Boot Linux faster!

Check our new training course

Boot Linux faster!

Check our new training course
and Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

/* i2c.h - public I2C driver API */

/*
 * Copyright (c) 2015 Intel Corporation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#ifndef __DRIVERS_I2C_H
#define __DRIVERS_I2C_H

/**
 * @brief I2C Interface
 * @defgroup i2c_interface I2C Interface
 * @ingroup io_interfaces
 * @{
 */

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>
#include <device.h>

/* I2C speeds */
#define I2C_SPEED_STANDARD		(0x1)
#define I2C_SPEED_FAST			(0x2)
#define I2C_SPEED_FAST_PLUS		(0x3)
#define I2C_SPEED_HIGH			(0x4)
#define I2C_SPEED_ULTRA			(0x5)

/* I2C dev_config bitfields */
#define I2C_ADDR_10_BITS		(1 << 0)
#define I2C_SPEED_MASK			(0x7 << 1)	/* 3 bits */
#define I2C_MODE_MASTER			(1 << 4)
#define I2C_MODE_SLAVE_READ		(1 << 5)

/* I2C Message Flags */
#define I2C_MSG_WRITE			(0 << 0)
#define I2C_MSG_READ			(1 << 0)
#define I2C_MSG_RW_MASK			(1 << 0)

/* STOP I2C transaction (drive should take care of this) */
#define I2C_MSG_STOP			(1 << 1)
/* RESTART I2C transaction */
#define I2C_MSG_RESTART			(1 << 2)

struct i2c_msg {
	/* Data buffer in bytes */
	uint8_t		*buf;

	/* Length of buffer in bytes */
	uint32_t	len;

	/* Flags for this message */
	uint8_t		flags;
};

union dev_config {
	uint32_t raw;
	struct {
		uint32_t        use_10_bit_addr : 1;
		uint32_t        speed : 3;
		uint32_t        is_master_device : 1;
		uint32_t        is_slave_read : 1;
		uint32_t        reserved : 26;
	} bits;
};

enum i2c_cb_type {
	I2C_CB_WRITE            = 1,
	I2C_CB_READ             = 2,
	I2C_CB_ERROR		= 3,
};

typedef int (*i2c_api_configure_t)(struct device *dev,
				   uint32_t dev_config);
typedef int (*i2c_api_full_io_t)(struct device *dev,
				 struct i2c_msg *msgs,
				 uint8_t num_msgs,
				 uint16_t addr);
typedef int (*i2c_api_suspend_t)(struct device *dev);
typedef int (*i2c_api_resume_t)(struct device *dev);

struct i2c_driver_api {
	i2c_api_configure_t configure;
	i2c_api_full_io_t transfer;
	i2c_api_suspend_t suspend;
	i2c_api_resume_t resume;
};

/**
 * @brief Configure a host controllers operation
 *
 * @param dev Pointer to the device structure for the driver instance
 * @param dev_config Bit-packed 32-bit value to the device runtime configuration
 *                   for the I2C controller.
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int i2c_configure(struct device *dev, uint32_t dev_config)
{
	struct i2c_driver_api *api;

	api = (struct i2c_driver_api *)dev->driver_api;
	return api->configure(dev, dev_config);
}

/**
 * @brief Write a set amount of data to an I2C device
 *
 * The function is synchronous.
 *
 * @param dev Pointer to the device structure for the driver instance
 * @param buf Memory pool that data should be transferred from
 * @param len Size of the memory pool available for reading from
 * @param addr Address of the I2C device to write to
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int i2c_write(struct device *dev, uint8_t *buf,
			    uint32_t len, uint16_t addr)
{
	struct i2c_driver_api *api;
	struct i2c_msg msg;

	msg.buf = buf;
	msg.len = len;
	msg.flags = I2C_MSG_WRITE | I2C_MSG_STOP;

	api = (struct i2c_driver_api *)dev->driver_api;
	return api->transfer(dev, &msg, 1, addr);
}

/**
 * @brief Read a set amount of data from an I2C device
 *
 * The function is synchronous.
 *
 * @param dev Pointer to the device structure for the driver instance
 * @param buf Memory pool that data should be transferred to
 * @param len Size of the memory pool available for writing to
 * @param addr Address of the I2C device to read from
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int i2c_read(struct device *dev, uint8_t *buf,
			   uint32_t len, uint16_t addr)
{
	struct i2c_driver_api *api;
	struct i2c_msg msg;

	msg.buf = buf;
	msg.len = len;
	msg.flags = I2C_MSG_READ | I2C_MSG_STOP;

	api = (struct i2c_driver_api *)dev->driver_api;
	return api->transfer(dev, &msg, 1, addr);
}

/**
 * @brief Performs data transfer to another I2C device
 *
 * This provides a generic interface to perform data transfer
 * to another I2C device. If a simple read or write is needed,
 * use i2c_read()/i2c_write() instead. The function is synchronous.
 *
 * @param dev Pointer to the device structure for the driver instance
 * @param msgs Array of messages
 * @param num_msgs Number of messages
 * @param addr Address of the I2C target device
 *
 * @return DEV_OK if successful, another DEV_* code otherwise.
 */
static inline int i2c_transfer(struct device *dev,
			       struct i2c_msg *msgs, uint8_t num_msgs,
			       uint16_t addr)
{
	struct i2c_driver_api *api;

	api = (struct i2c_driver_api *)dev->driver_api;
	return api->transfer(dev, msgs, num_msgs, addr);
}

/**
 * @brief Suspend an I2C driver
 * @param dev Pointer to the device structure for the driver instance
 *
 * @return DEV_OK
 */
static inline int i2c_suspend(struct device *dev)
{
	struct i2c_driver_api *api;

	api = (struct i2c_driver_api *)dev->driver_api;
	return api->suspend(dev);
}

/**
 * @brief Resume an I2C driver
 * @param dev Pointer to the device structure for the driver instance
 *
 * @return DEV_OK
 */
static inline int i2c_resume(struct device *dev)
{
	struct i2c_driver_api *api;

	api = (struct i2c_driver_api *)dev->driver_api;
	return api->resume(dev);
}

#ifdef __cplusplus
}
#endif

/**
 * @}
 */


#endif /* __DRIVERS_I2C_H */