[PATCH][V2] firmware: dmi_scan: add DMI_OEM_STRING support to dmi_matches

[Alex Hung <alex.hung@canonical.com>]

OEM strings are defined by each OEM and they contain customized and
useful OEM information. Supporting it provides more flexible uses of
the dmi_matches function.

Signed-off-by: Alex Hung <alex.hung@canonical.com>
---
 drivers/firmware/dmi_scan.c     | 11 +++++++++--
 include/linux/mod_devicetable.h |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index e763e14..c712e66 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -775,7 +775,15 @@ static bool dmi_matches(const struct dmi_system_id *dmi)
 		int s = dmi->matches[i].slot;
 		if (s == DMI_NONE)
 			break;
-		if (dmi_ident[s]) {
+		if (s == DMI_OEM_STRING) {
+			/* DMI_OEM_STRING must be exact match */
+			const struct dmi_device *valid;
+
+			valid = dmi_find_device(DMI_DEV_TYPE_OEM_STRING,
+						dmi->matches[i].substr, NULL);
+			if (valid)
+				continue;
+		} else if (dmi_ident[s]) {
 			if (dmi->matches[i].exact_match) {
 				if (!strcmp(dmi_ident[s],
 					    dmi->matches[i].substr))
@@ -786,7 +794,6 @@ static bool dmi_matches(const struct dmi_system_id *dmi)
 					continue;
 			}
 		}
-
 		/* No match */
 		return false;
 	}
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 48fb2b4..7d361be 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -502,6 +502,7 @@ enum dmi_field {
 	DMI_CHASSIS_SERIAL,
 	DMI_CHASSIS_ASSET_TAG,
 	DMI_STRING_MAX,
+	DMI_OEM_STRING,	/* special case - will not be in dmi_ident */
 };
 
 struct dmi_strmatch {
-- 
2.7.4