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
  15 #include <asm/cacheflush.h>
  16 #include <asm/smp_plat.h>
  17
  18 extern volatile int pen_release;
  19
  20 static inline void platform_do_lowpower(unsigned int cpu)
  21 {
  22         flush_cache_all();
  23
  24         /* we put the platform to just WFI */
  25         for (;;) {
  26                 __asm__ __volatile__("dsb\n\t" "wfi\n\t"
  27                                 : : : "memory");
  28                 if (pen_release == cpu_logical_map(cpu)) {
  29                         /*
  30                          * OK, proper wakeup, we're done
  31                          */
  32                         break;
  33                 }
  34         }
  35 }
  36
  37 int platform_cpu_kill(unsigned int cpu)
  38 {
  39         return 1;
  40 }
  41
  42 /*
  43  * platform-specific code to shutdown a CPU
  44  *
  45  * Called with IRQs disabled
  46  */
  47 void platform_cpu_die(unsigned int cpu)
  48 {
  49         /* directly enter low power state, skipping secure registers */
  50         platform_do_lowpower(cpu);
  51 }
  52
  53 int platform_cpu_disable(unsigned int cpu)
  54 {
  55         /*
  56          * we don't allow CPU 0 to be shutdown (it is still too special
  57          * e.g. clock tick interrupts)
  58          */
  59         return cpu == 0 ? -EPERM : 0;
  60 }