arch/arm/mach-imx/hotplug.c

   1 /*
   2  * Copyright 2011 Freescale Semiconductor, Inc.
   3  * Copyright 2011 Linaro Ltd.
   4  *
   5  * The code contained herein is licensed under the GNU General Public
   6  * License. You may obtain a copy of the GNU General Public License
   7  * Version 2 or later at the following locations:
   8  *
   9  * http://www.opensource.org/licenses/gpl-license.html
  10  * http://www.gnu.org/copyleft/gpl.html
  11  */
  12
  13 #include <linux/errno.h>
  14 #include <asm/cp15.h>
  15
  16 #include "common.h"
  17
  18 static inline void cpu_enter_lowpower(void)
  19 {
  20         unsigned int v;
  21
  22         asm volatile(
  23                 "mcr    p15, 0, %1, c7, c5, 0\n"
  24         "       mcr     p15, 0, %1, c7, c10, 4\n"
  25         /*
  26          * Turn off coherency
  27          */
  28         "       mrc     p15, 0, %0, c1, c0, 1\n"
  29         "       bic     %0, %0, %3\n"
  30         "       mcr     p15, 0, %0, c1, c0, 1\n"
  31         "       mrc     p15, 0, %0, c1, c0, 0\n"
  32         "       bic     %0, %0, %2\n"
  33         "       mcr     p15, 0, %0, c1, c0, 0\n"
  34           : "=&r" (v)
  35           : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  36           : "cc");
  37 }
  38
  39 /*
  40  * platform-specific code to shutdown a CPU
  41  *
  42  * Called with IRQs disabled
  43  */
  44 void imx_cpu_die(unsigned int cpu)
  45 {
  46         cpu_enter_lowpower();
  47         /*
  48          * We use the cpu jumping argument register to sync with
  49          * imx_cpu_kill() which is running on cpu0 and waiting for
  50          * the register being cleared to kill the cpu.
  51          */
  52         imx_set_cpu_arg(cpu, ~0);
  53         cpu_do_idle();
  54 }
  55
  56 int imx_cpu_kill(unsigned int cpu)
  57 {
  58         unsigned long timeout = jiffies + msecs_to_jiffies(50);
  59
  60         while (imx_get_cpu_arg(cpu) == 0)
  61                 if (time_after(jiffies, timeout))
  62                         return 0;
  63         imx_enable_cpu(cpu, false);
  64         imx_set_cpu_arg(cpu, 0);
  65         return 1;
  66 }