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IIC(4)		       FreeBSD Kernel Interfaces Manual			IIC(4)

NAME
     iic -- I2C	generic	I/O device driver

SYNOPSIS
     device iic

     #include <dev/iicbus/iic.h>

DESCRIPTION
     The iic 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	  (struct iiccmd) Sends	the start condition to the slave spec-
		  ified	by the slave element to	the bus.  The slave element
		  consists of a	7-bit address and a read/write bit (i.e.,
		  7-bit	address	<< 1 | r/w).  If the read/write	bit is set a
		  read operation is initiated, if the read/write bit is
		  cleared a write operation is initiated.  All other elements
		  are ignored.

     I2CRPTSTART  (struct iiccmd) Sends	the repeated start condition to	the
		  slave	specified by the slave element to the bus.  The	slave
		  address should be specified as in I2CSTART.  All other ele-
		  ments	are ignored.

     I2CSTOP	  No argument is passed.  Sends	the stop condition to the bus.
		  This terminates the current transaction.

     I2CRSTCARD	  (struct iiccmd) Resets the bus.  The argument	is completely
		  ignored.

     I2CWRITE	  (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	  (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	  (struct iic_rdwr_data) Generic read/write interface.	Allows
		  for an arbitrary number of commands to be sent to an arbi-
		  trary	number of devices on the bus.  A read transfer is
		  specified if IIC_M_RD	is set in flags.  Otherwise the	trans-
		  fer is a write transfer.  The	slave element specifies	the
		  7-bit	address	with the read/write bit	for the	transfer.  The
		  read/write bit will be handled by the	iicbus stack based on
		  the specified	transfer operation.  The len element is	the
		  number of (struct iic_msg) messages encoded on (struct
		  iic_rdwr_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 <dev/iicbus/iic.h> and ref-
     erenced 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 length */
		   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 hand-
     shake is managed by the iicbus(4) system.	However, the address used for
     the read/write routines is	the one	passed to last I2CSTART	ioctl(2) to
     this device.

SEE ALSO
     ioctl(2), read(2),	write(2), iicbus(4)

HISTORY
     The iic manual page first appeared	in FreeBSD 3.0.

AUTHORS
     This manual page was written by Nicolas Souchu and	M. Warner Losh.

BUGS
     Only the I2CRDWR ioctl(2) is thread safe.	All other interfaces suffer
     from some kind of race.

FreeBSD	11.0			 June 24, 2014			  FreeBSD 11.0

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | AUTHORS | BUGS

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