[S] Change in coreboot[main]: drivers/option: Add CBFS file based option backend

[Nicholas Chin (Code Review)]

Nicholas Chin has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/85905?usp=email )

Change subject: drivers/option: Add CBFS file based option backend
......................................................................

drivers/option: Add CBFS file based option backend

Add a new option backend that uses values stored in CBFS files, similar
to the SeaBIOS runtime config options stored in files with the etc/
prefix. Values can be set using `cbfstool coreboot.rom add-int -i value
-n option_name`.

Change-Id: Ifc0439ee42f13f49ae54d4855d1d9333c39b01f5
Signed-off-by: Nicholas Chin 
---
M src/Kconfig
M src/drivers/option/Makefile.mk
A src/drivers/option/cbfs_file_option.c
3 files changed, 33 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/05/85905/1

diff --git a/src/Kconfig b/src/Kconfig
index 55fad95..0a0643e 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -164,6 +164,12 @@
      Enable this option if coreboot shall read options from the "CMOS"
      NVRAM instead of using hard-coded values.

+config USE_CBFS_FILE_OPTION_BACKEND
+	bool "Use CBFS files for configuration values"
+	help
+	  Enable this option if coreboot shall read options from files in CBFS.
+	  Options can be set using `cbfstool add-int -n option-name -i value`.
+
 config USE_UEFI_VARIABLE_STORE
    bool "Use UEFI variable-store in SPI flash as option backend"
    depends on DRIVERS_EFI_VARIABLE_STORE
diff --git a/src/drivers/option/Makefile.mk b/src/drivers/option/Makefile.mk
index 7ca439d..1d1c05e 100644
--- a/src/drivers/option/Makefile.mk
+++ b/src/drivers/option/Makefile.mk
@@ -1,3 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only

ramstage-$(CONFIG_DRIVERS_OPTION_CFR) += cfr.c
+
+all-$(CONFIG_USE_CBFS_FILE_OPTION_BACKEND) += cbfs_file_option.c
+smm-$(CONFIG_USE_CBFS_FILE_OPTION_BACKEND) += cbfs_file_option.c
diff --git a/src/drivers/option/cbfs_file_option.c b/src/drivers/option/cbfs_file_option.c
new file mode 100644
index 0000000..7f7ade7
--- /dev/null
+++ b/src/drivers/option/cbfs_file_option.c
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <cbfs.h>
+#include <console/console.h>
+#include <option.h>
+
+unsigned int get_uint_option(const char *name, const unsigned int fallback)
+{
+	unsigned int value;
+	size_t size;
+	unsigned int *p = cbfs_map(name, &size);
+	if (!p || size < sizeof(value)) {
+		value = fallback;
+	} else {
+		value = *p;
+		cbfs_unmap(p);
+	}
+	return value;
+}
+
+enum cb_err set_uint_option(const char *name, unsigned int value)
+{
+	return CB_ERR_NOT_IMPLEMENTED;
+}