/******************************************************************************
*                                                                             *
* License Agreement                                                           *
*                                                                             *
* Copyright (c) 2003 Altera Corporation, San Jose, California, USA.           *
* All rights reserved.                                                        *
*                                                                             *
* Permission is hereby granted, free of charge, to any person obtaining a     *
* copy of this software and associated documentation files (the "Software"),  *
* to deal in the Software without restriction, including without limitation   *
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* Software is furnished to do so, subject to the following conditions:        *
*                                                                             *
* The above copyright notice and this permission notice shall be included in  *
* all copies or substantial portions of the Software.                         *
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* DEALINGS IN THE SOFTWARE.                                                   *
*                                                                             *
* This agreement shall be governed in all respects by the laws of the State   *
* of California and by the laws of the United States of America.              *
*                                                                             *
* Altera does not recommend, suggest or require that this reference design    *
* file be used in conjunction or combination with any other product.          *
******************************************************************************/

#include <string.h>

#include "sys/alt_alarm.h"
#include "sys/alt_irq.h"

#include "altera_avalon_timer.h"
#include "altera_avalon_timer_regs.h"

#include "alt_types.h"
#include "sys/alt_log_printf.h"

/* 
 * alt_avalon_timer_sc_irq() is the interrupt handler used for the system 
 * clock. This is called periodically when a timer interrupt occurs. The 
 * function first clears the interrupt condition, and then calls the 
 * alt_tick() function to notify the system that a timer tick has occurred.
 *
 * alt_tick() increments the system tick count, and updates any registered 
 * alarms, see alt_tick.c for further details.
 */
#ifdef ALT_ENHANCED_INTERRUPT_API_PRESENT
static void alt_avalon_timer_sc_irq (void* base)
#else
static void alt_avalon_timer_sc_irq (void* base, alt_u32 id)
#endif
{
  alt_irq_context cpu_sr;
  
  /* clear the interrupt */
  IOWR_ALTERA_AVALON_TIMER_STATUS (base, 0);
  
  /* 
   * Dummy read to ensure IRQ is negated before the ISR returns.
   * The control register is read because reading the status
   * register has side-effects per the register map documentation.
   */
  IORD_ALTERA_AVALON_TIMER_CONTROL (base);

  /* ALT_LOG - see altera_hal/HAL/inc/sys/alt_log_printf.h */
  ALT_LOG_SYS_CLK_HEARTBEAT();

  /* 
   * Notify the system of a clock tick. disable interrupts 
   * during this time to safely support ISR preemption
   */
  cpu_sr = alt_irq_disable_all();
  alt_tick ();
  alt_irq_enable_all(cpu_sr);
}

/*
 * alt_avalon_timer_sc_init() is called to initialise the timer that will be 
 * used to provide the periodic system clock. This is called from the 
 * auto-generated alt_sys_init() function.
 */

void alt_avalon_timer_sc_init (void* base, alt_u32 irq_controller_id, 
                                alt_u32 irq, alt_u32 freq)
{
  /* set the system clock frequency */
  
  alt_sysclk_init (freq);
  
  /* set to free running mode */
  
  IOWR_ALTERA_AVALON_TIMER_CONTROL (base, 
            ALTERA_AVALON_TIMER_CONTROL_ITO_MSK  |
            ALTERA_AVALON_TIMER_CONTROL_CONT_MSK |
            ALTERA_AVALON_TIMER_CONTROL_START_MSK);

  /* register the interrupt handler, and enable the interrupt */
#ifdef ALT_ENHANCED_INTERRUPT_API_PRESENT
  alt_ic_isr_register(irq_controller_id, irq, alt_avalon_timer_sc_irq, 
                      base, NULL);
#else
  alt_irq_register (irq, base, alt_avalon_timer_sc_irq);
#endif  
}