120 lines
4.2 KiB
C
120 lines
4.2 KiB
C
/****************************************************************************
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* drivers/i2c/i2c_writeread.c
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*
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* Copyright (C) 2016 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <assert.h>
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#include <nuttx/i2c/i2c_master.h>
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#if defined(CONFIG_I2C_TRANSFER)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: i2c_writeread
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*
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* Description:
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* Send a block of data on I2C using the previously, followed by restarted
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* read access. This provides a convenient wrapper to the transfer function.
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*
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* Input Parameters:
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* dev - Device-specific state data
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* config - Described the I2C configuration
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* wbuffer - A pointer to the read-only buffer of data to be written to device
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* wbuflen - The number of bytes to send from the buffer
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* rbuffer - A pointer to a buffer of data to receive the data from the device
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* rbuflen - The requested number of bytes to be read
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*
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* Returned Value:
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* 0: success, <0: A negated errno
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*
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****************************************************************************/
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int i2c_writeread(FAR struct i2c_master_s *dev,
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FAR const struct i2c_config_s *config,
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FAR const uint8_t *wbuffer, int wbuflen,
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FAR uint8_t *rbuffer, int rbuflen)
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{
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struct i2c_msg_s msg[2];
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unsigned int flags;
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/* 7- or 10-bit address? */
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DEBUGASSERT(config->addrlen == 10 || config->addrlen == 7);
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flags = (config->addrlen == 10) ? I2C_M_TEN : 0;
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/* Format two messages: The first is a write */
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msg[0].addr = config->address;
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msg[0].flags = flags;
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msg[0].buffer = (FAR uint8_t *)wbuffer; /* Override const */
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msg[0].length = wbuflen;
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/* The second is either a read (rbuflen > 0) or a write (rbuflen < 0) with
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* no restart.
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*/
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if (rbuflen > 0)
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{
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msg[1].flags = (flags | I2C_M_READ);
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}
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else
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{
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msg[1].flags = (flags | I2C_M_NORESTART);
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rbuflen = -rbuflen;
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}
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msg[1].addr = config->address;
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msg[1].buffer = rbuffer;
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msg[1].length = rbuflen;
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/* Then perform the transfer
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*
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* REVISIT: The following two operations must become atomic in order to
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* assure thread safety.
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*/
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I2C_SETFREQUENCY(dev, config->frequency);
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return I2C_TRANSFER(dev, msg, 2);
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}
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#endif /* CONFIG_I2C_TRANSFER */ |