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iic (4)
>> iic (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
iic
- I2C generic I/O device driver
SYNOPSIS
device iic
#include <dev/iicbus/iic.h>
DESCRIPTION
The
device driver provides generic I/O to any
iicbus(4)
instance.
In order to control I2C devices, use
/dev/iic?
with the
following ioctls:
I2CSTART
(Vt struct iiccmd
)
Sends the start condition to the slave specified by the
slave
element to the bus.
All other elements are ignored.
I2CSTOP
No argument is passed.
Sends the stop condition to the bus.
This terminates the current transaction.
I2CRSTCARD
(Vt struct iiccmd
)
Resets the bus.
The argument is completely ignored.
I2CWRITE
(Vt struct iiccmd
)
Writes data to the
iicbus(4).
The bus should already be started.
The
slave
element is ignored.
The
count
element is the number of bytes to write.
The
last
element is a boolean flag.
It is non-zero when additional write commands will follow.
The
buf
element is a pointer to the data to write to the bus.
I2CREAD
(Vt struct iiccmd
)
Reads data from the
iicbus(4).
The bus should already be started.
The
slave
element is ignored.
The
count
element is the number of bytes to write.
The
last
element is a boolean flag.
It is non-zero when additional write commands will follow.
The
buf
element is a pointer to where to store the data read from the bus.
Short reads on the bus produce undefined results.
I2CRDWR
(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 specified if
IIC_M_RD
is set in
flags
Otherwise the transfer is a write transfer.
The
slave
element specifies the 7-bit address for the transfer.
The
len
element is the length of the data.
The
buf
element is a buffer for that data.
This ioctl is intended to be
Linux
compatible.
The following data structures are defined in
#include <dev/iicbus/iic.h>
and referenced above:
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;
};
It is also possible to use read/write routines, then I2C start/stop handshake is
managed by the
iicbus(4)
system.
However, the address used for the read/write routines is the one
passed to last
I2CSTARTioctl(2)
to this device.
