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.Dd January 6, 2006
.Os
.Dt FIRMWARE 9
.Sh NAME
.Nm firmware_register ,
.Nm firmware_unregister ,
.Nm firmware_get ,
.Nm firmware_put
.Nd firmware image loading and management
.Sh SYNOPSIS
.In sys/param.h
.In sys/systm.h
.In sys/linker.h
.In sys/firmware.h
.Bd -literal
struct firmware {
	const char	*name;		/* system-wide name */
	const void	*data;		/* location of image */
	size_t		datasize;	/* size of image in bytes */
	unsigned int	version;	/* version of the image */
	int		refcnt;		/* held references */
	struct firmware	*parent;	/* not null if a subimage */
	linker_file_t	file;		/* loadable module */
};
.Ed
.Ft "struct firmware *"
.Fo firmware_register
.Fa "const char *imagename"
.Fa "const void *data"
.Fa "size_t datasize"
.Fa "unsigned int version"
.Fa "struct firmware *parent"
.Fc
.Ft int
.Fn firmware_unregister "const char *imagename"
.Ft "struct firmware *"
.Fn firmware_get "const char *imagename"
.Ft void
.Fn firmware_put "struct firmware *fp" "int flags"
.Sh DESCRIPTION
The
.Nm firmware
abstraction provides a convenient interface for loading firmware
images into the kernel.
Specially crafted kernel modules are used to hold the firmware images.
.Pp
The function
.Fn firmware_register
is used on load of such modules to register contained firmware images.
The arguments to
.Fn firmware_register
include a name that identifies the image for later requests to the
.Nm firmware
system, a pointer to the actual image, the size of the image and an optional
parent image.
The parent image is used to keep track of references to a given module so that
it can be unloaded on last reference.
.Pp
The function
.Fn firmware_unregister
removes the firmware image identified by the name from the system if there
are no pending references or returns an error otherwise.
.Pp
The function
.Fn firmware_get
returns the requested firmware image.
If the image is not yet registered with the system,
.Fn firmware_get
tries to load a module with the corresponding name.
This involves the linker subsystem and disk access which is why
.Fn firmware_get
must not be called with any locks (except for
.Va Giant ) .
On success,
.Fn firmware_get
returns a pointer to the image description and increases the reference count
for this image.
.Pp
The function
.Fn firmware_put
is used to drop the reference to a firmware image.
The
.Fa flags
argument may be set to
.Dv FIRMWARE_UNLOAD
to indicate that the caller wishes to unload the corresponding module if the
image becomes unreferenced.
.Sh SEE ALSO
.Xr module 9
.Pp
.Pa /usr/share/examples/kld
.Sh HISTORY
The
.Nm firmware
system was introduced in
.Fx 6.1 .
.Sh AUTHORS
This manual page was written by
.An Max Laier Aq mlaier@FreeBSD.org .