arch/arm/mach-zynq/hotplug.c

   1 /*
   2  * Copyright (C) 2012-2013 Xilinx
   3  *
   4  * based on linux/arch/arm/mach-realview/hotplug.c
   5  *
   6  * Copyright (C) 2002 ARM Ltd.
   7  * All Rights Reserved
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/smp.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/cp15.h>
  19 #include "common.h"
  20
  21 static inline void zynq_cpu_enter_lowpower(void)
  22 {
  23         unsigned int v;
  24
  25         flush_cache_all();
  26         asm volatile(
  27         "       mcr     p15, 0, %1, c7, c5, 0\n"
  28         "       dsb\n"
  29         /*
  30          * Turn off coherency
  31          */
  32         "       mrc     p15, 0, %0, c1, c0, 1\n"
  33         "       bic     %0, %0, #0x40\n"
  34         "       mcr     p15, 0, %0, c1, c0, 1\n"
  35         "       mrc     p15, 0, %0, c1, c0, 0\n"
  36         "       bic     %0, %0, %2\n"
  37         "       mcr     p15, 0, %0, c1, c0, 0\n"
  38           : "=&r" (v)
  39           : "r" (0), "Ir" (CR_C)
  40           : "cc");
  41 }
  42
  43 /*
  44  * platform-specific code to shutdown a CPU
  45  *
  46  * Called with IRQs disabled
  47  */
  48 void zynq_platform_cpu_die(unsigned int cpu)
  49 {
  50         zynq_cpu_enter_lowpower();
  51
  52         /*
  53          * there is no power-control hardware on this platform, so all
  54          * we can do is put the core into WFI; this is safe as the calling
  55          * code will have already disabled interrupts
  56          */
  57         for (;;)
  58                 cpu_do_idle();
  59 }