1.\"- 2.\" SPDX-License-Identifer: BSD-2-Clause 3.\" 4.\" Copyright (c) 1998, Nicolas Souchu 5.\" Copyright (c) 2004, Joerg Wunsch 6.\" Copyright (c) 2015, Michael Gmelin <freebsd@grem.de> 7.\" All rights reserved. 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 AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd April 25, 2015 31.Dt SMB 4 32.Os 33.Sh NAME 34.Nm smb 35.Nd System Management Bus (SMBus) generic I/O device driver 36.Sh SYNOPSIS 37.Cd "device smb" 38.Sh DESCRIPTION 39The 40.Em smb 41character device driver provides generic I/O to any 42.Xr smbus 4 43instance. 44To control SMB devices, use 45.Pa /dev/smb? 46with the ioctls described below. 47Any of these ioctl commands takes a pointer to 48.Vt struct smbcmd 49as its argument. 50.Bd -literal 51#include <sys/types.h> 52 53struct smbcmd { 54 u_char cmd; 55 u_char reserved; 56 u_short op; 57 union { 58 char byte; 59 char buf[2]; 60 short word; 61 } wdata; 62 union { 63 char byte; 64 char buf[2]; 65 short word; 66 } rdata; 67 int slave; 68 char *wbuf; /* use wdata if NULL */ 69 int wcount; 70 char *rbuf; /* use rdata if NULL */ 71 int rcount; 72}; 73.Ed 74.Pp 75The 76.Fa slave 77field is always used, and provides the address of the 78SMBus slave device. 79The slave address is specified in the seven most significant bits 80.Pq i.e., Dq "left-justified" . 81The least significant bit of the slave address must be zero. 82.Pp 83.Bl -column ".Dv SMB_QUICK_WRITE" -compact 84.It Em Ioctl Ta Em Description 85.Pp 86.It Dv SMB_QUICK_WRITE Ta 87.Em QuickWrite 88does not transfer any data. 89It just issues the device address with write intent to the bus. 90.It Dv SMB_QUICK_READ Ta 91.Em QuickRead 92does not transfer any data. 93It just issues the device address with read intent to the bus. 94.It Dv SMB_SENDB Ta 95.Em SendByte 96sends the byte provided in 97.Fa cmd 98to the device. 99.It Dv SMB_RECVB Ta 100.Em ReceiveByte 101reads a single byte from the device which is returned in 102.Fa cmd . 103.It Dv SMB_WRITEB Ta 104.Em WriteByte 105first sends the byte from 106.Fa cmd 107to the device, followed by the byte given in 108.Fa wdata.byte . 109.It Dv SMB_WRITEW Ta 110.Em WriteWord 111first sends the byte from 112.Fa cmd 113to the device, followed by the word given in 114.Fa wdata.word . 115Note that the SMBus byte-order is little-endian by definition. 116.It Dv SMB_READB Ta 117.Em ReadByte 118first sends the byte from 119.Fa cmd 120to the device, then reads one byte of data from 121the device. 122Returned data is stored in 123.Fa rdata.byte . 124.It Dv SMB_READW Ta 125.Em ReadWord 126first sends the byte from 127.Fa cmd 128to the device, then reads one word of data from 129the device. 130Returned data is stored in 131.Fa rdata.word . 132.It Dv SMB_PCALL Ta 133.Em ProcedureCall 134first sends the byte from 135.Fa cmd 136to the device, followed by the word provided in 137.Fa wdata.word . 138It then reads one word of data from the device and returns it 139in 140.Fa rdata.word . 141.It Dv SMB_BWRITE Ta 142.Em BlockWrite 143first sends the byte from 144.Fa cmd 145to the device, then the byte from 146.Fa wcount 147followed by 148.Fa wcount 149bytes of data that are taken from the buffer pointed to by 150.Fa wbuf . 151The SMBus specification mandates that no more than 32 bytes of 152data can be transferred in a single block read or write command. 153This value can be read from the constant 154.Dv SMB_MAXBLOCKSIZE . 155.It Dv SMB_BREAD Ta 156.Em BlockRead 157first sends the byte from 158.Fa cmd 159to the device, then reads a count of data bytes that the device 160is going to provide and then reads that many bytes. 161The count is returned in 162.Fa rcount . 163The data is returned in the buffer pointed to by 164.Fa rbuf . 165.El 166.Pp 167The 168.Xr read 2 169and 170.Xr write 2 171system calls are not implemented by this driver. 172.Sh ERRORS 173The 174.Xr ioctl 2 175commands can cause the following driver-specific errors: 176.Bl -tag -width Er 177.It Bq Er ENXIO 178Device did not respond to selection. 179.It Bq Er EBUSY 180Device still in use. 181.It Bq Er ENODEV 182Operation not supported by device (not supposed to happen). 183.It Bq Er EINVAL 184General argument error. 185.It Bq Er EWOULDBLOCK 186SMBus transaction timed out. 187.El 188.Sh SEE ALSO 189.Xr ioctl 2 , 190.Xr smbus 4 191.Sh HISTORY 192The 193.Nm 194manual page first appeared in 195.Fx 3.0 . 196.Sh AUTHORS 197This 198manual page was written by 199.An Nicolas Souchu 200and extended by 201.An Michael Gmelin Aq freebsd@grem.de . 202