Instead of hard-coding the peripheral clocks to CLOCK_CORECLOCK
introduce helper functions to return the frequency of the individual
GCLKs and use those for baud-rate calculations.
This requires the GCLK to be part of the peripheral's config struct.
While this is already the case for most peripherals, this also adds
it for those where it wasn't used before.
As it defaults to 0 (CLOCK_CORECLOCK) no change is to be expected.
There are some constraints to the oscillators on the samd5x.
- DFLL is fixed to run at 48 MHz
- DPLL can run at 96 to 200 MHz
Always use DFLL for frequencies <= 48 MHz.
For frequencies >= 96 MHz, use DPLL directly.
For frequencies < 96 MHz, clock DPLL at twice the desired frequency
and use a divider.
- Removed stdio_init() from newlib's _init(), as this is too late in the boot
process to allow DEBUG()ing during periph_init()
- Added stdio_init() to the various cpu_init() routines of the ARM CPUs just
before periph_init()
There were still some things wrong with samd5x CPU init which only
showed up when used in conjunction with RIOTBOOT, that is cpu_init()
was called twice.
- gclk_connect() should block until the GCLK is ready.
- DPLL should be disabled dring configuration.
- make sure not to use DPLL for MCLK when re-configuring DPLL
- All APBxMASK bits should be in a defined state.
- always enable 1kHz oscilator output.
This adds supoprt for the Atmel SAMD51 & SAME54 SoC.
The SAME5x/SAMD5x is a line of Cortex-M4F MCUs that share peripherals
with the samd2x Cortex-M0+ and saml1x Cortex-M23 parts.
