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.\" $FreeBSD$ 25.\" 26.Dd August 2, 2008 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 EBUSY. 131.Pp 132.Fn firmware_get 133returns the requested firmware image. 134If the image is not yet registered with the system, 135the function tries to load it. 136This involves the linker subsystem and disk access, so 137.Fn firmware_get 138must not be called with any locks (except for 139.Va Giant ) . 140Note also that if the firmware image is loaded from a filesystem 141it must already be mounted. 142In particular this means that it may be necessary to defer requests 143from a driver attach method unless it is known the root filesystem is 144already mounted. 145.Pp 146On success, 147.Fn firmware_get 148returns a pointer to the image description and increases the reference count 149for this image. On failure, the function returns NULL. 150.Pp 151.Fn firmware_put 152drops a reference to a firmware image. 153The 154.Fa flags 155argument may be set to 156.Dv FIRMWARE_UNLOAD 157to indicate that 158firmware_put is free to reclaim resources associated with 159the firmware image if this is the last reference. 160By default a firmware image will be deferred to a 161.Xr taskqueue 9 162thread so the call may be done while holding a lock. 163In certain cases, such as on driver detach, this cannot be allowed. 164.Sh FIRMWARE LOADING MECHANISMS 165As mentioned before, any component of the system can register 166firmware images at any time by simply calling 167.Fn firmware_register . 168.Pp 169This is typically done when a module containing 170a firmware image is given control, 171whether compiled in, or preloaded by 172.Nm /boot/loader , 173or manually loaded with 174.Xr kldload 8 . 175However, a system can implement additional mechanisms to bring 176these images in memory before calling 177.Fn firmware_register . 178.Pp 179When 180.Fn firmware_get 181does not find the requested image, it tries to load it using 182one of the available loading mechanisms. 183At the moment, there is only one, namely 184.Nm Loadable kernel modules : 185.Pp 186A firmware image named 187.Nm foo 188is looked up by trying to load the module named 189.Nm foo.ko , 190using the facilities described in 191.Xr kld 4 . 192In particular, images are looked up in the directories specified 193by the sysctl variable 194.Nm kern.module_path 195which on most systems defaults to 196.Nm /boot/kernel;/boot/modules . 197.Pp 198Note that in case a module contains multiple images, 199the caller should first request a 200.Fn firmware_get 201for the first image contained in the module, followed by requests 202for the other images. 203.Sh BUILDING FIRMWARE LOADABLE MODULES 204A firmware module is built by embedding the 205.Nm firmware image 206into a suitable loadable kernel module that calls 207.Fn firmware_register 208on loading, and 209.Fn firmware_unregister 210on unloading. 211.Pp 212Various system scripts and makefiles let you build a module 213by simply writing a Makefile with the following entries: 214.Bd -literal 215 216 KMOD= imagename 217 FIRMWS= image_file:imagename[:version] 218 .include <bsd.kmod.mk> 219 220.Ed 221where KMOD is the basename of the module; FIRMWS is a list of 222colon-separated tuples indicating the image_file's to be embedded 223in the module, the imagename and version of each firmware image. 224.Pp 225If you need to embed firmware images into a system, you should write 226appropriate entries in the <files.arch> file, e.g. this example is 227from 228.Nm sys/arm/xscale/ixp425/files.ixp425: 229.Bd -literal 230ixp425_npe_fw.c optional npe_fw \\ 231 compile-with "${AWK} -f $S/tools/fw_stub.awk \\ 232 IxNpeMicrocode.dat:npe_fw -mnpe -c${.TARGET}" \\ 233 no-implicit-rule before-depend local \\ 234 clean "ixp425_npe_fw.c" 235# 236# NB: ld encodes the path in the binary symbols generated for the 237# firmware image so link the file to the object directory to 238# get known values for reference in the _fw.c file. 239# 240IxNpeMicrocode.fwo optional npe_fw \\ 241 dependency "IxNpeMicrocode.dat" \\ 242 compile-with "${LD} -b binary -d -warn-common \\ 243 -r -d -o ${.TARGET} IxNpeMicrocode.dat" \\ 244 no-implicit-rule \\ 245 clean "IxNpeMicrocode.fwo" 246IxNpeMicrocode.dat optional npe_fw \\ 247 dependency ".PHONY" \\ 248 compile-with "uudecode < $S/contrib/dev/npe/IxNpeMicrocode.dat.uu" \\ 249 no-obj no-implicit-rule \\ 250 clean "IxNpeMicrocode.dat" 251.Ed 252.Pp 253Note that generating the firmware modules in this way requires 254the availability of the following tools: 255.Xr awk , 256.Xr Make , 257the compiler and the linker. 258.Sh SEE ALSO 259.Xr module 9 , 260.Xr kld 4 261.Pp 262.Pa /usr/share/examples/kld/firmware 263.Sh HISTORY 264The 265.Nm firmware 266system was introduced in 267.Fx 6.1 . 268.Sh AUTHORS 269This manual page was written by 270.An Max Laier Aq mlaier@FreeBSD.org . 271