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/*
* This file is part of the flashrom project.
*
* Copyright (C) 2020 The Chromium OS Authors
*
* 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.
*/
#ifndef I2C_HELPER_H
#define I2C_HELPER_H
#include <inttypes.h>
/**
* An convinent structure that contains the buffer size and the buffer
* pointer. Used to wrap buffer details while doing the I2C data
* transfer on both input and output. It is the client's responsibility
* to use i2c_buffer_t_fill to initialize this struct instead of
* trying to construct it directly.
*/
typedef struct {
void *buf;
uint16_t len;
} i2c_buffer_t;
/**
* i2c_buffer_t_fill - fills in the i2c_buffer_t
*
* @i2c_buf: pointer to the be constructed.
* @buf: buffer contains data to be included in i2c_buffer_t.
* @len: length of buffer to be included in i2c_buffer_t.
*
* This function takes in a pointer to an initialized i2c_buffer_t
* object with related information, and fill in the i2c_buffer_t with
* some validation applied. The function does allow initialization with
* NULL buffer but will make sure len == 0 in such case.
*
* returns 0 on success, <0 to indicate failure
*/
static inline int i2c_buffer_t_fill(i2c_buffer_t *i2c_buf, void *buf, uint16_t len)
{
if (!i2c_buf || (!buf && len))
return -1;
i2c_buf->buf = buf;
i2c_buf->len = len;
return 0;
}
/**
* i2c_open - opens the target I2C device and set the I2C slave address
*
* @bus: I2C bus number of the target device.
* @addr: I2C slave address.
* @force: whether to force set the I2C slave address.
*
* This function returns a file descriptor for the target device. It is
* the client's responsibility to pass the return value to i2c_close to
* clean up.
*
* returns fd of target device on success, <0 to indicate failure
*/
int i2c_open(int bus, uint16_t addr, int force);
/**
* i2c_open_path: open an I2C device by device path
*
* This function behaves the same as i2c_open, but takes a filesystem
* path (assumed to be an I2C device file) instead of a bus number.
*/
int i2c_open_path(const char *path, uint16_t addr, int force);
/**
* i2c_close - closes the file descriptor returned by i2c_open
*
* @fd: file descriptor to be closed.
*
* It is the client's responsibility to set fd = -1 when it is
* done with it.
*
* returns 0 on success, <0 to indicate failure
*/
int i2c_close(int fd);
/**
* i2c_read - reads data from the I2C device
*
* @fd: file descriptor of the target device.
* @addr: I2C slave address of the target device.
* @buf_read: data struct includes reading buffer and size.
*
* This function does accept empty read and do nothing on such case.
*
* returns read length on success, <0 to indicate failure
*/
int i2c_read(int fd, uint16_t addr, i2c_buffer_t *buf_read);
/**
* i2c_write - writes command/data into the I2C device
*
* @fd: file descriptor of the target device.
* @addr: I2C slave address of the target device.
* @buf_write: data struct includes writting buffer and size.
*
* This function does accept empty write and do nothing on such case.
*
* returns wrote length on success, <0 to indicate failure.
*/
int i2c_write(int fd, uint16_t addr, const i2c_buffer_t *buf_write);
#endif /* !I2C_HELPER_H */