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/************************************************************
* c5471/c5471_timerisr.c
*
* Copyright (C) 2007, 2009 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 <debug.h>
#include <nuttx/arch.h>
#include "chip.h"
#include "up_arch.h"
#include "clock_internal.h"
#include "up_internal.h"
/************************************************************
* Pre-processor Definitions
************************************************************/
/* We want the general purpose timer running at the rate
* MSEC_PER_TICK. The C5471 clock is 47.5MHz and we're using
* a timer PTV value of 3 (3 == divide incoming frequency by
* 16) which then yields a 16 bitCLKS_PER_INT value
* of 29687.
*
* 47500000 / 16 = 2968750 clocks/sec
* 2968750 / 100 = 29687 clocks/ 100Hz interrupt
*
*/
#define CLKS_PER_INT 29687
#define CLKS_PER_INT_SHIFT 5
#define AR 0x00000010
#define ST 0x00000008
#define PTV 0x00000003
/************************************************************
* 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 val;
up_disable_irq(C5471_IRQ_SYSTIMER);
/* Start the general purpose timer running in auto-reload mode
* so that an interrupt is generated at the rate MSEC_PER_TICK.
*/
val = ((CLKS_PER_INT-1) << CLKS_PER_INT_SHIFT) | AR | ST | PTV;
putreg32(val, C5471_TIMER2_CTRL);
/* Attach and enable the timer interrupt */
irq_attach(C5471_IRQ_SYSTIMER, (xcpt_t)up_timerisr);
up_enable_irq(C5471_IRQ_SYSTIMER);
}
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