serial: zynqmp: Fetch baudrate from dtb and update
The baudrate configured in .config is taken by default by serial. If
change of baudrate is required then the .config needs to changed and
u-boot recompilation is required or the u-boot environment needs to be
updated.
To avoid this, support is added to fetch the baudrate directly from the
device tree file and update.
The serial, prints the log with the configured baudrate in the dtb.
The commit c4df0f6f315c ("arm: mvebu: Espressobin: Set default value for
$fdtfile env variable") is taken as reference for changing the default
environment variable.
The default environment stores the default baudrate value, When default
baudrate and dtb baudrate are not same glitches are seen on the serial.
So, the environment also needs to be updated with the dtb baudrate to
avoid the glitches on the serial.
Also add test to cover this new function.
Signed-off-by: Algapally Santosh Sagar <santoshsagar.algapally@amd.com>
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Link: https://lore.kernel.org/r/20230921112043.3144726-3-venkatesh.abbarapu@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 8761a64..6628a88 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -24,6 +24,15 @@
in the SPL stage (most drivers) or for choosing a default baudrate
in the absence of an environment setting (serial_mxc.c).
+config OF_SERIAL_BAUD
+ bool "Fetch serial baudrate from device tree"
+ depends on DM_SERIAL && SPL_ENV_SUPPORT
+ select DEFAULT_ENV_IS_RW
+ help
+ Select this to enable fetching and setting of the baudrate
+ configured in the DT. Replace the default baudrate with the DT
+ baudrate and also set it to the environment.
+
config DEFAULT_ENV_IS_RW
bool "Make default environment as writable"
help