include/uapi/linux/i2c.h

   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., 51 Franklin Street, Fifth Floor, Boston,
  21     MA 02110-1301 USA.                                                       */
  22 /* ------------------------------------------------------------------------- */
  23
  24 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
  25    Frodo Looijaard <frodol@dds.nl> */
  26
  27 #ifndef _UAPI_LINUX_I2C_H
  28 #define _UAPI_LINUX_I2C_H
  29
  30 #include <linux/types.h>
  31
  32 /**
  33  * struct i2c_msg - an I2C transaction segment beginning with START
  34  * @addr: Slave address, either seven or ten bits.  When this is a ten
  35  *      bit address, I2C_M_TEN must be set in @flags and the adapter
  36  *      must support I2C_FUNC_10BIT_ADDR.
  37  * @flags: I2C_M_RD is handled by all adapters.  No other flags may be
  38  *      provided unless the adapter exported the relevant I2C_FUNC_*
  39  *      flags through i2c_check_functionality().
  40  * @len: Number of data bytes in @buf being read from or written to the
  41  *      I2C slave address.  For read transactions where I2C_M_RECV_LEN
  42  *      is set, the caller guarantees that this buffer can hold up to
  43  *      32 bytes in addition to the initial length byte sent by the
  44  *      slave (plus, if used, the SMBus PEC); and this value will be
  45  *      incremented by the number of block data bytes received.
  46  * @buf: The buffer into which data is read, or from which it's written.
  47  *
  48  * An i2c_msg is the low level representation of one segment of an I2C
  49  * transaction.  It is visible to drivers in the @i2c_transfer() procedure,
  50  * to userspace from i2c-dev, and to I2C adapter drivers through the
  51  * @i2c_adapter.@master_xfer() method.
  52  *
  53  * Except when I2C "protocol mangling" is used, all I2C adapters implement
  54  * the standard rules for I2C transactions.  Each transaction begins with a
  55  * START.  That is followed by the slave address, and a bit encoding read
  56  * versus write.  Then follow all the data bytes, possibly including a byte
  57  * with SMBus PEC.  The transfer terminates with a NAK, or when all those
  58  * bytes have been transferred and ACKed.  If this is the last message in a
  59  * group, it is followed by a STOP.  Otherwise it is followed by the next
  60  * @i2c_msg transaction segment, beginning with a (repeated) START.
  61  *
  62  * Alternatively, when the adapter supports I2C_FUNC_PROTOCOL_MANGLING then
  63  * passing certain @flags may have changed those standard protocol behaviors.
  64  * Those flags are only for use with broken/nonconforming slaves, and with
  65  * adapters which are known to support the specific mangling options they
  66  * need (one or more of IGNORE_NAK, NO_RD_ACK, NOSTART, and REV_DIR_ADDR).
  67  */
  68 struct i2c_msg {
  69         __u16 addr;     /* slave address                        */
  70         __u16 flags;
  71 #define I2C_M_TEN               0x0010  /* this is a ten bit chip address */
  72 #define I2C_M_RD                0x0001  /* read data, from slave to master */
  73 #define I2C_M_STOP              0x8000  /* if I2C_FUNC_PROTOCOL_MANGLING */
  74 #define I2C_M_NOSTART           0x4000  /* if I2C_FUNC_NOSTART */
  75 #define I2C_M_REV_DIR_ADDR      0x2000  /* if I2C_FUNC_PROTOCOL_MANGLING */
  76 #define I2C_M_IGNORE_NAK        0x1000  /* if I2C_FUNC_PROTOCOL_MANGLING */
  77 #define I2C_M_NO_RD_ACK         0x0800  /* if I2C_FUNC_PROTOCOL_MANGLING */
  78 #define I2C_M_RECV_LEN          0x0400  /* length will be first received byte */
  79         __u16 len;              /* msg length                           */
  80         __u8 *buf;              /* pointer to msg data                  */
  81 };
  82
  83 /* To determine what functionality is present */
  84
  85 #define I2C_FUNC_I2C                    0x00000001
  86 #define I2C_FUNC_10BIT_ADDR             0x00000002
  87 #define I2C_FUNC_PROTOCOL_MANGLING      0x00000004 /* I2C_M_IGNORE_NAK etc. */
  88 #define I2C_FUNC_SMBUS_PEC              0x00000008
  89 #define I2C_FUNC_NOSTART                0x00000010 /* I2C_M_NOSTART */
  90 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL  0x00008000 /* SMBus 2.0 */
  91 #define I2C_FUNC_SMBUS_QUICK            0x00010000
  92 #define I2C_FUNC_SMBUS_READ_BYTE        0x00020000
  93 #define I2C_FUNC_SMBUS_WRITE_BYTE       0x00040000
  94 #define I2C_FUNC_SMBUS_READ_BYTE_DATA   0x00080000
  95 #define I2C_FUNC_SMBUS_WRITE_BYTE_DATA  0x00100000
  96 #define I2C_FUNC_SMBUS_READ_WORD_DATA   0x00200000
  97 #define I2C_FUNC_SMBUS_WRITE_WORD_DATA  0x00400000
  98 #define I2C_FUNC_SMBUS_PROC_CALL        0x00800000
  99 #define I2C_FUNC_SMBUS_READ_BLOCK_DATA  0x01000000
 100 #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
 101 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK   0x04000000 /* I2C-like block xfer  */
 102 #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK  0x08000000 /* w/ 1-byte reg. addr. */
 103
 104 #define I2C_FUNC_SMBUS_BYTE             (I2C_FUNC_SMBUS_READ_BYTE | \
 105                                          I2C_FUNC_SMBUS_WRITE_BYTE)
 106 #define I2C_FUNC_SMBUS_BYTE_DATA        (I2C_FUNC_SMBUS_READ_BYTE_DATA | \
 107                                          I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
 108 #define I2C_FUNC_SMBUS_WORD_DATA        (I2C_FUNC_SMBUS_READ_WORD_DATA | \
 109                                          I2C_FUNC_SMBUS_WRITE_WORD_DATA)
 110 #define I2C_FUNC_SMBUS_BLOCK_DATA       (I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
 111                                          I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
 112 #define I2C_FUNC_SMBUS_I2C_BLOCK        (I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
 113                                          I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
 114
 115 #define I2C_FUNC_SMBUS_EMUL             (I2C_FUNC_SMBUS_QUICK | \
 116                                          I2C_FUNC_SMBUS_BYTE | \
 117                                          I2C_FUNC_SMBUS_BYTE_DATA | \
 118                                          I2C_FUNC_SMBUS_WORD_DATA | \
 119                                          I2C_FUNC_SMBUS_PROC_CALL | \
 120                                          I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
 121                                          I2C_FUNC_SMBUS_I2C_BLOCK | \
 122                                          I2C_FUNC_SMBUS_PEC)
 123
 124 /*
 125  * Data for SMBus Messages
 126  */
 127 #define I2C_SMBUS_BLOCK_MAX     32      /* As specified in SMBus standard */
 128 union i2c_smbus_data {
 129         __u8 byte;
 130         __u16 word;
 131         __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
 132                                /* and one more for user-space compatibility */
 133 };
 134
 135 /* i2c_smbus_xfer read or write markers */
 136 #define I2C_SMBUS_READ  1
 137 #define I2C_SMBUS_WRITE 0
 138
 139 /* SMBus transaction types (size parameter in the above functions)
 140    Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
 141 #define I2C_SMBUS_QUICK             0
 142 #define I2C_SMBUS_BYTE              1
 143 #define I2C_SMBUS_BYTE_DATA         2
 144 #define I2C_SMBUS_WORD_DATA         3
 145 #define I2C_SMBUS_PROC_CALL         4
 146 #define I2C_SMBUS_BLOCK_DATA        5
 147 #define I2C_SMBUS_I2C_BLOCK_BROKEN  6
 148 #define I2C_SMBUS_BLOCK_PROC_CALL   7           /* SMBus 2.0 */
 149 #define I2C_SMBUS_I2C_BLOCK_DATA    8
 150
 151 #endif /* _UAPI_LINUX_I2C_H */