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/****************************************************************************
* arch/mips/src/pic32mx/pic32mx_timerisr.c
*
* Copyright (C) 2011 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 "clock/clock.h"
#include "up_internal.h"
#include "up_arch.h"
#include "pic32mx-config.h"
#include "pic32mx-timer.h"
#include "pic32mx-int.h"
#include "pic32mx-internal.h"
/****************************************************************************
* Definitions
****************************************************************************/
/* Timer Setup **************************************************************/
/* Timer 1 is a type A timer. Setting the TCS bit in the timer control
* register will select the SOSC as the clock source. Otherwise, PBCLOCK
* is the clock source.
*/
#ifdef BOARD_TIMER1_SOSC
# define TIMER1_SRC_FREQ BOARD_SOSC_FREQ
# define TIMER1_CON_TCS TIMER_CON_TCS
#else
# define TIMER1_SRC_FREQ BOARD_PBCLOCK
# define TIMER1_CON_TCS (0)
#endif
/* Select a timer 1 prescale value. Our goal is to select the timer MATCH
* register value given the timer 1 input clock frequency and the desired
* system timer frequency:
*
* TIMER1_MATCH = TIMER1_SRC_FREQ / TIMER1_PRESCALE / CLOCKS_PER_SEC
*
* We want the largest possible value for MATCH that is less than 65,535, the
* maximum value for the 16-bit timer register:
*
* TIMER1_PRESCALE >= TIMER1_SRC_FREQ / CLOCKS_PER_SEC / 65535
*
* Timer 1 does not have very many options for the perscaler value. So we
* can pick the best by brute force. Example:
*
* Example 1. Given:
* BOARD_TIMER1_SOSC = Defined
* BOARD_SOSC_FREQ = 32768
* CLOCKS_PER_SEC = 100
* Then:
* OPTIMAL_PRESCALE = 1
* TIMER1_PRESCALE = 1
* TIMER1_MATCH = 327 -> 100.3 ticks/sec
*
* Example 2. Given:
* BOARD_TIMER1_SOSC = Not defined
* BOARD_PBCLOCK = 60000000
* CLOCKS_PER_SEC = 100
* Then:
* OPTIMAL_PRESCALE = 9.2
* TIMER1_PRESCALE = 64
* TIMER1_MATCH = 9375 -> 100.0 ticks/sec
*/
#define OPTIMAL_PRESCALE (TIMER1_SRC_FREQ / CLOCKS_PER_SEC / 65535)
#if OPTIMAL_PRESCALE <= 1
# define TIMER1_CON_TCKPS TIMER1_CON_TCKPS_1
# define TIMER1_PRESCALE 1
#elif OPTIMAL_PRESCALE <= 8
# define TIMER1_CON_TCKPS TIMER1_CON_TCKPS_8
# define TIMER1_PRESCALE 8
#elif OPTIMAL_PRESCALE <= 64
# define TIMER1_CON_TCKPS TIMER1_CON_TCKPS_64
# define TIMER1_PRESCALE 64
#elif OPTIMAL_PRESCALE <= 256
# define TIMER1_CON_TCKPS TIMER1_CON_TCKPS_256
# define TIMER1_PRESCALE 256
#else
# error "This timer frequency cannot be represented"
#endif
#define TIMER1_MATCH (TIMER1_SRC_FREQ / TIMER1_PRESCALE / CLOCKS_PER_SEC)
/****************************************************************************
* 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)
{
/* Clear the pending timer interrupt */
putreg32(INT_T1, PIC32MX_INT_IFS0CLR);
/* 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)
{
/* Configure and enable TIMER1. Used the computed TCKPS divider and timer
* match valude. The source will be either the internal PBCLOCK (TCS=0) or
* the external SOSC (TCS=1)
*/
putreg32((TIMER1_CON_TCKPS|TIMER1_CON_TCS), PIC32MX_TIMER1_CON);
putreg32(0, PIC32MX_TIMER1_CNT);
putreg32(TIMER1_MATCH-1, PIC32MX_TIMER1_PR);
putreg32(TIMER_CON_ON, PIC32MX_TIMER1_CONSET);
/* Configure the timer interrupt */
up_clrpend_irq(PIC32MX_IRQSRC_T1);
#ifdef CONFIG_ARCH_IRQPRIO
(void)up_prioritize_irq(PIC32MX_IRQ_T1, CONFIG_PIC32MX_T1PRIO);
#endif
/* Attach the timer interrupt vector */
(void)irq_attach(PIC32MX_IRQ_T1, (xcpt_t)up_timerisr);
/* And enable the timer interrupt */
up_enable_irq(PIC32MX_IRQSRC_T1);
}
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