/***************************************************************************
* arch/z80/src/z8/z8_timerisr.c
*
* Copyright (C) 2008-2009 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 <ez8.h>
#include <nuttx/arch.h>
#include "chip/chip.h"
#include "clock/clock.h"
#include "up_internal.h"
/***************************************************************************
* Definitions
***************************************************************************/
/***************************************************************************
* Private Types
***************************************************************************/
/***************************************************************************
* Private Functions
***************************************************************************/
/***************************************************************************
* Public Functions
***************************************************************************/
/* This function is normally prototyped int the ZiLOG header file sio.h */
extern uint32_t get_freq(void);
/***************************************************************************
* Function: up_timerisr
*
* Description:
* The timer ISR will perform a variety of services for various portions
* of the system.
*
***************************************************************************/
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)
{
uint32_t reload;
up_disable_irq(Z8_IRQ_SYSTIMER);
/* Write to the timer control register to disable the timer, configure
* the timer for continuous mode, and set up the pre-scale value for
* divide by 4.
*/
putreg8((Z8_TIMERCTL_DIV4|Z8_TIMERCTL_CONT), T0CTL);
/* Write to the timer high and low byte registers to set a starting
* count value (this effects only the first pass in continuous mode)
*/
putreg16(0x0001, T0);
/* Write to the timer reload register to set the reload value.
*
* In continuous mode:
*
* timer_period = reload_value x prescale / system_clock_frequency
* or
* reload_value = (timer_period * system_clock_frequency) / prescale
*
* For system_clock_frequency=18.432MHz, timer_period=10mS, and prescale=4,
* then reload_value=46,080 - OR:
*
* reload_value = system_clock_frequency / 400
*/
reload = get_freq() / 400;
putreg16((uint16_t)reload, T0R);
/* Write to the timer control register to enable the timer and to
* initiate counting
*/
putreg8((getreg8(T0CTL)|Z8_TIMERCTL_TEN), T0CTL);
/* Set the timer priority */
/* Attach and enable the timer interrupt (leaving at priority 0 */
irq_attach(Z8_IRQ_SYSTIMER, (xcpt_t)up_timerisr);
up_enable_irq(Z8_IRQ_SYSTIMER);
}
