/*
   * arch/xtensa/kernel/time.c
   *
   * Timer and clock support.
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2005 Tensilica Inc.
   *
   * Chris Zankel <chris@zankel.net>
   */

  #include <linux/errno.h>

  #include <linux/sched.h>

  #include <linux/time.h>

  #include <linux/clocksource.h>

  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/irq.h>
  #include <linux/profile.h>
  #include <linux/delay.h>
  
  #include <asm/timex.h>
  #include <asm/platform.h>

  #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
  unsigned long ccount_per_jiffy;		/* per 1/HZ */

  unsigned long nsec_per_ccount;		/* nsec per ccount increment */

  #endif

  static cycle_t ccount_read(void)
  {
  	return (cycle_t)get_ccount();
  }
  
  static struct clocksource ccount_clocksource = {
  	.name = "ccount",
  	.rating = 200,
  	.read = ccount_read,
  	.mask = CLOCKSOURCE_MASK(32),

  };

  static irqreturn_t timer_interrupt(int irq, void *dev_id);

  static struct irqaction timer_irqaction = {
  	.handler =	timer_interrupt,

  	.flags =	IRQF_DISABLED,

  	.name =		"timer",
  };
  
  void __init time_init(void)
  {

  #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT

  	printk("Calibrating CPU frequency ");
  	platform_calibrate_ccount();
  	printk("%d.%02d MHz
  ", (int)ccount_per_jiffy/(1000000/HZ),
  			(int)(ccount_per_jiffy/(10000/HZ))%100);
  #endif

  	clocksource_register_hz(&ccount_clocksource, CCOUNT_PER_JIFFY * HZ);

  
  	/* Initialize the linux timer interrupt. */
  
  	setup_irq(LINUX_TIMER_INT, &timer_irqaction);
  	set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
  }

  /*
   * The timer interrupt is called HZ times per second.
   */

  irqreturn_t timer_interrupt (int irq, void *dev_id)

  {
  
  	unsigned long next;
  
  	next = get_linux_timer();
  
  again:
  	while ((signed long)(get_ccount() - next) > 0) {

  		profile_tick(CPU_PROFILING);

  #ifndef CONFIG_SMP

  		update_process_times(user_mode(get_irq_regs()));

  #endif

  		xtime_update(1); /* Linux handler in kernel/time/timekeeping */

  
  		/* Note that writing CCOMPARE clears the interrupt. */

  		next += CCOUNT_PER_JIFFY;

  		set_linux_timer(next);

  	}

  	/* Allow platform to do something useful (Wdog). */

  	platform_heartbeat();

  
  	/* Make sure we didn't miss any tick... */
  
  	if ((signed long)(get_ccount() - next) > 0)
  		goto again;

  	return IRQ_HANDLED;
  }
  
  #ifndef CONFIG_GENERIC_CALIBRATE_DELAY

  void __cpuinit calibrate_delay(void)

  {
  	loops_per_jiffy = CCOUNT_PER_JIFFY;
  	printk("Calibrating delay loop (skipped)... "
  	       "%lu.%02lu BogoMIPS preset
  ",
  	       loops_per_jiffy/(1000000/HZ),
  	       (loops_per_jiffy/(10000/HZ)) % 100);
  }
  #endif