drivers/generic/cbfs-serial: Add driver to read serial from CBFS

Add a new driver to support reading a board serial number from
a text file in CBFS and injecting into the SMBIOS tables.
Allow driver to be selected at the .config level and not require
inclusion at the board level.

Signed-off-by: Matt DeVillier <matt.devillier@puri.sm>
Change-Id: Ieae39f39ab36e5b1f240383b7cf47681d9a311af
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37917
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>

3 files changed, 57 insertions, 0 deletions

diff --git a/src/drivers/generic/cbfs-serial/Kconfig b/src/drivers/generic/cbfs-serial/Kconfig
new file mode 100644
index 000000000000..209c242dbaec
--- /dev/null
+++ b/src/drivers/generic/cbfs-serial/Kconfig
@@ -0,0 +1,6 @@
+config DRIVERS_GENERIC_CBFS_SERIAL
+	bool "Serial number in CBFS"
+	default n
+	help
+	  Enable this option to read the board serial number from a
+	  text file located in CBFS.
diff --git a/src/drivers/generic/cbfs-serial/Makefile.inc b/src/drivers/generic/cbfs-serial/Makefile.inc
new file mode 100644
index 000000000000..163d439ba909
--- /dev/null
+++ b/src/drivers/generic/cbfs-serial/Makefile.inc
@@ -0,0 +1 @@
+ramstage-$(CONFIG_DRIVERS_GENERIC_CBFS_SERIAL) += cbfs-serial.c
diff --git a/src/drivers/generic/cbfs-serial/cbfs-serial.c b/src/drivers/generic/cbfs-serial/cbfs-serial.c
new file mode 100644
index 000000000000..ee3e36620c0c
--- /dev/null
+++ b/src/drivers/generic/cbfs-serial/cbfs-serial.c
@@ -0,0 +1,50 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <cbfs.h>
+#include <device/device.h>
+#include <smbios.h>
+#include <string.h>
+
+
+#define MAX_SERIAL_LENGTH 0x100
+
+const char *smbios_mainboard_serial_number(void)
+{
+	static char serial_number[MAX_SERIAL_LENGTH + 1] = {0};
+	struct cbfsf file;
+
+	if (serial_number[0] != 0)
+		return serial_number;
+
+	if (cbfs_boot_locate(&file, "serial_number", NULL) == 0) {
+		struct region_device cbfs_region;
+		size_t serial_len;
+
+		cbfs_file_data(&cbfs_region, &file);
+
+		serial_len = region_device_sz(&cbfs_region);
+		if (serial_len <= MAX_SERIAL_LENGTH) {
+			if (rdev_readat(&cbfs_region, serial_number, 0,
+					serial_len) == serial_len) {
+				serial_number[serial_len] = 0;
+				return serial_number;
+			}
+		}
+	}
+
+	strncpy(serial_number, CONFIG_MAINBOARD_SERIAL_NUMBER,
+			MAX_SERIAL_LENGTH);
+
+	return serial_number;
+}