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! 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 */ 74 struct 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 */ 142 union 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 /* _UAPI_LINUX_I2C_H */ 166