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 <linux/jiffies.h>
  15 #include <asm/cp15.h>
  16 #include <asm/proc-fns.h>
  17
  18 #include "common.h"
  19
  20 static inline void cpu_enter_lowpower(void)
  21 {
  22         unsigned int v;
  23
  24         asm volatile(
  25                 "mcr    p15, 0, %1, c7, c5, 0\n"
  26         "       mcr     p15, 0, %1, c7, c10, 4\n"
  27         /*
  28          * Turn off coherency
  29          */
  30         "       mrc     p15, 0, %0, c1, c0, 1\n"
  31         "       bic     %0, %0, %3\n"
  32         "       mcr     p15, 0, %0, c1, c0, 1\n"
  33         "       mrc     p15, 0, %0, c1, c0, 0\n"
  34         "       bic     %0, %0, %2\n"
  35         "       mcr     p15, 0, %0, c1, c0, 0\n"
  36           : "=&r" (v)
  37           : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  38           : "cc");
  39 }
  40
  41 /*
  42  * platform-specific code to shutdown a CPU
  43  *
  44  * Called with IRQs disabled
  45  */
  46 void imx_cpu_die(unsigned int cpu)
  47 {
  48         cpu_enter_lowpower();
  49         /*
  50          * We use the cpu jumping argument register to sync with
  51          * imx_cpu_kill() which is running on cpu0 and waiting for
  52          * the register being cleared to kill the cpu.
  53          */
  54         imx_set_cpu_arg(cpu, ~0);
  55
  56         while (1)
  57                 cpu_do_idle();
  58 }
  59
  60 int imx_cpu_kill(unsigned int cpu)
  61 {
  62         unsigned long timeout = jiffies + msecs_to_jiffies(50);
  63
  64         while (imx_get_cpu_arg(cpu) == 0)
  65                 if (time_after(jiffies, timeout))
  66                         return 0;
  67         imx_enable_cpu(cpu, false);
  68         imx_set_cpu_arg(cpu, 0);
  69         return 1;
  70 }