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/****************************************************************************
* arch/hc/src/m9s12/m9s12_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 "chip.h"
#include "m9s12_internal.h"
#include "m9s12_crg.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 timer frequency is the OSCCLK divided down. The divisor is
* (A+1)*(2**(B+9)) where:
*
* A = MODCNT RTR[0:3]
* B = PREP RTR[4:6]
*
* Maximum and minimum values:
*/
#define MIN_PRER 1024 /* 2**10, B=1 */
#define MAX_PRER 65536 /* 2**16, B=7 */
#define MIN_MODCNT 1 /* A=0 */
#define MAX_MODCNT 16 /* A=15 */
/* Pick the smallest value of B for which:
*
* OSCCLK/(MAX_MODCNT*(2**(B+9))) >= CLK_TCK >= OSCCLK/(MIN_MODCNT*(2**(B+9)))
*/
#if CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*1024) && HCS12_OSCCLK/(MIN_MODCNT*1024)
# define PRER_VALUE 1
# define PRER_DIV 1024
#elif CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*2048) && HCS12_OSCCLK/(MIN_MODCNT*2048)
# define PRER_VALUE 2
# define PRER_DIV 2048
#elif CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*4096) && HCS12_OSCCLK/(MIN_MODCNT*4096)
# define PRER_VALUE 3
# define PRER_DIV 4096
#elif CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*8192) && HCS12_OSCCLK/(MIN_MODCNT*8192)
# define PRER_VALUE 4
# define PRER_DIV 8192
#elif CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*16384) && HCS12_OSCCLK/(MIN_MODCNT*16384)
# define PRER_VALUE 5
# define PRER_DIV 16384
#elif CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*32768) && HCS12_OSCCLK/(MIN_MODCNT*32768)
# define PRER_VALUE 6
# define PRER_DIV 32768
#elif CLK_TCK >= HCS12_OSCCLK/(MAX_MODCNT*65536) && HCS12_OSCCLK/(MIN_MODCNT*65536)
# define PRER_VALUE 7
# define PRER_DIV 65536
#else
# error "Cannot generate CLK_TCK from HCSCLK_OSCCLK"
#endif
/* Now we can simply calculate A from:
*
* CLK_TCK = OSCCLK/((A+1)*PRER_DIV)
* OSCCLK / (CLK_TCK * PRER_DIV) - 1
*/
#define MODCNT_DENOM ((uint32_t)CLK_TCK * (uint32_t)PRER_DIV)
#define MODCNT_VALUE ((((uint32_t)HCS12_OSCCLK + (MODCNT_DENOM/2))/ MODCNT_DENOM) - 1)
/****************************************************************************
* 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 real time interrupt flag */
putreg8(CRG_CRGFLG_RTIF, HCS12_CRG_CRGFLG);
/* Process timer interrupt */
sched_process_timer();
return 0;
}
/****************************************************************************
* Function: up_timer_initialize
*
* Description:
* This function is called during start-up to initialize the system timer
* interrupt.
*
****************************************************************************/
void up_timer_initialize(void)
{
uint32_t tmp;
uint8_t regval;
/* Configure hardware RTI timer (with a hack to avoid and integer overflow
* error at compile time.. hopefully the optimizer will eliminate these
* uint32_t operations).
*/
tmp = MODCNT_VALUE << CRG_RTICTL_MODCNT_SHIFT | PRER_VALUE << CRG_RTICTL_PRER_SHIFT;
putreg8((uint8_t)tmp, HCS12_CRG_RTICTL);
/* Attach the timer interrupt vector */
(void)irq_attach(HCS12_IRQ_VRTI, (xcpt_t)up_timerisr);
/* Enable RTI interrupt by setting the RTIE bit */
regval = getreg8(HCS12_CRG_CRGINT);
regval |= CRG_CRGINT_RTIE;
putreg8(regval, HCS12_CRG_CRGINT);
}
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