/*
   *  linux/arch/arm/common/time-acorn.c
   *
   *  Copyright (c) 1996-2000 Russell King.
   *
   * 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.
   *
   *  Changelog:
   *   24-Sep-1996	RMK	Created
   *   10-Oct-1996	RMK	Brought up to date with arch-sa110eval
   *   04-Dec-1997	RMK	Updated for new arch/arm/time.c
   *   13=Jun-2004	DS	Moved to arch/arm/common b/c shared w/CLPS7500
   */
  #include <linux/timex.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>

  #include <linux/irq.h>

  #include <linux/io.h>

  #include <mach/hardware.h>

  #include <asm/hardware/ioc.h>
  
  #include <asm/mach/time.h>
  
  unsigned long ioc_timer_gettimeoffset(void)
  {
  	unsigned int count1, count2, status;
  	long offset;
  
  	ioc_writeb (0, IOC_T0LATCH);
  	barrier ();
  	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
  	barrier ();
  	status = ioc_readb(IOC_IRQREQA);
  	barrier ();
  	ioc_writeb (0, IOC_T0LATCH);
  	barrier ();
  	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
  
  	offset = count2;
  	if (count2 < count1) {
  		/*
  		 * We have not had an interrupt between reading count1
  		 * and count2.
  		 */
  		if (status & (1 << 5))
  			offset -= LATCH;
  	} else if (count2 > count1) {
  		/*
  		 * We have just had another interrupt between reading
  		 * count1 and count2.
  		 */
  		offset -= LATCH;
  	}
  
  	offset = (LATCH - offset) * (tick_nsec / 1000);
  	return (offset + LATCH/2) / LATCH;
  }
  
  void __init ioctime_init(void)
  {
  	ioc_writeb(LATCH & 255, IOC_T0LTCHL);
  	ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
  	ioc_writeb(0, IOC_T0GO);
  }
  
  static irqreturn_t

  ioc_timer_interrupt(int irq, void *dev_id)

  {

  	timer_tick();

  	return IRQ_HANDLED;
  }
  
  static struct irqaction ioc_timer_irq = {
  	.name		= "timer",

  	.flags		= IRQF_DISABLED,

  	.handler	= ioc_timer_interrupt
  };
  
  /*
   * Set up timer interrupt.
   */
  static void __init ioc_timer_init(void)
  {
  	ioctime_init();
  	setup_irq(IRQ_TIMER, &ioc_timer_irq);
  }
  
  struct sys_timer ioc_timer = {
  	.init		= ioc_timer_init,
  	.offset		= ioc_timer_gettimeoffset,
  };