183 lines
4.4 KiB
Groff
183 lines
4.4 KiB
Groff
.\" Copyright (c) 2006, M. Warner Losh
|
|
.\" Copyright (c) 1998, Nicolas Souchu
|
|
.\" 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.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd September 6, 2006
|
|
.Dt IIC 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm iic
|
|
.Nd I2C generic I/O device driver
|
|
.Sh SYNOPSIS
|
|
.Cd "device iic"
|
|
.Pp
|
|
.In dev/iicbus/iic.h
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
device driver provides generic I/O to any
|
|
.Xr iicbus 4
|
|
instance.
|
|
In order to control I2C devices, use
|
|
.Pa /dev/iic?
|
|
with the
|
|
following ioctls:
|
|
.Bl -tag -width ".Dv I2CRSTCARD"
|
|
.It Dv I2CSTART
|
|
.Pq Vt "struct iiccmd"
|
|
Sends the start condition to the slave specified by the
|
|
.Va slave
|
|
element to the bus.
|
|
All other elements are ignored.
|
|
.It Dv I2CSTOP
|
|
No argument is passed.
|
|
Sends the stop condition to the bus.
|
|
This terminates the current transaction.
|
|
.It Dv I2CRSTCARD
|
|
.Pq Vt "struct iiccmd"
|
|
Resets the bus.
|
|
The argument is completely ignored.
|
|
.It Dv I2CWRITE
|
|
.Pq Vt "struct iiccmd"
|
|
Writes data to the
|
|
.Xr iicbus 4 .
|
|
The bus should already be started.
|
|
The
|
|
.Va slave
|
|
element is ignored.
|
|
The
|
|
.Va count
|
|
element is the number of bytes to write.
|
|
The
|
|
.Va last
|
|
element is a boolean flag.
|
|
It is non-zero when additional write commands will follow.
|
|
The
|
|
.Va buf
|
|
element is a pointer to the data to write to the bus.
|
|
.It Dv I2CREAD
|
|
.Pq Vt "struct iiccmd"
|
|
Reads data from the
|
|
.Xr iicbus 4 .
|
|
The bus should already be started.
|
|
The
|
|
.Va slave
|
|
element is ignored.
|
|
The
|
|
.Va count
|
|
element is the number of bytes to write.
|
|
The
|
|
.Va last
|
|
element is a boolean flag.
|
|
It is non-zero when additional write commands will follow.
|
|
The
|
|
.Va buf
|
|
element is a pointer to where to store the data read from the bus.
|
|
Short reads on the bus produce undefined results.
|
|
.It Dv I2CRDWR
|
|
.Pq Vt "struct iic_rdwr_data"
|
|
Generic read/write interface.
|
|
Allows for an arbitrary number of commands to be sent to
|
|
an arbitrary number of devices on the bus.
|
|
A read transfer is speficied if
|
|
.Dv IIC_M_RD
|
|
is set in
|
|
.Va flags .
|
|
Otherwise the transfer is a write transfer.
|
|
The
|
|
.Va slave
|
|
element specifies the 7-bit address for the transfer.
|
|
The
|
|
.Va len
|
|
element is the length of the data.
|
|
The
|
|
.Va buf
|
|
element is a buffer for that data.
|
|
This ioctl is intended to be
|
|
.Tn Linux
|
|
compatible.
|
|
.El
|
|
.Pp
|
|
The following data structures are defined in
|
|
.In dev/iicbus/iic.h
|
|
and referenced above:
|
|
.Bd -literal -offset indent
|
|
struct iiccmd {
|
|
u_char slave;
|
|
int count;
|
|
int last;
|
|
char *buf;
|
|
};
|
|
|
|
/* Designed to be compatible with linux's struct i2c_msg */
|
|
struct iic_msg
|
|
{
|
|
uint16_t slave;
|
|
uint16_t flags;
|
|
#define IIC_M_RD 0x0001 /* read vs write */
|
|
uint16_t len; /* msg legnth */
|
|
uint8_t * buf;
|
|
};
|
|
|
|
struct iic_rdwr_data {
|
|
struct iic_msg *msgs;
|
|
uint32_t nmsgs;
|
|
};
|
|
.Ed
|
|
.Pp
|
|
It is also possible to use read/write routines, then I2C start/stop handshake is
|
|
managed by the
|
|
.Xr iicbus 4
|
|
system.
|
|
However, the address used for the read/write routines is the one
|
|
passed to last
|
|
.Dv I2CSTART
|
|
.Xr ioctl 2
|
|
to this device.
|
|
.Sh SEE ALSO
|
|
.Xr ioctl 2 ,
|
|
.Xr read 2 ,
|
|
.Xr write 2 ,
|
|
.Xr iicbus 4
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
manual page first appeared in
|
|
.Fx 3.0 .
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
This
|
|
manual page was written by
|
|
.An Nicolas Souchu
|
|
and
|
|
.An M. Warner Losh .
|
|
.Sh BUGS
|
|
Only the
|
|
.Dv I2CRDWR
|
|
.Xr ioctl 2
|
|
is thread safe.
|
|
All other interfaces suffer from some kind of race.
|