1.\" $NetBSD: ugen.4,v 1.39 2024/03/26 03:24:14 thorpej Exp $ 2.\" 3.\" Copyright (c) 1999 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Lennart Augustsson. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd March 25, 2024 31.Dt UGEN 4 32.Os 33.Sh NAME 34.Nm ugen 35.Nd USB generic device support 36.Sh SYNOPSIS 37.Cd "ugen* at uhub? flags N" 38.Cd "ugen* at uhub? vendor V product P flags 1" 39.Cd "ugenif* at uhub? vendor V product P configuration C interface I" 40.Cd "ugenif* at uhub? vendor V product P configuration C interface I flags 1" 41.Sh DESCRIPTION 42The 43.Nm 44driver provides support for all USB devices that do not have 45a special driver. 46It supports access to all parts of the device, 47but not in a way that is as convenient as a special purpose driver. 48.Pp 49Normally the 50.Nm 51driver is used when no other driver attaches to a device. 52If 53.Dq flags 1 54is specified, the 55.Nm 56will instead attach with a very high priority and always be used. 57Together with the 58.Cd vendor 59and 60.Cd product 61locators this can be used to force the 62.Nm 63driver to be used for a certain 64device. 65.Pp 66The 67.Sq ugenif 68form of attachment can be used to 69.Dq steal 70only one interface from some device for use by the 71.Nm 72driver. 73Most likely you want to explicitly specify at least vendor, 74product and interface with this form, 75as otherwise the 76.Nm 77driver would capture all of your 78.Nm usb 79devices. 80If 81.Dq flags 1 82is specified, the 83.Sq ugenif 84form will match at the lowest priority, thus allowing it to match only 85otherwise unclaimed interfaces. 86.Em NOTE : 87You have to be extremely careful, 88when using this form, 89as the attached 90.Nm 91driver has access to all of the device 92and can easily interfere with the driver(s) used for 93the other interface(s). 94.Pp 95As an example of this second form of attachment there are 96various debugging boards available based on some FTDI chip, 97where one interface is used for JTAG debugging 98and the other is used as a serial interface. 99In this case you want to attach the 100.Nm 101driver to interface 0 of this particular board identified by 102.Cd vendor 103and 104.Cd product 105while letting 106.Xr uftdi 4 107together with 108.Xr ucom 4 109to attach at interface 1. 110.Pp 111There can be up to 127 USB devices connected to a USB bus. 112Each USB device can have up to 16 endpoints. 113Each of these endpoints will communicate in one of four different 114modes: control, isochronous, bulk, or interrupt. 115Each of the endpoints will have a different device node. 116The four least significant bits in the minor device 117number determines which endpoint the device accesses and the rest 118of the bits determines which USB device. 119.Pp 120If an endpoint address is used both for input and output the device 121can be opened for both read or write. 122.Pp 123To find out what endpoints exist there are a series of 124.Xr ioctl 2 125operations on the control endpoint that return the USB descriptors 126of the device, configurations, interfaces, and endpoints. 127.Pp 128The control transfer mode can only happen on the control endpoint 129which is always endpoint 0. 130The control endpoint accepts requests 131and may respond with an answer to such requests. 132Control requests are issued by 133.Xr ioctl 2 134calls. 135.\" .Pp 136.\" The isochronous transfer mode can be in or out depending on the 137.\" endpoint. 138.\" To perform IO on an isochronous endpoint 139.\" .Xr read 2 140.\" and 141.\" .Xr write 2 142.\" should be used. 143.\" Before any IO operations can take place the transfer rate in 144.\" bytes/second has to be set. 145.\" This is done with 146.\" .Xr ioctl 2 147.\" .Dv USB_SET_ISO_RATE . 148.\" Performing this call sets up a buffer corresponding to 149.\" about 1 second of data. 150.Pp 151The bulk transfer mode can be in or out depending on the 152endpoint. 153To perform IO on a bulk endpoint 154.Xr read 2 155and 156.Xr write 2 157should be used. 158All IO operations on a bulk endpoint are normally unbuffered. 159The 160.Dv USB_SET_BULK_RA 161and 162.Dv USB_SET_BULK_WB 163.Xr ioctl 2 164calls enable read-ahead and write-behind buffering, respectively. 165This buffering supports fixed-sized USB transfers and is intended for 166devices with regular and continuing data transfers. 167When read-ahead or write-behind are enabled, the file descriptor 168may be set to use non-blocking IO. 169.Pp 170When in a read-ahead/writeback mode, 171.Xr select 2 172for read and write operates normally, returning true if there is data 173in the read buffer and space in the write buffer, respectively. 174When not, 175.Xr select 2 176always returns true, because there is no way to predict how the device 177will respond to a read or write request. 178.Pp 179The interrupt transfer mode can be in or out depending on the 180endpoint. 181To perform IO on an interrupt endpoint 182.Xr read 2 183and 184.Xr write 2 185should be used. 186A moderate amount of buffering is done 187by the driver. 188.Pp 189All endpoints handle the following 190.Xr ioctl 2 191calls: 192.Pp 193.Bl -tag -width indent -compact 194.It Dv USB_SET_SHORT_XFER ( int ) 195Allow short read transfer. 196Normally a transfer from the device which is shorter than the 197request specified is reported as an error. 198.It Dv USB_SET_TIMEOUT ( int ) 199Set the timeout on the device operations, the time is specified 200in milliseconds. 201The value 0 is used to indicate that there is no timeout. 202.El 203.Pp 204The control endpoint (endpoint 0) handles the following 205.Xr ioctl 2 206calls: 207.Pp 208.Bl -tag -width indent -compact 209.It Dv USB_GET_CONFIG ( int ) 210Get the device configuration number. 211.It Dv USB_SET_CONFIG ( int ) 212Set the device into the given configuration number. 213.Pp 214This operation can only be performed when the control endpoint 215is the sole open endpoint. 216.It Dv USB_GET_ALTINTERFACE ( struct usb_alt_interface ) 217Get the alternative setting number for the interface with the given 218index. 219The 220.Dv config_index 221is ignored in this call. 222.Bd -literal 223struct usb_alt_interface { 224 int uai_config_index; 225 int uai_interface_index; 226 int uai_alt_no; 227}; 228.Ed 229.It Dv USB_SET_ALTINTERFACE ( struct usb_alt_interface ) 230Set the alternative setting to the given number in the interface with the 231given index. 232The 233.Dv uai_config_index 234is ignored in this call. 235.Pp 236This operation can only be performed when no endpoints for the interface 237are open. 238.It Dv USB_GET_NO_ALT ( struct usb_alt_interface ) 239Return the number of different alternate settings in the 240.Dv uai_alt_no 241field. 242.It Dv USB_GET_DEVICE_DESC ( usb_device_descriptor_t ) 243Return the device descriptor. 244.It Dv USB_GET_CONFIG_DESC ( struct usb_config_desc ) 245Return the descriptor for the configuration with the given index. 246For convenience the current configuration can be specified by 247.Dv USB_CURRENT_CONFIG_INDEX . 248.Bd -literal 249struct usb_config_desc { 250 int ucd_config_index; 251 usb_config_descriptor_t ucd_desc; 252}; 253.Ed 254.It Dv USB_GET_INTERFACE_DESC ( struct usb_interface_desc ) 255Return the interface descriptor for an interface specified by its 256configuration index, interface index, and alternative index. 257For convenience the current alternative can be specified by 258.Dv USB_CURRENT_ALT_INDEX . 259.Bd -literal 260struct usb_interface_desc { 261 int uid_config_index; 262 int uid_interface_index; 263 int uid_alt_index; 264 usb_interface_descriptor_t uid_desc; 265}; 266.Ed 267.It Dv USB_GET_ENDPOINT_DESC ( struct usb_endpoint_desc ) 268Return the endpoint descriptor for the endpoint specified by its 269configuration index, interface index, alternative index, and 270endpoint index. 271.Bd -literal 272struct usb_endpoint_desc { 273 int ued_config_index; 274 int ued_interface_index; 275 int ued_alt_index; 276 int ued_endpoint_index; 277 usb_endpoint_descriptor_t ued_desc; 278}; 279.Ed 280.It Dv USB_GET_FULL_DESC ( struct usb_full_desc ) 281Return all the descriptors for the given configuration. 282.Bd -literal 283struct usb_full_desc { 284 int ufd_config_index; 285 u_int ufd_size; 286 u_char *ufd_data; 287}; 288.Ed 289The 290.Dv ufd_data 291field should point to a memory area of the size given in the 292.Dv ufd_size 293field. 294The proper size can be determined by first issuing a 295.Dv USB_GET_CONFIG_DESC 296and inspecting the 297.Dv wTotalLength 298field. 299.It Dv USB_GET_STRING_DESC ( struct usb_string_desc ) 300Get a string descriptor for the given language id and 301string index. 302.Bd -literal 303struct usb_string_desc { 304 int usd_string_index; 305 int usd_language_id; 306 usb_string_descriptor_t usd_desc; 307}; 308.Ed 309.It Dv USB_DO_REQUEST 310Send a USB request to the device on the control endpoint. 311Any data sent to/from the device is located at 312.Dv data . 313The size of the transferred data is determined from the 314.Dv request . 315The 316.Dv ucr_addr 317field is ignored in this call. 318The 319.Dv ucr_flags 320field can be used to flag that the request is allowed to 321be shorter than the requested size, and the 322.Dv ucr_actlen 323field will contain the actual size on completion. 324.Bd -literal 325struct usb_ctl_request { 326 int ucr_addr; 327 usb_device_request_t ucr_request; 328 void *ucr_data; 329 int ucr_flags; 330#define USBD_SHORT_XFER_OK 0x04 /* allow short reads */ 331 int ucr_actlen; /* actual length transferred */ 332}; 333.Ed 334This is a dangerous operation in that it can perform arbitrary operations 335on the device. 336Some of the most dangerous (e.g., changing the device 337address) are not allowed. 338.It Dv USB_GET_DEVICEINFO ( struct usb_device_info ) 339Get an information summary for the device. 340This call will not issue any USB transactions. 341.El 342.Pp 343Bulk endpoints handle the following 344.Xr ioctl 2 345calls: 346.Pp 347.Bl -tag -width indent -compact 348.It Dv USB_SET_BULK_RA ( int ) 349Enable or disable bulk read-ahead. 350When enabled, the driver will begin to read data from the device into 351a buffer, and will perform reads from the device whenever there is 352room in the buffer. 353The 354.Xr read 2 355call will read data from this buffer, blocking if necessary until 356there is enough data to read the length of data requested. 357The buffer size and the read request length can be set by the 358.Dv USB_SET_BULK_RA_OPT 359.Xr ioctl 2 360call. 361.It Dv USB_SET_BULK_WB ( int ) 362Enable or disable bulk write-behind. 363When enabled, the driver will buffer data from the 364.Xr write 2 365call before writing it to the device, enabling the 366.Xr write 2 367call to return immediately. 368.Xr write 2 369will block if there is not enough room in the buffer for all 370the data. 371The buffer size and the write request length can be set by the 372.Dv USB_SET_BULK_WB_OPT 373.Xr ioctl 2 374call. 375.It Dv USB_SET_BULK_RA_OPT ( struct usb_bulk_ra_wb_opt ) 376Set the size of the buffer and the length of the read requests used by 377the driver when bulk read-ahead is enabled. 378The changes do not take 379effect until the next time bulk read-ahead is enabled. 380Read requests 381are made for the length specified, and the host controller driver 382(i.e., 383.Xr ehci 4 , 384.Xr ohci 4 , 385and 386.Xr uhci 4 ) 387will perform as many bus transfers as required. 388If transfers from the device should be smaller than the maximum length, 389.Dv ra_wb_request_size 390must be set to the required length. 391.Bd -literal 392struct usb_bulk_ra_wb_opt { 393 u_int ra_wb_buffer_size; 394 u_int ra_wb_request_size; 395}; 396.Ed 397.It Dv USB_SET_BULK_WB_OPT ( struct usb_bulk_ra_wb_opt ) 398Set the size of the buffer and the length of the write requests used 399by the driver when bulk write-behind is enabled. 400The changes do not 401take effect until the next time bulk write-behind is enabled. 402.El 403.Pp 404Note that there are two different ways of addressing configurations, interfaces, 405alternatives, and endpoints: by index or by number. 406The index is the ordinal number (starting from 0) of the descriptor 407as presented by the device. 408The number is the respective number of 409the entity as found in its descriptor. 410Enumeration of descriptors 411use the index, getting and setting typically uses numbers. 412.Pp 413Example: 414All endpoints (except the control endpoint) for the current configuration 415can be found by iterating the 416.Dv interface_index 417from 0 to 418.Dv config_desc->bNumInterface-1 419and for each of these iterating the 420.Dv endpoint_index 421from 0 to 422.Dv interface_desc->bNumEndpoints . 423The 424.Dv config_index 425should set to 426.Dv USB_CURRENT_CONFIG_INDEX 427and 428.Dv alt_index 429should be set to 430.Dv USB_CURRENT_ALT_INDEX . 431.Sh FILES 432.Bl -tag -width Pa 433.It Pa /dev/ugenN.EE 434Endpoint 435.Pa EE 436of device 437.Pa N . 438.El 439.Sh SEE ALSO 440.Xr usb 4 441.Sh HISTORY 442The 443.Nm 444driver 445appeared in 446.Nx 1.4 . 447.\" .Sh BUGS 448.\" The driver is not yet finished; there is no access to isochronous endpoints. 449