xref: /openbmc/linux/include/uapi/linux/i2c.h (revision a701d28e)
1 /* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
2 /* ------------------------------------------------------------------------- */
3 /*									     */
4 /* i2c.h - definitions for the i2c-bus interface			     */
5 /*									     */
6 /* ------------------------------------------------------------------------- */
7 /*   Copyright (C) 1995-2000 Simon G. Vogl
8 
9     This program is free software; you can redistribute it and/or modify
10     it under the terms of the GNU General Public License as published by
11     the Free Software Foundation; either version 2 of the License, or
12     (at your option) any later version.
13 
14     This program is distributed in the hope that it will be useful,
15     but WITHOUT ANY WARRANTY; without even the implied warranty of
16     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17     GNU General Public License for more details.
18 
19     You should have received a copy of the GNU General Public License
20     along with this program; if not, write to the Free Software
21     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
22     MA 02110-1301 USA.							     */
23 /* ------------------------------------------------------------------------- */
24 
25 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
26    Frodo Looijaard <frodol@dds.nl> */
27 
28 #ifndef _UAPI_LINUX_I2C_H
29 #define _UAPI_LINUX_I2C_H
30 
31 #include <linux/types.h>
32 
33 /**
34  * struct i2c_msg - an I2C transaction segment beginning with START
35  * @addr: Slave address, either seven or ten bits.  When this is a ten
36  *	bit address, I2C_M_TEN must be set in @flags and the adapter
37  *	must support I2C_FUNC_10BIT_ADDR.
38  * @flags: I2C_M_RD is handled by all adapters.  No other flags may be
39  *	provided unless the adapter exported the relevant I2C_FUNC_*
40  *	flags through i2c_check_functionality().
41  * @len: Number of data bytes in @buf being read from or written to the
42  *	I2C slave address.  For read transactions where I2C_M_RECV_LEN
43  *	is set, the caller guarantees that this buffer can hold up to
44  *	32 bytes in addition to the initial length byte sent by the
45  *	slave (plus, if used, the SMBus PEC); and this value will be
46  *	incremented by the number of block data bytes received.
47  * @buf: The buffer into which data is read, or from which it's written.
48  *
49  * An i2c_msg is the low level representation of one segment of an I2C
50  * transaction.  It is visible to drivers in the @i2c_transfer() procedure,
51  * to userspace from i2c-dev, and to I2C adapter drivers through the
52  * @i2c_adapter.@master_xfer() method.
53  *
54  * Except when I2C "protocol mangling" is used, all I2C adapters implement
55  * the standard rules for I2C transactions.  Each transaction begins with a
56  * START.  That is followed by the slave address, and a bit encoding read
57  * versus write.  Then follow all the data bytes, possibly including a byte
58  * with SMBus PEC.  The transfer terminates with a NAK, or when all those
59  * bytes have been transferred and ACKed.  If this is the last message in a
60  * group, it is followed by a STOP.  Otherwise it is followed by the next
61  * @i2c_msg transaction segment, beginning with a (repeated) START.
62  *
63  * Alternatively, when the adapter supports I2C_FUNC_PROTOCOL_MANGLING then
64  * passing certain @flags may have changed those standard protocol behaviors.
65  * Those flags are only for use with broken/nonconforming slaves, and with
66  * adapters which are known to support the specific mangling options they
67  * need (one or more of IGNORE_NAK, NO_RD_ACK, NOSTART, and REV_DIR_ADDR).
68  */
69 struct i2c_msg {
70 	__u16 addr;	/* slave address			*/
71 	__u16 flags;
72 #define I2C_M_RD		0x0001	/* read data, from slave to master */
73 					/* I2C_M_RD is guaranteed to be 0x0001! */
74 #define I2C_M_TEN		0x0010	/* this is a ten bit chip address */
75 #define I2C_M_DMA_SAFE		0x0200	/* the buffer of this message is DMA safe */
76 					/* makes only sense in kernelspace */
77 					/* userspace buffers are copied anyway */
78 #define I2C_M_RECV_LEN		0x0400	/* length will be first received byte */
79 #define I2C_M_NO_RD_ACK		0x0800	/* if I2C_FUNC_PROTOCOL_MANGLING */
80 #define I2C_M_IGNORE_NAK	0x1000	/* if I2C_FUNC_PROTOCOL_MANGLING */
81 #define I2C_M_REV_DIR_ADDR	0x2000	/* if I2C_FUNC_PROTOCOL_MANGLING */
82 #define I2C_M_NOSTART		0x4000	/* if I2C_FUNC_NOSTART */
83 #define I2C_M_STOP		0x8000	/* if I2C_FUNC_PROTOCOL_MANGLING */
84 	__u16 len;		/* msg length				*/
85 	__u8 *buf;		/* pointer to msg data			*/
86 };
87 
88 /* To determine what functionality is present */
89 
90 #define I2C_FUNC_I2C			0x00000001
91 #define I2C_FUNC_10BIT_ADDR		0x00000002
92 #define I2C_FUNC_PROTOCOL_MANGLING	0x00000004 /* I2C_M_IGNORE_NAK etc. */
93 #define I2C_FUNC_SMBUS_PEC		0x00000008
94 #define I2C_FUNC_NOSTART		0x00000010 /* I2C_M_NOSTART */
95 #define I2C_FUNC_SLAVE			0x00000020
96 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL	0x00008000 /* SMBus 2.0 */
97 #define I2C_FUNC_SMBUS_QUICK		0x00010000
98 #define I2C_FUNC_SMBUS_READ_BYTE	0x00020000
99 #define I2C_FUNC_SMBUS_WRITE_BYTE	0x00040000
100 #define I2C_FUNC_SMBUS_READ_BYTE_DATA	0x00080000
101 #define I2C_FUNC_SMBUS_WRITE_BYTE_DATA	0x00100000
102 #define I2C_FUNC_SMBUS_READ_WORD_DATA	0x00200000
103 #define I2C_FUNC_SMBUS_WRITE_WORD_DATA	0x00400000
104 #define I2C_FUNC_SMBUS_PROC_CALL	0x00800000
105 #define I2C_FUNC_SMBUS_READ_BLOCK_DATA	0x01000000
106 #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
107 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK	0x04000000 /* I2C-like block xfer  */
108 #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK	0x08000000 /* w/ 1-byte reg. addr. */
109 #define I2C_FUNC_SMBUS_HOST_NOTIFY	0x10000000
110 
111 #define I2C_FUNC_SMBUS_BYTE		(I2C_FUNC_SMBUS_READ_BYTE | \
112 					 I2C_FUNC_SMBUS_WRITE_BYTE)
113 #define I2C_FUNC_SMBUS_BYTE_DATA	(I2C_FUNC_SMBUS_READ_BYTE_DATA | \
114 					 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
115 #define I2C_FUNC_SMBUS_WORD_DATA	(I2C_FUNC_SMBUS_READ_WORD_DATA | \
116 					 I2C_FUNC_SMBUS_WRITE_WORD_DATA)
117 #define I2C_FUNC_SMBUS_BLOCK_DATA	(I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
118 					 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
119 #define I2C_FUNC_SMBUS_I2C_BLOCK	(I2C_FUNC_SMBUS_READ_I2C_BLOCK | \
120 					 I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
121 
122 #define I2C_FUNC_SMBUS_EMUL		(I2C_FUNC_SMBUS_QUICK | \
123 					 I2C_FUNC_SMBUS_BYTE | \
124 					 I2C_FUNC_SMBUS_BYTE_DATA | \
125 					 I2C_FUNC_SMBUS_WORD_DATA | \
126 					 I2C_FUNC_SMBUS_PROC_CALL | \
127 					 I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
128 					 I2C_FUNC_SMBUS_I2C_BLOCK | \
129 					 I2C_FUNC_SMBUS_PEC)
130 
131 /*
132  * Data for SMBus Messages
133  */
134 #define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus standard */
135 union i2c_smbus_data {
136 	__u8 byte;
137 	__u16 word;
138 	__u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
139 			       /* and one more for user-space compatibility */
140 };
141 
142 /* i2c_smbus_xfer read or write markers */
143 #define I2C_SMBUS_READ	1
144 #define I2C_SMBUS_WRITE	0
145 
146 /* SMBus transaction types (size parameter in the above functions)
147    Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */
148 #define I2C_SMBUS_QUICK		    0
149 #define I2C_SMBUS_BYTE		    1
150 #define I2C_SMBUS_BYTE_DATA	    2
151 #define I2C_SMBUS_WORD_DATA	    3
152 #define I2C_SMBUS_PROC_CALL	    4
153 #define I2C_SMBUS_BLOCK_DATA	    5
154 #define I2C_SMBUS_I2C_BLOCK_BROKEN  6
155 #define I2C_SMBUS_BLOCK_PROC_CALL   7		/* SMBus 2.0 */
156 #define I2C_SMBUS_I2C_BLOCK_DATA    8
157 
158 #endif /* _UAPI_LINUX_I2C_H */
159