[PATCH v1 33/54] efi: loader: protocol: add device_path_utilities
Ahmad Fatoum
a.fatoum at pengutronix.de
Thu Dec 18 02:37:53 PST 2025
This protocol doesn't do much in barebox, but enough to be able to
execute the UEFI shell.
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
efi/loader/protocols/Kconfig | 7 +
efi/loader/protocols/Makefile | 1 +
efi/loader/protocols/device_path_utilities.c | 210 +++++++++++++++++++
include/efi/protocol/devicepath.h | 31 +++
4 files changed, 249 insertions(+)
create mode 100644 efi/loader/protocols/device_path_utilities.c
create mode 100644 include/efi/protocol/devicepath.h
diff --git a/efi/loader/protocols/Kconfig b/efi/loader/protocols/Kconfig
index 7d5e203d121a..3405de1acdfb 100644
--- a/efi/loader/protocols/Kconfig
+++ b/efi/loader/protocols/Kconfig
@@ -39,4 +39,11 @@ config EFI_LOADER_RNG
Provide a EFI_RNG_PROTOCOL implementation using the hardware random
number generator of the platform.
+config EFI_LOADER_DEVICE_PATH_UTIL
+ bool "Device path utilities protocol"
+ default y
+ help
+ The device path utilities protocol creates and manipulates device
+ paths and device nodes. It is required to run the EFI Shell.
+
endmenu
diff --git a/efi/loader/protocols/Makefile b/efi/loader/protocols/Makefile
index ecc0fc392856..b5ec5cf5dd46 100644
--- a/efi/loader/protocols/Makefile
+++ b/efi/loader/protocols/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_CONSOLE_FULL) += console.o
obj-$(CONFIG_EFI_LOADER_HII) += hii.o hii_config.o
obj-$(CONFIG_EFI_LOADER_UNICODE_COLLATION_PROTOCOL2) += unicode_collation.o
obj-$(CONFIG_EFI_LOADER_RNG) += rng.o
+obj-$(CONFIG_EFI_LOADER_DEVICE_PATH_UTIL) += device_path_utilities.o
diff --git a/efi/loader/protocols/device_path_utilities.c b/efi/loader/protocols/device_path_utilities.c
new file mode 100644
index 000000000000..ef88e2d647fb
--- /dev/null
+++ b/efi/loader/protocols/device_path_utilities.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * EFI device path interface
+ *
+ * Copyright (c) 2017 Leif Lindholm
+ */
+
+#include <efi/loader.h>
+#include <efi/devicepath.h>
+#include <efi/loader/devicepath.h>
+#include <efi/protocol/devicepath.h>
+#include <efi/loader/trace.h>
+#include <efi/loader/object.h>
+#include <efi/guid.h>
+#include <init.h>
+
+/*
+ * Get size of a device path.
+ *
+ * This function implements the GetDevicePathSize service of the device path
+ * utilities protocol. The device path length includes the end of path tag
+ * which may be an instance end.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @device_path device path
+ * Return: size in bytes
+ */
+static efi_uintn_t EFIAPI get_device_path_size(
+ const struct efi_device_path *device_path)
+{
+ efi_uintn_t sz = 0;
+
+ EFI_ENTRY("%pD", device_path);
+ /* size includes the END node: */
+ if (device_path)
+ sz = efi_dp_size(device_path) + sizeof(struct efi_device_path);
+ return EFI_EXIT(sz);
+}
+
+/*
+ * Duplicate a device path.
+ *
+ * This function implements the DuplicateDevicePath service of the device path
+ * utilities protocol.
+ *
+ * The UEFI spec does not indicate what happens to the end tag. We follow the
+ * EDK2 logic: In case the device path ends with an end of instance tag, the
+ * copy will also end with an end of instance tag.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @device_path device path
+ * Return: copy of the device path
+ */
+static struct efi_device_path * EFIAPI duplicate_device_path(
+ const struct efi_device_path *device_path)
+{
+ EFI_ENTRY("%pD", device_path);
+ return EFI_EXIT(efi_dp_dup(device_path));
+}
+
+/*
+ * Append device path.
+ *
+ * This function implements the AppendDevicePath service of the device path
+ * utilities protocol.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @src1 1st device path
+ * @src2 2nd device path
+ * Return: concatenated device path
+ */
+static struct efi_device_path * EFIAPI append_device_path(
+ const struct efi_device_path *src1,
+ const struct efi_device_path *src2)
+{
+ EFI_ENTRY("%pD, %pD", src1, src2);
+ return EFI_EXIT(efi_dp_concat(src1, src2, 0));
+}
+
+/*
+ * Append device path node.
+ *
+ * This function implements the AppendDeviceNode service of the device path
+ * utilities protocol.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @device_path device path
+ * @device_node device node
+ * Return: concatenated device path
+ */
+static struct efi_device_path * EFIAPI append_device_node(
+ const struct efi_device_path *device_path,
+ const struct efi_device_path *device_node)
+{
+ EFI_ENTRY("%pD, %p", device_path, device_node);
+ return EFI_EXIT(efi_dp_append_node(device_path, device_node));
+}
+
+/*
+ * Append device path instance.
+ *
+ * This function implements the AppendDevicePathInstance service of the device
+ * path utilities protocol.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @device_path 1st device path
+ * @device_path_instance 2nd device path
+ * Return: concatenated device path
+ */
+static struct efi_device_path * EFIAPI append_device_path_instance(
+ const struct efi_device_path *device_path,
+ const struct efi_device_path *device_path_instance)
+{
+ EFI_ENTRY("%pD, %pD", device_path, device_path_instance);
+ return EFI_EXIT(efi_dp_append_instance(device_path,
+ device_path_instance));
+}
+
+/*
+ * Get next device path instance.
+ *
+ * This function implements the GetNextDevicePathInstance service of the device
+ * path utilities protocol.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @device_path_instance next device path instance
+ * @device_path_instance_size size of the device path instance
+ * Return: concatenated device path
+ */
+static struct efi_device_path * EFIAPI get_next_device_path_instance(
+ struct efi_device_path **device_path_instance,
+ efi_uintn_t *device_path_instance_size)
+{
+ EFI_ENTRY("%pD, %p", device_path_instance, device_path_instance_size);
+ return EFI_EXIT(efi_dp_get_next_instance(device_path_instance,
+ device_path_instance_size));
+}
+
+/*
+ * Check if a device path contains more than one instance.
+ *
+ * This function implements the AppendDeviceNode service of the device path
+ * utilities protocol.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @device_path device path
+ * @device_node device node
+ * Return: concatenated device path
+ */
+static bool EFIAPI is_device_path_multi_instance(
+ const struct efi_device_path *device_path)
+{
+ EFI_ENTRY("%pD", device_path);
+ return EFI_EXIT(efi_dp_is_multi_instance(device_path));
+}
+
+/*
+ * Create device node.
+ *
+ * This function implements the CreateDeviceNode service of the device path
+ * utilities protocol.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification
+ * for details.
+ *
+ * @node_type node type
+ * @node_sub_type node sub type
+ * @node_length node length
+ * Return: device path node
+ */
+static struct efi_device_path * EFIAPI create_device_node(
+ uint8_t node_type, uint8_t node_sub_type, uint16_t node_length)
+{
+ EFI_ENTRY("%u, %u, %u", node_type, node_sub_type, node_length);
+ return EFI_EXIT(efi_dp_create_device_node(node_type, node_sub_type,
+ node_length));
+}
+
+static const struct efi_device_path_utilities_protocol efi_device_path_utilities = {
+ .get_device_path_size = get_device_path_size,
+ .duplicate_device_path = duplicate_device_path,
+ .append_device_path = append_device_path,
+ .append_device_node = append_device_node,
+ .append_device_path_instance = append_device_path_instance,
+ .get_next_device_path_instance = get_next_device_path_instance,
+ .is_device_path_multi_instance = is_device_path_multi_instance,
+ .create_device_node = create_device_node,
+};
+
+static int efi_device_path_utilities_init(void)
+{
+ efi_add_root_node_protocol_deferred(&efi_device_path_utilities_protocol_guid,
+ &efi_device_path_utilities);
+ return 0;
+}
+postcore_initcall(efi_device_path_utilities_init);
diff --git a/include/efi/protocol/devicepath.h b/include/efi/protocol/devicepath.h
new file mode 100644
index 000000000000..19a35888f9cc
--- /dev/null
+++ b/include/efi/protocol/devicepath.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __EFI_PROTOCOL_DEVICE_PATH_H
+#define __EFI_PROTOCOL_DEVICE_PATH_H
+
+#include <efi/types.h>
+
+struct efi_device_path_utilities_protocol {
+ size_t (EFIAPI *get_device_path_size)(
+ const struct efi_device_path *device_path);
+ struct efi_device_path *(EFIAPI *duplicate_device_path)(
+ const struct efi_device_path *device_path);
+ struct efi_device_path *(EFIAPI *append_device_path)(
+ const struct efi_device_path *src1,
+ const struct efi_device_path *src2);
+ struct efi_device_path *(EFIAPI *append_device_node)(
+ const struct efi_device_path *device_path,
+ const struct efi_device_path *device_node);
+ struct efi_device_path *(EFIAPI *append_device_path_instance)(
+ const struct efi_device_path *device_path,
+ const struct efi_device_path *device_path_instance);
+ struct efi_device_path *(EFIAPI *get_next_device_path_instance)(
+ struct efi_device_path **device_path_instance,
+ size_t *device_path_instance_size);
+ bool (EFIAPI *is_device_path_multi_instance)(
+ const struct efi_device_path *device_path);
+ struct efi_device_path *(EFIAPI *create_device_node)(
+ uint8_t node_type,
+ uint8_t node_sub_type,
+ uint16_t node_length);
+};
+#endif
--
2.47.3
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