serial: sh: Add DEBUG_UART support
Add support for debug output very early during boot using the DEBUG_UART
mechanism. This uses a static fixed UART port configuration selected via
Kconfig options and dedicated print functions from debug_uart.h. This is
useful e.g. when debugging problems so early during boot, that not even
the DM is initialized at that point, and thus DM_SERIAL is not available
either.
This functionality is disabled by default. To activate it, define the
following Kconfig options and select SCIF type using CFG_SCI/CFG_SCIF_A/
CFG_HSCIF/<nothing for regular SCIF>:
CONFIG_DEBUG_UART=y
CONFIG_DEBUG_UART_SCIF=y
CONFIG_DEBUG_UART_BASE=0xe6540000
CONFIG_DEBUG_UART_CLOCK=24000000
The later two options define the SCIF physical base address and SCIF
input clock in Hz. Optionally, to validate DEBUG_UART works, enable
the following as well to get early serial output message by default:
CONFIG_DEBUG_UART_ANNOUNCE=y
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index bb50832..10d07da 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -415,6 +415,14 @@
start up driver model. The driver will be available until the real
driver model serial is running.
+config DEBUG_UART_SCIF
+ bool "Renesas SCIF UART"
+ depends on SH || ARCH_RMOBILE
+ help
+ Select this to enable a debug UART using the serial_sh driver. You
+ will need to provide parameters to make this work. The driver will
+ be available until the real driver-model serial is running.
+
config DEBUG_UART_SIFIVE
bool "SiFive UART"
depends on SIFIVE_SERIAL