1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  EFI device path interface
4  *
5  *  Copyright (c) 2017 Leif Lindholm
6  */
7 
8 #include <common.h>
9 #include <efi_loader.h>
10 
11 const efi_guid_t efi_guid_device_path_utilities_protocol =
12 		EFI_DEVICE_PATH_UTILITIES_PROTOCOL_GUID;
13 
14 /*
15  * Get size of a device path.
16  *
17  * This function implements the GetDevicePathSize service of the device path
18  * utilities protocol. The device path length includes the end of path tag
19  * which may be an instance end.
20  *
21  * See the Unified Extensible Firmware Interface (UEFI) specification
22  * for details.
23  *
24  * @device_path		device path
25  * @return		size in bytes
26  */
27 static efi_uintn_t EFIAPI get_device_path_size(
28 	const struct efi_device_path *device_path)
29 {
30 	efi_uintn_t sz = 0;
31 
32 	EFI_ENTRY("%pD", device_path);
33 	/* size includes the END node: */
34 	if (device_path)
35 		sz = efi_dp_size(device_path) + sizeof(struct efi_device_path);
36 	return EFI_EXIT(sz);
37 }
38 
39 /*
40  * Duplicate a device path.
41  *
42  * This function implements the DuplicateDevicePath service of the device path
43  * utilities protocol.
44  *
45  * The UEFI spec does not indicate what happens to the end tag. We follow the
46  * EDK2 logic: In case the device path ends with an end of instance tag, the
47  * copy will also end with an end of instance tag.
48  *
49  * See the Unified Extensible Firmware Interface (UEFI) specification
50  * for details.
51  *
52  * @device_path		device path
53  * @return		copy of the device path
54  */
55 static struct efi_device_path * EFIAPI duplicate_device_path(
56 	const struct efi_device_path *device_path)
57 {
58 	EFI_ENTRY("%pD", device_path);
59 	return EFI_EXIT(efi_dp_dup(device_path));
60 }
61 
62 /*
63  * Append device path.
64  *
65  * This function implements the AppendDevicePath service of the device path
66  * utilities protocol.
67  *
68  * See the Unified Extensible Firmware Interface (UEFI) specification
69  * for details.
70  *
71  * @src1		1st device path
72  * @src2		2nd device path
73  * @return		concatenated device path
74  */
75 static struct efi_device_path * EFIAPI append_device_path(
76 	const struct efi_device_path *src1,
77 	const struct efi_device_path *src2)
78 {
79 	EFI_ENTRY("%pD, %pD", src1, src2);
80 	return EFI_EXIT(efi_dp_append(src1, src2));
81 }
82 
83 /*
84  * Append device path node.
85  *
86  * This function implements the AppendDeviceNode service of the device path
87  * utilities protocol.
88  *
89  * See the Unified Extensible Firmware Interface (UEFI) specification
90  * for details.
91  *
92  * @device_path		device path
93  * @device_node		device node
94  * @return		concatenated device path
95  */
96 static struct efi_device_path * EFIAPI append_device_node(
97 	const struct efi_device_path *device_path,
98 	const struct efi_device_path *device_node)
99 {
100 	EFI_ENTRY("%pD, %p", device_path, device_node);
101 	return EFI_EXIT(efi_dp_append_node(device_path, device_node));
102 }
103 
104 /*
105  * Append device path instance.
106  *
107  * This function implements the AppendDevicePathInstance service of the device
108  * path utilities protocol.
109  *
110  * See the Unified Extensible Firmware Interface (UEFI) specification
111  * for details.
112  *
113  * @device_path			1st device path
114  * @device_path_instance	2nd device path
115  * @return			concatenated device path
116  */
117 static struct efi_device_path * EFIAPI append_device_path_instance(
118 	const struct efi_device_path *device_path,
119 	const struct efi_device_path *device_path_instance)
120 {
121 	EFI_ENTRY("%pD, %pD", device_path, device_path_instance);
122 	return EFI_EXIT(efi_dp_append_instance(device_path,
123 					       device_path_instance));
124 }
125 
126 /*
127  * Get next device path instance.
128  *
129  * This function implements the GetNextDevicePathInstance service of the device
130  * path utilities protocol.
131  *
132  * See the Unified Extensible Firmware Interface (UEFI) specification
133  * for details.
134  *
135  * @device_path_instance	next device path instance
136  * @device_path_instance_size	size of the device path instance
137  * @return			concatenated device path
138  */
139 static struct efi_device_path * EFIAPI get_next_device_path_instance(
140 	struct efi_device_path **device_path_instance,
141 	efi_uintn_t *device_path_instance_size)
142 {
143 	EFI_ENTRY("%pD, %p", device_path_instance, device_path_instance_size);
144 	return EFI_EXIT(efi_dp_get_next_instance(device_path_instance,
145 						 device_path_instance_size));
146 }
147 
148 /*
149  * Check if a device path contains more than one instance.
150  *
151  * This function implements the AppendDeviceNode service of the device path
152  * utilities protocol.
153  *
154  * See the Unified Extensible Firmware Interface (UEFI) specification
155  * for details.
156  *
157  * @device_path		device path
158  * @device_node		device node
159  * @return		concatenated device path
160  */
161 static bool EFIAPI is_device_path_multi_instance(
162 	const struct efi_device_path *device_path)
163 {
164 	EFI_ENTRY("%pD", device_path);
165 	return EFI_EXIT(efi_dp_is_multi_instance(device_path));
166 }
167 
168 /*
169  * Create device node.
170  *
171  * This function implements the CreateDeviceNode service of the device path
172  * utilities protocol.
173  *
174  * See the Unified Extensible Firmware Interface (UEFI) specification
175  * for details.
176  *
177  * @node_type		node type
178  * @node_sub_type	node sub type
179  * @node_length		node length
180  * @return		device path node
181  */
182 static struct efi_device_path * EFIAPI create_device_node(
183 	uint8_t node_type, uint8_t node_sub_type, uint16_t node_length)
184 {
185 	EFI_ENTRY("%u, %u, %u", node_type, node_sub_type, node_length);
186 	return EFI_EXIT(efi_dp_create_device_node(node_type, node_sub_type,
187 			node_length));
188 }
189 
190 const struct efi_device_path_utilities_protocol efi_device_path_utilities = {
191 	.get_device_path_size = get_device_path_size,
192 	.duplicate_device_path = duplicate_device_path,
193 	.append_device_path = append_device_path,
194 	.append_device_node = append_device_node,
195 	.append_device_path_instance = append_device_path_instance,
196 	.get_next_device_path_instance = get_next_device_path_instance,
197 	.is_device_path_multi_instance = is_device_path_multi_instance,
198 	.create_device_node = create_device_node,
199 };
200