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
10struct builtin_fw {
11 char *name;
12 void *data;
13 unsigned long size;
14};
15
16extern struct builtin_fw __start_builtin_fw[];
17extern struct builtin_fw __end_builtin_fw[];
18
19static 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 **/
47bool 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}
64EXPORT_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 **/
86bool 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
95bool 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

source code of linux/drivers/base/firmware_loader/builtin/main.c