From 9e86dd7db7e8cc17a851d348917cbe7cdd489ce1 Mon Sep 17 00:00:00 2001 From: Joel Sherrill Date: Wed, 7 Jun 1995 01:27:28 +0000 Subject: incorporated mc68302 support --- c/src/lib/libbsp/m68k/gen68302/timer/timer.c | 130 +++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100644 c/src/lib/libbsp/m68k/gen68302/timer/timer.c (limited to 'c/src/lib/libbsp/m68k/gen68302/timer/timer.c') diff --git a/c/src/lib/libbsp/m68k/gen68302/timer/timer.c b/c/src/lib/libbsp/m68k/gen68302/timer/timer.c new file mode 100644 index 0000000000..4d60b6a82b --- /dev/null +++ b/c/src/lib/libbsp/m68k/gen68302/timer/timer.c @@ -0,0 +1,130 @@ +/* Timer_init() + * + * This routine initializes TIMER 2 for an MC68302. + * + * Input parameters: NONE + * + * Output parameters: NONE + * + * NOTE: It is important that the timer start/stop overhead be + * determined when porting or modifying this code. + * + * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. + * On-Line Applications Research Corporation (OAR). + * All rights assigned to U.S. Government, 1994. + * + * This material may be reproduced by or for the U.S. Government pursuant + * to the copyright license under the clause at DFARS 252.227-7013. This + * notice must appear in all copies of this file and its derivatives. + * + * $Id$ + */ + + +#include +#include +#include "m68302.h" + + +#define TMR2_VAL 0x071b /* Timer mode register + * (section 3.5.2.1 in 68302 manual) + * 15-8: "7" prescaler divide by 8 (x+1) + * 7-6: 00 dis. intr. on capture event + * 5: 0 active-low pulse + * 4: 1 intr. on reaching reference + * 3: 1 restart counter on reference + * 2-1: 01 master clock input source + * 0: 1 enable timer + */ +#define TRR2_VAL 2000 /* Timer reference register + * (section 3.5.2.2 in 68302 manual) + * 2000 ticks @ (16MHz/1)/8 = 1-ms count + */ + +rtems_unsigned32 Timer_interrupts; + +rtems_boolean Timer_driver_Find_average_overhead; + +rtems_isr timerisr(); + +void Timer_initialize( void ) +{ + m302.reg.tmr2 = 0; /* disable timer */ + + Timer_interrupts = 0; /* clear timer ISR count */ + + m302.reg.trr2 = TRR2_VAL; /* set timer reference register */ + m302.reg.tmr2 = TMR2_VAL; /* set timer mode register */ + m302.reg.imr |= RBIT_IMR_TIMER2; /* set 68302 int-mask to allow ints */ +} + +/* + * The following controls the behavior of Read_timer(). + * + * FIND_AVG_OVERHEAD * instructs the routine to return the "raw" count. + * + * AVG_OVEREHAD is the overhead for starting and stopping the timer. It + * is usually deducted from the number returned. + * + * LEAST_VALID is the lowest number this routine should trust. Numbers + * below this are "noise" and zero is returned. + */ + +#define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ + /* (Y countdowns) to start/stop the timer. */ + /* This value is in microseconds. */ +#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ + +/* + * Return timer value in 1/2-microsecond units + */ +int Read_timer( void ) +{ + rtems_unsigned16 clicks; + rtems_unsigned32 total; + + /* + * Read the timer and see how many clicks it has been since counter + * rolled over. + */ + + clicks = m302.reg.tcn2; + + /* + * Total is calculated by taking into account the number of timer overflow + * interrupts since the timer was initialized and clicks since the last + * interrupts. + */ + + total = (Timer_interrupts * TRR2_VAL) + clicks; + + if ( Timer_driver_Find_average_overhead == 1 ) + return total; /* in XXX microsecond units */ + + if ( total < LEAST_VALID ) + return 0; /* below timer resolution */ + + /* + * Convert 1/2-microsecond count into microseconds + */ + + return (total - AVG_OVERHEAD) >> 1; +} + + +/* + * Empty function call used in loops to measure basic cost of looping + * in Timing Test Suite. + */ + +rtems_status_code Empty_function(void) +{ + return RTEMS_SUCCESSFUL; +} + +void Set_find_average_overhead( + rtems_boolean find_flag +) +{ + Timer_driver_Find_average_overhead = find_flag; +} -- cgit v1.2.3