i2c_master_recv(9) [centos man page]

I2C_MASTER_RECV(9)					      I2C and SMBus Subsystem						I2C_MASTER_RECV(9)

NAME

       i2c_master_recv - issue a single I2C message in master receive mode

SYNOPSIS

       int i2c_master_recv(const struct i2c_client * client, char * buf, int count);

ARGUMENTS

       client
	   Handle to slave device

       buf
	   Where to store data read from slave

       count
	   How many bytes to read, must be less than 64k since msg.len is u16

DESCRIPTION

       Returns negative errno, or else the number of bytes read.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014							I2C_MASTER_RECV(9)

IIC(4)							   BSD 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 specified by the slave element to the bus.  All other elements are
		  ignored.

     I2CRPTSTART  (struct iiccmd) Sends the repeated 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   (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 ele-
		  ment 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 unde-
		  fined results.

     I2CRDWR	  (struct iic_rdwr_data) Generic read/write interface.	Allows for an arbitrary number of commands to be sent to an arbitrary num-
		  ber of devices on the bus.  A read transfer is specified if IIC_M_RD is set in flags.  Otherwise the transfer is a write trans-
		  fer.	The slave element specifies the 7-bit address for the transfer.  The len element is the length of the data.  The buf ele-
		  ment 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 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 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.

BSD
								 September 6, 2006							       BSD