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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2014 Google, Inc.
*
* 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; version 2 of the License.
*
* 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.
*/
#ifndef _DEVICE_I2C_H_
#define _DEVICE_I2C_H_
#include <stdint.h>
#include <stdlib.h>
/**
* 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.
* @flags: I2C_M_RD is handled by all adapters.
* @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).
* @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.
*
* 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.
*/
struct i2c_msg {
uint16_t flags;
#define I2C_M_RD 0x0001 /* read data, from slave to master */
#define I2C_M_TEN 0x0010 /* this is a ten bit chip address */
#define I2C_M_RECV_LEN 0x0400 /* length will be first received byte */
#define I2C_M_NOSTART 0x4000 /* don't send a repeated START */
uint16_t slave; /* slave address */
uint16_t len; /* msg length */
uint8_t *buf; /* pointer to msg data */
};
enum i2c_speed {
I2C_SPEED_STANDARD = 100000,
I2C_SPEED_FAST = 400000,
I2C_SPEED_FAST_PLUS = 1000000,
I2C_SPEED_HIGH = 3400000,
I2C_SPEED_FAST_ULTRA = 5000000,
};
enum i2c_address_mode {
I2C_MODE_7_BIT,
I2C_MODE_10_BIT
};
int platform_i2c_transfer(unsigned int bus, struct i2c_msg *segments,
int count);
#define SOFTWARE_I2C_MAX_BUS 10 /* increase as necessary */
struct software_i2c_ops {
void (*set_sda)(unsigned int bus, int high);
void (*set_scl)(unsigned int bus, int high);
int (*get_sda)(unsigned int bus);
int (*get_scl)(unsigned int bus);
};
extern struct software_i2c_ops *software_i2c[];
int software_i2c_transfer(unsigned int bus, struct i2c_msg *segments,
int count);
void software_i2c_wedge_ack(unsigned int bus, u8 slave);
void software_i2c_wedge_read(unsigned int bus, u8 slave, u8 reg, int bit_count);
void software_i2c_wedge_write(unsigned int bus, u8 slave, u8 reg,
int bit_count);
int i2c_read_field(unsigned int bus, uint8_t slave, uint8_t reg, uint8_t *data,
uint8_t mask, uint8_t shift);
int i2c_write_field(unsigned int bus, uint8_t slave, uint8_t reg, uint8_t data,
uint8_t mask, uint8_t shift);
/*
* software_i2c is supposed to be a debug feature. It's usually not compiled in,
* but when it is it can be dynamically enabled at runtime for certain busses.
* Need this ugly stub to arbitrate since I2C device drivers hardcode
* 'i2c_transfer()' as their entry point.
*/
static inline int i2c_transfer(unsigned int bus, struct i2c_msg *segments,
int count)
{
if (CONFIG_SOFTWARE_I2C)
if (bus < SOFTWARE_I2C_MAX_BUS && software_i2c[bus])
return software_i2c_transfer(bus, segments, count);
return platform_i2c_transfer(bus, segments, count);
}
/*
* Read a raw chunk of data in one segment and one frame.
*
* [start][slave addr][r][data][stop]
*/
static inline int i2c_read_raw(unsigned int bus, uint8_t slave, uint8_t *data,
int len)
{
struct i2c_msg seg = {
.flags = I2C_M_RD, .slave = slave, .buf = data, .len = len
};
return i2c_transfer(bus, &seg, 1);
}
/*
* Write a raw chunk of data in one segment and one frame.
*
* [start][slave addr][w][data][stop]
*/
static inline int i2c_write_raw(unsigned int bus, uint8_t slave, uint8_t *data,
int len)
{
struct i2c_msg seg = {
.flags = 0, .slave = slave, .buf = data, .len = len
};
return i2c_transfer(bus, &seg, 1);
}
/**
* Read multi-bytes with two segments in one frame
*
* [start][slave addr][w][register addr][start][slave addr][r][data...][stop]
*/
static inline int i2c_read_bytes(unsigned int bus, uint8_t slave, uint8_t reg,
uint8_t *data, int len)
{
struct i2c_msg seg[2];
seg[0].flags = 0;
seg[0].slave = slave;
seg[0].buf = ®
seg[0].len = 1;
seg[1].flags = I2C_M_RD;
seg[1].slave = slave;
seg[1].buf = data;
seg[1].len = len;
return i2c_transfer(bus, seg, ARRAY_SIZE(seg));
}
/**
* Read a byte with two segments in one frame
*
* [start][slave addr][w][register addr][start][slave addr][r][data][stop]
*/
static inline int i2c_readb(unsigned int bus, uint8_t slave, uint8_t reg,
uint8_t *data)
{
struct i2c_msg seg[2];
seg[0].flags = 0;
seg[0].slave = slave;
seg[0].buf = ®
seg[0].len = 1;
seg[1].flags = I2C_M_RD;
seg[1].slave = slave;
seg[1].buf = data;
seg[1].len = 1;
return i2c_transfer(bus, seg, ARRAY_SIZE(seg));
}
/**
* Write a byte with one segment in one frame.
*
* [start][slave addr][w][register addr][data][stop]
*/
static inline int i2c_writeb(unsigned int bus, uint8_t slave, uint8_t reg,
uint8_t data)
{
struct i2c_msg seg;
uint8_t buf[] = {reg, data};
seg.flags = 0;
seg.slave = slave;
seg.buf = buf;
seg.len = ARRAY_SIZE(buf);
return i2c_transfer(bus, &seg, 1);
}
/* I2C bus operation for ramstage drivers */
struct device;
struct i2c_bus_operations {
/*
* This is an SOC specific method that can be provided to translate the
* 'struct device' for an I2C controller into a unique I2C bus number.
* Returns -1 if the bus number for this device cannot be determined.
*/
int (*dev_to_bus)(struct device *dev);
};
/* Return I2C bus number for provided device, -1 if not found */
int i2c_dev_find_bus(struct device *dev);
/* Variants of I2C helper functions that take a device instead of bus number */
int i2c_dev_transfer(struct device *dev, struct i2c_msg *segments, int count);
int i2c_dev_readb(struct device *dev, uint8_t reg, uint8_t *data);
int i2c_dev_writeb(struct device *dev, uint8_t reg, uint8_t data);
int i2c_dev_read_bytes(struct device *dev, uint8_t reg, uint8_t *data, int len);
int i2c_dev_read_raw(struct device *dev, uint8_t *data, int len);
int i2c_dev_write_raw(struct device *dev, uint8_t *data, int len);
#endif /* _DEVICE_I2C_H_ */
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