.\" Copyright (c) 1998, Nicolas Souchu .\" Copyright (c) 2004, Joerg Wunsch .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: src/share/man/man4/smb.4,v 1.13.2.1.6.1 2010/12/21 17:09:25 kensmith Exp $ .\" .Dd February 6, 2009 .Dt SMB 4 .Os .Sh NAME .Nm smb .Nd SMB generic I/O device driver .Sh SYNOPSIS .Cd "device smb" .Sh DESCRIPTION The .Em smb character device driver provides generic i/o to any .Xr smbus 4 instance. In order to control SMB devices, use .Pa /dev/smb? with the ioctls described below. Any of these ioctl commands takes a pointer to .Vt struct smbcmd as its argument. .Pp .Bd -literal #include struct smbcmd { char cmd; int count; u_char slave; union { char byte; short word; char *byte_ptr; short *word_ptr; struct { short sdata; short *rdata; } process; } data; }; .Ed .Pp The .Fa slave field is always used, and provides the address of the SMBus slave device to talk to. The slave address is specified in the seven most significant bits .Pq i.e. Dq "left-justified" . The least significant bit of the slave address must be zero. .Pp .Bl -column ".Dv SMB_QUICK_WRITE" -compact .It Em Ioctl Ta Em Description .Pp .It Dv SMB_QUICK_WRITE Ta The .Em QuickWrite command just issues the device address with write intent to the bus, without transferring any data. .It Dv SMB_QUICK_READ Ta The .Em QuickRead command just issues the device address with read intent to the bus, without transferring any data. .It Dv SMB_SENDB Ta The .Em SendByte command sends the byte provided in the .Fa cmd field to the device. .It Dv SMB_RECVB Ta The .Em ReceiveByte command reads a single byte from the device which will be returned in the .Fa cmd field. .It Dv SMB_WRITEB Ta The .Em WriteByte command first sends the byte from the .Fa cmd field to the device, followed by the byte given in .Fa data.byte . .It Dv SMB_WRITEW Ta The .Em WriteWord command first sends the byte from the .Fa cmd field to the device, followed by the word given in .Fa data.word . Note that the SMBus byte-order is little-endian by definition. .It Dv SMB_READB Ta The .Em ReadByte command first sends the byte from the .Fa cmd field to the device, and then reads one byte of data from the device. The returned data will be stored in the location pointed to by .Fa data.byte_ptr . .It Dv SMB_READW Ta The .Em ReadWord command first sends the byte from the .Fa cmd field to the device, and then reads one word of data from the device. The returned data will be stored in the location pointed to by .Fa data.word_ptr . .It Dv SMB_PCALL Ta The .Em ProcedureCall command first sends the byte from the .Fa cmd field to the device, followed by the word provided in .Fa data.process.sdata . It then reads one word of data from the device, and returns it in the location pointed to by .Fa data.process.rdata . .It Dv SMB_BWRITE Ta The .Em BlockWrite command first sends the byte from the .Fa cmd field to the device, followed by .Fa count bytes of data that are taken from the buffer pointed to by .Fa data.byte_ptr . The SMBus specification mandates that no more than 32 bytes of data can be transferred in a single block read or write command. This value is available in the constant .Dv SMB_MAXBLOCKSIZE . .It Dv SMB_BREAD Ta The .Em BlockRead command first sends the byte from the .Fa cmd field to the device, and then reads .Fa count bytes of data that from the device. These data will be returned in the buffer pointed to by .Fa data.byte_ptr . .El .Pp The .Xr read 2 and .Xr write 2 system calls are not implemented by this driver. .Sh ERRORS The .Xr ioctl 2 commands can cause the following driver-specific errors: .Bl -tag -width Er .It Bq Er ENXIO Device did not respond to selection. .It Bq Er EBUSY Device still in use. .It Bq Er ENODEV Operation not supported by device (not supposed to happen). .It Bq Er EINVAL General argument error. .It Bq Er EWOULDBLOCK SMBus transaction timed out. .El .Sh SEE ALSO .Xr ioctl 2 , .Xr smbus 4 .Sh HISTORY The .Nm manual page first appeared in .Fx 3.0 . .Sh AUTHORS This manual page was written by .An Nicolas Souchu .