17389 #+ˆl–Ãa¾”êh¥8 \¸È®JbÑ¿Ë ƒqà½ÈÀÍ¢+/* ------------------------------------------------------------------------- */ /* */ /* i2c.h - definitions for the i2c-bus interface */ /* */ /* ------------------------------------------------------------------------- */ /* Copyright (C) 1995-2000 Simon G. Vogl This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ /* ------------------------------------------------------------------------- */ /* With some changes from Kyösti Mälkki and Frodo Looijaard */ #ifndef _LINUX_I2C_H #define _LINUX_I2C_H #include /** * struct i2c_msg - an I2C transaction segment beginning with START * @addr: Slave address, either seven or ten bits. When this is a ten * bit address, I2C_M_TEN must be set in @flags and the adapter * must support I2C_FUNC_10BIT_ADDR. * @flags: I2C_M_RD is handled by all adapters. No other flags may be * provided unless the adapter exported the relevant I2C_FUNC_* * flags through i2c_check_functionality(). * @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 * 32 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 (one or more of IGNORE_NAK, NO_RD_ACK, NOSTART, and REV_DIR_ADDR). */ struct i2c_msg { __u16 addr; /* slave address */ __u16 flags; #define I2C_M_TEN 0x0010 /* this is a ten bit chip address */ #define I2C_M_RD 0x0001 /* read data, from slave to master */ #define I2C_M_STOP 0x8000 /* if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_NOSTART 0x4000 /* if I2C_FUNC_NOSTART */ #define I2C_M_REV_DIR_ADDR 0x2000 /* if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_IGNORE_NAK 0x1000 /* if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_NO_RD_ACK 0x0800 /* if I2C_FUNC_PROTOCOL_MANGLING */ #define I2C_M_RECV_LEN 0x0400 /* length will be first received byte */ __u16 len; /* msg length