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i2c.h
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/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ /* * i2c.h - definitions for the I2C bus interface * * Copyright (C) 1995-2000 Simon G. Vogl * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and * Frodo Looijaard <frodol@dds.nl> */ #ifndef _LINUX_I2C_H #define _LINUX_I2C_H #include <linux/types.h> /** * struct i2c_msg - an I2C transaction segment beginning with START * * @addr: Slave address, either 7 or 10 bits. When this is a 10 bit address, * %I2C_M_TEN must be set in @flags and the adapter must support * %I2C_FUNC_10BIT_ADDR. * * @flags: * Supported by all adapters: * %I2C_M_RD: read data (from slave to master). Guaranteed to be 0x0001! * * Optional: * %I2C_M_DMA_SAFE: the buffer of this message is DMA safe. Makes only sense * in kernelspace, because userspace buffers are copied anyway * * Only if I2C_FUNC_10BIT_ADDR is set: * %I2C_M_TEN: this is a 10 bit chip address * * Only if I2C_FUNC_SMBUS_READ_BLOCK_DATA is set: * %I2C_M_RECV_LEN: message length will be first received byte * * Only if I2C_FUNC_NOSTART is set: * %I2C_M_NOSTART: skip repeated start sequence * Only if I2C_FUNC_PROTOCOL_MANGLING is set: * %I2C_M_NO_RD_ACK: in a read message, master ACK/NACK bit is skipped * %I2C_M_IGNORE_NAK: treat NACK from client as ACK * %I2C_M_REV_DIR_ADDR: toggles the Rd/Wr bit * %I2C_M_STOP: force a STOP condition after the message * * @len: Number of data bytes in @buf being read from or written to the I2C * slave address. For read transactions where %I2C_M_RECV_LEN is set, the * caller guarantees that this buffer can hold up to %I2C_SMBUS_BLOCK_MAX * bytes in addition to the initial length byte sent by the slave (plus, * if used, the SMBus PEC); and this value will be incremented by the number * of block data bytes received. * * @buf: The buffer into which data is read, or from which it's written. * * An i2c_msg is the low level representation of one segment of an I2C * transaction. It is visible to drivers in the @i2c_transfer() procedure, * to userspace from i2c-dev, and to I2C adapter drivers through the * @i2c_adapter.@master_xfer() method. * * Except when I2C "protocol mangling" is used, all I2C adapters implement * the standard rules for I2C transactions. Each transaction begins with a * START. That is followed by the slave address, and a bit encoding read * versus write. Then follow all the data bytes, possibly including a byte * with SMBus PEC. The transfer terminates with a NAK, or when all those * bytes have been transferred and ACKed. If this is the last message in a * group, it is followed by a STOP. Otherwise it is followed by the next * @i2c_msg transaction segment, beginning with a (repeated) START. * * Alternatively, when the adapter supports %I2C_FUNC_PROTOCOL_MANGLING then * passing certain @flags may have changed those standard protocol behaviors. * Those flags are only for use with broken/nonconforming slaves, and with * adapters which are known to support the specific mangling options they need. */ struct i2c_msg { __u16 addr; __u16 flags; #define I2C_M_RD 0x0001 /* guaranteed to be 0x0001! */ #define I2C_M_TEN 0x0010 /* use only if I2C_FUNC_10BIT_ADDR */ #define I2C_M_DMA_SAFE 0x0200 /* use only in kernel space */ #define I2C_M_RECV_LEN 0x0400 /* use only if I2C_FUNC_SMBUS_READ_BLOCK_DATA */ #define I2C_M_NO_RD_ACK 0x0800 /* use only if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_IGNORE_NAK 0x1000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_REV_DIR_ADDR 0x2000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_NOSTART 0x4000 /* use only if I2C_FUNC_NOSTART */ #define I2C_M_STOP 0x8000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */ __u16 len; __u8 *buf; }; /* To determine what functionality is present */ #define I2C_FUNC_I2C 0x00000001 #define I2C_FUNC_10BIT_ADDR 0x00000002 /* required for I2C_M_TEN */ #define I2C_FUNC_PROTOCOL_MANGLING 0x00000004 /* required for I2C_M_IGNORE_NAK etc. */ #define I2C_FUNC_SMBUS_PEC 0x00000008 #define I2C_FUNC_NOSTART 0x00000010 /* required for I2C_M_NOSTART */ #define I2C_FUNC_SLAVE 0x00000020 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL 0x00008000 /* SMBus 2.0 or later */ #define I2C_FUNC_SMBUS_QUICK 0x00010000 #define I2C_FUNC_SMBUS_READ_BYTE 0x00020000 #define I2C_FUNC_SMBUS_WRITE_BYTE 0x00040000 #define I2C_FUNC_SMBUS_READ_BYTE_DATA 0x00080000 #define I2C_FUNC_SMBUS_WRITE_BYTE_DATA 0x00100000 #define I2C_FUNC_SMBUS_READ_WORD_DATA 0x00200000 #define I2C_FUNC_SMBUS_WRITE_WORD_DATA 0x00400000 #define I2C_FUNC_SMBUS_PROC_CALL 0x00800000 #define I2C_FUNC_SMBUS_READ_BLOCK_DATA 0x01000000 /* required for I2C_M_RECV_LEN */ #define I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK 0x04000000 /* I2C-like block xfer */ #define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */ #define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000 /* SMBus 2.0 or later */ #define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \ I2C_FUNC_SMBUS_WRITE_BYTE) #define I2C_FUNC_SMBUS_BYTE_DATA (I2C_FUNC_SMBUS_READ_BYTE_DATA | \ I2C_FUNC_SMBUS_WRITE_BYTE_DATA) #define I2C_FUNC_SMBUS_WORD_DATA (I2C_FUNC_SMBUS_READ_WORD_DATA | \ I2C_FUNC_SMBUS_WRITE_WORD_DATA) #define I2C_FUNC_SMBUS_BLOCK_DATA (I2C_FUNC_SMBUS_READ_BLOCK_DATA | \ I2C_FUNC_SMBUS_WRITE_BLOCK_DATA) #define I2C_FUNC_SMBUS_I2C_BLOCK (I2C_FUNC_SMBUS_READ_I2C_BLOCK | \ I2C_FUNC_SMBUS_WRITE_I2C_BLOCK) #define I2C_FUNC_SMBUS_EMUL (I2C_FUNC_SMBUS_QUICK | \ I2C_FUNC_SMBUS_BYTE | \ I2C_FUNC_SMBUS_BYTE_DATA | \ I2C_FUNC_SMBUS_WORD_DATA | \ I2C_FUNC_SMBUS_PROC_CALL | \ I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \ I2C_FUNC_SMBUS_I2C_BLOCK | \ I2C_FUNC_SMBUS_PEC) /* if I2C_M_RECV_LEN is also supported */ #define I2C_FUNC_SMBUS_EMUL_ALL (I2C_FUNC_SMBUS_EMUL | \ I2C_FUNC_SMBUS_READ_BLOCK_DATA | \ I2C_FUNC_SMBUS_BLOCK_PROC_CALL) /* * Data for SMBus Messages */ #define I2C_SMBUS_BLOCK_MAX 32 /* As specified in SMBus standard */ union i2c_smbus_data { __u8 byte; __u16 word; __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */ /* and one more for user-space compatibility */ }; /* i2c_smbus_xfer read or write markers */ #define I2C_SMBUS_READ 1 #define I2C_SMBUS_WRITE 0 /* SMBus transaction types (size parameter in the above functions) Note: these no longer correspond to the (arbitrary) PIIX4 internal codes! */ #define I2C_SMBUS_QUICK 0 #define I2C_SMBUS_BYTE 1 #define I2C_SMBUS_BYTE_DATA 2 #define I2C_SMBUS_WORD_DATA 3 #define I2C_SMBUS_PROC_CALL 4 #define I2C_SMBUS_BLOCK_DATA 5 #define I2C_SMBUS_I2C_BLOCK_BROKEN 6 #define I2C_SMBUS_BLOCK_PROC_CALL 7 /* SMBus 2.0 */ #define I2C_SMBUS_I2C_BLOCK_DATA 8 #endif /* _LINUX_I2C_H */