/*
   *  linux/arch/arm/kernel/fiq.c
   *
   *  Copyright (C) 1998 Russell King
   *  Copyright (C) 1998, 1999 Phil Blundell
   *
   *  FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
   *
   *  FIQ support re-written by Russell King to be more generic
   *
   * We now properly support a method by which the FIQ handlers can
   * be stacked onto the vector.  We still do not support sharing
   * the FIQ vector itself.
   *
   * Operation is as follows:
   *  1. Owner A claims FIQ:
   *     - default_fiq relinquishes control.
   *  2. Owner A:
   *     - inserts code.
   *     - sets any registers,
   *     - enables FIQ.
   *  3. Owner B claims FIQ:
   *     - if owner A has a relinquish function.
   *       - disable FIQs.
   *       - saves any registers.
   *       - returns zero.
   *  4. Owner B:
   *     - inserts code.
   *     - sets any registers,
   *     - enables FIQ.
   *  5. Owner B releases FIQ:
   *     - Owner A is asked to reacquire FIQ:
   *	 - inserts code.
   *	 - restores saved registers.
   *	 - enables FIQ.
   *  6. Goto 3
   */
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>

  #include <linux/interrupt.h>

  #include <linux/seq_file.h>
  
  #include <asm/cacheflush.h>
  #include <asm/fiq.h>
  #include <asm/irq.h>
  #include <asm/system.h>

  #include <asm/traps.h>

  
  static unsigned long no_fiq_insn;
  
  /* Default reacquire function
   * - we always relinquish FIQ control
   * - we always reacquire FIQ control
   */
  static int fiq_def_op(void *ref, int relinquish)
  {
  	if (!relinquish)
  		set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
  
  	return 0;
  }
  
  static struct fiq_handler default_owner = {
  	.name	= "default",
  	.fiq_op = fiq_def_op,
  };
  
  static struct fiq_handler *current_fiq = &default_owner;

  int show_fiq_list(struct seq_file *p, int prec)

  {
  	if (current_fiq != &default_owner)

  		seq_printf(p, "%*s:              %s
  ", prec, "FIQ",
  			current_fiq->name);

  
  	return 0;
  }
  
  void set_fiq_handler(void *start, unsigned int length)
  {

  #if defined(CONFIG_CPU_USE_DOMAINS)

  	memcpy((void *)0xffff001c, start, length);

  #else
  	memcpy(vectors_page + 0x1c, start, length);
  #endif

  	flush_icache_range(0xffff001c, 0xffff001c + length);
  	if (!vectors_high())
  		flush_icache_range(0x1c, 0x1c + length);
  }

  int claim_fiq(struct fiq_handler *f)
  {
  	int ret = 0;
  
  	if (current_fiq) {
  		ret = -EBUSY;
  
  		if (current_fiq->fiq_op != NULL)
  			ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
  	}
  
  	if (!ret) {
  		f->next = current_fiq;
  		current_fiq = f;
  	}
  
  	return ret;
  }
  
  void release_fiq(struct fiq_handler *f)
  {
  	if (current_fiq != f) {
  		printk(KERN_ERR "%s FIQ trying to release %s FIQ
  ",
  		       f->name, current_fiq->name);
  		dump_stack();
  		return;
  	}
  
  	do
  		current_fiq = current_fiq->next;
  	while (current_fiq->fiq_op(current_fiq->dev_id, 0));
  }
  
  void enable_fiq(int fiq)
  {
  	enable_irq(fiq + FIQ_START);
  }
  
  void disable_fiq(int fiq)
  {
  	disable_irq(fiq + FIQ_START);
  }
  
  EXPORT_SYMBOL(set_fiq_handler);

  EXPORT_SYMBOL(__set_fiq_regs);	/* defined in fiqasm.S */
  EXPORT_SYMBOL(__get_fiq_regs);	/* defined in fiqasm.S */

  EXPORT_SYMBOL(claim_fiq);
  EXPORT_SYMBOL(release_fiq);
  EXPORT_SYMBOL(enable_fiq);
  EXPORT_SYMBOL(disable_fiq);
  
  void __init init_FIQ(void)
  {
  	no_fiq_insn = *(unsigned long *)0xffff001c;
  }