1.\" Copyright (c) 2006 Max Laier <mlaier@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 14.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 17.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23.\" 24.\" $FreeBSD: src/share/man/man9/firmware.9,v 1.9 2010/04/14 19:08:06 uqs Exp $ 25.\" 26.Dd April 14, 2010 27.Dt FIRMWARE 9 28.Os 29.Sh NAME 30.Nm firmware_register , 31.Nm firmware_unregister , 32.Nm firmware_get , 33.Nm firmware_put 34.Nd firmware image loading and management 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/systm.h 38.In sys/linker.h 39.In sys/firmware.h 40.Bd -literal 41struct firmware { 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 */ 46}; 47.Ed 48.Ft "const struct firmware *" 49.Fo firmware_register 50.Fa "const char *imagename" 51.Fa "const void *data" 52.Fa "size_t datasize" 53.Fa "unsigned int version" 54.Fa "const struct firmware *parent" 55.Fc 56.Ft int 57.Fn firmware_unregister "const char *imagename" 58.Ft "const struct firmware *" 59.Fn firmware_get "const char *imagename" 60.Ft void 61.Fn firmware_put "const struct firmware *fp" "int flags" 62.Sh DESCRIPTION 63The 64.Nm firmware 65abstraction provides a convenient interface for loading 66.Nm firmware images 67into the kernel, and for accessing such images from kernel components. 68.Pp 69A 70.Nm firmware image 71(or 72.Nm image 73for brevity) 74is an opaque block of data residing in kernel memory. 75It is associated to a unique 76.Nm imagename 77which constitutes a search key, and to an integer 78.Nm version 79number, which is also an opaque piece of information for the 80firmware subsystem. 81.Pp 82An image is registered with the 83.Nm firmware 84subsystem by calling the function 85.Fn firmware_register , 86and unregistered by calling 87.Fn firmware_unregister . 88These functions are usually (but not exclusively) called by 89specially crafted kernel modules that contain the firmware image. 90The modules can be statically compiled in the kernel, or loaded by 91.Nm /boot/loader , 92manually at runtime, or on demand by the firmware subsystem. 93.Pp 94.Nm Clients 95of the firmware subsystem can request access to a given image 96by calling the function 97.Fn firmware_get 98with the 99.Nm imagename 100they want as an argument. If a matching image is not already registered, 101the firmware subsystem will try to load it using the 102mechanisms specified below (typically, a kernel module 103with 104.Nm the same name 105as the image). 106.Sh API DESCRIPTION 107The kernel 108.Nm firmware API 109is made of the following functions: 110.Pp 111.Fn firmware_register 112registers with the kernel an image of size 113.Nm datasize 114located at address 115.Nm data , 116under the name 117.Nm imagename . 118.Pp 119The function returns NULL on error (e.g. because an 120image with the same name already exists, or the image 121table is full), or a 122.Ft const struct firmware * 123pointer to the image requested. 124.Pp 125.Fn firmware_unregister 126tries to unregister the firmware image 127.Nm imagename 128from the system. The function is successful and returns 0 129if there are no pending references to the image, otherwise 130it does not unregister the image and returns 131.Er EBUSY . 132.Pp 133.Fn firmware_get 134returns the requested firmware image. 135If the image is not yet registered with the system, 136the function tries to load it. 137This involves the linker subsystem and disk access, so 138.Fn firmware_get 139must not be called with any locks (except for 140.Va Giant ) . 141Note also that if the firmware image is loaded from a filesystem 142it must already be mounted. 143In particular this means that it may be necessary to defer requests 144from a driver attach method unless it is known the root filesystem is 145already mounted. 146.Pp 147On success, 148.Fn firmware_get 149returns a pointer to the image description and increases the reference count 150for this image. On failure, the function returns NULL. 151.Pp 152.Fn firmware_put 153drops a reference to a firmware image. 154The 155.Fa flags 156argument may be set to 157.Dv FIRMWARE_UNLOAD 158to indicate that 159firmware_put is free to reclaim resources associated with 160the firmware image if this is the last reference. 161By default a firmware image will be deferred to a 162.Xr taskqueue 9 163thread so the call may be done while holding a lock. 164In certain cases, such as on driver detach, this cannot be allowed. 165.Sh FIRMWARE LOADING MECHANISMS 166As mentioned before, any component of the system can register 167firmware images at any time by simply calling 168.Fn firmware_register . 169.Pp 170This is typically done when a module containing 171a firmware image is given control, 172whether compiled in, or preloaded by 173.Nm /boot/loader , 174or manually loaded with 175.Xr kldload 8 . 176However, a system can implement additional mechanisms to bring 177these images in memory before calling 178.Fn firmware_register . 179.Pp 180When 181.Fn firmware_get 182does not find the requested image, it tries to load it using 183one of the available loading mechanisms. 184At the moment, there is only one, namely 185.Nm Loadable kernel modules : 186.Pp 187A firmware image named 188.Nm foo 189is looked up by trying to load the module named 190.Nm foo.ko , 191using the facilities described in 192.Xr kld 4 . 193In particular, images are looked up in the directories specified 194by the sysctl variable 195.Nm kern.module_path 196which on most systems defaults to 197.Nm /boot/kernel;/boot/modules . 198.Pp 199Note that in case a module contains multiple images, 200the caller should first request a 201.Fn firmware_get 202for the first image contained in the module, followed by requests 203for the other images. 204.Sh BUILDING FIRMWARE LOADABLE MODULES 205A firmware module is built by embedding the 206.Nm firmware image 207into a suitable loadable kernel module that calls 208.Fn firmware_register 209on loading, and 210.Fn firmware_unregister 211on unloading. 212.Pp 213Various system scripts and makefiles let you build a module 214by simply writing a Makefile with the following entries: 215.Bd -literal 216 217 KMOD= imagename 218 FIRMWS= image_file:imagename[:version] 219 .include <bsd.kmod.mk> 220 221.Ed 222where KMOD is the basename of the module; FIRMWS is a list of 223colon-separated tuples indicating the image_file's to be embedded 224in the module, the imagename and version of each firmware image. 225.Pp 226If you need to embed firmware images into a system, you should write 227appropriate entries in the <files.arch> file, e.g. this example is 228from 229.Nm sys/arm/xscale/ixp425/files.ixp425: 230.Bd -literal 231ixp425_npe_fw.c optional npe_fw \\ 232 compile-with "${AWK} -f $S/tools/fw_stub.awk \\ 233 IxNpeMicrocode.dat:npe_fw -mnpe -c${.TARGET}" \\ 234 no-implicit-rule before-depend local \\ 235 clean "ixp425_npe_fw.c" 236# 237# NB: ld encodes the path in the binary symbols generated for the 238# firmware image so link the file to the object directory to 239# get known values for reference in the _fw.c file. 240# 241IxNpeMicrocode.fwo optional npe_fw \\ 242 dependency "IxNpeMicrocode.dat" \\ 243 compile-with "${LD} -b binary -d -warn-common \\ 244 -r -d -o ${.TARGET} IxNpeMicrocode.dat" \\ 245 no-implicit-rule \\ 246 clean "IxNpeMicrocode.fwo" 247IxNpeMicrocode.dat optional npe_fw \\ 248 dependency ".PHONY" \\ 249 compile-with "uudecode < $S/contrib/dev/npe/IxNpeMicrocode.dat.uu" \\ 250 no-obj no-implicit-rule \\ 251 clean "IxNpeMicrocode.dat" 252.Ed 253.Pp 254Note that generating the firmware modules in this way requires 255the availability of the following tools: 256.Xr awk 1 , 257.Xr make 1 , 258the compiler and the linker. 259.Sh SEE ALSO 260.Xr kld 4 , 261.Xr module 9 262.Pp 263.Pa /usr/share/examples/kld/firmware 264.Sh HISTORY 265The 266.Nm firmware 267system was introduced in 268.Fx 6.1 . 269.Sh AUTHORS 270This manual page was written by 271.An Max Laier Aq mlaier@FreeBSD.org . 272