128 lines
4.0 KiB
C
128 lines
4.0 KiB
C
/****************************************************************************
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* arch/z80/src/z8/z8_timerisr.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <debug.h>
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#include <ez8.h>
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#include <nuttx/arch.h>
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#include "chip.h"
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#include "clock/clock.h"
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#include "z80_internal.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/* This function is normally prototyped int the ZiLOG header file sio.h */
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extern uint32_t get_freq(void);
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Function: z8_timerisr
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*
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* Description:
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* The timer ISR will perform a variety of services for various portions
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* of the system.
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*
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****************************************************************************/
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static int z8_timerisr(int irq, uint32_t *regs, void *arg)
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{
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/* Process timer interrupt */
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nxsched_process_timer();
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return 0;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Function: up_timer_initialize
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*
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* Description:
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* This function is called during start-up to initialize the timer
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* interrupt.
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*
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****************************************************************************/
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void up_timer_initialize(void)
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{
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uint32_t reload;
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up_disable_irq(Z8_IRQ_SYSTIMER);
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/* Write to the timer control register to disable the timer, configure
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* the timer for continuous mode, and set up the pre-scale value for
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* divide by 4.
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*/
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putreg8((Z8_TIMERCTL_DIV4 | Z8_TIMERCTL_CONT), T0CTL);
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/* Write to the timer high and low byte registers to set a starting
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* count value (this effects only the first pass in continuous mode)
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*/
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putreg16(0x0001, T0);
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/* Write to the timer reload register to set the reload value.
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*
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* In continuous mode:
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*
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* timer_period = reload_value x prescale / system_clock_frequency
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* or
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* reload_value = (timer_period * system_clock_frequency) / prescale
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*
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* For system_clock_frequency=18.432MHz, timer_period=10mS, and prescale=4,
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* then reload_value=46,080 - OR:
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*
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* reload_value = system_clock_frequency / 400
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*/
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reload = get_freq() / 400;
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putreg16((uint16_t)reload, T0R);
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/* Write to the timer control register to enable the timer and to
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* initiate counting
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*/
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putreg8((getreg8(T0CTL) | Z8_TIMERCTL_TEN), T0CTL);
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/* Set the timer priority */
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/* Attach and enable the timer interrupt (leaving at priority 0 */
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irq_attach(Z8_IRQ_SYSTIMER, (xcpt_t)z8_timerisr, NULL);
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up_enable_irq(Z8_IRQ_SYSTIMER);
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}
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