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 105the same name 106as the image). 107.Sh API DESCRIPTION 108The kernel 109.Nm 110firmware API 111is made of the following functions: 112.Pp 113.Fn firmware_register 114registers with the kernel an image of size 115.Nm datasize 116located at address 117.Nm data , 118under the name 119.Nm imagename . 120.Pp 121The function returns NULL on error (e.g. because an 122image with the same name already exists, or the image 123table is full), or a 124.Ft const struct firmware * 125pointer to the image requested. 126.Pp 127.Fn firmware_unregister 128tries to unregister the firmware image 129.Nm imagename 130from the system. The function is successful and returns 0 131if there are no pending references to the image, otherwise 132it does not unregister the image and returns EBUSY. 133.Pp 134.Fn firmware_get 135returns the requested firmware image. 136If the image is not yet registered with the system, 137the function tries to load it. 138This involves the linker subsystem and disk access, so 139.Fn firmware_get 140must not be called with any locks (except for 141.Va Giant ) . 142Note also that if the firmware image is loaded from a filesystem 143it must already be mounted. 144In particular this means that it may be necessary to defer requests 145from a driver attach method unless it is known the root filesystem is 146already mounted. 147.Pp 148On success, 149.Fn firmware_get 150returns a pointer to the image description and increases the reference count 151for this image. On failure, the function returns NULL. 152.Pp 153.Fn firmware_put 154drops a reference to a firmware image. 155The 156.Fa flags 157argument may be set to 158.Dv FIRMWARE_UNLOAD 159to indicate that 160firmware_put is free to reclaim resources associated with 161the firmware image if this is the last reference. 162By default a firmware image will be deferred to a 163.Xr taskqueue 9 164thread so the call may be done while holding a lock. 165In certain cases, such as on driver detach, this cannot be allowed. 166.Sh FIRMWARE LOADING MECHANISMS 167As mentioned before, any component of the system can register 168firmware images at any time by simply calling 169.Fn firmware_register . 170.Pp 171This is typically done when a module containing 172a firmware image is given control, 173whether compiled in, or preloaded by 174.Nm /boot/loader , 175or manually loaded with 176.Xr kldload 8 . 177However, a system can implement additional mechanisms to bring 178these images in memory before calling 179.Fn firmware_register . 180.Pp 181When 182.Fn firmware_get 183does not find the requested image, it tries to load it using 184one of the available loading mechanisms. 185At the moment, there is only one, namely 186.Nm Loadable kernel modules : 187.Pp 188A firmware image named 189.Nm foo 190is looked up by trying to load the module named 191.Nm foo.ko , 192using the facilities described in 193.Xr kld 4 . 194In particular, images are looked up in the directories specified 195by the sysctl variable 196.Nm kern.module_path 197which on most systems defaults to 198.Nm /boot/kernel;/boot/modules . 199.Pp 200Note that in case a module contains multiple images, 201the caller should first request a 202.Fn firmware_get 203for the first image contained in the module, followed by requests 204for the other images. 205.Sh BUILDING FIRMWARE LOADABLE MODULES 206A firmware module is built by embedding the 207.Nm firmware image 208into a suitable loadable kernel module that calls 209.Fn firmware_register 210on loading, and 211.Fn firmware_unregister 212on unloading. 213.Pp 214Various system scripts and makefiles let you build a module 215by simply writing a Makefile with the following entries: 216.Bd -literal 217 218 KMOD= imagename 219 FIRMWS= image_file:imagename[:version] 220 .include <bsd.kmod.mk> 221 222.Ed 223where KMOD is the basename of the module; FIRMWS is a list of 224colon-separated tuples indicating the image_file's to be embedded 225in the module, the imagename and version of each firmware image. 226.Pp 227If you need to embed firmware images into a system, you should write 228appropriate entries in the <files.arch> file, e.g. this example is 229from 230.Nm sys/arm/xscale/ixp425/files.ixp425 : 231.Bd -literal 232ixp425_npe_fw.c optional npe_fw \\ 233 compile-with "${AWK} -f $S/tools/fw_stub.awk \\ 234 IxNpeMicrocode.dat:npe_fw -mnpe -c${.TARGET}" \\ 235 no-implicit-rule before-depend local \\ 236 clean "ixp425_npe_fw.c" 237# 238# NB: ld encodes the path in the binary symbols generated for the 239# firmware image so link the file to the object directory to 240# get known values for reference in the _fw.c file. 241# 242IxNpeMicrocode.fwo optional npe_fw \\ 243 dependency "IxNpeMicrocode.dat" \\ 244 compile-with "${LD} -b binary -d -warn-common \\ 245 -r -d -o ${.TARGET} IxNpeMicrocode.dat" \\ 246 no-implicit-rule \\ 247 clean "IxNpeMicrocode.fwo" 248IxNpeMicrocode.dat optional npe_fw \\ 249 dependency ".PHONY" \\ 250 compile-with "uudecode < $S/contrib/dev/npe/IxNpeMicrocode.dat.uu" \\ 251 no-obj no-implicit-rule \\ 252 clean "IxNpeMicrocode.dat" 253.Ed 254.Pp 255Note that generating the firmware modules in this way requires 256the availability of the following tools: 257.Xr awk 1 , 258.Xr make 1 , 259the compiler and the linker. 260.Sh SEE ALSO 261.Xr kld 4 , 262.Xr module 9 263.Pp 264.Pa /usr/share/examples/kld/firmware 265.Sh HISTORY 266The 267.Nm firmware 268system was introduced in 269.Fx 6.1 . 270.Sh AUTHORS 271This manual page was written by 272.An Max Laier Aq mlaier@FreeBSD.org . 273