drivers/vpd: Add vpd_get_feature_level() API

This patch introduces the vpd_get_feature_level() API to specifically
extract the "feature_level" field from the "feature_device_info" VPD
key.

This is used to distinguish between Chromebook-Plus and regular
Chromebook devices.

The previous vpd_get_feature_device_info() API is removed as
vpd_get_feature_level() is enough to find VPD and extract the data.

Note: The new API decodes the base64-encoded "feature_device_info" VPD
data.

BUG=b:324107408
TEST=Able to build and boot google/rex0.

Change-Id: I76fc220ed792abdfefb0b1a37873b5b828bfdda8
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80805
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Dinesh Gehlot <digehlot@google.com>
Reviewed-by: Eric Lai <ericllai@google.com>

2 files changed, 33 insertions, 9 deletions

diff --git a/src/drivers/vpd/vpd.h b/src/drivers/vpd/vpd.h
index a23005fca1..a6631aab55 100644
--- a/src/drivers/vpd/vpd.h
+++ b/src/drivers/vpd/vpd.h
@@ -60,8 +60,9 @@ bool vpd_get_bool(const char *key, enum vpd_region region,
 bool vpd_get_int(const char *key, enum vpd_region region, int *val);
 
 /*
- * Return the value after reading the VPD key named "feature_device_info".
+ * Extracts the "feature_level" from the "feature_device_info" VPD key.
+ * This key holds a base64-encoded protobuf where "feature_level" is the first entry.
  */
-const char *vpd_get_feature_device_info(void);
+uint8_t vpd_get_feature_level(void);
 
 #endif  /* __VPD_H__ */
diff --git a/src/drivers/vpd/vpd_device_feature.c b/src/drivers/vpd/vpd_device_feature.c
index 1c8682ab7e..7b92756e54 100644
--- a/src/drivers/vpd/vpd_device_feature.c
+++ b/src/drivers/vpd/vpd_device_feature.c
@@ -1,15 +1,38 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <b64_decode.h>
+#include <console/console.h>
 #include <drivers/vpd/vpd.h>
+#include <stdlib.h>
 
 #define VPD_KEY_FEATURE_DEVICE_INFO	"feature_device_info"
-#define VPD_FEATURE_DEVICE_INFO_LEN	64
 
-const char *vpd_get_feature_device_info(void)
+/*
+ * Extracts the "feature_level" from the "feature_device_info" VPD key.
+ * This key holds a base64-encoded protobuf where "feature_level" is the first entry.
+ */
+uint8_t vpd_get_feature_level(void)
 {
-	static char device_info[VPD_FEATURE_DEVICE_INFO_LEN];
-	if (vpd_gets(VPD_KEY_FEATURE_DEVICE_INFO, device_info, VPD_FEATURE_DEVICE_INFO_LEN,
-			 VPD_RW))
-		return device_info;
-	return "";
+	const uint8_t *device_info;
+	int device_info_size, feature_level = 0;
+	uint8_t *decoded_device_info;
+	size_t decoded_size;
+
+	device_info = vpd_find(VPD_KEY_FEATURE_DEVICE_INFO, &device_info_size, VPD_RW);
+	if (!device_info)
+		return feature_level;
+
+	decoded_size = B64_DECODED_SIZE(device_info_size);
+	decoded_device_info = malloc(decoded_size);
+	if (!decoded_device_info) {
+		printk(BIOS_ERR, "%s: failed allocating %zd bytes\n", __func__, decoded_size);
+		return feature_level;
+	}
+
+	/* The index 1 of the decoded data is the "feature level" value */
+	if (b64_decode(device_info, device_info_size, decoded_device_info))
+		feature_level = decoded_device_info[1];
+
+	free(decoded_device_info);
+	return feature_level;
 }