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/*
* 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) 1989-2007.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may in
* the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* Modified to support the MPC750.
* Modifications Copyright (c) 1999 Eric Valette valette@crf.canon.fr
*/
#include <rtems/system.h>
#include <rtems.h>
#include <rtems/libio.h>
#include <stdlib.h> /* for atexit() */
#include <assert.h>
#include <libcpu/c_clock.h>
#include <libcpu/cpuIdent.h>
#include <libcpu/spr.h>
#include <rtems/bspIo.h> /* for printk() */
#include <libcpu/powerpc-utility.h>
#include <bspopts.h> /* for CLOCK_DRIVER_USE_FAST_IDLE */
SPR_RW(BOOKE_TCR)
SPR_RW(BOOKE_TSR)
SPR_RW(BOOKE_DECAR)
extern int BSP_connect_clock_handler (void);
/*
* Clock ticks since initialization
*/
volatile uint32_t Clock_driver_ticks;
/*
* This is the value programmed into the count down timer.
*/
uint32_t Clock_Decrementer_value;
/*
* These are set by clock driver during its init
*/
rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;
void clockOff(void* unused)
{
rtems_interrupt_level l;
if ( ppc_cpu_is_bookE() ) {
rtems_interrupt_disable(l);
_write_BOOKE_TCR(_read_BOOKE_TCR() & ~BOOKE_TCR_DIE);
rtems_interrupt_enable(l);
} else {
/*
* Nothing to do as we cannot disable all interrupts and
* the decrementer interrupt enable is MSR_EE
*/
}
}
void clockOn(void* unused)
{
rtems_interrupt_level l;
PPC_Set_decrementer( Clock_Decrementer_value );
if ( ppc_cpu_is_bookE() ) {
_write_BOOKE_DECAR( Clock_Decrementer_value );
rtems_interrupt_disable(l);
/* clear pending/stale irq */
_write_BOOKE_TSR( BOOKE_TSR_DIS );
/* enable */
_write_BOOKE_TCR( _read_BOOKE_TCR() | BOOKE_TCR_DIE );
rtems_interrupt_enable(l);
}
}
static void clockHandler(void)
{
#if (CLOCK_DRIVER_USE_FAST_IDLE == 1)
do {
rtems_clock_tick();
} while (
_Thread_Heir == _Thread_Executing
&& _Thread_Executing->Start.entry_point
== rtems_configuration_get_idle_task()
);
#else
rtems_clock_tick();
#endif
}
static void (*clock_handler)(void);
/*
* Clock_isr
*
* This is the clock tick interrupt handler.
*
* Input parameters:
* vector - vector number
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
void clockIsr(void *unused)
{
int decr;
/*
* The driver has seen another tick.
*/
do {
register uint32_t flags;
rtems_interrupt_disable(flags);
__asm__ volatile (
"mfdec %0; add %0, %0, %1; mtdec %0"
: "=&r"(decr)
: "r"(Clock_Decrementer_value));
rtems_interrupt_enable(flags);
Clock_driver_ticks += 1;
/*
* Real Time Clock counter/timer is set to automatically reload.
*/
clock_handler();
} while ( decr < 0 );
}
/*
* Clock_isr_bookE
*
* This is the clock tick interrupt handler
* for bookE CPUs. For efficiency reasons we
* provide a separate handler rather than
* checking the CPU type each time.
*
* Input parameters:
* vector - vector number
*
* Output parameters: NONE
*
* Return values: NONE
*
*/
void clockIsrBookE(void *unused)
{
/* Note: TSR bit has already been cleared in the exception handler */
/*
* The driver has seen another tick.
*/
Clock_driver_ticks += 1;
/*
* Real Time Clock counter/timer is set to automatically reload.
*/
clock_handler();
}
int clockIsOn(void* unused)
{
uint32_t msr_value;
_CPU_MSR_GET( msr_value );
if ( ppc_cpu_is_bookE() && ! (_read_BOOKE_TCR() & BOOKE_TCR_DIE) )
msr_value = 0;
if (msr_value & MSR_EE) return 1;
return 0;
}
/*
* 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 )
{
(void) BSP_disconnect_clock_handler ();
}
uint32_t Clock_driver_nanoseconds_since_last_tick(void)
{
uint32_t clicks, tmp;
PPC_Get_decrementer( clicks );
/*
* Multiply by 1000 here separately from below so we do not overflow
* and get a negative value.
*/
tmp = (Clock_Decrementer_value - clicks) * 1000;
tmp /= (BSP_bus_frequency/BSP_time_base_divisor);
return tmp * 1000;
}
/*
* 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
)
{
rtems_interrupt_level l,tcr;
Clock_Decrementer_value = (BSP_bus_frequency/BSP_time_base_divisor)*
(rtems_configuration_get_microseconds_per_tick()/1000);
/* set the decrementer now, prior to installing the handler
* so no interrupts will happen in a while.
*/
PPC_Set_decrementer( (unsigned)-1 );
/* On a bookE CPU the decrementer works differently. It doesn't
* count past zero but we can enable auto-reload :-)
*/
if ( ppc_cpu_is_bookE() ) {
rtems_interrupt_disable(l);
tcr = _read_BOOKE_TCR();
tcr |= BOOKE_TCR_ARE;
tcr &= ~BOOKE_TCR_DIE;
_write_BOOKE_TCR(tcr);
rtems_interrupt_enable(l);
}
/*
* Set the nanoseconds since last tick handler
*/
rtems_clock_set_nanoseconds_extension(
Clock_driver_nanoseconds_since_last_tick
);
/* if a decrementer exception was pending, it is cleared by
* executing the default (nop) handler at this point;
* The next exception will then be taken by our clock handler.
* Clock handler installation initializes the decrementer to
* the correct value.
*/
clock_handler = clockHandler;
if (!BSP_connect_clock_handler ()) {
printk("Unable to initialize system clock\n");
rtems_fatal_error_occurred(1);
}
/* make major/minor avail to others such as shared memory driver */
rtems_clock_major = major;
rtems_clock_minor = minor;
return RTEMS_SUCCESSFUL;
} /* Clock_initialize */
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