Kconfig
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config DM_SERIAL
bool "Enable Driver Model for serial drivers"
depends on DM
help
Enable driver model for serial. This replaces
drivers/serial/serial.c with the serial uclass, which
implements serial_putc() etc. The uclass interface is
defined in include/serial.h.
config DEBUG_UART
bool "Enable an early debug UART for debugging"
help
The debug UART is intended for use very early in U-Boot to debug
problems when an ICE or other debug mechanism is not available.
To use it you should:
- Make sure your UART supports this interface
- Enable CONFIG_DEBUG_UART
- Enable the CONFIG for your UART to tell it to provide this interface
(e.g. CONFIG_DEBUG_UART_NS16550)
- Define the required settings as needed (see below)
- Call debug_uart_init() before use
- Call debug_uart_putc() to output a character
Depending on your platform it may be possible to use this UART before
a stack is available.
If your UART does not support this interface you can probably add
support quite easily. Remember that you cannot use driver model and
it is preferred to use no stack.
You must not use this UART once driver model is working and the
serial drivers are up and running (done in serial_init()). Otherwise
the drivers may conflict and you will get strange output.
choice
prompt "Select which UART will provide the debug UART"
depends on DEBUG_UART
config DEBUG_UART_NS16550
bool "ns16550"
help
Select this to enable a debug UART using the ns16550 driver. You
will need to provide parameters to make this work. The driver will
be available until the real driver model serial is running.
endchoice
config DEBUG_UART_BASE
hex "Base address of UART"
depends on DEBUG_UART
help
This is the base address of your UART for memory-mapped UARTs.
A default should be provided by your board, but if not you will need
to use the correct value here.
config DEBUG_UART_CLOCK
int "UART input clock"
depends on DEBUG_UART
help
The UART input clock determines the speed of the internal UART
circuitry. The baud rate is derived from this by dividing the input
clock down.
A default should be provided by your board, but if not you will need
to use the correct value here.
config UNIPHIER_SERIAL
bool "UniPhier on-chip UART support"
depends on ARCH_UNIPHIER && DM_SERIAL
help
Support for the on-chip UARTs on the Panasonic UniPhier platform.