diff options
Diffstat (limited to 'c/src/lib/libcpu/powerpc/mpc8xx/clock/clock.c')
| -rw-r--r-- | c/src/lib/libcpu/powerpc/mpc8xx/clock/clock.c | 34 |
1 files changed, 29 insertions, 5 deletions
diff --git a/c/src/lib/libcpu/powerpc/mpc8xx/clock/clock.c b/c/src/lib/libcpu/powerpc/mpc8xx/clock/clock.c index 37dbc80f2c..61ae4e3ed8 100644 --- a/c/src/lib/libcpu/powerpc/mpc8xx/clock/clock.c +++ b/c/src/lib/libcpu/powerpc/mpc8xx/clock/clock.c @@ -71,15 +71,39 @@ void clockOn(void* unused) { unsigned desiredLevel; rtems_unsigned32 pit_value; + rtems_unsigned32 mf_value; + rtems_unsigned32 extclk_value; - pit_value = (rtems_configuration_get_microseconds_per_tick() * - rtems_cpu_configuration_get_clicks_per_usec()) - 1 ; + if (rtems_cpu_configuration_get_clicks_per_usec() == 0) { + /* + * oscclk is too low for PIT, compute extclk and derive PIT from there + */ + mf_value = m8xx.plprcr >> 20; + pit_value = (_CPU_Table.clock_speed + / (mf_value+1) + / 4 + * rtems_configuration_get_microseconds_per_tick() + / 1000000); + m8xx.sccr |= (1<<24); + } + else { + pit_value = (rtems_configuration_get_microseconds_per_tick() * + rtems_cpu_configuration_get_clicks_per_usec()); - if (pit_value > 0xffff) { /* pit is only 16 bits long */ + m8xx.sccr &= ~(1<<24); + } + if (pit_value > (0xffff+1)) { + /* + * try to activate prescaler + * NOTE: divider generates odd values now... + */ + pit_value = pit_value / 128; + m8xx.sccr |= (1<<25); + } + if (pit_value > (0xffff+1)) { /* pit is only 16 bits long */ rtems_fatal_error_occurred(-1); } - m8xx.sccr &= ~(1<<24); - m8xx.pitc = pit_value; + m8xx.pitc = pit_value - 1; desiredLevel = BSP_get_clock_irq_level(); /* set PIT irq level, enable PIT, PIT interrupts */ |