static int ppc_clock_exception_handler(
BSP_Exception_frame *frame,
unsigned number
)
{
uint32_t delta = ppc_clock_decrementer_value;
uint32_t next = ppc_clock_next_time_base;
uint32_t dec = 0;
uint32_t now = 0;
uint32_t msr = 0;
do {
/* Increment clock ticks */
Clock_driver_ticks += 1;
/* Enable external exceptions */
msr = ppc_external_exceptions_enable();
/* Call clock ticker */
ppc_clock_tick();
/* Restore machine state */
ppc_external_exceptions_disable( msr);
/* Next time base */
next += delta;
/* Current time */
now = ppc_time_base();
/* New decrementer value */
dec = next - now;
} while (dec > delta);
/* Set decrementer */
ppc_set_decrementer_register( dec);
/* Expected next time base */
ppc_clock_next_time_base = next;
return 0;
}
rtems_device_driver Clock_initialize( rtems_device_major_number major, rtems_device_minor_number minor, void *arg)
{
/* Current CPU type */
ppc_cpu_id_t cpu_type = get_ppc_cpu_type();
/* Make major/minor available to others such as shared memory driver */
rtems_clock_major = major;
rtems_clock_minor = minor;
/*
* Set default ticker.
*
* The function rtems_clock_tick() returns a status code. This value
* will be discarded since the RTEMS documentation claims that it is
* always successful.
*/
ppc_clock_tick = (void (*)(void)) rtems_clock_tick;
/* Set the decrementer to the maximum value */
ppc_set_decrementer_register( PPC_CLOCK_DECREMENTER_MAX);
/* Decrementer value */
ppc_clock_decrementer_value = bsp_clicks_per_usec * rtems_configuration_get_microseconds_per_tick() - 1;
/* Check decrementer value */
if (ppc_clock_decrementer_value == 0) {
ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX;
RTEMS_SYSLOG_ERROR( "decrementer value would be zero, will be set to maximum value instead\n");
}
/* Set the nanoseconds since last tick handler */
rtems_clock_set_nanoseconds_extension( ppc_clock_nanoseconds_since_last_tick);
if (ppc_cpu_is_bookE()) {
/* Set decrementer auto-reload value */
PPC_SET_SPECIAL_PURPOSE_REGISTER( BOOKE_DECAR, ppc_clock_decrementer_value);
/* Install exception handler */
ppc_exc_set_handler( ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_booke);
/* Enable decrementer and auto-reload */
PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS( BOOKE_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE);
} else if (cpu_type == PPC_e300c2 || cpu_type == PPC_e300c3) {
/* TODO: Not tested for e300c2 */
/* Enable auto-reload */
PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS( HID0, 0x00000040);
/* Install exception handler */
ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler_e300);
} else {
/* Here the decrementer value is actually the interval */
++ppc_clock_decrementer_value;
/* Initialize next time base */
ppc_clock_next_time_base = ppc_time_base() + ppc_clock_decrementer_value;
/* Install exception handler */
ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler_first);
}
/* Set the decrementer value */
ppc_set_decrementer_register( ppc_clock_decrementer_value);
return RTEMS_SUCCESSFUL;
}
static uint32_t t32mppc_clock_get_timecount(struct timecounter *tc)
{
return ppc_time_base();
}
rtems_device_driver Clock_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *arg
)
{
uint64_t frequency = bsp_time_base_frequency;
uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick();
uint32_t interval = (uint32_t) ((frequency * us_per_tick) / 1000000);
/*
* Set default ticker.
*/
ppc_clock_tick = rtems_timecounter_tick;
if (ppc_cpu_is_bookE() != PPC_BOOKE_405) {
/* Decrementer value */
ppc_clock_decrementer_value = interval - 1;
/* Check decrementer value */
if (ppc_clock_decrementer_value == 0) {
ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX;
RTEMS_SYSLOG_ERROR( "decrementer value would be zero, will be set to maximum value instead\n");
}
if (ppc_cpu_is_bookE()) {
/* Set decrementer auto-reload value */
PPC_SET_SPECIAL_PURPOSE_REGISTER( BOOKE_DECAR, ppc_clock_decrementer_value);
/* Install exception handler */
ppc_exc_set_handler( ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_booke);
/* Enable decrementer and auto-reload */
PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS( BOOKE_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE);
} else {
/* Here the decrementer value is actually the interval */
++ppc_clock_decrementer_value;
/* Initialize next time base */
ppc_clock_next_time_base = ppc_time_base() + ppc_clock_decrementer_value;
/* Install exception handler */
ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler_first);
}
/* Set the decrementer value */
ppc_set_decrementer_register( ppc_clock_decrementer_value);
} else {
/* PIT interval value */
ppc_clock_decrementer_value = interval;
/* Install exception handler */
ppc_exc_set_handler(ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_ppc405);
/* Enable PIT and auto-reload */
PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS(PPC405_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE);
/* Set PIT auto-reload and initial value */
PPC_SET_SPECIAL_PURPOSE_REGISTER(PPC405_PIT, interval);
}
/* Install timecounter */
ppc_tc.tc_get_timecount = ppc_get_timecount;
ppc_tc.tc_counter_mask = 0xffffffff;
ppc_tc.tc_frequency = frequency;
ppc_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
rtems_timecounter_install(&ppc_tc);
return RTEMS_SUCCESSFUL;
}
