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30 .Nm firmware_register ,
31 .Nm firmware_unregister ,
34 .Nd firmware image loading and management
42 const char *name; /* system-wide name */
43 const void *data; /* location of image */
44 size_t datasize; /* size of image in bytes */
45 unsigned int version; /* version of the image */
48 .Ft "const struct firmware *"
50 .Fa "const char *imagename"
51 .Fa "const void *data"
53 .Fa "unsigned int version"
54 .Fa "const struct firmware *parent"
57 .Fn firmware_unregister "const char *imagename"
58 .Ft "const struct firmware *"
59 .Fn firmware_get "const char *imagename"
61 .Fn firmware_put "const struct firmware *fp" "int flags"
65 abstraction provides a convenient interface for loading
67 into the kernel, and for accessing such images from kernel components.
74 is an opaque block of data residing in kernel memory.
75 It is associated to a unique
77 which constitutes a search key, and to an integer
79 number, which is also an opaque piece of information for the
82 An image is registered with the
84 subsystem by calling the function
85 .Fn firmware_register ,
86 and unregistered by calling
87 .Fn firmware_unregister .
88 These functions are usually (but not exclusively) called by
89 specially crafted kernel modules that contain the firmware image.
90 The modules can be statically compiled in the kernel, or loaded by
92 manually at runtime, or on demand by the firmware subsystem.
95 of the firmware subsystem can request access to a given image
96 by calling the function
100 they want as an argument. If a matching image is not already registered,
101 the firmware subsystem will try to load it using the
102 mechanisms specified below (typically, a kernel module
109 is made of the following functions:
111 .Fn firmware_register
112 registers with the kernel an image of size
119 The function returns NULL on error (e.g. because an
120 image with the same name already exists, or the image
122 .Ft const struct firmware *
123 pointer to the image requested.
125 .Fn firmware_unregister
126 tries to unregister the firmware image
128 from the system. The function is successful and returns 0
129 if there are no pending references to the image, otherwise
130 it does not unregister the image and returns EBUSY.
133 returns the requested firmware image.
134 If the image is not yet registered with the system,
135 the function tries to load it.
136 This involves the linker subsystem and disk access, so
138 must not be called with any locks (except for
140 The caller must also have a process context so filesystem state such as
141 the root vnode is defined (e.g. you cannot load from a taskqueue thread).
145 returns a pointer to the image description and increases the reference count
146 for this image. On failure, the function returns NULL.
149 drops a reference to a firmware image.
152 argument may be set to
155 firmware_put is free to reclaim resources associated with
156 the firmware image if this is the last reference.
157 .Sh FIRMWARE LOADING MECHANISMS
158 As mentioned before, any component of the system can register
159 firmware images at any time by simply calling
160 .Fn firmware_register .
162 This is typically done when a module containing
163 a firmware image is given control,
164 whether compiled in, or preloaded by
166 or manually loaded with
168 However, a system can implement additional mechanisms to bring
169 these images in memory before calling
170 .Fn firmware_register .
174 does not find the requested image, it tries to load it using
175 one of the available loading mechanisms.
176 At the moment, there is only one, namely
177 .Nm Loadable kernel modules :
179 A firmware image named
181 is looked up by trying to load the module named
183 using the facilities described in
185 In particular, images are looked up in the directories specified
186 by the sysctl variable
188 which on most systems defaults to
189 .Nm /boot/kernel;/boot/modules .
191 Note that in case a module contains multiple images,
192 the caller should first request a
194 for the first image contained in the module, followed by requests
195 for the other images.
196 .Sh BUILDING FIRMWARE LOADABLE MODULES
197 A firmware module is built by embedding the
199 into a suitable loadable kernel module that calls
200 .Fn firmware_register
202 .Fn firmware_unregister
205 Various system scripts and makefiles let you build a module
206 by simply writing a Makefile with the following entries:
210 FIRMWS= image_file:imagename[:version]
211 .include <bsd.kmod.mk>
214 where KMOD is the basename of the module; FIRMWS is a list of
215 colon-separated tuples indicating the image_file's to be embedded
216 in the module, the imagename and version of each firmware image.
218 If you need to embed firmware images into a system, you should write
219 appropriate entries in the <files.arch> file, e.g. this example is
221 .Nm sys/arm/xscale/ixp425/files.ixp425:
223 ixp425_npe_fw.c optional npe_fw \\
224 compile-with "${AWK} -f $S/tools/fw_stub.awk \\
225 IxNpeMicrocode.dat:npe_fw -mnpe -c${.TARGET}" \\
226 no-implicit-rule before-depend local \\
227 clean "ixp425_npe_fw.c"
229 # NB: ld encodes the path in the binary symbols generated for the
230 # firmware image so link the file to the object directory to
231 # get known values for reference in the _fw.c file.
233 IxNpeMicrocode.fwo optional npe_fw \\
234 dependency "IxNpeMicrocode.dat" \\
235 compile-with "${LD} -b binary -d -warn-common \\
236 -r -d -o ${.TARGET} IxNpeMicrocode.dat" \\
238 clean "IxNpeMicrocode.fwo"
239 IxNpeMicrocode.dat optional npe_fw \\
240 dependency ".PHONY" \\
241 compile-with "if [ -e $S/arm/xscale/ixp425/IxNpeMicrocode.dat ]; \\
243 ln -sf $S/arm/xscale/ixp425/IxNpeMicrocode.dat .; \\
244 else echo 'WARNING, no IxNpeMicrocode.dat file; you must obtain this from the Intel web site'; false; \\
246 no-obj no-implicit-rule \\
247 clean "IxNpeMicrocode.dat"
250 Note that generating the firmware modules in this way requires
251 the availability of the following tools:
254 the compiler and the linker.
259 .Pa /usr/share/examples/kld/firmware
263 system was introduced in
266 This manual page was written by
267 .An Max Laier Aq mlaier@FreeBSD.org .