1.\" 2.\" Copyright (c) 1994 Wilko Bulte 3.\" Copyright (c) 2001 Joerg Wunsch 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. The name of the author may not be used to endorse or promote products 15.\" derived from this software without specific prior written permission 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd December 16, 2001 31.Dt FDC 4 32.Os 33.Sh NAME 34.Nm fdc 35.Nd "PC architecture floppy disk controller driver" 36.Sh SYNOPSIS 37.Cd device fdc 38.Cd device fd 39.Pp 40In 41.Pa /boot/device.hints : 42.Cd hint.fdc.0.at="isa" 43.Cd hint.fdc.0.port="0x3F0" 44.Cd hint.fdc.0.irq="6" 45.Cd hint.fdc.0.drq="2" 46.Cd hint.fdc.0.flags="0x0" 47.Cd hint.fd.0.at="fdc0" 48.Cd hint.fd.0.drive="0" 49.Cd hint.fd.0.flags="0x0" 50.Cd hint.fd.1.at="fdc0" 51.Cd hint.fd.1.drive="1" 52.Cd hint.fd.1.flags="0x0" 53.Sh DESCRIPTION 54.Ss Device Usage 55This driver provides access to floppy disk drives. 56Floppy disks using 57either FM (single-density) or MFM (double or high-density) recording 58can be handled. 59.Pp 60Floppy disk controllers can connect up to four drives each. 61The 62.Nm 63driver can currently handle up to two drives per controller. 64Upon 65driver initialization, an attempt is made to find out the type of the 66floppy controller in use. 67The known controller types are either the 68original NE765 or i8272 chips, or alternatively 69.Em enhanced 70controllers that are compatible with the NE72065 or i82077 chips. 71These enhanced controllers (among other enhancements) implement a FIFO 72for floppy data transfers that will automatically be enabled once an 73enhanced chip has been detected. 74This FIFO activation can be disabled 75using the per-controller flags value of 76.Ar 0x1 . 77.Pp 78By default, this driver creates a single device node 79.Pa /dev/fd Ns Ar N 80for each attached drive with number 81.Ar N . 82For historical reasons, device nodes that use a trailing UFS-style 83partition letter (ranging from 84.Sq a 85through 86.Sq h ) 87can also be accessed, which will be implemented as symbolic links to 88the main device node. 89.Pp 90Accessing the main device node will attempt to autodetect the density 91of the available medium for multi-density devices. 92Thus it is 93possible to use either a 720 KB medium or a 1440 KB medium in a 94high-density 3.5 inch standard floppy drive. 95Normally, this 96autodetection will only happen once at the first call to 97.Xr open 2 98for the device after inserting the medium. 99This assumes the drive 100offers proper changeline support so media changes can be detected by 101the driver. 102To indicate a drive that does not have the changeline support, 103this can be overridden using the per-drive device flags value of 104.Ar 0x10 105(causing each call to 106.Xr open 2 107to perform the autodetection). 108.Pp 109When trying to use a floppy device with special-density media, other 110device nodes can be created, of the form 111.Pa /dev/fd Ns Ar N . Ns Ar MMMM , 112where 113.Ar N 114is the drive number, and 115.Ar MMMM 116is a number between one and four digits describing the device density. 117Up to 15 additional subdevices per drive can be created that way. 118The 119administrator is free to decide on a policy how to assign these 120numbers. 121The two common policies are to either implement subdevices 122numbered 1 through 15, or to use a number that describes the medium 123density in kilobytes. 124Initially, each of those devices will be 125configured to the maximal density that is possible for the drive type 126(like 1200 KB for 5.25 inch HD drives or 1440 KB for 3.5 inch HD 127drives). 128The desired density to be used on that subdevice needs to be 129configured using 130.Xr fdcontrol 8 . 131.Pp 132Drive types are configured using the lower four bits of the per-drive 133device flags. 134The following values can be specified: 135.Bl -tag -width 2n -offset indent 136.It Ar 1 1375.25 inch double-density device with 40 cylinders (360 KB native 138capacity) 139.It Ar 2 1405.25 inch high-density device with 80 cylinders (1200 KB native 141capacity) 142.It Ar 3 1433.5 inch double-density device with 80 cylinders (720 KB native 144capacity) 145.It Ar 4 1463.5 inch high-density device with 80 cylinders (1440 KB native 147capacity) 148.It Ar 5 1493.5 inch extra-density device with 80 cylinders (2880 KB native 150capacity, usage currently restricted to at most 1440 KB media) 151.It Ar 6 152Same as type 5, available for compatibility with some BIOSes 153.El 154.Pp 155On IA32 architectures, the drive type can be specified as 0 for the 156first two drives. 157In that case, the CMOS configuration memory will be 158consulted to obtain the value for that drive. 159.Pp 160Normally, each configured drive will be probed at initialization 161time, using a short seek sequence. 162This is intended to find out about 163drives that have been configured but are actually missing or 164otherwise not responding. 165In some environments (like laptops with 166detachable drives), it might be desirable to bypass this drive probe, 167and pretend a drive to be there so the driver autoconfiguration will 168work even if the drive is currently not present. 169For that purpose, a 170per-drive device flags value of 171.Ar 0x20 172needs to be specified. 173.Pp 174.Ss Programming Interface 175In addition to the normal read and write functionality, the 176.Nm 177driver offers a number of configurable options using 178.Xr ioctl 2 . 179In order to access any of this functionality, programmers need to 180include the header file 181.In sys/fdcio.h 182into their programs. 183The call to 184.Xr open 2 185can be performed in two possible ways. 186When opening the device 187without the 188.Dv O_NONBLOCK 189flag set, the device is opened in a normal way, which would cause the 190main device nodes to perform automatic media density selection, and which 191will yield a file descriptor that is fully available for any I/O operation 192or any of the following 193.Xr ioctl 2 194commands. 195.Pp 196When opening the device with 197.Dv O_NONBLOCK 198set, automatic media density selection will be bypassed, and the device 199remains in a half-opened state. 200No actual I/O operations are possible, but 201many of the 202.Xr ioctl 2 203commands described below can be performed. 204This mode is intended for 205access to the device without the requirement to have an accessible 206media present, like for status inquiries to the drive, or in order to 207format a medium. 208.Dv O_NONBLOCK 209needs to be cleared before I/O operations are possible on the descriptor, 210which requires a prior specification of the density using the 211.Dv FD_STYPE 212command (see below). 213Operations that are not allowed on the half-opened 214descriptor will cause an error value of 215.Er EAGAIN . 216.Pp 217The following 218.Xr ioctl 2 219commands are currently available: 220.Bl -tag -width ".Dv FD_READID" 221.It Dv FD_FORM 222Used to format a floppy disk medium. 223Third argument is a pointer to a 224.Vt "struct fd_formb" 225specifying which track to format, and which parameters to fill into 226the ID fields of the floppy disk medium. 227.It Dv FD_GTYPE 228Returns the current density definition record for the selected device. 229Third argument is a pointer to 230.Vt "struct fd_type" . 231.It Dv FD_STYPE 232Adjusts the density definition of the selected device. 233Third argument 234is a pointer to 235.Vt "struct fd_type" . 236For the fixed-density subdevices (1 through 15 per drive), this 237operation is restricted to a process with superuser privileges. 238For 239the auto-selecting subdevice 0, the operation is temporarily allowed 240to any process, but this setting will be lost again upon the next 241autoselection. 242This can be used when formatting a new medium (which 243will require to open the device using 244.Dv O_NONBLOCK , 245and thus to later adjust the density using 246.Dv FD_STYPE ) . 247.It Dv FD_GOPTS 248Obtain the current drive options. 249Third argument is a pointer to 250.Vt int , 251containing a bitwise union of the following possible flag values: 252.Bl -tag -width ".Dv FDOPT_NOERRLOG" 253.It Dv FDOPT_NORETRY 254Do not automatically retry operations upon failure. 255.It Dv FDOPT_NOERRLOG 256Do not cause 257.Dq "hard error" 258kernel logs for failed I/O operations. 259.It Dv FDOPT_NOERROR 260Do not indicate I/O errors when returning from 261.Xr read 2 262or 263.Xr write 2 264system calls. 265The caller is assumed to use 266.Dv FD_GSTAT 267calls in order to inquire about the success of each operation. 268This 269is intended to allow even erroneous data from bad blocks to be 270retrieved using normal I/O operations. 271.It Dv FDOPT_AUTOSEL 272Device performs automatic density selection. 273Unlike the above flags, 274this one is read-only. 275.El 276.It Dv FD_SOPTS 277Set device options, see above for their meaning. 278Third argument is a 279pointer to 280.Vt int . 281Drive options will always be cleared when closing the descriptor. 282.It Dv FD_DEBUG 283Set the driver debug level. 284Third argument is a pointer to 285.Vt int , 286level 0 turns off all debugging. 287Only applicable if the driver has 288been configured with 289.Cd "options FDC_DEBUG" . 290.It Dv FD_CLRERR 291Clear the internal low-level error counter. 292Normally, controller-level 293I/O errors are only logged up to 294.Dv FDC_ERRMAX 295errors (currently defined to 100). 296This command resets the counter. 297Requires superuser privileges. 298.It Dv FD_READID 299Read one sector ID field from the floppy disk medium. 300Third argument is 301a pointer to 302.Vt "struct fdc_readid" , 303where the read data will be returned. 304Can be used to analyze a floppy 305disk medium. 306.It Dv FD_GSTAT 307Return the recent floppy disk controller status, if available. 308Third 309argument is a pointer to 310.Vt "struct fdc_status" , 311where the status registers (ST0, ST1, ST2, C, H, R, and N) are being 312returned. 313.Er EINVAL 314will be caused if no recent status is available. 315.It Dv FD_GDTYPE 316Returns the floppy disk drive type. 317Third argument is a pointer to 318.Vt "enum fd_drivetype" . 319This type is the same as being used in the per-drive configuration 320flags, or in the CMOS configuration data on IA32 systems. 321.El 322.Sh FILES 323.Bl -tag -width ".Pa /dev/fd*" -compact 324.It Pa /dev/fd* 325floppy disk device nodes 326.El 327.Sh SEE ALSO 328.Xr fdformat 1 , 329.Xr fdread 1 , 330.Xr fdwrite 1 , 331.Xr ioctl 2 , 332.Xr open 2 , 333.Xr read 2 , 334.Xr write 2 , 335.Xr fdcontrol 8 336.Sh AUTHORS 337.An -nosplit 338This man page was initially written by 339.An Wilko Bulte , 340and later vastly rewritten by 341.An J\(:org Wunsch . 342