1 // SPDX-License-Identifier: GPL-2.0
2 /* Builtin firmware support */
3 
4 #include <linux/firmware.h>
5 #include "../firmware.h"
6 
7 /* Only if FW_LOADER=y */
8 #ifdef CONFIG_FW_LOADER
9 
10 struct builtin_fw {
11 	char *name;
12 	void *data;
13 	unsigned long size;
14 };
15 
16 extern struct builtin_fw __start_builtin_fw[];
17 extern struct builtin_fw __end_builtin_fw[];
18 
19 static bool fw_copy_to_prealloc_buf(struct firmware *fw,
20 				    void *buf, size_t size)
21 {
22 	if (!buf)
23 		return true;
24 	if (size < fw->size)
25 		return false;
26 	memcpy(buf, fw->data, fw->size);
27 	return true;
28 }
29 
30 /**
31  * firmware_request_builtin() - load builtin firmware
32  * @fw: pointer to firmware struct
33  * @name: name of firmware file
34  *
35  * Some use cases in the kernel have a requirement so that no memory allocator
36  * is involved as these calls take place early in boot process. An example is
37  * the x86 CPU microcode loader. In these cases all the caller wants is to see
38  * if the firmware was built-in and if so use it right away. This can be used
39  * for such cases.
40  *
41  * This looks for the firmware in the built-in kernel. Only if the kernel was
42  * built-in with the firmware you are looking for will this return successfully.
43  *
44  * Callers of this API do not need to use release_firmware() as the pointer to
45  * the firmware is expected to be provided locally on the stack of the caller.
46  **/
47 bool firmware_request_builtin(struct firmware *fw, const char *name)
48 {
49 	struct builtin_fw *b_fw;
50 
51 	if (!fw)
52 		return false;
53 
54 	for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
55 		if (strcmp(name, b_fw->name) == 0) {
56 			fw->size = b_fw->size;
57 			fw->data = b_fw->data;
58 			return true;
59 		}
60 	}
61 
62 	return false;
63 }
64 EXPORT_SYMBOL_NS_GPL(firmware_request_builtin, TEST_FIRMWARE);
65 
66 /**
67  * firmware_request_builtin_buf() - load builtin firmware into optional buffer
68  * @fw: pointer to firmware struct
69  * @name: name of firmware file
70  * @buf: If set this lets you use a pre-allocated buffer so that the built-in
71  *	firmware into is copied into. This field can be NULL. It is used by
72  *	callers such as request_firmware_into_buf() and
73  *	request_partial_firmware_into_buf()
74  * @size: if buf was provided, the max size of the allocated buffer available.
75  *	If the built-in firmware does not fit into the pre-allocated @buf this
76  *	call will fail.
77  *
78  * This looks for the firmware in the built-in kernel. Only if the kernel was
79  * built-in with the firmware you are looking for will this call possibly
80  * succeed. If you passed a @buf the firmware will be copied into it *iff* the
81  * built-in firmware fits into the pre-allocated buffer size specified in
82  * @size.
83  *
84  * This caller is to be used internally by the firmware_loader only.
85  **/
86 bool firmware_request_builtin_buf(struct firmware *fw, const char *name,
87 				  void *buf, size_t size)
88 {
89 	if (!firmware_request_builtin(fw, name))
90 		return false;
91 
92 	return fw_copy_to_prealloc_buf(fw, buf, size);
93 }
94 
95 bool firmware_is_builtin(const struct firmware *fw)
96 {
97 	struct builtin_fw *b_fw;
98 
99 	for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++)
100 		if (fw->data == b_fw->data)
101 			return true;
102 
103 	return false;
104 }
105 
106 #endif
107