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kernel/linux-imx6_3.14.28/arch/arm/mach-spear/hotplug.c 2.03 KB
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6b13f685e   김민수   BSP 최초 추가 
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  /*
   * linux/arch/arm/mach-spear13xx/hotplug.c
   *
   * Copyright (C) 2012 ST Microelectronics Ltd.
   * Deepak Sikri <deepak.sikri@st.com>
   *
   * based upon linux/arch/arm/mach-realview/hotplug.c
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/smp.h>
  #include <asm/cp15.h>
  #include <asm/smp_plat.h>
  
  static inline void cpu_enter_lowpower(void)
  {
  	unsigned int v;
  
  	asm volatile(
  	"	mcr	p15, 0, %1, c7, c5, 0
  "
  	"	dsb
  "
  	/*
  	 * Turn off coherency
  	 */
  	"	mrc	p15, 0, %0, c1, c0, 1
  "
  	"	bic	%0, %0, #0x20
  "
  	"	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)
  	: "cc", "memory");
  }
  
  static inline void cpu_leave_lowpower(void)
  {
  	unsigned int v;
  
  	asm volatile("mrc	p15, 0, %0, c1, c0, 0
  "
  	"	orr	%0, %0, %1
  "
  	"	mcr	p15, 0, %0, c1, c0, 0
  "
  	"	mrc	p15, 0, %0, c1, c0, 1
  "
  	"	orr	%0, %0, #0x20
  "
  	"	mcr	p15, 0, %0, c1, c0, 1
  "
  	: "=&r" (v)
  	: "Ir" (CR_C)
  	: "cc");
  }
  
  static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious)
  {
  	for (;;) {
  		wfi();
  
  		if (pen_release == cpu) {
  			/*
  			 * OK, proper wakeup, we're done
  			 */
  			break;
  		}
  
  		/*
  		 * Getting here, means that we have come out of WFI without
  		 * having been woken up - this shouldn't happen
  		 *
  		 * Just note it happening - when we're woken, we can report
  		 * its occurrence.
  		 */
  		(*spurious)++;
  	}
  }
  
  /*
   * platform-specific code to shutdown a CPU
   *
   * Called with IRQs disabled
   */
  void __ref spear13xx_cpu_die(unsigned int cpu)
  {
  	int spurious = 0;
  
  	/*
  	 * we're ready for shutdown now, so do it
  	 */
  	cpu_enter_lowpower();
  	spear13xx_do_lowpower(cpu, &spurious);
  
  	/*
  	 * bring this CPU back into the world of cache
  	 * coherency, and then restore interrupts
  	 */
  	cpu_leave_lowpower();
  
  	if (spurious)
  		pr_warn("CPU%u: %u spurious wakeup calls
  ", cpu, spurious);
  }