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 _UAPI_LINUX_I2C_H
11 #define _UAPI_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!
25 *
26 * Optional:
27 * %I2C_M_DMA_SAFE: the buffer of this message is DMA safe. Makes only sense
28 * in kernelspace, because userspace buffers are copied anyway
29 *
30 * Only if I2C_FUNC_10BIT_ADDR is set:
31 * %I2C_M_TEN: this is a 10 bit chip address
32 *
33 * Only if I2C_FUNC_SMBUS_READ_BLOCK_DATA is set:
34 * %I2C_M_RECV_LEN: message length will be first received byte
35 *
36 * Only if I2C_FUNC_NOSTART is set:
37 * %I2C_M_NOSTART: skip repeated start sequence
38
39 * Only if I2C_FUNC_PROTOCOL_MANGLING is set:
40 * %I2C_M_NO_RD_ACK: in a read message, master ACK/NACK bit is skipped
41 * %I2C_M_IGNORE_NAK: treat NACK from client as ACK
42 * %I2C_M_REV_DIR_ADDR: toggles the Rd/Wr bit
43 * %I2C_M_STOP: force a STOP condition after the message
44 *
45 * @len: Number of data bytes in @buf being read from or written to the I2C
46 * slave address. For read transactions where %I2C_M_RECV_LEN is set, the
47 * caller guarantees that this buffer can hold up to %I2C_SMBUS_BLOCK_MAX
48 * bytes in addition to the initial length byte sent by the slave (plus,
49 * if used, the SMBus PEC); and this value will be incremented by the number
50 * of block data bytes received.
51 *
52 * @buf: The buffer into which data is read, or from which it's written.
53 *
54 * An i2c_msg is the low level representation of one segment of an I2C
55 * transaction. It is visible to drivers in the @i2c_transfer() procedure,
56 * to userspace from i2c-dev, and to I2C adapter drivers through the
57 * @i2c_adapter.@master_xfer() method.
58 *
59 * Except when I2C "protocol mangling" is used, all I2C adapters implement
60 * the standard rules for I2C transactions. Each transaction begins with a
61 * START. That is followed by the slave address, and a bit encoding read
62 * versus write. Then follow all the data bytes, possibly including a byte
63 * with SMBus PEC. The transfer terminates with a NAK, or when all those
64 * bytes have been transferred and ACKed. If this is the last message in a
65 * group, it is followed by a STOP. Otherwise it is followed by the next
66 * @i2c_msg transaction segment, beginning with a (repeated) START.
67 *
68 * Alternatively, when the adapter supports %I2C_FUNC_PROTOCOL_MANGLING then
69 * passing certain @flags may have changed those standard protocol behaviors.
70 * Those flags are only for use with broken/nonconforming slaves, and with
71 * adapters which are known to support the specific mangling options they need.
72 */
73 struct i2c_msg {
74 __u16 addr;
75 __u16 flags;
76 #define I2C_M_RD 0x0001 /* guaranteed to be 0x0001! */
77 #define I2C_M_TEN 0x0010 /* use only if I2C_FUNC_10BIT_ADDR */
78 #define I2C_M_DMA_SAFE 0x0200 /* use only in kernel space */
79 #define I2C_M_RECV_LEN 0x0400 /* use only if I2C_FUNC_SMBUS_READ_BLOCK_DATA */
80 #define I2C_M_NO_RD_ACK 0x0800 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
81 #define I2C_M_IGNORE_NAK 0x1000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
82 #define I2C_M_REV_DIR_ADDR 0x2000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
83 #define I2C_M_NOSTART 0x4000 /* use only if I2C_FUNC_NOSTART */
84 #define I2C_M_STOP 0x8000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
85 __u16 len;
86 __u8 *buf;
87 };
88
89 /* To determine what functionality is present */
90
91 #define I2C_FUNC_I2C 0x00000001
92 #define I2C_FUNC_10BIT_ADDR 0x00000002 /* required for I2C_M_TEN */
93 #define I2C_FUNC_PROTOCOL_MANGLING 0x00000004 /* required for I2C_M_IGNORE_NAK etc. */
94 #define I2C_FUNC_SMBUS_PEC 0x00000008
95 #define I2C_FUNC_NOSTART 0x00000010 /* required for I2C_M_NOSTART */
96 #define I2C_FUNC_SLAVE 0x00000020
97 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL 0x00008000 /* SMBus 2.0 or later */
98 #define I2C_FUNC_SMBUS_QUICK 0x00010000
99 #define I2C_FUNC_SMBUS_READ_BYTE 0x00020000
100 #define I2C_FUNC_SMBUS_WRITE_BYTE 0x00040000
101 #define I2C_FUNC_SMBUS_READ_BYTE_DATA 0x00080000
102 #define I2C_FUNC_SMBUS_WRITE_BYTE_DATA 0x00100000
103 #define I2C_FUNC_SMBUS_READ_WORD_DATA 0x00200000
104 #define I2C_FUNC_SMBUS_WRITE_WORD_DATA 0x00400000
105 #define I2C_FUNC_SMBUS_PROC_CALL 0x00800000
106 #define I2C_FUNC_SMBUS_READ_BLOCK_DATA 0x01000000 /* required for I2C_M_RECV_LEN */
107 #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
108 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK 0x04000000 /* I2C-like block xfer */
109 #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */
110 #define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000 /* SMBus 2.0 or later */
111
112 #define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \
113 I2C_FUNC_SMBUS_WRITE_BYTE)
114 #define I2C_FUNC_SMBUS_BYTE_DATA (I2C_FUNC_SMBUS_READ_BYTE_DATA | \
115 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
116 #define I2C_FUNC_SMBUS_WORD_DATA (I2C_FUNC_SMBUS_READ_WORD_DATA | \
117 I2C_FUNC_SMBUS_WRITE_WORD_DATA)
118 #define I2C_FUNC_SMBUS_BLOCK_DATA (I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
119 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
120 #define I2C_FUNC_SMBUS_I2C_BLOCK (I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
121 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
122
123 #define I2C_FUNC_SMBUS_EMUL (I2C_FUNC_SMBUS_QUICK | \
124 I2C_FUNC_SMBUS_BYTE | \
125 I2C_FUNC_SMBUS_BYTE_DATA | \
126 I2C_FUNC_SMBUS_WORD_DATA | \
127 I2C_FUNC_SMBUS_PROC_CALL | \
128 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
129 I2C_FUNC_SMBUS_I2C_BLOCK | \
130 I2C_FUNC_SMBUS_PEC)
131
132 /* if I2C_M_RECV_LEN is also supported */
133 #define I2C_FUNC_SMBUS_EMUL_ALL (I2C_FUNC_SMBUS_EMUL | \
134 I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
135 I2C_FUNC_SMBUS_BLOCK_PROC_CALL)
136
137 /*
138 * Data for SMBus Messages
139 */
140 #define I2C_SMBUS_BLOCK_MAX 32 /* As specified in SMBus standard */
141 union i2c_smbus_data {
142 __u8 byte;
143 __u16 word;
144 __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
145 /* and one more for user-space compatibility */
146 };
147
148 /* i2c_smbus_xfer read or write markers */
149 #define I2C_SMBUS_READ 1
150 #define I2C_SMBUS_WRITE 0
151
152 /* SMBus transaction types (size parameter in the above functions)
153 Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
154 #define I2C_SMBUS_QUICK 0
155 #define I2C_SMBUS_BYTE 1
156 #define I2C_SMBUS_BYTE_DATA 2
157 #define I2C_SMBUS_WORD_DATA 3
158 #define I2C_SMBUS_PROC_CALL 4
159 #define I2C_SMBUS_BLOCK_DATA 5
160 #define I2C_SMBUS_I2C_BLOCK_BROKEN 6
161 #define I2C_SMBUS_BLOCK_PROC_CALL 7 /* SMBus 2.0 */
162 #define I2C_SMBUS_I2C_BLOCK_DATA 8
163
164 #endif /* _UAPI_LINUX_I2C_H */
165
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