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kernel/linux-imx6_3.14.28/arch/arm/mach-ep93xx/crunch.c 2.02 KB
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  /*
   * arch/arm/kernel/crunch.c
   * Cirrus MaverickCrunch context switching and handling
   *
   * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
   *
   * 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/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/signal.h>
  #include <linux/sched.h>
  #include <linux/init.h>
  #include <linux/io.h>
  
  #include <asm/thread_notify.h>
  
  #include "soc.h"
  
  struct crunch_state *crunch_owner;
  
  void crunch_task_release(struct thread_info *thread)
  {
  	local_irq_disable();
  	if (crunch_owner == &thread->crunchstate)
  		crunch_owner = NULL;
  	local_irq_enable();
  }
  
  static int crunch_enabled(u32 devcfg)
  {
  	return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
  }
  
  static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
  {
  	struct thread_info *thread = (struct thread_info *)t;
  	struct crunch_state *crunch_state;
  	u32 devcfg;
  
  	crunch_state = &thread->crunchstate;
  
  	switch (cmd) {
  	case THREAD_NOTIFY_FLUSH:
  		memset(crunch_state, 0, sizeof(*crunch_state));
  
  		/*
  		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
  		 * initialised state information on the first fault.
  		 */
  
  	case THREAD_NOTIFY_EXIT:
  		crunch_task_release(thread);
  		break;
  
  	case THREAD_NOTIFY_SWITCH:
  		devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
  		if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
  			/*
  			 * We don't use ep93xx_syscon_swlocked_write() here
  			 * because we are on the context switch path and
  			 * preemption is already disabled.
  			 */
  			devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
  			__raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
  			__raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
  		}
  		break;
  	}
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block crunch_notifier_block = {
  	.notifier_call	= crunch_do,
  };
  
  int __init crunch_init(void)
  {
  	thread_register_notifier(&crunch_notifier_block);
  	elf_hwcap |= HWCAP_CRUNCH;
  
  	return 0;
  }