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