master
1/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
2/*
3 * i2c.h - definitions for the I2C bus interface
4 *
5 * Copyright (C) 1995-2000 Simon G. Vogl
6 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
7 * Frodo Looijaard <frodol@dds.nl>
8 */
9
10#ifndef _LINUX_I2C_H
11#define _LINUX_I2C_H
12
13#include <linux/types.h>
14
15/**
16 * struct i2c_msg - an I2C transaction segment beginning with START
17 *
18 * @addr: Slave address, either 7 or 10 bits. When this is a 10 bit address,
19 * %I2C_M_TEN must be set in @flags and the adapter must support
20 * %I2C_FUNC_10BIT_ADDR.
21 *
22 * @flags:
23 * Supported by all adapters:
24 * %I2C_M_RD: read data (from slave to master). Guaranteed to be 0x0001! If
25 * not set, the transaction is interpreted as write.
26 *
27 * Optional:
28 * %I2C_M_DMA_SAFE: the buffer of this message is DMA safe. Makes only sense
29 * in kernelspace, because userspace buffers are copied anyway
30 *
31 * Only if I2C_FUNC_10BIT_ADDR is set:
32 * %I2C_M_TEN: this is a 10 bit chip address
33 *
34 * Only if I2C_FUNC_SMBUS_READ_BLOCK_DATA is set:
35 * %I2C_M_RECV_LEN: message length will be first received byte
36 *
37 * Only if I2C_FUNC_NOSTART is set:
38 * %I2C_M_NOSTART: skip repeated start sequence
39
40 * Only if I2C_FUNC_PROTOCOL_MANGLING is set:
41 * %I2C_M_NO_RD_ACK: in a read message, master ACK/NACK bit is skipped
42 * %I2C_M_IGNORE_NAK: treat NACK from client as ACK
43 * %I2C_M_REV_DIR_ADDR: toggles the Rd/Wr bit
44 * %I2C_M_STOP: force a STOP condition after the message
45 *
46 * @len: Number of data bytes in @buf being read from or written to the I2C
47 * slave address. For read transactions where %I2C_M_RECV_LEN is set, the
48 * caller guarantees that this buffer can hold up to %I2C_SMBUS_BLOCK_MAX
49 * bytes in addition to the initial length byte sent by the slave (plus,
50 * if used, the SMBus PEC); and this value will be incremented by the number
51 * of block data bytes received.
52 *
53 * @buf: The buffer into which data is read, or from which it's written.
54 *
55 * An i2c_msg is the low level representation of one segment of an I2C
56 * transaction. It is visible to drivers in the @i2c_transfer() procedure,
57 * to userspace from i2c-dev, and to I2C adapter drivers through the
58 * @i2c_adapter.@master_xfer() method.
59 *
60 * Except when I2C "protocol mangling" is used, all I2C adapters implement
61 * the standard rules for I2C transactions. Each transaction begins with a
62 * START. That is followed by the slave address, and a bit encoding read
63 * versus write. Then follow all the data bytes, possibly including a byte
64 * with SMBus PEC. The transfer terminates with a NAK, or when all those
65 * bytes have been transferred and ACKed. If this is the last message in a
66 * group, it is followed by a STOP. Otherwise it is followed by the next
67 * @i2c_msg transaction segment, beginning with a (repeated) START.
68 *
69 * Alternatively, when the adapter supports %I2C_FUNC_PROTOCOL_MANGLING then
70 * passing certain @flags may have changed those standard protocol behaviors.
71 * Those flags are only for use with broken/nonconforming slaves, and with
72 * adapters which are known to support the specific mangling options they need.
73 */
74struct i2c_msg {
75 __u16 addr;
76 __u16 flags;
77#define I2C_M_RD 0x0001 /* guaranteed to be 0x0001! */
78#define I2C_M_TEN 0x0010 /* use only if I2C_FUNC_10BIT_ADDR */
79#define I2C_M_DMA_SAFE 0x0200 /* use only in kernel space */
80#define I2C_M_RECV_LEN 0x0400 /* use only if I2C_FUNC_SMBUS_READ_BLOCK_DATA */
81#define I2C_M_NO_RD_ACK 0x0800 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
82#define I2C_M_IGNORE_NAK 0x1000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
83#define I2C_M_REV_DIR_ADDR 0x2000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
84#define I2C_M_NOSTART 0x4000 /* use only if I2C_FUNC_NOSTART */
85#define I2C_M_STOP 0x8000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
86 __u16 len;
87 __u8 *buf;
88};
89
90/* To determine what functionality is present */
91
92#define I2C_FUNC_I2C 0x00000001
93#define I2C_FUNC_10BIT_ADDR 0x00000002 /* required for I2C_M_TEN */
94#define I2C_FUNC_PROTOCOL_MANGLING 0x00000004 /* required for I2C_M_IGNORE_NAK etc. */
95#define I2C_FUNC_SMBUS_PEC 0x00000008
96#define I2C_FUNC_NOSTART 0x00000010 /* required for I2C_M_NOSTART */
97#define I2C_FUNC_SLAVE 0x00000020
98#define I2C_FUNC_SMBUS_BLOCK_PROC_CALL 0x00008000 /* SMBus 2.0 or later */
99#define I2C_FUNC_SMBUS_QUICK 0x00010000
100#define I2C_FUNC_SMBUS_READ_BYTE 0x00020000
101#define I2C_FUNC_SMBUS_WRITE_BYTE 0x00040000
102#define I2C_FUNC_SMBUS_READ_BYTE_DATA 0x00080000
103#define I2C_FUNC_SMBUS_WRITE_BYTE_DATA 0x00100000
104#define I2C_FUNC_SMBUS_READ_WORD_DATA 0x00200000
105#define I2C_FUNC_SMBUS_WRITE_WORD_DATA 0x00400000
106#define I2C_FUNC_SMBUS_PROC_CALL 0x00800000
107#define I2C_FUNC_SMBUS_READ_BLOCK_DATA 0x01000000 /* required for I2C_M_RECV_LEN */
108#define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
109#define I2C_FUNC_SMBUS_READ_I2C_BLOCK 0x04000000 /* I2C-like block xfer */
110#define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */
111#define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000 /* SMBus 2.0 or later */
112
113#define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \
114 I2C_FUNC_SMBUS_WRITE_BYTE)
115#define I2C_FUNC_SMBUS_BYTE_DATA (I2C_FUNC_SMBUS_READ_BYTE_DATA | \
116 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
117#define I2C_FUNC_SMBUS_WORD_DATA (I2C_FUNC_SMBUS_READ_WORD_DATA | \
118 I2C_FUNC_SMBUS_WRITE_WORD_DATA)
119#define I2C_FUNC_SMBUS_BLOCK_DATA (I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
120 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
121#define I2C_FUNC_SMBUS_I2C_BLOCK (I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
122 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
123
124#define I2C_FUNC_SMBUS_EMUL (I2C_FUNC_SMBUS_QUICK | \
125 I2C_FUNC_SMBUS_BYTE | \
126 I2C_FUNC_SMBUS_BYTE_DATA | \
127 I2C_FUNC_SMBUS_WORD_DATA | \
128 I2C_FUNC_SMBUS_PROC_CALL | \
129 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
130 I2C_FUNC_SMBUS_I2C_BLOCK | \
131 I2C_FUNC_SMBUS_PEC)
132
133/* if I2C_M_RECV_LEN is also supported */
134#define I2C_FUNC_SMBUS_EMUL_ALL (I2C_FUNC_SMBUS_EMUL | \
135 I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
136 I2C_FUNC_SMBUS_BLOCK_PROC_CALL)
137
138/*
139 * Data for SMBus Messages
140 */
141#define I2C_SMBUS_BLOCK_MAX 32 /* As specified in SMBus standard */
142union i2c_smbus_data {
143 __u8 byte;
144 __u16 word;
145 __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
146 /* and one more for user-space compatibility */
147};
148
149/* i2c_smbus_xfer read or write markers */
150#define I2C_SMBUS_READ 1
151#define I2C_SMBUS_WRITE 0
152
153/* SMBus transaction types (size parameter in the above functions)
154 Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
155#define I2C_SMBUS_QUICK 0
156#define I2C_SMBUS_BYTE 1
157#define I2C_SMBUS_BYTE_DATA 2
158#define I2C_SMBUS_WORD_DATA 3
159#define I2C_SMBUS_PROC_CALL 4
160#define I2C_SMBUS_BLOCK_DATA 5
161#define I2C_SMBUS_I2C_BLOCK_BROKEN 6
162#define I2C_SMBUS_BLOCK_PROC_CALL 7 /* SMBus 2.0 */
163#define I2C_SMBUS_I2C_BLOCK_DATA 8
164
165#endif /* _LINUX_I2C_H */