/* clock.c
*
* This routine initializes the PIT on the MPC821.
* The tick frequency is specified by the bsp.
*
* Author: Jay Monkman (jmonkman@frasca.com)
* Copyright (C) 1998 by Frasca International, Inc.
*
* Derived from c/src/lib/libcpu/ppc/ppc403/clock/clock.c:
*
* Author: Andrew Bray <andy@i-cubed.co.uk>
*
* COPYRIGHT (c) 1995 by i-cubed ltd.
*
* To anyone who acknowledges that this file is provided "AS IS"
* without any express or implied warranty:
* permission to use, copy, modify, and distribute this file
* for any purpose is hereby granted without fee, provided that
* the above copyright notice and this notice appears in all
* copies, and that the name of i-cubed limited not be used in
* advertising or publicity pertaining to distribution of the
* software without specific, written prior permission.
* i-cubed limited makes no representations about the suitability
* of this software for any purpose.
*
* Derived from c/src/lib/libcpu/hppa1_1/clock/clock.c:
*
* COPYRIGHT (c) 1989-1999.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <clockdrv.h>
#include <rtems/libio.h>
#include <stdlib.h> /* for atexit() */
#include <mpc821.h>
volatile rtems_unsigned32 Clock_driver_ticks;
extern volatile m821_t m821;
void Clock_exit( void );
/*
* These are set by clock driver during its init
*/
rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;
/*
* ISR Handler
*/
rtems_isr Clock_isr(rtems_vector_number vector)
{
m821.piscr |= M821_PISCR_PS;
Clock_driver_ticks++;
rtems_clock_tick();
}
void Install_clock(rtems_isr_entry clock_isr)
{
rtems_isr_entry previous_isr;
rtems_unsigned32 pit_value;
Clock_driver_ticks = 0;
pit_value = rtems_configuration_get_microseconds_per_tick() /
rtems_cpu_configuration_get_clicks_per_usec();
if (pit_value == 0) {
pit_value = 0xffff;
} else {
pit_value--;
}
if (pit_value > 0xffff) { /* pit is only 16 bits long */
rtems_fatal_error_occurred(-1);
}
if ( rtems_configuration_get_ticks_per_timeslice() ) {
/*
* initialize the interval here
* First tick is set to right amount of time in the future
* Future ticks will be incremented over last value set
* in order to provide consistent clicks in the face of
* interrupt overhead
*/
rtems_interrupt_catch(clock_isr, PPC_IRQ_LVL0, &previous_isr);
m821.sccr &= ~(1<<24);
m821.pitc = pit_value;
/* set PIT irq level, enable PIT, PIT interrupts */
/* and clear int. status */
m821.piscr = M821_PISCR_PIRQ(0) |
M821_PISCR_PTE | M821_PISCR_PS | M821_PISCR_PIE;
m821.simask |= M821_SIMASK_LVM0;
}
atexit(Clock_exit);
}
void
ReInstall_clock(rtems_isr_entry new_clock_isr)
{
rtems_isr_entry previous_isr;
rtems_unsigned32 isrlevel = 0;
rtems_interrupt_disable(isrlevel);
rtems_interrupt_catch(new_clock_isr, PPC_IRQ_LVL0, &previous_isr);
rtems_interrupt_enable(isrlevel);
}
/*
* Called via atexit()
* Remove the clock interrupt handler by setting handler to NULL
*/
void
Clock_exit(void)
{
if ( rtems_configuration_get_ticks_per_timeslice() ) {
/* disable PIT and PIT interrupts */
m821.piscr &= ~(M821_PISCR_PTE | M821_PISCR_PIE);
(void) set_vector(0, PPC_IRQ_LVL0, 1);
}
}
rtems_device_driver Clock_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
Install_clock( Clock_isr );
/*
* make major/minor avail to others such as shared memory driver
*/
rtems_clock_major = major;
rtems_clock_minor = minor;
return RTEMS_SUCCESSFUL;
}
rtems_device_driver Clock_control(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
rtems_libio_ioctl_args_t *args = pargp;
if (args == 0)
goto done;
/*
* This is hokey, but until we get a defined interface
* to do this, it will just be this simple...
*/
if (args->command == rtems_build_name('I', 'S', 'R', ' ')) {
Clock_isr(PPC_IRQ_LVL0);
}
else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) {
ReInstall_clock(args->buffer);
}
done:
return RTEMS_SUCCESSFUL;
}