/* Clock
*
* This routine initializes the interval timer on the
* PA-RISC CPU. The tick frequency is specified by the bsp.
*
* 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.rtems.com/license/LICENSE.
*
* $Id$
*/
#include <rtems.h>
#include <rtems/libio.h>
/* should get this from bsp.h, but it is not installed yet */
rtems_isr_entry set_vector(rtems_isr_entry, rtems_vector_number, int);
#include <stdlib.h> /* for atexit() */
typedef unsigned long long hppa_click_count_t;
/*
* These are set by clock driver during its init
*/
rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;
/*
* CPU_HPPA_CLICKS_PER_TICK is either a #define or an rtems_unsigned32
* allocated and set by bsp_start()
*/
#ifndef CPU_HPPA_CLICKS_PER_TICK
extern rtems_unsigned32 CPU_HPPA_CLICKS_PER_TICK;
#endif
volatile rtems_unsigned32 Clock_driver_ticks;
rtems_unsigned32 Clock_isrs; /* ISRs until next tick */
rtems_unsigned32 most_recent_itimer_value;
rtems_unsigned64 Clock_clicks; /* running total of cycles */
rtems_unsigned32 Clock_clicks_interrupt;
void Clock_exit(void);
void
ReInstall_clock(rtems_isr_entry new_clock_isr)
{
rtems_unsigned32 isrlevel = 0;
rtems_interrupt_disable(isrlevel);
(void) set_vector(
new_clock_isr,
HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER,
1
);
rtems_interrupt_enable(isrlevel);
}
/*
* read itimer and update Clock_clicks as appropriate
*/
rtems_unsigned32
Clock_read_itimer()
{
rtems_unsigned32 isrlevel;
rtems_unsigned32 itimer_value;
rtems_unsigned32 wrap_count;
rtems_unsigned32 recent_count;
rtems_interrupt_disable(isrlevel);
wrap_count = (Clock_clicks & 0xFFFFFFFF00000000ULL) >> 32;
recent_count = (rtems_unsigned32) Clock_clicks;
itimer_value = get_itimer();
if (itimer_value < recent_count)
wrap_count++;
Clock_clicks = (((rtems_unsigned64) wrap_count) << 32) + itimer_value;
rtems_interrupt_enable(isrlevel);
return itimer_value;
}
void Install_clock(rtems_isr_entry clock_isr)
{
Clock_driver_ticks = 0;
Clock_clicks_interrupt = 0;
Clock_clicks = 0;
Clock_isrs = rtems_configuration_get_milliseconds_per_tick();
/*
* 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
*/
Clock_clicks_interrupt = Clock_read_itimer() + CPU_HPPA_CLICKS_PER_TICK;
set_itimer((rtems_unsigned32) Clock_clicks_interrupt);
(void) set_vector(clock_isr, HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER, 1);
atexit(Clock_exit);
}
rtems_isr
Clock_isr(rtems_vector_number vector)
{
rtems_unsigned32 clicks_til_next_interrupt;
rtems_unsigned32 itimer_value;
/*
* setup for next interrupt; making sure the new value is reasonably
* in the future.... in case we lost out on an interrupt somehow
*/
itimer_value = Clock_read_itimer();
Clock_clicks_interrupt += CPU_HPPA_CLICKS_PER_TICK;
/*
* how far away is next interrupt *really*
* It may be a long time; this subtraction works even if
* Clock_clicks_interrupt < Clock_clicks_low_order via
* the miracle of unsigned math.
*/
clicks_til_next_interrupt = Clock_clicks_interrupt - itimer_value;
/*
* If it is too soon then bump it up.
* This should only happen if CPU_HPPA_CLICKS_PER_TICK is too small.
* But setting it low is useful for debug, so...
*/
if (clicks_til_next_interrupt < 400)
{
Clock_clicks_interrupt = itimer_value + 1000;
/* XXX: count these! this should be rare */
}
/*
* If it is too late, that means we missed the interrupt somehow.
* Rather than wait 35-50s for a wrap, we just fudge it here.
*/
if (clicks_til_next_interrupt > CPU_HPPA_CLICKS_PER_TICK)
{
Clock_clicks_interrupt = itimer_value + 1000;
/* XXX: count these! this should never happen :-) */
}
set_itimer((rtems_unsigned32) Clock_clicks_interrupt);
Clock_driver_ticks++;
if (Clock_isrs == 1)
{
rtems_clock_tick();
Clock_isrs = rtems_configuration_get_milliseconds_per_tick();
if (Clock_isrs == 0)
Clock_isrs = 1;
}
else
Clock_isrs--;
}
/*
* Called via atexit()
* Remove the clock interrupt handler by setting handler to NULL
*/
void
Clock_exit(void)
{
(void) set_vector(0, HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER, 1);
}
/*
* spin delay for specified number of microseconds
* used by RTEMS delay macro
*/
void
Clock_delay(rtems_unsigned32 microseconds)
{
rtems_unsigned64 future_time;
(void) Clock_read_itimer();
future_time = Clock_clicks +
((rtems_unsigned64) microseconds) *
rtems_cpu_configuration_get_itimer_clicks_per_microsecond();
for (;;)
{
(void) Clock_read_itimer();
if (future_time <= Clock_clicks)
break;
}
}
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(HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER);
}
else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
{
ReInstall_clock(args->buffer);
}
done:
return RTEMS_SUCCESSFUL;
}