Ambiq UART requires specific busy wait during initialization for
propagating powering control registers, original k_busy_wait()
used here generated a dead loop because k_busy_wait() relays on
timer, who's driver is initialized after UART(UART init in
PRE_KERNEL_1, timer init in PRE_KERNEL_2), replace k_busy_wait()
with checking power status register is more suitable here.
Signed-off-by: Bryan Zhu <bzhu@ambiq.com>
UART controller present in Ambiq SoCs is mostly compatible with PL011, but
requires some quirks that are implemented in this commit:
- the peripheral needs to be powered on first, via the PWRCTRL core,
- peripheral clock needs to be enabled and configured via the CLKEN/CLKSEL.
registers.
The quirks mechanism was inspired by support for STM32F4 SoC in the
usb_dc_dw driver (fce0b85eca).
Co-authored-by: Mateusz Sierszulski <msierszulski@antmicro.com>
Signed-off-by: Maciej Sobkowski <msobkowski@antmicro.com>
Signed-off-by: Mateusz Sierszulski <msierszulski@antmicro.com>
