uapi/linux/i2c.h

0001 /* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
0002 /*
0003  * i2c.h - definitions for the I2C bus interface
0004  *
0005  * Copyright (C) 1995-2000 Simon G. Vogl
0006  * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
0007  * Frodo Looijaard <frodol@dds.nl>
0008  */
0009
0010 #ifndef _UAPI_LINUX_I2C_H
0011 #define _UAPI_LINUX_I2C_H
0012
0013 #include <linux/types.h>
0014
0015 /**
0016  * struct i2c_msg - an I2C transaction segment beginning with START
0017  *
0018  * @addr: Slave address, either 7 or 10 bits. When this is a 10 bit address,
0019  *   %I2C_M_TEN must be set in @flags and the adapter must support
0020  *   %I2C_FUNC_10BIT_ADDR.
0021  *
0022  * @flags:
0023  *   Supported by all adapters:
0024  *   %I2C_M_RD: read data (from slave to master). Guaranteed to be 0x0001!
0025  *
0026  *   Optional:
0027  *   %I2C_M_DMA_SAFE: the buffer of this message is DMA safe. Makes only sense
0028  *     in kernelspace, because userspace buffers are copied anyway
0029  *
0030  *   Only if I2C_FUNC_10BIT_ADDR is set:
0031  *   %I2C_M_TEN: this is a 10 bit chip address
0032  *
0033  *   Only if I2C_FUNC_SMBUS_READ_BLOCK_DATA is set:
0034  *   %I2C_M_RECV_LEN: message length will be first received byte
0035  *
0036  *   Only if I2C_FUNC_NOSTART is set:
0037  *   %I2C_M_NOSTART: skip repeated start sequence
0038
0039  *   Only if I2C_FUNC_PROTOCOL_MANGLING is set:
0040  *   %I2C_M_NO_RD_ACK: in a read message, master ACK/NACK bit is skipped
0041  *   %I2C_M_IGNORE_NAK: treat NACK from client as ACK
0042  *   %I2C_M_REV_DIR_ADDR: toggles the Rd/Wr bit
0043  *   %I2C_M_STOP: force a STOP condition after the message
0044  *
0045  * @len: Number of data bytes in @buf being read from or written to the I2C
0046  *   slave address. For read transactions where %I2C_M_RECV_LEN is set, the
0047  *   caller guarantees that this buffer can hold up to %I2C_SMBUS_BLOCK_MAX
0048  *   bytes in addition to the initial length byte sent by the slave (plus,
0049  *   if used, the SMBus PEC); and this value will be incremented by the number
0050  *   of block data bytes received.
0051  *
0052  * @buf: The buffer into which data is read, or from which it's written.
0053  *
0054  * An i2c_msg is the low level representation of one segment of an I2C
0055  * transaction.  It is visible to drivers in the @i2c_transfer() procedure,
0056  * to userspace from i2c-dev, and to I2C adapter drivers through the
0057  * @i2c_adapter.@master_xfer() method.
0058  *
0059  * Except when I2C "protocol mangling" is used, all I2C adapters implement
0060  * the standard rules for I2C transactions.  Each transaction begins with a
0061  * START.  That is followed by the slave address, and a bit encoding read
0062  * versus write.  Then follow all the data bytes, possibly including a byte
0063  * with SMBus PEC.  The transfer terminates with a NAK, or when all those
0064  * bytes have been transferred and ACKed.  If this is the last message in a
0065  * group, it is followed by a STOP.  Otherwise it is followed by the next
0066  * @i2c_msg transaction segment, beginning with a (repeated) START.
0067  *
0068  * Alternatively, when the adapter supports %I2C_FUNC_PROTOCOL_MANGLING then
0069  * passing certain @flags may have changed those standard protocol behaviors.
0070  * Those flags are only for use with broken/nonconforming slaves, and with
0071  * adapters which are known to support the specific mangling options they need.
0072  */
0073 struct i2c_msg {
0074     __u16 addr;
0075     __u16 flags;
0076 #define I2C_M_RD        0x0001  /* guaranteed to be 0x0001! */
0077 #define I2C_M_TEN       0x0010  /* use only if I2C_FUNC_10BIT_ADDR */
0078 #define I2C_M_DMA_SAFE      0x0200  /* use only in kernel space */
0079 #define I2C_M_RECV_LEN      0x0400  /* use only if I2C_FUNC_SMBUS_READ_BLOCK_DATA */
0080 #define I2C_M_NO_RD_ACK     0x0800  /* use only if I2C_FUNC_PROTOCOL_MANGLING */
0081 #define I2C_M_IGNORE_NAK    0x1000  /* use only if I2C_FUNC_PROTOCOL_MANGLING */
0082 #define I2C_M_REV_DIR_ADDR  0x2000  /* use only if I2C_FUNC_PROTOCOL_MANGLING */
0083 #define I2C_M_NOSTART       0x4000  /* use only if I2C_FUNC_NOSTART */
0084 #define I2C_M_STOP      0x8000  /* use only if I2C_FUNC_PROTOCOL_MANGLING */
0085     __u16 len;
0086     __u8 *buf;
0087 };
0088
0089 /* To determine what functionality is present */
0090
0091 #define I2C_FUNC_I2C            0x00000001
0092 #define I2C_FUNC_10BIT_ADDR     0x00000002 /* required for I2C_M_TEN */
0093 #define I2C_FUNC_PROTOCOL_MANGLING  0x00000004 /* required for I2C_M_IGNORE_NAK etc. */
0094 #define I2C_FUNC_SMBUS_PEC      0x00000008
0095 #define I2C_FUNC_NOSTART        0x00000010 /* required for I2C_M_NOSTART */
0096 #define I2C_FUNC_SLAVE          0x00000020
0097 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL  0x00008000 /* SMBus 2.0 or later */
0098 #define I2C_FUNC_SMBUS_QUICK        0x00010000
0099 #define I2C_FUNC_SMBUS_READ_BYTE    0x00020000
0100 #define I2C_FUNC_SMBUS_WRITE_BYTE   0x00040000
0101 #define I2C_FUNC_SMBUS_READ_BYTE_DATA   0x00080000
0102 #define I2C_FUNC_SMBUS_WRITE_BYTE_DATA  0x00100000
0103 #define I2C_FUNC_SMBUS_READ_WORD_DATA   0x00200000
0104 #define I2C_FUNC_SMBUS_WRITE_WORD_DATA  0x00400000
0105 #define I2C_FUNC_SMBUS_PROC_CALL    0x00800000
0106 #define I2C_FUNC_SMBUS_READ_BLOCK_DATA  0x01000000 /* required for I2C_M_RECV_LEN */
0107 #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
0108 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK   0x04000000 /* I2C-like block xfer  */
0109 #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK  0x08000000 /* w/ 1-byte reg. addr. */
0110 #define I2C_FUNC_SMBUS_HOST_NOTIFY  0x10000000 /* SMBus 2.0 or later */
0111
0112 #define I2C_FUNC_SMBUS_BYTE     (I2C_FUNC_SMBUS_READ_BYTE | \
0113                      I2C_FUNC_SMBUS_WRITE_BYTE)
0114 #define I2C_FUNC_SMBUS_BYTE_DATA    (I2C_FUNC_SMBUS_READ_BYTE_DATA | \
0115                      I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
0116 #define I2C_FUNC_SMBUS_WORD_DATA    (I2C_FUNC_SMBUS_READ_WORD_DATA | \
0117                      I2C_FUNC_SMBUS_WRITE_WORD_DATA)
0118 #define I2C_FUNC_SMBUS_BLOCK_DATA   (I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
0119                      I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
0120 #define I2C_FUNC_SMBUS_I2C_BLOCK    (I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
0121                      I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
0122
0123 #define I2C_FUNC_SMBUS_EMUL     (I2C_FUNC_SMBUS_QUICK | \
0124                      I2C_FUNC_SMBUS_BYTE | \
0125                      I2C_FUNC_SMBUS_BYTE_DATA | \
0126                      I2C_FUNC_SMBUS_WORD_DATA | \
0127                      I2C_FUNC_SMBUS_PROC_CALL | \
0128                      I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
0129                      I2C_FUNC_SMBUS_I2C_BLOCK | \
0130                      I2C_FUNC_SMBUS_PEC)
0131
0132 /* if I2C_M_RECV_LEN is also supported */
0133 #define I2C_FUNC_SMBUS_EMUL_ALL     (I2C_FUNC_SMBUS_EMUL | \
0134                      I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
0135                      I2C_FUNC_SMBUS_BLOCK_PROC_CALL)
0136
0137 /*
0138  * Data for SMBus Messages
0139  */
0140 #define I2C_SMBUS_BLOCK_MAX 32  /* As specified in SMBus standard */
0141 union i2c_smbus_data {
0142     __u8 byte;
0143     __u16 word;
0144     __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
0145                    /* and one more for user-space compatibility */
0146 };
0147
0148 /* i2c_smbus_xfer read or write markers */
0149 #define I2C_SMBUS_READ  1
0150 #define I2C_SMBUS_WRITE 0
0151
0152 /* SMBus transaction types (size parameter in the above functions)
0153    Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
0154 #define I2C_SMBUS_QUICK         0
0155 #define I2C_SMBUS_BYTE          1
0156 #define I2C_SMBUS_BYTE_DATA     2
0157 #define I2C_SMBUS_WORD_DATA     3
0158 #define I2C_SMBUS_PROC_CALL     4
0159 #define I2C_SMBUS_BLOCK_DATA        5
0160 #define I2C_SMBUS_I2C_BLOCK_BROKEN  6
0161 #define I2C_SMBUS_BLOCK_PROC_CALL   7       /* SMBus 2.0 */
0162 #define I2C_SMBUS_I2C_BLOCK_DATA    8
0163
0164 #endif /* _UAPI_LINUX_I2C_H */