/*
* Clock Tick Device Driver
*
* This routine utilizes the Decrementer Register common to the PPC family.
*
* The tick frequency is directly programmed to the configured number of
* microseconds per tick.
*
* COPYRIGHT (c) 1989-1997.
* On-Line Applications Research Corporation (OAR).
* Copyright assigned to U.S. Government, 1994.
*
* The license and distribution terms for this file may in
* the file LICENSE in this distribution or at
* http://www.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <stdlib.h>
#include <bsp.h>
#include <rtems/libio.h>
#include <assert.h>
/*
* The Real Time Clock Counter Timer uses this trap type.
*/
#define CLOCK_VECTOR PPC_IRQ_DECREMENTER
/*
* Clock ticks since initialization
*/
volatile rtems_unsigned32 Clock_driver_ticks;
/*
* This is the value programmed into the count down timer.
*/
rtems_unsigned32 Clock_Decrementer_value;
rtems_isr_entry Old_ticker;
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;
#define PPC_Set_decrementer( _clicks ) \
do { \
asm volatile( "mtdec %0" : "=r" ((_clicks)) : "r" ((_clicks)) ); \
} while (0)
/*
* Clock_isr
*
* This is the clock tick interrupt handler.
*
* Input parameters:
* vector - vector number
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
rtems_isr Clock_isr(
rtems_vector_number vector,
CPU_Interrupt_frame *frame
)
{
/*
* Set the decrementer.
*/
PPC_Set_decrementer( Clock_Decrementer_value );
/*
* The driver has seen another tick.
*/
Clock_driver_ticks += 1;
/*
* Real Time Clock counter/timer is set to automatically reload.
*/
rtems_clock_tick();
}
/*
* Install_clock
*
* This routine actually performs the hardware initialization for the clock.
*
* Input parameters:
* clock_isr - clock interrupt service routine entry point
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
extern int CLOCK_SPEED;
void Install_clock(
rtems_isr_entry clock_isr
)
{
Clock_driver_ticks = 0;
if ( BSP_Configuration.ticks_per_timeslice ) {
Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );
PPC_Set_decrementer( Clock_Decrementer_value );
atexit( Clock_exit );
}
}
/*
* Clock_exit
*
* This routine allows the clock driver to exit by masking the interrupt and
* disabling the clock's counter.
*
* Input parameters: NONE
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
void Clock_exit( void )
{
if ( BSP_Configuration.ticks_per_timeslice ) {
/* nothing to do */;
/* do not restore old vector */
}
}
/*
* Clock_initialize
*
* This routine initializes the clock driver.
*
* Input parameters:
* major - clock device major number
* minor - clock device minor number
* parg - pointer to optional device driver arguments
*
* Output parameters: NONE
*
* Return values:
* rtems_device_driver status code
*/
rtems_device_driver Clock_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
Clock_Decrementer_value = (int) &CPU_PPC_CLICKS_PER_MS *
(BSP_Configuration.microseconds_per_tick / 1000);
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;
}
/*
* Clock_control
*
* This routine is the clock device driver control entry point.
*
* Input parameters:
* major - clock device major number
* minor - clock device minor number
* parg - pointer to optional device driver arguments
*
* Output parameters: NONE
*
* Return values:
* rtems_device_driver status code
*/
rtems_device_driver Clock_control(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
rtems_unsigned32 isrlevel;
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( CLOCK_VECTOR, pargp );
}
else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
{
rtems_interrupt_disable( isrlevel );
(void) set_vector( args->buffer, CLOCK_VECTOR, 1 );
rtems_interrupt_enable( isrlevel );
}
done:
return RTEMS_SUCCESSFUL;
}
