drivers/base/firmware_loader/builtin/main.c

   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