path: root/nuttx/arch/arm/src/sam3u/sam3u_timerisr.c

/****************************************************************************
 * arch/arm/src/sam3u/sam3u_timerisr.c
 *
 *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>
#include <time.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <arch/board/board.h>

#include "nvic.h"
#include "clock_internal.h"
#include "up_internal.h"
#include "up_arch.h"

#include "chip.h"
#include "sam3u_internal.h"

/****************************************************************************
 * Definitions
 ****************************************************************************/

/* The desired timer interrupt frequency is provided by the definition
 * CLK_TCK (see include/time.h).  CLK_TCK defines the desired number of
 * system clock ticks per second.  That value is a user configurable setting
 * that defaults to 100 (100 ticks per second = 10 MS interval).
 *
 * The SAM3U feeds the Cortex System Timer (SysTick) with the MCK clock or
 * the MCK clock divided by 8, configurable with the CLKSOURCE bit in the
 * SysTick Control and Status register.
 */

#undef CONFIG_SAM3U_SYSTICK_HCLKd8 /* Power up default is MCK, not MCK/8 */

#if CONFIG_SAM3U_SYSTICK_HCLKd8
#  define SYSTICK_RELOAD ((SAM3U_MCK_FREQUENCY / 8 / CLK_TCK) - 1)
#else
#  define SYSTICK_RELOAD ((SAM3U_MCK_FREQUENCY / CLK_TCK) - 1)
#endif

/* The size of the reload field is 24 bits.  Verify that the reload value
 * will fit in the reload register.
 */

#if SYSTICK_RELOAD > 0x00ffffff
#  error SYSTICK_RELOAD exceeds the range of the RELOAD register
#endif

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Global Functions
 ****************************************************************************/

/****************************************************************************
 * Function:  up_timerisr
 *
 * Description:
 *   The timer ISR will perform a variety of services for various portions
 *   of the systems.
 *
 ****************************************************************************/

int up_timerisr(int irq, uint32_t *regs)
{
   /* Process timer interrupt */

   sched_process_timer();
   return 0;
}

/****************************************************************************
 * Function:  up_timerinit
 *
 * Description:
 *   This function is called during start-up to initialize
 *   the timer interrupt.
 *
 ****************************************************************************/

void up_timerinit(void)
{
  uint32_t regval;

  /* Set the SysTick interrupt to the default priority */

  regval = getreg32(NVIC_SYSH12_15_PRIORITY);
  regval &= ~NVIC_SYSH_PRIORITY_PR15_MASK;
  regval |= (NVIC_SYSH_PRIORITY_DEFAULT << NVIC_SYSH_PRIORITY_PR15_SHIFT);
  putreg32(regval, NVIC_SYSH12_15_PRIORITY);

  /* Make sure that the SYSTICK clock source is set correctly */

#if 0 /* Does not work.  Comes up with HCLK source and I can't change it */
  regval = getreg32(NVIC_SYSTICK_CTRL);
#if CONFIG_SAM3U_SYSTICK_HCLKd8
  regval &= ~NVIC_SYSTICK_CTRL_CLKSOURCE;
#else
  regval |= NVIC_SYSTICK_CTRL_CLKSOURCE;
#endif
  putreg32(regval, NVIC_SYSTICK_CTRL);
#endif

  /* Configure SysTick to interrupt at the requested rate */

  putreg32(SYSTICK_RELOAD, NVIC_SYSTICK_RELOAD);

  /* Attach the timer interrupt vector */

  (void)irq_attach(SAM3U_IRQ_SYSTICK, (xcpt_t)up_timerisr);

  /* Enable SysTick interrupts */

  putreg32((NVIC_SYSTICK_CTRL_CLKSOURCE|NVIC_SYSTICK_CTRL_TICKINT|NVIC_SYSTICK_CTRL_ENABLE), NVIC_SYSTICK_CTRL);

  /* And enable the timer interrupt */

  up_enable_irq(SAM3U_IRQ_SYSTICK);
}