1.\" $OpenBSD: usbhid.3,v 1.10 2007/05/31 19:19:38 jmc Exp $ 2.\" $NetBSD: usbhid.3,v 1.5 2002/02/07 07:00:52 ross Exp $ 3.\" 4.\" Copyright (c) 1999, 2001 Lennart Augustsson <augustss@netbsd.org> 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd $Mdocdate: May 31 2007 $ 29.Dt USBHID 3 30.Os 31.Sh NAME 32.Nm usbhid , 33.Nm hid_get_report_desc , 34.Nm hid_use_report_desc , 35.Nm hid_dispose_report_desc , 36.Nm hid_start_parse , 37.Nm hid_end_parse , 38.Nm hid_get_item , 39.Nm hid_report_size , 40.Nm hid_locate , 41.Nm hid_usage_page , 42.Nm hid_usage_in_page , 43.Nm hid_parse_usage_page , 44.Nm hid_parse_usage_in_page , 45.Nm hid_start , 46.Nm hid_init , 47.Nm hid_get_data , 48.Nm hid_set_data 49.Nd USB HID access routines 50.Sh SYNOPSIS 51.Fd #include \*[Lt]usbhid.h\*[Gt] 52.Ft report_desc_t 53.Fn hid_get_report_desc "int file" 54.Ft report_desc_t 55.Fn hid_use_report_desc "unsigned char *data" "unsigned int size" 56.Ft void 57.Fn hid_dispose_report_desc "report_desc_t d" 58.Ft hid_data_t 59.Fn hid_start_parse "report_desc_t d" "int kindset" "int id" 60.Ft void 61.Fn hid_end_parse "hid_data_t s" 62.Ft int 63.Fn hid_get_item "hid_data_t s" "hid_item_t *h" 64.Ft int 65.Fn hid_report_size "report_desc_t d" "hid_kind_t k" "int id" 66.Ft int 67.Fn hid_locate "report_desc_t d" "u_int usage" "hid_kind_t k" "hid_item_t *h" "int id" 68.Ft char * 69.Fn hid_usage_page "int i" 70.Ft char * 71.Fn hid_usage_in_page "u_int u" 72.Ft int 73.Fn hid_parse_usage_page "const char *" 74.Ft char * 75.Fn hid_parse_usage_in_page "const char *" 76.Ft void 77.Fn hid_init "char *file" 78.Ft int 79.Fn hid_start "char *file" 80.Ft int 81.Fn hid_get_data "void *data" "hid_item_t *h" 82.Ft void 83.Fn hid_set_data "void *data" "hid_item_t *h" "u_int data" 84.Sh DESCRIPTION 85The 86.Nm 87library provides routines to extract data from USB Human Interface Devices. 88.Ss INTRODUCTION 89USB HID devices send and receive data laid out in a device dependent way. 90The 91.Nm 92library contains routines to extract the 93.Em report descriptor 94which contains the data layout information and then use this information. 95.Pp 96The routines can be divided into four parts: extraction of the descriptor, 97parsing of the descriptor, translating to/from symbolic names, and 98data manipulation. 99.Ss DESCRIPTOR FUNCTIONS 100A report descriptor can be obtained by calling 101.Fn hid_get_report_desc 102with a file descriptor obtained by opening a 103.Xr uhid 4 104device. 105Alternatively a data buffer containing the report descriptor can be passed into 106.Fn hid_use_report_desc . 107The data is copied into an internal structure. 108When the report descriptor is no longer needed it should be freed by calling 109.Fn hid_dispose_report_desc . 110The type 111.Fa report_desc_t 112is opaque and should be used when calling the parsing functions. 113If 114.Fn hid_dispose_report_desc 115fails it will return 116.Fa NULL . 117.Ss DESCRIPTOR PARSING FUNCTIONS 118To parse the report descriptor the 119.Fn hid_start_parse 120function should be called with a report descriptor and a set that 121describes which items that are interesting. 122The set is obtained by or-ing together values 123.Fa "(1 \*[Lt]\*[Lt] k)" 124where 125.Fa k 126is an item of type 127.Fa hid_kind_t . 128The report ID (if present) is given by 129.Fa id . 130The function returns 131.Fa NULL 132if the initialization fails, otherwise an opaque value to be used 133in subsequent calls. 134After parsing the 135.Fn hid_end_parse 136function should be called to free internal data structures. 137.Pp 138To iterate through all the items in the report descriptor, 139.Fn hid_get_item 140should be called while it returns a value greater than 0. 141When the report descriptor ends it will return 0; a syntax 142error within the report descriptor will cause a return value less 143than 0. 144The struct pointed to by 145.Fa h 146will be filled with the relevant data for the item. 147The definition of 148.Fa hid_item_t 149can be found in 150.Aq Pa usbhid.h 151and the meaning of the components in the USB HID documentation. 152.Pp 153Data should be read/written to the device in the size of 154the report. 155The size of a report (of a certain kind) can be computed by the 156.Fn hid_report_size 157function. 158If the report is prefixed by an ID byte it is given by 159.Fa id . 160.Pp 161To locate a single item the 162.Fn hid_locate 163function can be used. 164It should be given the usage code of 165the item and its kind and it will fill the item and return 166non-zero if the item was found. 167.Ss NAME TRANSLATION FUNCTIONS 168The function 169.Fn hid_usage_page 170will return the symbolic name of a usage page, and the function 171.Fn hid_usage_in_page 172will return the symbolic name of the usage within the page. 173Both these functions may return a pointer to static data. 174.Pp 175The functions 176.Fn hid_parse_usage_page 177and 178.Fn hid_parse_usage_in_page 179are the inverses of 180.Fn hid_usage_page 181and 182.Fn hid_usage_in_page . 183They take a usage string and return the number of the usage, or \-1 184if it cannot be found. 185.Pp 186Before any of these functions can be called the usage table 187must be parsed, this is done by calling 188.Fn hid_start 189with the name of the table. 190Passing 191.Fa NULL 192to this function will cause it to use the default table. 193A return value of \-1 indicates that an error has occurred, and 194.Va errno 195is set. 196.Ss DATA EXTRACTION FUNCTIONS 197Given the data obtained from a HID device and an item in the 198report descriptor the 199.Fn hid_get_data 200function extracts the value of the item. 201Conversely 202.Fn hid_set_data 203can be used to put data into a report (which must be zeroed first). 204.Sh FILES 205.Pa /usr/share/misc/usb_hid_usages 206The default HID usage table. 207.\" .Sh EXAMPLES 208.Sh SEE ALSO 209The 210.Tn USB 211specifications can be found at: 212.Pa http://www.usb.org/developers/docs/ 213.Pp 214.Xr uhid 4 , 215.Xr usb 4 216.Sh HISTORY 217The 218.Nm 219library first appeared in 220.Ox 3.0 . 221.Sh BUGS 222This man page is woefully incomplete. 223