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https://gitlab.rtems.org/rtems/rtos/rtems.git
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150 lines
3.3 KiB
C
150 lines
3.3 KiB
C
/*
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* This routine initializes the MC68360 Periodic Interval Timer
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*
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* The PIT has rather poor resolution, but it is easy to set up
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* and requires no housekeeping once it is going.
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*
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* Based on the `gen68302' board support package, and covered by the
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* original distribution terms.
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*
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* W. Eric Norum
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* Saskatchewan Accelerator Laboratory
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* University of Saskatchewan
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* Saskatoon, Saskatchewan, CANADA
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* eric@skatter.usask.ca
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*
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* $Id$
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*/
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/*
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* Input parameters: NONE
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*
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* Output parameters: NONE
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*
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* COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
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* On-Line Applications Research Corporation (OAR).
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* All rights assigned to U.S. Government, 1994.
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*
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* This material may be reproduced by or for the U.S. Government pursuant
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* to the copyright license under the clause at DFARS 252.227-7013. This
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* notice must appear in all copies of this file and its derivatives.
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*/
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#include <stdlib.h> /* for atexit() */
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#include <bsp.h>
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#include <rtems/libio.h>
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#include "m68360.h"
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#define CLOCK_VECTOR 120
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#define CLOCK_IRQ_LEVEL 6
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/*
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* Clock_driver_ticks is a monotonically increasing counter of the
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* number of clock ticks since the driver was initialized.
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*/
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volatile rtems_unsigned32 Clock_driver_ticks;
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/*
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* These are set by clock driver during its init
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*/
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rtems_device_major_number rtems_clock_major = ~0;
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rtems_device_minor_number rtems_clock_minor;
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/*
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* Periodic interval timer interrupt handler
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*/
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rtems_isr
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Clock_isr (rtems_vector_number vector)
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{
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Clock_driver_ticks++;
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rtems_clock_tick();
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}
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void
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Clock_exit (void)
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{
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if (BSP_Configuration.ticks_per_timeslice ) {
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/*
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* Turn off periodic interval timer
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*/
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m360.pitr &= ~0xFF;
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}
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}
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static void
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Install_clock (rtems_isr_entry clock_isr)
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{
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Clock_driver_ticks = 0;
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if ( BSP_Configuration.ticks_per_timeslice ) {
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int pitr;
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/*
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* Choose periodic interval timer register value
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* For a 25 MHz external clock the basic clock rate is
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* 40 nsec * 128 * 4 = 20.48 usec/tick
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*/
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pitr = ((BSP_Configuration.microseconds_per_tick * 100) + 1023) / 2048;
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if (pitr >= 256) {
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pitr = (pitr + 255) / 512;
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if (pitr >= 256)
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pitr = 255;
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else if (pitr == 0)
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pitr = 1;
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pitr |= 0x100;
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}
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else if (pitr == 0) {
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pitr = 1;
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}
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m360.pitr &= ~0x1FF;
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m360.picr = (CLOCK_IRQ_LEVEL << 8) | CLOCK_VECTOR;
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set_vector (clock_isr, CLOCK_VECTOR, 1);
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m360.pitr |= pitr;
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atexit (Clock_exit);
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}
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}
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rtems_device_driver
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Clock_initialize(
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rtems_device_major_number major,
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rtems_device_minor_number minor,
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void *pargp
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)
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{
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Install_clock (Clock_isr);
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/*
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* make major/minor avail to others such as shared memory driver
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*/
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rtems_clock_major = major;
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rtems_clock_minor = minor;
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return RTEMS_SUCCESSFUL;
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}
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rtems_device_driver Clock_control(
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rtems_device_major_number major,
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rtems_device_minor_number minor,
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void *pargp
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)
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{
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rtems_unsigned32 isrlevel;
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rtems_libio_ioctl_args_t *args = pargp;
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if (args) {
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/*
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* This is hokey, but until we get a defined interface
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* to do this, it will just be this simple...
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*/
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if (args->command == rtems_build_name('I', 'S', 'R', ' ')) {
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Clock_isr( CLOCK_VECTOR);
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}
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else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) {
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rtems_interrupt_disable( isrlevel );
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(void) set_vector( args->buffer, CLOCK_VECTOR, 1 );
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rtems_interrupt_enable( isrlevel );
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}
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}
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return RTEMS_SUCCESSFUL;
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}
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