1.\" Copyright (c) 2006, M. Warner Losh 2.\" Copyright (c) 1998, Nicolas Souchu 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd September 6, 2006 29.Dt IIC 4 30.Os 31.Sh NAME 32.Nm iic 33.Nd I2C generic I/O device driver 34.Sh SYNOPSIS 35.Cd "device iic" 36.Pp 37.In dev/iicbus/iic.h 38.Sh DESCRIPTION 39The 40.Nm 41device driver provides generic I/O to any 42.Xr iicbus 4 43instance. 44In order to control I2C devices, use 45.Pa /dev/iic? 46with the 47following ioctls: 48.Bl -tag -width ".Dv I2CRPTSTART" 49.It Dv I2CSTART 50.Pq Vt "struct iiccmd" 51Sends the start condition to the slave specified by the 52.Va slave 53element to the bus. 54All other elements are ignored. 55.It Dv I2CRPTSTART 56.Pq Vt "struct iiccmd" 57Sends the repeated start condition to the slave specified by the 58.Va slave 59element to the bus. 60All other elements are ignored. 61.It Dv I2CSTOP 62No argument is passed. 63Sends the stop condition to the bus. 64This terminates the current transaction. 65.It Dv I2CRSTCARD 66.Pq Vt "struct iiccmd" 67Resets the bus. 68The argument is completely ignored. 69.It Dv I2CWRITE 70.Pq Vt "struct iiccmd" 71Writes data to the 72.Xr iicbus 4 . 73The bus should already be started. 74The 75.Va slave 76element is ignored. 77The 78.Va count 79element is the number of bytes to write. 80The 81.Va last 82element is a boolean flag. 83It is non-zero when additional write commands will follow. 84The 85.Va buf 86element is a pointer to the data to write to the bus. 87.It Dv I2CREAD 88.Pq Vt "struct iiccmd" 89Reads data from the 90.Xr iicbus 4 . 91The bus should already be started. 92The 93.Va slave 94element is ignored. 95The 96.Va count 97element is the number of bytes to write. 98The 99.Va last 100element is a boolean flag. 101It is non-zero when additional write commands will follow. 102The 103.Va buf 104element is a pointer to where to store the data read from the bus. 105Short reads on the bus produce undefined results. 106.It Dv I2CRDWR 107.Pq Vt "struct iic_rdwr_data" 108Generic read/write interface. 109Allows for an arbitrary number of commands to be sent to 110an arbitrary number of devices on the bus. 111A read transfer is specified if 112.Dv IIC_M_RD 113is set in 114.Va flags . 115Otherwise the transfer is a write transfer. 116The 117.Va slave 118element specifies the 7-bit address for the transfer. 119The 120.Va len 121element is the length of the data. 122The 123.Va buf 124element is a buffer for that data. 125This ioctl is intended to be 126.Tn Linux 127compatible. 128.El 129.Pp 130The following data structures are defined in 131.In dev/iicbus/iic.h 132and referenced above: 133.Bd -literal -offset indent 134struct iiccmd { 135 u_char slave; 136 int count; 137 int last; 138 char *buf; 139}; 140 141/* Designed to be compatible with linux's struct i2c_msg */ 142struct iic_msg 143{ 144 uint16_t slave; 145 uint16_t flags; 146#define IIC_M_RD 0x0001 /* read vs write */ 147 uint16_t len; /* msg length */ 148 uint8_t * buf; 149}; 150 151struct iic_rdwr_data { 152 struct iic_msg *msgs; 153 uint32_t nmsgs; 154}; 155.Ed 156.Pp 157It is also possible to use read/write routines, then I2C start/stop handshake is 158managed by the 159.Xr iicbus 4 160system. 161However, the address used for the read/write routines is the one 162passed to last 163.Dv I2CSTART 164.Xr ioctl 2 165to this device. 166.Sh SEE ALSO 167.Xr ioctl 2 , 168.Xr read 2 , 169.Xr write 2 , 170.Xr iicbus 4 171.Sh HISTORY 172The 173.Nm 174manual page first appeared in 175.Fx 3.0 . 176.Sh AUTHORS 177.An -nosplit 178This 179manual page was written by 180.An Nicolas Souchu 181and 182.An M. Warner Losh . 183.Sh BUGS 184Only the 185.Dv I2CRDWR 186.Xr ioctl 2 187is thread safe. 188All other interfaces suffer from some kind of race. 189