/**************************************************************************** * 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 * * 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 #include #include #include #include "chip.h" #include "up_arch.h" #include "clock_internal.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_timerinit * * Description: * This function is called during start-up to initialize the timer * interrupt. * ****************************************************************************/ void up_timerinit(void) { up_disable_irq(DM320_IRQ_SYSTIMER); /* Start timer0 running so that an interrupt is generated at * the rate MSEC_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); }