.\"	$NetBSD: firmload.9,v 1.8 2014/03/18 18:20:40 riastradh Exp $
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.\" Copyright 2016 Hans Rosenfeld <rosenfeld@grumpf.hope-2000.org>
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.\" by Jason R. Thorpe.
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.Dd January 22, 2016
.Dt FIRMLOAD 9F
.Os
.Sh NAME
.Nm firmload
.Nd Firmware loader API for device drivers
.Sh SYNOPSIS
.In sys/firmload.h
.Ft int
.Fo "firmware_open"
.Fa "const char *drvname"
.Fa "const char *imgname"
.Fa "firmware_handle_t *fhp"
.Fc
.Ft int
.Fo "firmware_close"
.Fa "firmware_handle_t fh"
.Fc
.Ft off_t
.Fo "firmware_get_size"
.Fa "firmware_handle_t fh"
.Fc
.Ft int
.Fo "firmware_read"
.Fa "firmware_handle_t fh"
.Fa "off_t offset"
.Fa "void *buf"
.Fa "size_t size"
.Fc
.Sh PARAMETERS
.Bl -tag -width Va
.It Fa drvname
The name of the driver using
.Nm .
This is used as the subdirectory holding the firmware images.
.It Fa imgname
The file name of a firmware image.
.It Fa fhp
The pointer used for returing a firmware handle.
.It Fa fh
The firmware handle.
.It Fa offset
The offset in the firmware image to start reading from.
.It Fa buf
Pointer to a buffer to hold the firmware data.
.It Fa size
Size of the buffer to hold the firmware data.
.El
.Sh DESCRIPTION
.Nm
provides a simple and convenient API for device drivers to load firmware
images from files residing in the file system that are necessary for the
devices that they control.
It is primarily intended for devices without non-volatile firmware
memory, which usually require the driver to load a firmware image at
attach time.
Firmware images reside in sub-directories, one for each driver, in the
namespace "firmware" in the system default module search path as
described in
.Xr system 5 .
.sp
The following functions are provided by the
.Nm
API:
.Bl -tag -width indent
.It Fn "firmware_open"
Open the firmware image
.Fa imgname
for the driver
.Fa drvname .
The path to the firmware image file is constructed by appending the string
.Dq "firmware/drvname/imgname"
to each system module path prefix until opening the firmware image
file succeeds.
.It Fn "firmware_close"
Close the firmware image file associated with the firmware handle
.Fa fh .
.It Fn "firmware_get_size"
Returns the size of the image file associated with the firmware handle
.Fa fh .
.It Fn "firmware_read"
Reads from the image file associated with the firmware handle
.Fa fh
beginning at offset
.Fa offset
for length
.Fa size .
The firmware image data is placed into the buffer specified by
.Fa buf .
.Fn "firmware_read"
will either read as much data as requested or fail, there are no short
reads.
.El
.Sh CONTEXT
These functions can be called from user and kernel context.
.Sh RETURN VALUES
Upon successful completion, the
.Fn firmware_open
function returns zero and stores a firmware handle in
.Fa fhp .
Otherwise a non-zero error code is returned.
.sp
The function
.Fn firmware_read
will return zero on success and
.Fa buf
will be filled with
.Fa size
bytes of data.
On failure -1 is returned.
.sp
The function
.Fn firmware_get_size
returns the size of a firmware image.
.sp
.Fn firmware_close
will always return zero.
.Sh INTERFACE STABILITY
.Sy Committed
.Sh SEE ALSO
.Xr system 5