1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 3 #ifndef _DEVICE_I2C_H_ 4 #define _DEVICE_I2C_H_ 5 6 #include <stdint.h> 7 8 /** 9 * struct i2c_msg - an I2C transaction segment beginning with START 10 * @addr: Slave address, either seven or ten bits. When this is a ten 11 * bit address, I2C_M_TEN must be set in @flags. 12 * @flags: I2C_M_RD is handled by all adapters. 13 * @len: Number of data bytes in @buf being read from or written to the 14 * I2C slave address. For read transactions where I2C_M_RECV_LEN 15 * is set, the caller guarantees that this buffer can hold up to 16 * 32 bytes in addition to the initial length byte sent by the 17 * slave (plus, if used, the SMBus PEC). 18 * @buf: The buffer into which data is read, or from which it's written. 19 * 20 * An i2c_msg is the low level representation of one segment of an I2C 21 * transaction. It is visible to drivers in the @i2c_transfer() procedure. 22 * 23 * All I2C adapters implement the standard rules for I2C transactions. Each 24 * transaction begins with a START. That is followed by the slave address, 25 * and a bit encoding read versus write. Then follow all the data bytes, 26 * possibly including a byte with SMBus PEC. The transfer terminates with 27 * a NAK, or when all those bytes have been transferred and ACKed. If this 28 * is the last message in a group, it is followed by a STOP. Otherwise it 29 * is followed by the next @i2c_msg transaction segment, beginning with a 30 * (repeated) START. 31 */ 32 struct i2c_msg { 33 uint16_t flags; 34 #define I2C_M_RD 0x0001 /* read data, from slave to master */ 35 #define I2C_M_TEN 0x0010 /* this is a ten bit chip address */ 36 #define I2C_M_RECV_LEN 0x0400 /* length will be first received byte */ 37 #define I2C_M_NOSTART 0x4000 /* don't send a repeated START */ 38 uint16_t slave; /* slave address */ 39 uint16_t len; /* msg length */ 40 uint8_t *buf; /* pointer to msg data */ 41 }; 42 43 enum i2c_speed { 44 I2C_SPEED_STANDARD = 100000, 45 I2C_SPEED_FAST = 400000, 46 I2C_SPEED_FAST_PLUS = 1000000, 47 I2C_SPEED_HIGH = 3400000, 48 I2C_SPEED_FAST_ULTRA = 5000000, 49 }; 50 51 enum i2c_address_mode { 52 I2C_MODE_7_BIT, 53 I2C_MODE_10_BIT 54 }; 55 56 #endif /* _DEVICE_I2C_H_ */ 57