printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",
  56                            this_cpu, cpu);
  57                 BUG();
  58         }
  59 #endif
  60
  61         printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
  62         complete(&cpu_killed);
  63
  64         /* directly enter low power state, skipping secure registers */
  65         platform_do_lowpower(cpu);
  66 }
  67
  68 int platform_cpu_disable(unsigned int cpu)
  69 {
  70         /*
  71          * we don't allow CPU 0 to be shutdown (it is still too special
  72          * e.g. clock tick interrupts)
  73          */
  74         return cpu == 0 ? -EPERM : 0;
  75 }