Change in coreboot[master]: drivers/intel/fsp2_0: Allow coreboot to control FSP serial redirection

[Subrata Banik (Code Review)]

Subrata Banik has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/63166 )

Change subject: drivers/intel/fsp2_0: Allow coreboot to control FSP serial redirection
......................................................................

drivers/intel/fsp2_0: Allow coreboot to control FSP serial redirection

coreboot has implemented native FSP debug handler with commit hash
3ba6f8cdf (drivers/intel/fsp2_0: Add native implementation for FSP
Debug Handler).
However,  coreboot still can't control when to redirect FSP debug
output to the serial console, i.e., at present, integrating a FSP debug
binary is enough to redirect FSP debug output to serial port,
irrespective of whether coreboot user really wish to see FSP debug log
with all the coreboot serial image.

coreboot needs additional mechanism to control FSP debug binary to
redirect debug messages over serial port. This patch introduces an
config `HAVE_FSP_DEBUG` to control the FSP debug output, user to select
this config from site-local config file incase like to override the
default settings.

There could be scenarios as below:

Scenario 1: Non-serial coreboot image integrated with the FSP debug
binaries, is capable of redirecting to the serial console, but coreboot
decides to override the config as below to skip FSP debug output
redirection to the serial port.

`#`FSP Serial console disabled by default (do not remove)
     `#`CONFIG_HAVE_FSP_DEBUG is not set

Scenario 2: For coreboot serial image with FSP debug binaries integrated
but coreboot decides to skip FSP debug output redirection to the serial
port.

`#`FSP Serial console disabled by default (do not remove)
     `#`CONFIG_HAVE_FSP_DEBUG is not set
        CONFIG_CONSOLE_SERIAL=y
        CONFIG_CONSOLE_SERIAL_115200=y
        CONFIG_UART_DEBUG=y
        CONFIG_UART_FOR_CONSOLE=0

Scenario 3: The final image could be a coreboot serial image with FSP
serial redirection enabled to output to the serial port.

CONFIG_HAVE_FSP_DEBUG=y
        CONFIG_CONSOLE_SERIAL=y
        CONFIG_CONSOLE_SERIAL_115200=y
        CONFIG_UART_DEBUG=y
        CONFIG_UART_FOR_CONSOLE=0

BUG=b:227151510
TEST=Able to build and boot Redrix with all scenarios between #1- #3,
and able to meet the expectation as mentioned above.

Signed-off-by: Subrata Banik 
Change-Id: I0b008ca9d4f40bfa6a989a6fd655c234f91fde65
---
M src/drivers/intel/fsp2_0/Kconfig
1 file changed, 12 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/66/63166/1

diff --git a/src/drivers/intel/fsp2_0/Kconfig b/src/drivers/intel/fsp2_0/Kconfig
index 0823aa3..45467f8 100644
--- a/src/drivers/intel/fsp2_0/Kconfig
+++ b/src/drivers/intel/fsp2_0/Kconfig
@@ -359,4 +359,16 @@
      This option allows to create `Debug Event Handler` to print FSP debug messages
      to output device using coreboot native implementation.

+config HAVE_FSP_DEBUG
+	bool "Have FSP debug binaries to get the console output"
+	default y
+	depends on FSP_USES_CB_DEBUG_EVENT_HANDLER
+	help
+	  Send FSP debug output to the serial port.
+
+	  The config option is selected based on your FSP configuration i.e., debug or
+	  release. Select this option from site-local to print FSP serial messages using
+	  coreboot native serial debug driver when coreboot has integrated the debug FSP
+	  binaries.
+
 endif