drivers/efi: Derive ESRT version from LOCALVERSION

fwupd shows the ESRT (UEFI System Resource Table) version as 0 when
DRIVERS_EFI_MAIN_FW_VERSION is left at the default. That makes it easy
to ship firmware with no meaningful ESRT version and forces maintainers
to duplicate versioning in multiple places.

If DRIVERS_EFI_MAIN_FW_VERSION is 0, parse a leading "<major>.<minor>"
from LOCALVERSION (ignoring non-digits before/after) and encode it as
(major << 16) | minor (e.g. "v26.01-rc1" -> 0x001A0001).

If DRIVERS_EFI_MAIN_FW_LSV is 0, default it to the effective firmware
version. This provides a sane, more secure default (prevents accidental
rollback to older versions) while still allowing platforms to override
LSV explicitly when rollback is desired.

Test=boot adl/horizon and check `fwupdmgr get-devices` shows a
version:
    ├─System Firmware:
    │     Device ID:          f48f261c7fc0724729b817bfd4e8340e3195a6bc
    │     Current version:    26.3


Change-Id: I3f47ee7a38e79312532f4ed5d4516c57911f727e
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90861
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/drivers/efi/Kconfig

@@ -29,6 +29,15 @@ config DRIVERS_EFI_MAIN_FW_VERSION
 	help
 	  32-bit unsigned integer representing current firmware's version.
 
+	  If set to 0, coreboot will try to derive a version from LOCALVERSION by
+	  parsing a leading "<major>.<minor>" and encoding it as
+	  (major << 16) | minor.
+
+	  Non-digits before and after "<major>.<minor>" are ignored.
+	  Examples:
+	  - "26.01" -> 0x001A0001
+	  - "v26.01-rc1" -> 0x001A0001
+
 config DRIVERS_EFI_MAIN_FW_LSV
 	hex "Lowest supported firmware version"
 	range 0x00000000 0xFFFFFFFF
@@ -39,6 +48,8 @@ config DRIVERS_EFI_MAIN_FW_LSV
 	  that is allowed to replace the current one.  Can be used to forbid
 	  bugged versions.
 
+	  If set to 0, coreboot uses DRIVERS_EFI_MAIN_FW_VERSION.
+
 config DRIVERS_EFI_UPDATE_CAPSULES
 	bool "Include EFI update capsules driver"
 	depends on DRIVERS_EFI_VARIABLE_STORE && SMMSTORE_V2 && DRIVERS_EFI_FW_INFO

src/drivers/efi/info.c

@@ -6,10 +6,42 @@
 #include <string.h>
 #include <uuid.h>
 
+static uint32_t efi_fw_version_from_localversion(void)
+{
+	const char *localversion = CONFIG_LOCALVERSION;
+	uint32_t major = 0;
+	uint32_t minor = 0;
+	const char *p = localversion;
+
+	while (*p != '\0' && (*p < '0' || *p > '9'))
+		p++;
+
+	while (*p >= '0' && *p <= '9') {
+		major = major * 10 + (*p - '0');
+		p++;
+	}
+
+	if (*p != '.')
+		return 0;
+	p++;
+
+	while (*p >= '0' && *p <= '9') {
+		minor = minor * 10 + (*p - '0');
+		p++;
+	}
+
+	if (major > 0xffff || minor > 0xffff)
+		return 0;
+
+	return (major << 16) | minor;
+}
+
 void lb_efi_fw_info(struct lb_header *header)
 {
 	uint8_t guid[16];
 	struct lb_efi_fw_info *fw_info;
+	uint32_t fw_version;
+	uint32_t lsv;
 
 	if (parse_uuid(guid, CONFIG_DRIVERS_EFI_MAIN_FW_GUID)) {
 		printk(BIOS_ERR, "%s(): failed to parse firmware's GUID: '%s'\n", __func__,
@@ -22,7 +54,21 @@ void lb_efi_fw_info(struct lb_header *header)
 	fw_info->size = sizeof(*fw_info);
 
 	memcpy(fw_info->guid, guid, sizeof(guid));
-	fw_info->version = CONFIG_DRIVERS_EFI_MAIN_FW_VERSION;
-	fw_info->lowest_supported_version = CONFIG_DRIVERS_EFI_MAIN_FW_LSV;
+
+	fw_version = CONFIG_DRIVERS_EFI_MAIN_FW_VERSION;
+	if (fw_version == 0) {
+		fw_version = efi_fw_version_from_localversion();
+		if (fw_version != 0)
+			printk(BIOS_DEBUG,
+			       "EFI FW version derived from CONFIG_LOCALVERSION '%s': 0x%08x\n",
+			       CONFIG_LOCALVERSION, fw_version);
+	}
+
+	lsv = CONFIG_DRIVERS_EFI_MAIN_FW_LSV;
+	if (lsv == 0)
+		lsv = fw_version;
+
+	fw_info->version = fw_version;
+	fw_info->lowest_supported_version = lsv;
 	fw_info->fw_size = CONFIG_ROM_SIZE;
 }