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