diff options
| -rw-r--r-- | c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c | 66 |
1 files changed, 57 insertions, 9 deletions
diff --git a/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c b/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c index f14acab1d8..218828cf4a 100644 --- a/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c +++ b/c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c @@ -46,7 +46,13 @@ volatile uint32_t Clock_driver_ticks; /* * This is the value programmed into the count down timer. */ -uint32_t Clock_Decrementer_value; +static uint32_t Clock_Decrementer_value; + +/* + * This is the value by which elapsed count down timer ticks are multiplied to + * give an elapsed duration in nanoseconds, left-shifted by 32 bits + */ +static uint64_t Clock_Decrementer_reference; void clockOff(void* unused) { @@ -209,6 +215,37 @@ static uint32_t Clock_driver_nanoseconds_since_last_tick(void) return tmp * 1000; } +static uint32_t Clock_driver_nanoseconds_since_last_tick_bookE(void) +{ + uint32_t clicks; + uint64_t c; + + PPC_Get_decrementer( clicks ); + c = Clock_Decrementer_value - clicks; + + /* + * Check whether a clock tick interrupt is pending and hence that the + * decrementer's wrapped. If it has, we'll compensate by returning a time one + * tick period longer. + * + * We have to check interrupt status after reading the decrementer. If we + * don't, we may miss an interrupt and read a wrapped decrementer value + * without compensating for it + */ + if ( _read_BOOKE_TSR() & BOOKE_TSR_DIS ) + { + /* + * Re-read the decrementer: The tick interrupt may have been + * generated and the decrementer wrapped during the time since we + * last read it and the time we checked the interrupt status + */ + PPC_Get_decrementer( clicks ); + c = (Clock_Decrementer_value - clicks) + Clock_Decrementer_value; + } + + return (uint32_t)((c * Clock_Decrementer_reference) >> 32); +} + /* * Clock_initialize * @@ -223,7 +260,10 @@ rtems_device_driver Clock_initialize( rtems_interrupt_level l,tcr; Clock_Decrementer_value = (BSP_bus_frequency/BSP_time_base_divisor)* - (rtems_configuration_get_microseconds_per_tick()/1000); + rtems_configuration_get_milliseconds_per_tick(); + + Clock_Decrementer_reference = ((uint64_t)1000000U<<32)/ + (BSP_bus_frequency/BSP_time_base_divisor); /* set the decrementer now, prior to installing the handler * so no interrupts will happen in a while. @@ -244,14 +284,22 @@ rtems_device_driver Clock_initialize( rtems_interrupt_enable(l); + /* + * Set the nanoseconds since last tick handler + */ + rtems_clock_set_nanoseconds_extension( + Clock_driver_nanoseconds_since_last_tick_bookE + ); + } + else + { + /* + * Set the nanoseconds since last tick handler + */ + rtems_clock_set_nanoseconds_extension( + Clock_driver_nanoseconds_since_last_tick + ); } - - /* - * 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 |