1 files changed, 98 insertions, 0 deletions
diff --git a/roms/u-boot/lib/efi_loader/efi_helper.c b/roms/u-boot/lib/efi_loader/efi_helper.c
new file mode 100644
index 000000000..d03a73646
--- /dev/null
+++ b/roms/u-boot/lib/efi_loader/efi_helper.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2020, Linaro Limited
+ */
+
+#define LOG_CATEGORY LOGC_EFI
+#include <common.h>
+#include <env.h>
+#include <malloc.h>
+#include <dm.h>
+#include <fs.h>
+#include <efi_load_initrd.h>
+#include <efi_loader.h>
+#include <efi_variable.h>
+
+/**
+ * efi_create_current_boot_var() - Return Boot#### name were #### is replaced by
+ *			           the value of BootCurrent
+ *
+ * @var_name:		variable name
+ * @var_name_size:	size of var_name
+ *
+ * Return:	Status code
+ */
+static efi_status_t efi_create_current_boot_var(u16 var_name[],
+						size_t var_name_size)
+{
+	efi_uintn_t boot_current_size;
+	efi_status_t ret;
+	u16 boot_current;
+	u16 *pos;
+
+	boot_current_size = sizeof(boot_current);
+	ret = efi_get_variable_int(L"BootCurrent",
+				   &efi_global_variable_guid, NULL,
+				   &boot_current_size, &boot_current, NULL);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	pos = efi_create_indexed_name(var_name, var_name_size, "Boot",
+				      boot_current);
+	if (!pos) {
+		ret = EFI_OUT_OF_RESOURCES;
+		goto out;
+	}
+
+out:
+	return ret;
+}
+
+/**
+ * efi_get_dp_from_boot() - Retrieve and return a device path from an EFI
+ *			    Boot### variable.
+ *			    A boot option may contain an array of device paths.
+ *			    We use a VenMedia() with a specific GUID to identify
+ *			    the usage of the array members. This function is
+ *			    used to extract a specific device path
+ *
+ * @guid:	vendor GUID of the VenMedia() device path node identifying the
+ *		device path
+ *
+ * Return:	device path or NULL. Caller must free the returned value
+ */
+struct efi_device_path *efi_get_dp_from_boot(const efi_guid_t guid)
+{
+	struct efi_device_path *file_path = NULL;
+	struct efi_device_path *tmp = NULL;
+	struct efi_load_option lo;
+	void *var_value = NULL;
+	efi_uintn_t size;
+	efi_status_t ret;
+	u16 var_name[16];
+
+	ret = efi_create_current_boot_var(var_name, sizeof(var_name));
+	if (ret != EFI_SUCCESS)
+		return NULL;
+
+	var_value = efi_get_var(var_name, &efi_global_variable_guid, &size);
+	if (!var_value)
+		return NULL;
+
+	ret = efi_deserialize_load_option(&lo, var_value, &size);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	tmp = efi_dp_from_lo(&lo, &size, guid);
+	if (!tmp)
+		goto out;
+
+	/* efi_dp_dup will just return NULL if efi_dp_next is NULL */
+	file_path = efi_dp_dup(efi_dp_next(tmp));
+
+out:
+	efi_free_pool(tmp);
+	free(var_value);
+
+	return file_path;
+}