Home | History | Annotate | Download | only in linux
      1 /* ------------------------------------------------------------------------- */
      2 /*									     */
      3 /* i2c.h - definitions for the i2c-bus interface			     */
      4 /*									     */
      5 /* ------------------------------------------------------------------------- */
      6 /*   Copyright (C) 1995-2000 Simon G. Vogl
      7 
      8     This program is free software; you can redistribute it and/or modify
      9     it under the terms of the GNU General Public License as published by
     10     the Free Software Foundation; either version 2 of the License, or
     11     (at your option) any later version.
     12 
     13     This program is distributed in the hope that it will be useful,
     14     but WITHOUT ANY WARRANTY; without even the implied warranty of
     15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     16     GNU General Public License for more details.
     17 
     18     You should have received a copy of the GNU General Public License
     19     along with this program; if not, write to the Free Software
     20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.		     */
     21 /* ------------------------------------------------------------------------- */
     22 
     23 /* With some changes from Kysti Mlkki <kmalkki (at) cc.hut.fi> and
     24    Frodo Looijaard <frodol (at) dds.nl> */
     25 
     26 #ifndef _LINUX_I2C_H
     27 #define _LINUX_I2C_H
     28 
     29 #include <linux/types.h>
     30 
     31 /**
     32  * struct i2c_msg - an I2C transaction segment beginning with START
     33  * @addr: Slave address, either seven or ten bits.  When this is a ten
     34  *	bit address, I2C_M_TEN must be set in @flags and the adapter
     35  *	must support I2C_FUNC_10BIT_ADDR.
     36  * @flags: I2C_M_RD is handled by all adapters.  No other flags may be
     37  *	provided unless the adapter exported the relevant I2C_FUNC_*
     38  *	flags through i2c_check_functionality().
     39  * @len: Number of data bytes in @buf being read from or written to the
     40  *	I2C slave address.  For read transactions where I2C_M_RECV_LEN
     41  *	is set, the caller guarantees that this buffer can hold up to
     42  *	32 bytes in addition to the initial length byte sent by the
     43  *	slave (plus, if used, the SMBus PEC); and this value will be
     44  *	incremented by the number of block data bytes received.
     45  * @buf: The buffer into which data is read, or from which it's written.
     46  *
     47  * An i2c_msg is the low level representation of one segment of an I2C
     48  * transaction.  It is visible to drivers in the @i2c_transfer() procedure,
     49  * to userspace from i2c-dev, and to I2C adapter drivers through the
     50  * @i2c_adapter.@master_xfer() method.
     51  *
     52  * Except when I2C "protocol mangling" is used, all I2C adapters implement
     53  * the standard rules for I2C transactions.  Each transaction begins with a
     54  * START.  That is followed by the slave address, and a bit encoding read
     55  * versus write.  Then follow all the data bytes, possibly including a byte
     56  * with SMBus PEC.  The transfer terminates with a NAK, or when all those
     57  * bytes have been transferred and ACKed.  If this is the last message in a
     58  * group, it is followed by a STOP.  Otherwise it is followed by the next
     59  * @i2c_msg transaction segment, beginning with a (repeated) START.
     60  *
     61  * Alternatively, when the adapter supports I2C_FUNC_PROTOCOL_MANGLING then
     62  * passing certain @flags may have changed those standard protocol behaviors.
     63  * Those flags are only for use with broken/nonconforming slaves, and with
     64  * adapters which are known to support the specific mangling options they
     65  * need (one or more of IGNORE_NAK, NO_RD_ACK, NOSTART, and REV_DIR_ADDR).
     66  */
     67 struct i2c_msg {
     68 	__u16 addr;	/* slave address			*/
     69 	__u16 flags;
     70 #define I2C_M_TEN		0x0010	/* this is a ten bit chip address */
     71 #define I2C_M_RD		0x0001	/* read data, from slave to master */
     72 #define I2C_M_NOSTART		0x4000	/* if I2C_FUNC_PROTOCOL_MANGLING */
     73 #define I2C_M_REV_DIR_ADDR	0x2000	/* if I2C_FUNC_PROTOCOL_MANGLING */
     74 #define I2C_M_IGNORE_NAK	0x1000	/* if I2C_FUNC_PROTOCOL_MANGLING */
     75 #define I2C_M_NO_RD_ACK		0x0800	/* if I2C_FUNC_PROTOCOL_MANGLING */
     76 #define I2C_M_RECV_LEN		0x0400	/* length will be first received byte */
     77 	__u16 len;		/* msg length				*/
     78 	__u8 *buf;		/* pointer to msg data			*/
     79 };
     80 
     81 /* To determine what functionality is present */
     82 
     83 #define I2C_FUNC_I2C			0x00000001
     84 #define I2C_FUNC_10BIT_ADDR		0x00000002
     85 #define I2C_FUNC_PROTOCOL_MANGLING	0x00000004 /* I2C_M_NOSTART etc. */
     86 #define I2C_FUNC_SMBUS_PEC		0x00000008
     87 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL	0x00008000 /* SMBus 2.0 */
     88 #define I2C_FUNC_SMBUS_QUICK		0x00010000
     89 #define I2C_FUNC_SMBUS_READ_BYTE	0x00020000
     90 #define I2C_FUNC_SMBUS_WRITE_BYTE	0x00040000
     91 #define I2C_FUNC_SMBUS_READ_BYTE_DATA	0x00080000
     92 #define I2C_FUNC_SMBUS_WRITE_BYTE_DATA	0x00100000
     93 #define I2C_FUNC_SMBUS_READ_WORD_DATA	0x00200000
     94 #define I2C_FUNC_SMBUS_WRITE_WORD_DATA	0x00400000
     95 #define I2C_FUNC_SMBUS_PROC_CALL	0x00800000
     96 #define I2C_FUNC_SMBUS_READ_BLOCK_DATA	0x01000000
     97 #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
     98 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK	0x04000000 /* I2C-like block xfer  */
     99 #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK	0x08000000 /* w/ 1-byte reg. addr. */
    100 
    101 #define I2C_FUNC_SMBUS_BYTE		(I2C_FUNC_SMBUS_READ_BYTE | \
    102 					 I2C_FUNC_SMBUS_WRITE_BYTE)
    103 #define I2C_FUNC_SMBUS_BYTE_DATA	(I2C_FUNC_SMBUS_READ_BYTE_DATA | \
    104 					 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
    105 #define I2C_FUNC_SMBUS_WORD_DATA	(I2C_FUNC_SMBUS_READ_WORD_DATA | \
    106 					 I2C_FUNC_SMBUS_WRITE_WORD_DATA)
    107 #define I2C_FUNC_SMBUS_BLOCK_DATA	(I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
    108 					 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
    109 #define I2C_FUNC_SMBUS_I2C_BLOCK	(I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
    110 					 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
    111 
    112 #define I2C_FUNC_SMBUS_EMUL		(I2C_FUNC_SMBUS_QUICK | \
    113 					 I2C_FUNC_SMBUS_BYTE | \
    114 					 I2C_FUNC_SMBUS_BYTE_DATA | \
    115 					 I2C_FUNC_SMBUS_WORD_DATA | \
    116 					 I2C_FUNC_SMBUS_PROC_CALL | \
    117 					 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
    118 					 I2C_FUNC_SMBUS_I2C_BLOCK | \
    119 					 I2C_FUNC_SMBUS_PEC)
    120 
    121 /*
    122  * Data for SMBus Messages
    123  */
    124 #define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus standard */
    125 union i2c_smbus_data {
    126 	__u8 byte;
    127 	__u16 word;
    128 	__u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
    129 			       /* and one more for user-space compatibility */
    130 };
    131 
    132 /* i2c_smbus_xfer read or write markers */
    133 #define I2C_SMBUS_READ	1
    134 #define I2C_SMBUS_WRITE	0
    135 
    136 /* SMBus transaction types (size parameter in the above functions)
    137    Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
    138 #define I2C_SMBUS_QUICK		    0
    139 #define I2C_SMBUS_BYTE		    1
    140 #define I2C_SMBUS_BYTE_DATA	    2
    141 #define I2C_SMBUS_WORD_DATA	    3
    142 #define I2C_SMBUS_PROC_CALL	    4
    143 #define I2C_SMBUS_BLOCK_DATA	    5
    144 #define I2C_SMBUS_I2C_BLOCK_BROKEN  6
    145 #define I2C_SMBUS_BLOCK_PROC_CALL   7		/* SMBus 2.0 */
    146 #define I2C_SMBUS_I2C_BLOCK_DATA    8
    147 
    148 
    149 #endif /* _LINUX_I2C_H */
    150