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/****************************************************************************
* arch/arm/src/dm320/dm320_timerisr.c
* arch/arm/src/chip/dm320_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/clock.h"
#include "up_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* DM320 Timers
*
* Each of the general-purpose timers can run in one of two modes: one-
* shot mode and free-run mode. In one-shot mode, an interrupt only
* occurs once and then the timer must be explicitly reset to begin the
* timing operation again. In free-run mode, when the timer generates an
* interrupt, the timer counter is automatically reloaded to start the count
* operation again. Use the bit field MODE in TMMDx to configure the
* timer for one-shot more or free-run mode. The bit field MODE in TMMDx
* also allows you to stop the timer.
*
* Either the ARM clock divided by 2 (CLK_ARM/2) or an external clock
* connected to the M27XI pin can be selected as the clock source of the
* timer.
*
* The actual clock frequency used in the timer count operation is the input
* clock divided by: 1 plus the value set in the bit field PRSCL of the
* register TMPRSCLx (10 bits). The timer expires when it reaches the
* value set in the bit field DIV of the register TMDIVx (16 bits) plus 1.
* PRSCL+1 is the source clock frequency divide factor and DIV+1 is the
* timer count value. The frequency of a timer interrupt is given by the
* following equation:
*
* Interrupt Frequency = (Source Clock Frequency) / (PRSCL+1) / (DIV+1)
*/
/* System Timer
*
* Timer0 is dedicated as the system timer. The rate of system timer
* interrupts is assumed to to 10MS per tick / 100Hz. The following
* register settings are used for timer 0
*
* System clock formula:
* Interrupt Frequency = (Source Clock Frequency) / (PRSCL+1) / (DIV+1)
* Source Clock Frequency = 27MHz (PLL clock)
* DIV = 26,999 (Yields 1Khz timer clock)
* PRSCL = 9 (Produces 100Hz interrupts)
*/
#define DM320_TMR0_MODE DM320_TMR_MODE_FREERUN /* Free running */
#define DM320_TMR0_DIV 26999 /* (see above) */
#define DM320_TMR0_PRSCL 9 /* (see above) */
/****************************************************************************
* 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_timer_initialize
*
* Description:
* This function is called during start-up to initialize the timer
* interrupt.
*
****************************************************************************/
void up_timer_initialize(void)
{
up_disable_irq(DM320_IRQ_SYSTIMER);
/* Start timer0 running so that an interrupt is generated at
* the rate USEC_PER_TICK.
*/
putreg16(DM320_TMR0_PRSCL, DM320_TIMER0_TMPRSCL); /* Timer 0 Prescalar */
putreg16(DM320_TMR0_DIV, DM320_TIMER0_TMDIV); /* Timer 0 Divisor (count) */
/* Start the timer */
putreg16(DM320_TMR0_MODE, DM320_TIMER0_TMMD); /* Timer 0 Mode */
/* Attach and enable the timer interrupt */
irq_attach(DM320_IRQ_SYSTIMER, (xcpt_t)up_timerisr);
up_enable_irq(DM320_IRQ_SYSTIMER);
}
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