1.\" Copyright (c) 1998, Nicolas Souchu 2.\" Copyright (c) 2004, Joerg Wunsch 3.\" Copyright (c) 2015, Michael Gmelin <freebsd@grem.de> 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.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd April 25, 2015 30.Dt SMB 4 31.Os 32.Sh NAME 33.Nm smb 34.Nd SMB generic I/O device driver 35.Sh SYNOPSIS 36.Cd "device smb" 37.Sh DESCRIPTION 38The 39.Em smb 40character device driver provides generic I/O to any 41.Xr smbus 4 42instance. 43To control SMB devices, use 44.Pa /dev/smb? 45with the ioctls described below. 46Any of these ioctl commands takes a pointer to 47.Vt struct smbcmd 48as its argument. 49.Bd -literal 50#include <sys/types.h> 51 52struct smbcmd { 53 u_char cmd; 54 u_char reserved; 55 u_short op; 56 union { 57 char byte; 58 char buf[2]; 59 short word; 60 } wdata; 61 union { 62 char byte; 63 char buf[2]; 64 short word; 65 } rdata; 66 int slave; 67 char *wbuf; /* use wdata if NULL */ 68 int wcount; 69 char *rbuf; /* use rdata if NULL */ 70 int rcount; 71}; 72.Ed 73.Pp 74The 75.Fa slave 76field is always used, and provides the address of the 77SMBus slave device. 78The slave address is specified in the seven most significant bits 79.Pq i.e., Dq "left-justified" . 80The least significant bit of the slave address must be zero. 81.Pp 82.Bl -column ".Dv SMB_QUICK_WRITE" -compact 83.It Em Ioctl Ta Em Description 84.Pp 85.It Dv SMB_QUICK_WRITE Ta 86.Em QuickWrite 87does not transfer any data. 88It just issues the device address with write intent to the bus. 89.It Dv SMB_QUICK_READ Ta 90.Em QuickRead 91does not transfer any data. 92It just issues the device address with read intent to the bus. 93.It Dv SMB_SENDB Ta 94.Em SendByte 95sends the byte provided in 96.Fa cmd 97to the device. 98.It Dv SMB_RECVB Ta 99.Em ReceiveByte 100reads a single byte from the device which is returned in 101.Fa cmd . 102.It Dv SMB_WRITEB Ta 103.Em WriteByte 104first sends the byte from 105.Fa cmd 106to the device, followed by the byte given in 107.Fa wdata.byte . 108.It Dv SMB_WRITEW Ta 109.Em WriteWord 110first sends the byte from 111.Fa cmd 112to the device, followed by the word given in 113.Fa wdata.word . 114Note that the SMBus byte-order is little-endian by definition. 115.It Dv SMB_READB Ta 116.Em ReadByte 117first sends the byte from 118.Fa cmd 119to the device, then reads one byte of data from 120the device. 121Returned data is stored in 122.Fa rdata.byte . 123.It Dv SMB_READW Ta 124.Em ReadWord 125first sends the byte from 126.Fa cmd 127to the device, then reads one word of data from 128the device. 129Returned data is stored in 130.Fa rdata.word . 131.It Dv SMB_PCALL Ta 132.Em ProcedureCall 133first sends the byte from 134.Fa cmd 135to the device, followed by the word provided in 136.Fa wdata.word . 137It then reads one word of data from the device and returns it 138in 139.Fa rdata.word . 140.It Dv SMB_BWRITE Ta 141.Em BlockWrite 142first sends the byte from 143.Fa cmd 144to the device, then the byte from 145.Fa wcount 146followed by 147.Fa wcount 148bytes of data that are taken from the buffer pointed to by 149.Fa wbuf . 150The SMBus specification mandates that no more than 32 bytes of 151data can be transferred in a single block read or write command. 152This value can be read from the constant 153.Dv SMB_MAXBLOCKSIZE . 154.It Dv SMB_BREAD Ta 155.Em BlockRead 156first sends the byte from 157.Fa cmd 158to the device, then reads a count of data bytes that the device 159is going to provide and then reads that many bytes. 160The count is returned in 161.Fa rcount . 162The data is returned in the buffer pointed to by 163.Fa rbuf . 164.El 165.Pp 166The 167.Xr read 2 168and 169.Xr write 2 170system calls are not implemented by this driver. 171.Sh ERRORS 172The 173.Xr ioctl 2 174commands can cause the following driver-specific errors: 175.Bl -tag -width Er 176.It Bq Er ENXIO 177Device did not respond to selection. 178.It Bq Er EBUSY 179Device still in use. 180.It Bq Er ENODEV 181Operation not supported by device (not supposed to happen). 182.It Bq Er EINVAL 183General argument error. 184.It Bq Er EWOULDBLOCK 185SMBus transaction timed out. 186.El 187.Sh SEE ALSO 188.Xr ioctl 2 , 189.Xr smbus 4 190.Sh HISTORY 191The 192.Nm 193manual page first appeared in 194.Fx 3.0 . 195.Sh AUTHORS 196This 197manual page was written by 198.An Nicolas Souchu 199and extended by 200.An Michael Gmelin Aq freebsd@grem.de . 201