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- /****************************************************************************
- * drivers/i2c/i2c_writeread.c
- *
- * Copyright (C) 2016 Gregory Nutt. All rights reserved.
- * Author: Gregory Nutt <gnutt@nuttx.org>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <assert.h>
- #include <nuttx/i2c/i2c_master.h>
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: i2c_writeread
- *
- * Description:
- * Send a block of data on I2C followed by restarted read access. This
- * provides a convenient wrapper to the transfer function.
- *
- * Input Parameters:
- * dev - Device-specific state data
- * config - Described the I2C configuration
- * wbuffer - A pointer to the read-only buffer of data to be written to device
- * wbuflen - The number of bytes to send from the buffer
- * rbuffer - A pointer to a buffer of data to receive the data from the device
- * rbuflen - The requested number of bytes to be read
- *
- * Returned Value:
- * 0: success, <0: A negated errno
- *
- ****************************************************************************/
- int i2c_writeread(FAR struct i2c_master_s *dev,
- FAR const struct i2c_config_s *config,
- FAR const uint8_t *wbuffer, int wbuflen,
- FAR uint8_t *rbuffer, int rbuflen)
- {
- struct i2c_msg_s msg[2];
- unsigned int flags;
- int ret;
- /* 7- or 10-bit address? */
- DEBUGASSERT(config->addrlen == 10 || config->addrlen == 7);
- flags = (config->addrlen == 10) ? I2C_M_TEN : 0;
- /* Format two messages: The first is a write */
- msg[0].frequency = config->frequency,
- msg[0].addr = config->address;
- msg[0].flags = flags;
- msg[0].buffer = (FAR uint8_t *)wbuffer; /* Override const */
- msg[0].length = wbuflen;
- /* The second is either a read (rbuflen > 0) or a write (rbuflen < 0) with
- * no restart.
- */
- if (rbuflen > 0)
- {
- msg[1].flags = (flags | I2C_M_READ);
- }
- else
- {
- msg[1].flags = (flags | I2C_M_NORESTART);
- rbuflen = -rbuflen;
- }
- msg[1].frequency = config->frequency,
- msg[1].addr = config->address;
- msg[1].buffer = rbuffer;
- msg[1].length = rbuflen;
- /* Then perform the transfer. */
- ret = I2C_TRANSFER(dev, msg, 2);
- return (ret >= 0) ? OK : ret;
- }
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