src/include/device/i2c.h

   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_ */