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kernel/linux-imx6_3.14.28/arch/arm/mach-imx/hotplug.c 1.61 KB
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  /*
   * Copyright 2011-2014 Freescale Semiconductor, Inc.
   * Copyright 2011 Linaro Ltd.
   *
   * The code contained herein is licensed under the GNU General Public
   * License. You may obtain a copy of the GNU General Public License
   * Version 2 or later at the following locations:
   *
   * http://www.opensource.org/licenses/gpl-license.html
   * http://www.gnu.org/copyleft/gpl.html
   */
  
  #include <linux/errno.h>
  #include <linux/jiffies.h>
  #include <asm/cp15.h>
  #include <asm/proc-fns.h>
  #include <asm/smp_scu.h>
  
  #include "common.h"
  
  extern void __iomem *imx_scu_base;
  
  static inline void cpu_enter_lowpower(void)
  {
  	unsigned int v;
  
  	asm volatile(
  		"mcr	p15, 0, %1, c7, c5, 0
  "
  	"	mcr	p15, 0, %1, c7, c10, 4
  "
  	/*
  	 * Turn off coherency
  	 */
  	"	mrc	p15, 0, %0, c1, c0, 1
  "
  	"	bic	%0, %0, %3
  "
  	"	mcr	p15, 0, %0, c1, c0, 1
  "
  	"	mrc	p15, 0, %0, c1, c0, 0
  "
  	"	bic	%0, %0, %2
  "
  	"	mcr	p15, 0, %0, c1, c0, 0
  "
  	  : "=&r" (v)
  	  : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  	  : "cc");
  
  	scu_power_mode(imx_scu_base, SCU_PM_DORMANT);
  }
  
  /*
   * platform-specific code to shutdown a CPU
   *
   * Called with IRQs disabled
   */
  void imx_cpu_die(unsigned int cpu)
  {
  	cpu_enter_lowpower();
  	/*
  	 * We use the cpu jumping argument register to sync with
  	 * imx_cpu_kill() which is running on cpu0 and waiting for
  	 * the register being cleared to kill the cpu.
  	 */
  	imx_set_cpu_arg(cpu, ~0);
  	for (;;)
  		cpu_do_idle();
  }
  
  int imx_cpu_kill(unsigned int cpu)
  {
  	unsigned long timeout = jiffies + msecs_to_jiffies(50);
  
  	while (imx_get_cpu_arg(cpu) == 0)
  		if (time_after(jiffies, timeout))
  			return 0;
  	imx_enable_cpu(cpu, false);
  	imx_set_cpu_arg(cpu, 0);
  	return 1;
  }